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commit 954157679ec34661c2e87e7eb796104a797c32db upstream.
damon_set_regions() assumes the input ranges are sorted by the address and
don't overlap each other. Hence the assumption was initially to be
explicitly validated. But commit 97d482f4592f ("mm/damon/sysfs: reuse
damon_set_regions() for regions setting") has mistakenly removed the
validation.
This can make DAMON behave in unexpected ways. At the best, the
monitoring results snapshot will just look weird since there will be
overlapping regions. DAMOS will also work weirdly, applying the same
action multiple times for overlapping regions, and make DAMOS quota weird.
More seriously, depending on the setup and regions updates sequence,
negative size regions can be made. It will trigger WARN_ONCE() if the
kernel is built with CONFIG_DAMON_DEBUG_SANITY=y. Depending on the
monitoring results, the negative size region can further trigger division
by zero in damon_merge_two_regions().
Note that some of the consequences including the WARN_ONCE() and the
divide by zero depend on commits that were introduced after the root cause
commit 97d482f4592f ("mm/damon/sysfs: reuse damon_set_regions() for
regions setting").
Fix the problems by checking the assumption and returning an error if
the input ranges don't meet the assumption.
The issue was discovered [1] by Sashiko.
Link: https://lore.kernel.org/20260703165610.92894-1-sj@kernel.org
Link: https://lore.kernel.org/20260630041806.151124-1-sj@kernel.org [1]
Fixes: 97d482f4592f ("mm/damon/sysfs: reuse damon_set_regions() for regions setting")
Signed-off-by: SJ Park <sj@kernel.org>
Cc: <stable@vger.kernel.org> # 5.19.x
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: SJ Park <sj@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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commit 1292c0ecb1caefb8ca064a3639d5673991e8810c upstream.
DAMON core logic assumes zero length regions don't exist. However, a few
DAMON API callers including DAMON_SYSFS, DAMON_RECLAIM and DAMON_LRU_SORT
allow users to set empty monitoring target regions. This could result in
WARN_ONCE() on CONFIG_DAMON_DEBUG_SANITY enabled kernel, and
divide-by-zero from damon_merge_two_regions().
For example, the WANR_ONCE() can be triggered like below.
# grep DAMON_DEBUG_SANITY /boot/config-$(uname -r)
# CONFIG_DAMON_DEBUG_SANITY=y
# damo start
# cd /sys/kernel/mm/damon/admin/kdamonds/0
# echo 0 > contexts/0/targets/0/regions/0/start
# echo 0 > contexts/0/targets/0/regions/0/end
# echo commit > state
# dmesg
[....]
[ 73.705780] ------------[ cut here ]------------
[ 73.707552] start 0 >= end 0
[ 73.708452] WARNING: mm/damon/core.c:359 at damon_new_region+0x6e/0x80, CPU#1: kdamond.0/758
[...]
All DAMON API callers eventually use damon_set_regions() to setup the
regions. Add the validation logic in the function.
Link: https://lore.kernel.org/20260630035221.146458-1-sj@kernel.org
Fixes: 43b0536cb471 ("mm/damon: introduce DAMON-based Reclamation (DAMON_RECLAIM)")
Signed-off-by: SJ Park <sj@kernel.org>
Cc: Yang yingliang <yangyingliang@huawei.com>
Cc: <stable@vger.kernel.org> # 5.16.x
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: SJ Park <sj@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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[ Upstream commit 94405c6136839f7c462249c8b4b957bcb9527a9d ]
The memmap_init_zone_device() function only initializes the migratetype of
the first pageblock of a compound page. If the compound page size exceeds
pageblock_nr_pages (e.g., 1GB hugepages with 2MB pageblocks), subsequent
pageblocks in the compound page remain uninitialized.
Move the migratetype initialization out of __init_zone_device_page() and
into a separate pageblock_migratetype_init_range() function. This
iterates over the entire PFN range of the memory, ensuring that all
pageblocks are correctly initialized.
Also remove the stale confusing comment about MEMINIT_HOTPLUG above the
migratetype setting since it is an obsolete relic from commit 966cf44f637e
("mm: defer ZONE_DEVICE page initialization to the point where we init
pgmap") and no longer makes sense here.
Link: https://lore.kernel.org/20260428081855.1249045-6-songmuchun@bytedance.com
Fixes: c4386bd8ee3a ("mm/memremap: add ZONE_DEVICE support for compound pages")
Signed-off-by: Muchun Song <songmuchun@bytedance.com>
Reviewed-by: Mike Rapoport (Microsoft) <rppt@kernel.org>
Reviewed-by: Oscar Salvador <osalvador@suse.de>
Acked-by: David Hildenbrand (Arm) <david@kernel.org>
Acked-by: Liam R. Howlett <liam@infradead.org>
Cc: "Aneesh Kumar K.V" <aneesh.kumar@linux.ibm.com>
Cc: Joao Martins <joao.m.martins@oracle.com>
Cc: Lorenzo Stoakes <ljs@kernel.org>
Cc: Madhavan Srinivasan <maddy@linux.ibm.com>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Nicholas Piggin <npiggin@gmail.com>
Cc: Suren Baghdasaryan <surenb@google.com>
Cc: Vlastimil Babka <vbabka@kernel.org>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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[ Upstream commit cd3f8467afd470ccab0de2fbc7c76664af4a0bac ]
mm_access() can return NULL if the mm is not found, but this is handled
the same as an error in all callers, with some translating this into an
-ESRCH error.
Only proc_mem_open() returns NULL if no mm is found, however in this case
it is clearer and makes more sense to explicitly handle the error.
Additionally we take the opportunity to refactor the function to eliminate
unnecessary nesting.
Simplify things by simply returning -ESRCH if no mm is found - this both
eliminates confusing use of the IS_ERR_OR_NULL() macro, and simplifies
callers which would return -ESRCH by returning this error directly.
[lorenzo.stoakes@oracle.com: prefer neater pointer error comparison]
Link: https://lkml.kernel.org/r/2fae1834-749a-45e1-8594-5e5979cf7103@lucifer.local
Link: https://lkml.kernel.org/r/20240924201023.193135-1-lorenzo.stoakes@oracle.com
Signed-off-by: Lorenzo Stoakes <lorenzo.stoakes@oracle.com>
Suggested-by: Arnd Bergmann <arnd@arndb.de>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
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[ Upstream commit e187bc02f8fa4226d62814592cf064ee4557c470 ]
Ever since idmapped mounts were introduced, inode ownership checks (for
side-channel protection) in mincore() and madvise(MADV_PAGEOUT) were done
against the nop_mnt_idmap, which completely ignores the file's mount's
idmap. This results in odd edgecases like:
1) mount/bind-mount with an idmap userA:userB:1
2) userB runs an owner_or_capable() check on file that is owned by userA
on-disk/in-memory, but owned by userB after idmap translation
3) owner_or_capable() mysteriously fails as the correct idmap wasn't supplied
In the case of mincore/madvise MADV_PAGEOUT, this is usually benign,
because file_permission(file, MAY_WRITE) will probably succeed, as it uses
the proper idmap internally, but it does not need to be the case on e.g a
0444 file where even the owner itself doesn't have permissions to write to
it.
Since this is clearly not trivial to get right, introduce a
file_owner_or_capable() that can carry the correct semantics, and switch
the various users in mm to it.
The issue was found by manual code inspection & an off-list discussion
with Jan Kara.
Link: https://lore.kernel.org/20260625153853.913949-1-pfalcato@suse.de
Fixes: 9caccd41541a ("fs: introduce MOUNT_ATTR_IDMAP")
Signed-off-by: Pedro Falcato <pfalcato@suse.de>
Reviewed-by: Jan Kara <jack@suse.cz>
Reviewed-by: Christian Brauner (Amutable) <brauner@kernel.org>
Acked-by: David Hildenbrand (Arm) <david@kernel.org>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: Jann Horn <jannh@google.com>
Cc: Liam R. Howlett <liam@infradead.org>
Cc: Matthew Wilcox (Oracle) <willy@infradead.org>
Cc: Vlastimil Babka <vbabka@kernel.org>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
[ dropped const from file_owner_or_capable()'s parameter since 6.6's file_mnt_idmap() takes a non-const struct file * ]
Signed-off-by: Sasha Levin <sashal@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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[ Upstream commit 648927ceb84021a25a0fbd5673740956f318d534 ]
When init (zeroing) on allocation is requested, for kmalloc() we
generally have to zero the full object size even if a smaller size is
requested, in order to provide krealloc()'s __GFP_ZERO guarantees.
But if we track the requested size, krealloc() uses that information to
do the right thing, so we can zero only the requested size. With red
zoning also enabled, any extra size became part of the red zone, so it
must not be zeroed and thus we must zero only the requested size.
However the current check is imprecise, and will trigger also when only
SLAB_RED_ZONE is enabled without SLAB_STORE_USER (which enables tracking
the requested size). This means enabling red zoning alone can compromise
krealloc()'s __GFP_ZERO contract.
Fix this by using slub_debug_orig_size() instead, which is the exact
check for whether the requested size is tracked. We don't need to care
if red zoning is also enabled or not. Also update and expand the
comment accordingly.
Fixes: 9ce67395f5a0 ("mm/slub: only zero requested size of buffer for kzalloc when debug enabled")
Cc: stable@vger.kernel.org
Link: https://patch.msgid.link/20260610-slab_alloc_flags-v2-1-7190909db118@kernel.org
Reviewed-by: Harry Yoo (Oracle) <harry@kernel.org>
Reviewed-by: Hao Li <hao.li@linux.dev>
Signed-off-by: Vlastimil Babka (SUSE) <vbabka@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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[ Upstream commit e1b849cfa6b61f1c866a908c9e8dd9b5aaab820b ]
There can be multiple inode switch works that are trying to switch
inodes to / from the same wb. This can happen in particular if some
cgroup exits which owns many (thousands) inodes and we need to switch
them all. In this case several inode_switch_wbs_work_fn() instances will
be just spinning on the same wb->list_lock while only one of them makes
forward progress. This wastes CPU cycles and quickly leads to softlockup
reports and unusable system.
Instead of running several inode_switch_wbs_work_fn() instances in
parallel switching to the same wb and contending on wb->list_lock, run
just one work item per wb and manage a queue of isw items switching to
this wb.
Acked-by: Tejun Heo <tj@kernel.org>
Signed-off-by: Jan Kara <jack@suse.cz>
Stable-dep-of: cba38ec4cbd3 ("writeback: fix race between cgroup_writeback_umount() and inode_switch_wbs()")
Signed-off-by: Sasha Levin <sashal@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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[ Upstream commit b902890c62d200b3509cb5e09cf1e0a66553c128 ]
Reading the debugfs "count" file of a memcg-aware shrinker can sleep
inside an RCU read-side critical section:
BUG: sleeping function called from invalid context at kernel/cgroup/rstat.c:421
RCU nest depth: 1, expected: 0
css_rstat_flush
mem_cgroup_flush_stats
zswap_shrinker_count
shrinker_debugfs_count_show
shrinker_debugfs_count_show() invokes the ->count_objects() callback under
rcu_read_lock(). The zswap callback flushes memcg stats via
css_rstat_flush(), which may sleep, so it must not run under RCU.
The RCU lock is not needed here. mem_cgroup_iter() takes RCU internally
and returns a memcg holding a css reference (dropped on the next iteration
or by mem_cgroup_iter_break()), so the memcg stays alive without it. The
shrinker is kept alive by the open debugfs file: shrinker_free() removes
the debugfs entries via debugfs_remove_recursive(), which waits for
in-flight readers to drain, before call_rcu(..., shrinker_free_rcu_cb).
The sibling "scan" handler already invokes the sleeping ->scan_objects()
callback with no RCU section.
Drop the rcu_read_lock()/rcu_read_unlock().
Link: https://lore.kernel.org/20260610232048.62930-1-shakeel.butt@linux.dev
Fixes: 5035ebc644ae ("mm: shrinkers: introduce debugfs interface for memory shrinkers")
Signed-off-by: Shakeel Butt <shakeel.butt@linux.dev>
Reported-by: Zenghui Yu <zenghui.yu@linux.dev>
Closes: https://lore.kernel.org/all/c052a064-cddb-494f-a0d8-f8a10b4b1c4d@linux.dev/
Suggested-by: Nhat Pham <nphamcs@gmail.com>
Reviewed-by: SeongJae Park <sj@kernel.org>
Reviewed-by: Qi Zheng <qi.zheng@linux.dev>
Tested-by: Zenghui Yu (Huawei) <zenghui.yu@linux.dev>
Reviewed-by: Nhat Pham <nphamcs@gmail.com>
Acked-by: Muchun Song <muchun.song@linux.dev>
Reviewed-by: Roman Gushchin <roman.gushchin@linux.dev>
Cc: Dave Chinner <david@fromorbit.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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[ Upstream commit 1dd49e58f966b1eecd935dc28458a8369ae94ad1 ]
debugfs_remove_recursive() will wait for debugfs_file_put() to return, so
the shrinker will not be freed when doing debugfs operations (such as
shrinker_debugfs_count_show() and shrinker_debugfs_scan_write()), so there
is no need to hold shrinker_rwsem during debugfs operations.
Link: https://lkml.kernel.org/r/20230911092517.64141-4-zhengqi.arch@bytedance.com
Signed-off-by: Qi Zheng <zhengqi.arch@bytedance.com>
Reviewed-by: Muchun Song <songmuchun@bytedance.com>
Cc: Christian Brauner <brauner@kernel.org>
Cc: Christian König <christian.koenig@amd.com>
Cc: Chuck Lever <cel@kernel.org>
Cc: Daniel Vetter <daniel@ffwll.ch>
Cc: Daniel Vetter <daniel.vetter@ffwll.ch>
Cc: Darrick J. Wong <djwong@kernel.org>
Cc: Dave Chinner <david@fromorbit.com>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Joel Fernandes <joel@joelfernandes.org>
Cc: Kirill Tkhai <tkhai@ya.ru>
Cc: Paul E. McKenney <paulmck@kernel.org>
Cc: Roman Gushchin <roman.gushchin@linux.dev>
Cc: Sergey Senozhatsky <senozhatsky@chromium.org>
Cc: Steven Price <steven.price@arm.com>
Cc: Theodore Ts'o <tytso@mit.edu>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Abhinav Kumar <quic_abhinavk@quicinc.com>
Cc: Alasdair Kergon <agk@redhat.com>
Cc: Alexander Viro <viro@zeniv.linux.org.uk>
Cc: Alyssa Rosenzweig <alyssa.rosenzweig@collabora.com>
Cc: Andreas Dilger <adilger.kernel@dilger.ca>
Cc: Andreas Gruenbacher <agruenba@redhat.com>
Cc: Anna Schumaker <anna@kernel.org>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Bob Peterson <rpeterso@redhat.com>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Carlos Llamas <cmllamas@google.com>
Cc: Chandan Babu R <chandan.babu@oracle.com>
Cc: Chao Yu <chao@kernel.org>
Cc: Chris Mason <clm@fb.com>
Cc: Coly Li <colyli@suse.de>
Cc: Dai Ngo <Dai.Ngo@oracle.com>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: David Airlie <airlied@gmail.com>
Cc: David Hildenbrand <david@redhat.com>
Cc: David Sterba <dsterba@suse.com>
Cc: Dmitry Baryshkov <dmitry.baryshkov@linaro.org>
Cc: Gao Xiang <hsiangkao@linux.alibaba.com>
Cc: Huang Rui <ray.huang@amd.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Jaegeuk Kim <jaegeuk@kernel.org>
Cc: Jani Nikula <jani.nikula@linux.intel.com>
Cc: Jan Kara <jack@suse.cz>
Cc: Jason Wang <jasowang@redhat.com>
Cc: Jeff Layton <jlayton@kernel.org>
Cc: Jeffle Xu <jefflexu@linux.alibaba.com>
Cc: Joonas Lahtinen <joonas.lahtinen@linux.intel.com>
Cc: Josef Bacik <josef@toxicpanda.com>
Cc: Juergen Gross <jgross@suse.com>
Cc: Kent Overstreet <kent.overstreet@gmail.com>
Cc: Marijn Suijten <marijn.suijten@somainline.org>
Cc: "Michael S. Tsirkin" <mst@redhat.com>
Cc: Mike Snitzer <snitzer@kernel.org>
Cc: Minchan Kim <minchan@kernel.org>
Cc: Muchun Song <muchun.song@linux.dev>
Cc: Nadav Amit <namit@vmware.com>
Cc: Neil Brown <neilb@suse.de>
Cc: Oleksandr Tyshchenko <oleksandr_tyshchenko@epam.com>
Cc: Olga Kornievskaia <kolga@netapp.com>
Cc: Richard Weinberger <richard@nod.at>
Cc: Rob Clark <robdclark@gmail.com>
Cc: Rob Herring <robh@kernel.org>
Cc: Rodrigo Vivi <rodrigo.vivi@intel.com>
Cc: Sean Paul <sean@poorly.run>
Cc: Song Liu <song@kernel.org>
Cc: Stefano Stabellini <sstabellini@kernel.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Tomeu Vizoso <tomeu.vizoso@collabora.com>
Cc: Tom Talpey <tom@talpey.com>
Cc: Trond Myklebust <trond.myklebust@hammerspace.com>
Cc: Tvrtko Ursulin <tvrtko.ursulin@linux.intel.com>
Cc: Xuan Zhuo <xuanzhuo@linux.alibaba.com>
Cc: Yue Hu <huyue2@coolpad.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Stable-dep-of: b902890c62d2 ("mm/shrinker: do not hold RCU lock in shrinker_debugfs_count_show()")
Signed-off-by: Sasha Levin <sashal@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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commit cd681403a87085562499d60325b7b45d3be11217 upstream.
If DAX memory is hotplugged into an unoccupied subsection of an early
section, section_activate() reuses the unoptimized boot memmap. However,
compound_nr_pages() still assumes that vmemmap optimization is in effect
and initializes only the reduced number of struct pages. As a result, the
remaining tail struct pages are left uninitialized, which can later lead
to unexpected behavior or crashes.
Fix this by treating early sections as unoptimized when calculating how
many struct pages to initialize.
Link: https://lore.kernel.org/20260428081855.1249045-7-songmuchun@bytedance.com
Fixes: 6fd3620b3428 ("mm/page_alloc: reuse tail struct pages for compound devmaps")
Signed-off-by: Muchun Song <songmuchun@bytedance.com>
Acked-by: David Hildenbrand (Arm) <david@kernel.org>
Acked-by: Mike Rapoport (Microsoft) <rppt@kernel.org>
Acked-by: Liam R. Howlett <liam@infradead.org>
Cc: "Aneesh Kumar K.V" <aneesh.kumar@linux.ibm.com>
Cc: Joao Martins <joao.m.martins@oracle.com>
Cc: Lorenzo Stoakes <ljs@kernel.org>
Cc: Madhavan Srinivasan <maddy@linux.ibm.com>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Nicholas Piggin <npiggin@gmail.com>
Cc: Oscar Salvador <osalvador@suse.de>
Cc: Suren Baghdasaryan <surenb@google.com>
Cc: Vlastimil Babka <vbabka@kernel.org>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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commit 05ea83ee88ca70f8932906d9f2617ff996f45b50 upstream.
damon_sysfs_scheme_add_dirs() setup the tried_regions directory after the
stats directory setup is completed. When the tried_regions directory
setup is failed, the setup function ensures the reference for the tried
regions directory is released. Hence the error path should put references
on setup succeeded directory objects, starting from the stats directory.
However, the error path is putting the tried_regions directory instead of
the stats directory.
As a direct result, the stats directory object is leaked. Worse yet, if
the tried_regions directory setup failed from the initial allocation, the
scheme->tried_regions field remains uninitialized. The following
kobject_put(&scheme->tried_regions->kobj) call in the error path will
dereference the uninitialized memory. The setup failures should not be
common. But once it happens, the consequence is quite bad.
Fix this issue by correctly putting the stats directory instead of the
tried_regions directory.
The issue was discovered [1] by Sashiko.
Link: https://lore.kernel.org/20260618005650.83868-3-sj@kernel.org
Link: https://lore.kernel.org/20260617005223.96813-1-sj@kernel.org [1]
Fixes: 5181b75f438d ("mm/damon/sysfs-schemes: implement schemes/tried_regions directory")
Signed-off-by: SeongJae Park <sj@kernel.org>
Cc: <stable@vger.kernel.org> # 6.2.x
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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commit d58fdbe37a829fd2e5803dd4e5a72992dd8c5368 upstream.
Patch series "mm/damon/sysfs-schemes: fix wrong directories put orders in
error paths".
Error paths of damon_sysfs_access_pattern_add_dirs() and
damon_sysfs_scheme_add_dirs() functions put references to directories in
wrong orders. As a result, uninitialized memory dereference and/or
memory leak can happen. Fix those.
This patch (of 2):
In access_pattern_add_dirs(), error handling path puts references starting
from setup failed directories. If the failure happpened from the initial
allication in the setup functions, uninitialized memory dereference
happen. The allocation failures will not commonly happen, but the
consequence is quite bad. Fix the wrong reference put orders.
The issue was discovered [1] by Sashiko.
Link: https://lore.kernel.org/20260618005650.83868-2-sj@kernel.org
Link: https://lore.kernel.org/20260617060005.86852-1-sj@kernel.org [1]
Fixes: 7e84b1f8212a ("mm/damon/sysfs: support DAMON-based Operation Schemes")
Signed-off-by: SeongJae Park <sj@kernel.org>
Cc: <stable@vger.kernel.org> # 5.18.x
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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commit 5a2d162e22bf33eb89d53e802d0fc1ec422e19b6 upstream.
DAMON region end address is exclusive one, but charge_addr_from is
assigned assuming the end address is inclusive. As a result, DAMOS action
to next up to min_region_sz memory can be skipped. This is quite
negligible user impact. But, the bug is a bug that can be very simply
fixed. Fix the wrong assignment to respect the exclusiveness of the
address.
The issue was discovered [1] by Sashiko.
Link: https://lore.kernel.org/20260428042942.118230-1-sj@kernel.org
Link: https://lore.kernel.org/20260428032324.115663-1-sj@kernel.org [1]
Fixes: 50585192bc2e ("mm/damon/schemes: skip already charged targets and regions")
Signed-off-by: SeongJae Park <sj@kernel.org>
Cc: <stable@vger.kernel.org> # 5.16.x
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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commit e30453c61e185e914fde83c650e268067b140218 upstream.
shrinker_debugfs_add() creates both "count" and "scan" debugfs files
unconditionally.
That assumes every shrinker implements both count_objects() and
scan_objects(), which is not guaranteed. For example, the xen-backend
shrinker sets count_objects() but leaves scan_objects() NULL, so writing
to its scan file calls through a NULL function pointer and panics the
kernel:
BUG: kernel NULL pointer dereference, address: 0000000000000000
RIP: 0010:0x0
Code: Unable to access opcode bytes at 0xffffffffffffffd6.
Call Trace:
<TASK>
shrinker_debugfs_scan_write+0x12e/0x270
full_proxy_write+0x5f/0x90
vfs_write+0xde/0x420
? filp_flush+0x75/0x90
? filp_close+0x1d/0x30
? do_dup2+0xb8/0x120
ksys_write+0x68/0xf0
? filp_flush+0x75/0x90
do_syscall_64+0xb3/0x5b0
entry_SYSCALL_64_after_hwframe+0x76/0x7e
The count path has the same issue in principle if a shrinker omits
count_objects().
To fix it, only create "count" and "scan" debugfs files when the
corresponding callbacks are present.
Link: https://lore.kernel.org/20260617090052.27325-1-qi.zheng@linux.dev
Fixes: bbf535fd6f06 ("mm: shrinkers: add scan interface for shrinker debugfs")
Signed-off-by: Qi Zheng <zhengqi.arch@bytedance.com>
Reviewed-by: Muchun Song <muchun.song@linux.dev>
Cc: Dave Chinner <david@fromorbit.com>
Cc: Qi Zheng <zhengqi.arch@bytedance.com>
Cc: Roman Gushchin <roman.gushchin@linux.dev>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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commit 35d4a3cf70a855b50e53189ac2f8463e20a02046 upstream.
Fix three issues in damon_hot_score() that comes from wrong handling of
extreme (zero or too high) monitoring intervals user setup.
When the user sets sampling interval zero, damon_max_nr_accesses(), which
is called from damon_hot_score(), causes a divide-by-zero. Needless to
say, it is a problem.
When the user sets the aggregation interval zero, the function returns
zero. It is wrong, since the real maximum nr_acceses in the setup should
be one. Worse yet, it can cause another divide-by-zero from its caller,
damon_hot_score(), since it uses damon_max_nr_accesses() return value as a
denominator.
When the user sets the aggregation interval very high, damon_hot_score()
could return a value out of [0, DAMOS_MAX_SCORE] range. Since the return
value is used as an index to the regions_score_histogram array, which is
DAMOS_MAX_SCORE+1 size, it causes out of bounds array access.
The issues can be relatively easily reproduced like below. The sysfs
write permission is required, though.
# ./damo start --damos_action lru_prio --damos_quota_space 100M \
--damos_quota_interval 1s
# cd /sys/kernel/mm/damon/admin/kdamonds/0
# echo 0 > contexts/0/monitoring_attrs/intervals/sample_us
# echo 0 > contexts/0/monitoring_attrs/intervals/aggr_us
# echo commit > state
# dmesg
[...]
[ 131.329762] Oops: divide error: 0000 [#1] SMP NOPTI
[...]
[ 131.336089] RIP: 0010:damon_hot_score+0x27/0xd0
[...]
Fix the divide-by-zero intervals problems by explicitly handling the zero
intervals in damon_max_nr_accesses(). Fix the out-of-bound array access
by applying [0, DAMOS_MAX_SCORE] bounds before returning from
damon_hot_score().
The issue was discovered [1] by Sashiko.
Link: https://lore.kernel.org/20260623135834.67189-1-sj@kernel.org
Link: https://lore.kernel.org/20260619202459.145010-1-sj@kernel.org [1]
Fixes: 198f0f4c58b9 ("mm/damon/vaddr,paddr: support pageout prioritization")
Signed-off-by: SeongJae Park <sj@kernel.org>
Cc: <stable@vger.kernel.org> # 5.16.x
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
|
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In reclaim, shrink_folio_list() unmaps PTEs with a deferred, batched TLB
flush. The batch is only flushed by try_to_unmap_flush() near the end of
the function, just before the order-0 folios collected in @free_folios are
handed back to the allocator.
Large folios don't go through @free_folios -- they're freed inline at the
free_it label via destroy_large_folio(), which runs before that flush. So
a large folio's pages can be returned to the buddy allocator and reused
while another CPU still holds a stale TLB entry for them, and that CPU then
reads or executes through the stale translation into the reused page. For
file-backed large folios (e.g. executable text) this shows up as random
SIGSEGV/SIGILL in user space, with fault addresses that don't match the
code being run.
Flush the deferred batch before freeing a large folio inline, the same way
the order-0 path already waits for the flush.
Upstream this is fixed as a side effect of commit bc2ff4cbc329 ("mm: free
folios in a batch in shrink_folio_list()"), which is a larger change; this
is the minimal fix for -stable.
Reported-by: Yingfu Zhou <yingfu.zhou@shopee.com>
Fixes: bd4c82c22c36 ("mm, THP, swap: delay splitting THP after swapped out")
Cc: Jiayuan Chen <jiayuan.chen@linux.dev>
Signed-off-by: Jiayuan Chen <jiayuan.chen@shopee.com>
Reviewed-by: Matthew Wilcox <willy@infradead.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
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[ Upstream commit 3c2d42b8ee345b17a4ba56b0f6492d1ff4c1178e ]
Two concurrent madvise(MADV_HWPOISON) calls on the same hugetlb page can
trigger a recursive spinlock self-deadlock (AA deadlock) on hugetlb_lock
when racing with a concurrent unmap:
thread#0 thread#1
-------- --------
madvise(folio, MADV_HWPOISON)
-> poisons the folio successfully
madvise(folio, MADV_HWPOISON) unmap(folio)
try_memory_failure_hugetlb
get_huge_page_for_hwpoison
spin_lock_irq(&hugetlb_lock) <- held
__get_huge_page_for_hwpoison
hugetlb_update_hwpoison()
-> MF_HUGETLB_FOLIO_PRE_POISONED
goto out:
folio_put()
refcount: 1 -> 0
free_huge_folio()
spin_lock_irqsave(&hugetlb_lock)
-> AA DEADLOCK!
The out: path in __get_huge_page_for_hwpoison() calls folio_put() to drop
the GUP reference while the hugetlb_lock is still held by the hugetlb.c
wrapper get_huge_page_for_hwpoison(). If concurrent unmap has released
the page table mapping reference, folio_put() drops the folio refcount to
zero, triggering free_huge_folio() which attempts to re-acquire the
non-recursive hugetlb_lock.
Fix this by moving hugetlb_lock acquisition from the hugetlb.c wrapper
into get_huge_page_for_hwpoison(). Place spin_unlock_irq() before the
folio_put() at the out: label so the folio is always released outside the
lock.
[akpm@linux-foundation.org: fix race, rename label per Miaohe]
Link: https://sashiko.dev/#/patchset/20260522010305.4099834-1-mawupeng1@huawei.com
Link: https://lore.kernel.org/f39f405e-4b4b-8f79-70fe-a2b5b62114eb@huawei.com
Link: https://lore.kernel.org/20260522010305.4099834-1-mawupeng1@huawei.com
Fixes: 405ce051236c ("mm/hwpoison: fix race between hugetlb free/demotion and memory_failure_hugetlb()")
Signed-off-by: Wupeng Ma <mawupeng1@huawei.com>
Acked-by: Oscar Salvador (SUSE) <osalvador@kernel.org>
Acked-by: Muchun Song <muchun.song@linux.dev>
Reviewed-by: Kefeng Wang <wangkefeng.wang@huawei.com>
Acked-by: Miaohe Lin <linmiaohe@huawei.com>
Cc: David Hildenbrand <david@kernel.org>
Cc: Liam Howlett <liam.howlett@oracle.com>
Cc: Lorenzo Stoakes <ljs@kernel.org>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Mike Rapoport <rppt@kernel.org>
Cc: Naoya Horiguchi <nao.horiguchi@gmail.com>
Cc: Suren Baghdasaryan <surenb@google.com>
Cc: Vlastimil Babka <vbabka@kernel.org>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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[ Upstream commit a148a2040191b12b45b82cb29c281cb3036baf90 ]
When a newly poisoned subpage ends up in an already poisoned hugetlb
folio, 'num_poisoned_pages' is incremented, but the per node ->mf_stats is
not. Fix the inconsistency by designating action_result() to update them
both.
While at it, define __get_huge_page_for_hwpoison() return values in terms
of symbol names for better readibility. Also rename
folio_set_hugetlb_hwpoison() to hugetlb_update_hwpoison() since the
function does more than the conventional bit setting and the fact three
possible return values are expected.
Link: https://lkml.kernel.org/r/20260120232234.3462258-1-jane.chu@oracle.com
Fixes: 18f41fa616ee ("mm: memory-failure: bump memory failure stats to pglist_data")
Signed-off-by: Jane Chu <jane.chu@oracle.com>
Acked-by: Miaohe Lin <linmiaohe@huawei.com>
Cc: Chris Mason <clm@meta.com>
Cc: David Hildenbrand <david@kernel.org>
Cc: David Rientjes <rientjes@google.com>
Cc: Jiaqi Yan <jiaqiyan@google.com>
Cc: Liam R. Howlett <Liam.Howlett@oracle.com>
Cc: Lorenzo Stoakes <lorenzo.stoakes@oracle.com>
Cc: Matthew Wilcox (Oracle) <willy@infradead.org>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Mike Rapoport <rppt@kernel.org>
Cc: Muchun Song <muchun.song@linux.dev>
Cc: Naoya Horiguchi <nao.horiguchi@gmail.com>
Cc: Oscar Salvador <osalvador@suse.de>
Cc: Suren Baghdasaryan <surenb@google.com>
Cc: William Roche <william.roche@oracle.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Stable-dep-of: 3c2d42b8ee34 ("mm/memory-failure: fix hugetlb_lock AA deadlock in get_huge_page_for_hwpoison")
Signed-off-by: Sasha Levin <sashal@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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[ Upstream commit b235448e8cab7eea17d164efc7bf55505985ba65 ]
Now that folio_putback_hugetlb() is only called on folios that were
previously isolated through folio_isolate_hugetlb(), let's rename it to
match folio_putback_lru().
Add some kernel doc to clarify how this function is supposed to be used.
Link: https://lkml.kernel.org/r/20250113131611.2554758-5-david@redhat.com
Signed-off-by: David Hildenbrand <david@redhat.com>
Reviewed-by: Baolin Wang <baolin.wang@linux.alibaba.com>
Cc: Matthew Wilcox (Oracle) <willy@infradead.org>
Cc: Muchun Song <muchun.song@linux.dev>
Cc: Sidhartha Kumar <sidhartha.kumar@oracle.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Stable-dep-of: 3c2d42b8ee34 ("mm/memory-failure: fix hugetlb_lock AA deadlock in get_huge_page_for_hwpoison")
Signed-off-by: Sasha Levin <sashal@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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[ Upstream commit ba23f58de896842028b4b33b95530f08288396fe ]
We replaced a simple put_page() by a putback_active_hugepage() call in
commit 3aaa76e125c1 ("mm: migrate: hugetlb: putback destination hugepage
to active list"), to set the "active" flag on the dst hugetlb folio.
Nowadays, we decoupled the "active" list from the flag, by calling the
flag "migratable".
Calling "putback" on something that wasn't allocated is weird and not
future proof, especially if we might reach that path when migration failed
and we just want to free the freshly allocated hugetlb folio.
Let's simply handle the migratable flag and the active list flag in
move_hugetlb_state(), where we know that allocation succeeded and already
handle the temporary flag; use a simple folio_put() to return our
reference.
Link: https://lkml.kernel.org/r/20250113131611.2554758-4-david@redhat.com
Signed-off-by: David Hildenbrand <david@redhat.com>
Reviewed-by: Baolin Wang <baolin.wang@linux.alibaba.com>
Cc: Matthew Wilcox (Oracle) <willy@infradead.org>
Cc: Muchun Song <muchun.song@linux.dev>
Cc: Sidhartha Kumar <sidhartha.kumar@oracle.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Stable-dep-of: 3c2d42b8ee34 ("mm/memory-failure: fix hugetlb_lock AA deadlock in get_huge_page_for_hwpoison")
Signed-off-by: Sasha Levin <sashal@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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[ Upstream commit 4c640f128074e0d4459ecf072595a44df5c2ae18 ]
Let's make the function name match "folio_isolate_lru()", and add some
kernel doc.
Link: https://lkml.kernel.org/r/20250113131611.2554758-3-david@redhat.com
Signed-off-by: David Hildenbrand <david@redhat.com>
Reviewed-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Reviewed-by: Baolin Wang <baolin.wang@linux.alibaba.com>
Cc: Muchun Song <muchun.song@linux.dev>
Cc: Sidhartha Kumar <sidhartha.kumar@oracle.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Stable-dep-of: 3c2d42b8ee34 ("mm/memory-failure: fix hugetlb_lock AA deadlock in get_huge_page_for_hwpoison")
Signed-off-by: Sasha Levin <sashal@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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[ Upstream commit 3b041514cb6eae45869b020f743c14d983363222 ]
When SEAL_EXEC is added, SEAL_WRITE is implied to make W^X. But the
implied seal is set after the check that makes sure the memfd can not have
any writable mappings. This means one can use SEAL_EXEC to apply
SEAL_WRITE while having writeable mappings.
This breaks the contract that SEAL_WRITE provides and can be used by an
attacker to pass a memfd that appears to be write sealed but can still be
modified arbitrarily.
Fix this by adding the implied seals before the call for
mapping_deny_writable() is done.
Link: https://lore.kernel.org/20260505133922.797635-1-pratyush@kernel.org
Fixes: c4f75bc8bd6b ("mm/memfd: add write seals when apply SEAL_EXEC to executable memfd")
Signed-off-by: Pratyush Yadav (Google) <pratyush@kernel.org>
Reviewed-by: Pasha Tatashin <pasha.tatashin@soleen.com>
Acked-by: Jeff Xu <jeffxu@google.com>
Cc: Baolin Wang <baolin.wang@linux.alibaba.com>
Cc: Brendan Jackman <jackmanb@google.com>
Cc: Greg Thelen <gthelen@google.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: Kees Cook <kees@kernel.org>
Cc: "David Hildenbrand (Arm)" <david@kernel.org>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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[ Upstream commit 441f92f7d386b85bad16de49db95a307cba048a2 ]
DAMON sysfs maintains the DAMOS tried region directory objects via a
linked list. When the user requests refresh of the directories, DAMON
sysfs removes all the region directories first, and then generate updated
regions directory on the empty space. The removal function
(damon_sysfs_scheme_regions_rm_dirs()) only puts the kobj objects.
Deletion of the container region object from the linked list is done
inside the kobj release callback function.
If somehow the callback invocation is delayed, the list will contain
regions list that gonna be freed. If the updated region directories
creation is started in this situation, the list can be corrupted and
use-after-free can happen.
Because the kobj objects are managed by only DAMON sysfs, the issue cannot
happen in normal situation. But, such delays can be made on kernels that
built with CONFIG_DEBUG_KOBJECT_RELEASE. On the kernel, the issue can
indeed be reproduced like below.
# damo start --damos_action stat
# cd /sys/kernel/mm/damon/admin/kdamonds/0/
# for i in {1..10}; do echo update_schemes_tried_regions > state; done
# dmesg | grep underflow
[ 89.296152] refcount_t: underflow; use-after-free.
Fix the issue by removing the region object from the list when
decrementing the reference count.
Also update damos_sysfs_populate_region_dir() to add the region object to
the list only after the kobject_init_and_add() is success, so that fail of
kobject_init_and_add() is not leaving the deallocated object on the list.
The issue was discovered [1] by Sashiko.
Link: https://lore.kernel.org/20260518152559.93038-1-sj@kernel.org
Link: https://lore.kernel.org/20260513011920.119183-1-sj@kernel.org [1]
Fixes: 9277d0367ba1 ("mm/damon/sysfs-schemes: implement scheme region directory")
Signed-off-by: SeongJae Park <sj@kernel.org>
Cc: <stable@vger.kernel.org> # 6.2.x
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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[ Upstream commit be3f38d05cc5a7c3f13e51994c5dd043ab604d28 ]
Device private and exclusive entries are only supported for anonymous
folios. This condition is tested in __migrate_device_pages() and
make_device_exclusive() using folio_test_anon(). However the unmap path
tests this assumption using vma_is_anonymous().
This is wrong because whilst anonymous VMAs can only contain folios where
folio_test_anon() is true the opposite relation does not hold. A folio
for which folio_test_anon() is true does not imply vma_is_anonymous() is
true. Such a condition can occur if for example a folio is part of a
private filebacked mapping.
In this case vma_is_anonymous() is false as the mapping is filebacked, but
folio_test_anon() may be true, thus permitting devices to migrate the
folio to device private memory. This can lead to the following spurious
warnings during process teardown:
[ 772.737706] ------------[ cut here ]------------
[ 772.739201] WARNING: mm/memory.c:1754 at unmap_page_range.cold+0x26/0x18a, CPU#17: hmm-tests/2041
[ 772.742050] Modules linked in: test_hmm nvidia_uvm(O) nvidia(O)
[ 772.743959] CPU: 17 UID: 0 PID: 2041 Comm: hmm-tests Tainted: G W O 7.0.0+ #387 PREEMPT(full)
[ 772.747104] Tainted: [W]=WARN, [O]=OOT_MODULE
[ 772.748509] Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS rel-1.17.0-0-gb52ca86e094d-prebuilt.qemu.org 04/01/2014
[ 772.752117] RIP: 0010:unmap_page_range.cold+0x26/0x18a
[ 772.753780] Code: 7e fe ff ff 48 89 4c 24 78 4c 89 44 24 38 e8 f2 ff b1 00 48 8b 4c 24 78 4c 8b 44 24 38 48 8b 44 24 18 48 83 78 48 00 74 04 90 <0f> 0b 90 48 89 ca b8 ff ff 37 00 48 c1 ea 03 48 c1 e0 2a 80 3c 02
[ 772.759602] RSP: 0018:ffff888112607550 EFLAGS: 00010286
[ 772.761310] RAX: ffff88811bbf4dc0 RBX: dffffc0000000000 RCX: ffffea03e9bfffd8
[ 772.763583] RDX: 1ffff1102377e9c1 RSI: 0000000000000008 RDI: ffff88811bbf4e08
[ 772.765914] RBP: 0000000000000006 R08: ffff8881059f7448 R09: ffffed10224c0e68
[ 772.768184] R10: ffff888112607347 R11: 0000000000000001 R12: 0000000000000001
[ 772.770461] R13: ffffea03e9bfffc0 R14: ffff888112607908 R15: ffffea03e9bfffc0
[ 772.772782] FS: 00007f327caa2780(0000) GS:ffff888427b7d000(0000) knlGS:0000000000000000
[ 772.775328] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
[ 772.777187] CR2: 00007f327ca89000 CR3: 00000001994d5000 CR4: 00000000000006f0
[ 772.779135] Call Trace:
[ 772.779792] <TASK>
[ 772.780317] ? dmirror_interval_invalidate+0x1a3/0x290 [test_hmm]
[ 772.781873] ? vm_normal_page_pud+0x2b0/0x2b0
[ 772.782992] ? __rwlock_init+0x150/0x150
[ 772.784006] ? lock_release+0x216/0x2b0
[ 772.785008] ? __mmu_notifier_invalidate_range_start+0x505/0x6e0
[ 772.786522] ? lock_release+0x216/0x2b0
[ 772.787498] ? unmap_single_vma+0xb6/0x210
[ 772.788573] unmap_vmas+0x27d/0x520
[ 772.789506] ? unmap_single_vma+0x210/0x210
[ 772.790607] ? mas_update_gap.part.0+0x620/0x620
[ 772.791834] unmap_region+0x19e/0x350
[ 772.792769] ? remove_vma+0x130/0x130
[ 772.793684] ? mas_alloc_nodes+0x1f2/0x300
[ 772.794730] vms_complete_munmap_vmas+0x8c1/0xe20
[ 772.795926] ? unmap_region+0x350/0x350
[ 772.796917] do_vmi_align_munmap+0x36a/0x4e0
[ 772.798018] ? lock_release+0x216/0x2b0
[ 772.799024] ? vma_shrink+0x620/0x620
[ 772.799983] do_vmi_munmap+0x150/0x2c0
[ 772.800939] __vm_munmap+0x161/0x2c0
[ 772.801872] ? expand_downwards+0xd60/0xd60
[ 772.802948] ? clockevents_program_event+0x1ef/0x540
[ 772.804217] ? lock_release+0x216/0x2b0
[ 772.805158] __x64_sys_munmap+0x59/0x80
[ 772.805776] do_syscall_64+0xfc/0x670
[ 772.806336] ? irqentry_exit+0xda/0x580
[ 772.806976] entry_SYSCALL_64_after_hwframe+0x4b/0x53
[ 772.807772] RIP: 0033:0x7f327cbb2717
[ 772.808323] Code: 73 01 c3 48 8b 0d f9 76 0d 00 f7 d8 64 89 01 48 83 c8 ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 44 00 00 b8 0b 00 00 00 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 8b 0d c9 76 0d 00 f7 d8 64 89 01 48
[ 772.811337] RSP: 002b:00007ffde7f57d38 EFLAGS: 00000202 ORIG_RAX: 000000000000000b
[ 772.812564] RAX: ffffffffffffffda RBX: 00007f327cc9c000 RCX: 00007f327cbb2717
[ 772.813733] RDX: 0000000000000000 RSI: 0000000000400000 RDI: 00007f327c289000
[ 772.814867] RBP: 0000000000421360 R08: 000000000000001a R09: 0000000000000000
[ 772.815991] R10: 0000000000000003 R11: 0000000000000202 R12: 00007ffde7f57d74
[ 772.817121] R13: 00007f327c689010 R14: 0000000000100000 R15: 00007f327c289000
[ 772.818272] </TASK>
[ 772.818614] irq event stamp: 0
[ 772.819159] hardirqs last enabled at (0): [<0000000000000000>] 0x0
[ 772.820174] hardirqs last disabled at (0): [<ffffffff82a57ab3>] copy_process+0x19f3/0x6440
[ 772.821511] softirqs last enabled at (0): [<ffffffff82a57b00>] copy_process+0x1a40/0x6440
[ 772.822869] softirqs last disabled at (0): [<0000000000000000>] 0x0
[ 772.823871] ---[ end trace 0000000000000000 ]---
Fix this by using the same check for folio_test_anon() in
zap_nonpresent_ptes(). Also add a hmm-test case for this.
Link: https://lore.kernel.org/20260501065116.2057242-1-apopple@nvidia.com
Fixes: 999dad824c39 ("mm/shmem: persist uffd-wp bit across zapping for file-backed")
Signed-off-by: Alistair Popple <apopple@nvidia.com>
Reported-by: Arsen Arsenović <aarsenovic@baylibre.com>
Reviewed-by: Balbir Singh <balbirs@nvidia.com>
Cc: David Hildenbrand <david@kernel.org>
Cc: Jason Gunthorpe <jgg@ziepe.ca>
Cc: John Hubbard <jhubbard@nvidia.com>
Cc: Leon Romanovsky <leon@kernel.org>
Cc: Liam R. Howlett <liam@infradead.org>
Cc: Lorenzo Stoakes <ljs@kernel.org>
Cc: Peter Xu <peterx@redhat.com>
Cc: Matthew Brost <matthew.brost@intel.com>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Mike Rapoport <rppt@kernel.org>
Cc: Shuah Khan <shuah@kernel.org>
Cc: Suren Baghdasaryan <surenb@google.com>
Cc: Thomas Hellström <thomas.hellstrom@linux.intel.com>
Cc: Vlastimil Babka <vbabka@kernel.org>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
[ adapted `folio_test_anon(folio)` to `PageAnon(page)` ]
Signed-off-by: Sasha Levin <sashal@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
|
|
[ Upstream commit 8d878059924f12c1bc24556a92ec56add74de3c8 ]
__split_huge_pmd_locked() updates the file/shmem RSS counter after
dropping the PMD mapping's folio reference. If folio_put() drops the last
reference, mm_counter_file() can later read freed folio state via
folio_test_swapbacked().
Move the counter update before folio_put().
Link: https://lore.kernel.org/20260526101337.1984081-1-yintirui@huawei.com
Fixes: fadae2953072 ("thp: use mm_file_counter to determine update which rss counter")
Signed-off-by: Yin Tirui <yintirui@huawei.com>
Reviewed-by: Lorenzo Stoakes <ljs@kernel.org>
Acked-by: David Hildenbrand (arm) <david@kernel.org>
Reviewed-by: Lance Yang <lance.yang@linux.dev>
Reviewed-by: Dev Jain <dev.jain@arm.com>
Cc: Baolin Wang <baolin.wang@linux.alibaba.com>
Cc: Barry Song <baohua@kernel.org>
Cc: Chen Jun <chenjun102@huawei.com>
Cc: Kefeng Wang <wangkefeng.wang@huawei.com>
Cc: Liam R. Howlett <liam@infradead.org>
Cc: Nico Pache <npache@redhat.com>
Cc: Ryan Roberts <ryan.roberts@arm.com>
Cc: Vlastimil Babka <vbabka@kernel.org>
Cc: Yang Shi <yang.shi@linux.alibaba.com>
Cc: Zi Yan <ziy@nvidia.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
[ changed folio API calls (folio_remove_rmap_pmd/mm_counter_file(folio)/folio_put) to page-based equivalents (page_remove_rmap/mm_counter_file(page)/put_page) ]
Signed-off-by: Sasha Levin <sashal@kernel.org>
|
|
[ Upstream commit b4aea43cd37afad714b5684fe9fdfcb0e78dba26 ]
Commit 081056dc00a2 ("mm/hugetlb: unshare page tables during VMA split,
not before") changed the locking model around hugetlbfs PMD unsharing on
VMA split, but did not update the function which asserts the locks,
hugetlb_vma_assert_locked().
This function asserts that either the hugetlb VMA lock is held (if a
shared mapping) or that the reservation map lock is held (if private).
If you get an unfortunate race between something which results in one of
these locks being released and a hugetlb VMA split and you have
CONFIG_LOCKDEP enabled, you can therefore see a false positive assertion
arise when there is in fact no issue.
Since this change introduced a new take_locks parameter to
hugetlb_unshare_pmds(), which, when set to false, indicates that locking
is sufficient, simply pass this to the unsharing logic and predicate the
lock assertions on this.
This is safe, as we already asserted the file rmap lock and the VMA write
lock prior to this (implying exclusive mmap write lock), so we cannot be
raced by either rmap or page fault page table walkers which the asserted
locks are intended to protect against (we don't mind GUP-fast).
Separate out huge_pmd_unshare() into __huge_pmd_unshare() to add a
check_locks parameter, and update hugetlb_unshare_pmds() to pass this
parameter to it.
This leaves all other callers of huge_pmd_unshare() still correctly
asserting the locks.
The below reproducer will trigger the assert in a kernel with
CONFIG_LOCKDEP enabled by racing process teardown (which will release the
hugetlb lock) against a hugetlb split.
void execute_one(void)
{
void *ptr;
pid_t pid;
/*
* Create a hugetlb mapping spanning a PUD entry.
*
* We force the hugetlb page allocation with populate and
* noreserve.
*
* |---------------------|
* | |
* |---------------------|
* 0 PUD boundary
*/
ptr = mmap(0, PUD_SIZE, PROT_READ | PROT_WRITE,
MAP_FIXED | MAP_SHARED | MAP_ANON |
MAP_NORESERVE | MAP_HUGETLB | MAP_POPULATE,
-1, 0);
if (ptr == MAP_FAILED) {
perror("mmap");
exit(EXIT_FAILURE);
}
/*
* Fork but with a bogus stack pointer so we try to execute code in
* a non-VM_EXEC VMA, causing segfault + teardown via exit_mmap().
*
* The clone will cause PMD page table sharing between the
* processes first via:
* copy_process() -> ... -> huge_pte_alloc() -> huge_pmd_share()
*
* Then tear down and release the hugetlb 'VMA' lock via:
* exit_mmap() -> ... -> vma_close() -> hugetlb_vma_lock_free()
*/
pid = syscall(__NR_clone, 0, 2 * PMD_SIZE, 0, 0, 0);
if (pid < 0) {
perror("clone");
exit(EXIT_FAILURE);
} if (pid == 0) {
/* Pop stack... */
return;
}
/*
* We are the parent process.
*
* Race the child process's teardown with a PMD unshare.
*
* We do this by triggering:
*
* __split_vma() -> hugetlb_split() -> hugetlb_unshare_pmds()
*
* Which, importantly, doesn't hold the hugetlb VMA lock (nor can
* it), meaning we assert in hugetlb_vma_assert_locked().
*
* .
* |----------.----------|
* | . |
* |----------.----------|
* 0 . PUD boundary
*/
mmap(0, PUD_SIZE / 2, PROT_READ | PROT_WRITE,
MAP_FIXED | MAP_ANON | MAP_PRIVATE, -1, 0);
}
int main(void)
{
int i;
/* Kick off fork children. */
for (i = 0; i < NUM_FORKS; i++) {
pid_t pid = fork();
if (pid < 0) {
perror("fork");
exit(EXIT_FAILURE);
}
/* Fork children do their work and exit. */
if (!pid) {
int j;
for (j = 0; j < NUM_ITERS; j++)
execute_one();
return EXIT_SUCCESS;
}
}
/* If we succeeded, wait on children. */
for (i = 0; i < NUM_FORKS; i++)
wait(NULL);
return EXIT_SUCCESS;
}
[ljs@kernel.org: account for the !CONFIG_HUGETLB_PMD_PAGE_TABLE_SHARING case]
Link: https://lore.kernel.org/agWZsPGYid08uU6O@lucifer
Link: https://lore.kernel.org/20260513085658.45264-1-ljs@kernel.org
Fixes: 081056dc00a2 ("mm/hugetlb: unshare page tables during VMA split, not before")
Signed-off-by: Lorenzo Stoakes <ljs@kernel.org>
Acked-by: David Hildenbrand (Arm) <david@kernel.org>
Acked-by: Oscar Salvador <osalvador@suse.de>
Cc: Jann Horn <jannh@google.com>
Cc: Muchun Song <muchun.song@linux.dev>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Lorenzo Stoakes <ljs@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
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commit 40c81856e622a9dc59294a90d169ac07ea25b0b0 upstream.
Two sites in mm/hugetlb.c allocate a hugetlb folio via
alloc_hugetlb_folio() (consuming a VMA reservation) and then call
copy_user_large_folio(), which became int-returning in commit 1cb9dc4b475c
("mm: hwpoison: support recovery from HugePage copy-on-write faults") and
can now fail (e.g. -EHWPOISON on a hwpoisoned source page). On the
failure path, folio_put() restores the global hugetlb pool count through
free_huge_folio(), but the per-VMA reservation map entry is left marked
consumed:
- hugetlb_mfill_atomic_pte() resubmission path (UFFDIO_COPY)
- copy_hugetlb_page_range() fork-time CoW path when
hugetlb_try_dup_anon_rmap() fails (rare: pinned hugetlb anon
folio under fork)
User-visible effect: on UFFDIO_COPY into a private hugetlb VMA where the
resubmission copy fails, the reservation for that address is leaked from
the VMA's reserve map. A subsequent fault at the same address takes the
no-reservation path, and under hugetlb pool pressure the task is SIGBUSed
at an address it had previously reserved. The fork-time CoW path leaks
the same way in the child VMA's reserve map, though it requires the much
rarer combination of pinned hugetlb anon page + hwpoisoned source.
Add the missing restore_reserve_on_error() call before folio_put() on both
error paths.
Link: https://lore.kernel.org/20260520044912.6751-1-devnexen@gmail.com
Fixes: 1cb9dc4b475c ("mm: hwpoison: support recovery from HugePage copy-on-write faults")
Signed-off-by: David Carlier <devnexen@gmail.com>
Reviewed-by: Muchun Song <muchun.song@linux.dev>
Cc: David Hildenbrand <david@kernel.org>
Cc: Mina Almasry <almasrymina@google.com>
Cc: Muchun Song <muchun.song@linux.dev>
Cc: Oscar Salvador <osalvador@suse.de>
Cc: yuehaibing <yuehaibing@huawei.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
|
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commit d6b8b02a27b3dd09ec12144322b3dac46d9bc9ef upstream.
damon_get_folio() speculatively calls folio_test_lru() before
folio_try_get(). The folio can get freed and reallocated to a tail page.
In the case, VM_BUG_ON_PGFLAGS() in const_folio_flags() can be triggered.
Remove the speculative call.
Also mark folio_test_lru() check right after folio_try_get() success as no
more unlikely.
The race should be rare. Also the problem can happen only if the kernel
has enabled CONFIG_DEBUG_VM_PGFLAGS. No real world report of this issue
has been made so far. This fix is based on only theoretical analysis.
That said, a bug is a bug. A similar issue was also fixed via commit
3203b3ab0fcf ("mm/filemap: don't call folio_test_locked() without a
reference in next_uptodate_folio()"). I don't expect this change will
make a meaningful impact to DAMON performance in the real world, though I
will be happy to be corrected from the real world reports.
The issue was discovered [1] by Sashiko.
Link: https://lore.kernel.org/20260525162256.8317-1-sj@kernel.org
Link: https://lore.kernel.org/20260517234112.89245-1-sj@kernel.org [1]
Fixes: 3f49584b262c ("mm/damon: implement primitives for the virtual memory address spaces")
Signed-off-by: SeongJae Park <sj@kernel.org>
Cc: Fernand Sieber <sieberf@amazon.com>
Cc: Leonard Foerster <foersleo@amazon.de>
Cc: Shakeel Butt <shakeel.butt@linux.dev>
Cc: <stable@vger.kernel.org> # 5.15.x
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
|
|
[ Upstream commit ac1ea219590c09572ed5992dc233bbf7bb70fef9 ]
Several subsystems (slub, shmem, ttm, etc.) use page->private but don't
clear it before freeing pages. When these pages are later allocated as
high-order pages and split via split_page(), tail pages retain stale
page->private values.
This causes a use-after-free in the swap subsystem. The swap code uses
page->private to track swap count continuations, assuming freshly
allocated pages have page->private == 0. When stale values are present,
swap_count_continued() incorrectly assumes the continuation list is valid
and iterates over uninitialized page->lru containing LIST_POISON values,
causing a crash:
KASAN: maybe wild-memory-access in range [0xdead000000000100-0xdead000000000107]
RIP: 0010:__do_sys_swapoff+0x1151/0x1860
Fix this by clearing page->private in free_pages_prepare(), ensuring all
freed pages have clean state regardless of previous use.
Link: https://lkml.kernel.org/r/20260207173615.146159-1-mikhail.v.gavrilov@gmail.com
Fixes: 3b8000ae185c ("mm/vmalloc: huge vmalloc backing pages should be split rather than compound")
Signed-off-by: Mikhail Gavrilov <mikhail.v.gavrilov@gmail.com>
Suggested-by: Zi Yan <ziy@nvidia.com>
Acked-by: Zi Yan <ziy@nvidia.com>
Acked-by: David Hildenbrand (Arm) <david@kernel.org>
Reviewed-by: Vlastimil Babka <vbabka@suse.cz>
Cc: Brendan Jackman <jackmanb@google.com>
Cc: Chris Li <chrisl@kernel.org>
Cc: Hugh Dickins <hughd@google.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Kairui Song <ryncsn@gmail.com>
Cc: Matthew Wilcox (Oracle) <willy@infradead.org>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Nicholas Piggin <npiggin@gmail.com>
Cc: Suren Baghdasaryan <surenb@google.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
[backport: context only]
Signed-off-by: Li Wang <li.wang@windriver.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
|
|
commit d4e7b5c4cc353f154d5ab8bb2e1ce7714d77a6e9 upstream.
damon_sysfs_memcg_path_to_id() breaks mem_cgroup_iter() loop without
calling mem_cgroup_iter_break(). This leaks the cgroup reference. Fix
the issue by calling mem_cgroup_iter_break() before the break.
The issue was discovered [1] by Sashiko.
Link: https://lore.kernel.org/20260426173625.86521-1-sj@kernel.org
Link: https://lore.kernel.org/20260423004148.74722-1-sj@kernel.org [1]
Fixes: 29cbb9a13f05 ("mm/damon/sysfs-schemes: implement scheme filters")
Signed-off-by: SeongJae Park <sj@kernel.org>
Cc: <stable@vger.kernel.org> # 6.3.x
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
|
|
commit 64a140afa5ed1c6f5ba6d451512cbdbbab1ba339 upstream.
Patch series "mm/damon/modules: detect and use fresh status", v3.
DAMON modules including DAMON_RECLAIM, DAMON_LRU_SORT and DAMON_STAT
commonly expose the kdamond running status via their parameters. Under
certain scenarios including wrong user inputs and memory allocation
failures, those parameter values can be stale. It can confuse users. For
DAMON_RECLAIM and DAMON_LRU_SORT, it even makes the kdamond unable to be
restarted before the system reboot.
The problem comes from the fact that there are multiple events for the
status changes and it is difficult to follow up all the scenarios. Fix
the issue by detecting and using the status on demand, instead of using a
cached status that is difficult to be updated.
Patches 1-3 fix the bugs in DAMON_RECLAIM, DAMON_LRU_SORT and DAMON_STAT
in the order.
This patch (of 3):
DAMON_RECLAIM updates 'enabled' and 'kdamond_pid' parameter values, which
represents the running status of its kdamond, when the user explicitly
requests start/stop of the kdamond. The kdamond can, however, be stopped
in events other than the explicit user request in the following three
events.
1. ctx->regions_score_histogram allocation failure at beginning of the
execution,
2. damon_commit_ctx() failure due to invalid user input, and
3. damon_commit_ctx() failure due to its internal allocation failures.
Hence, if the kdamond is stopped by the above three events, the values of
the status parameters can be stale. Users could show the stale values and
be confused. This is already bad, but the real consequence is worse.
DAMON_RECLAIM avoids unnecessary damon_start() and damon_stop() calls
based on the 'enabled' parameter value. And the update of 'enabled'
parameter value depends on the damon_start() and damon_stop() call
results. Hence, once the kdamond has stopped by the unintentional events,
the user cannot restart the kdamond before the system reboot. For
example, the issue can be reproduced via below steps.
# cd /sys/module/damon_reclaim/parameters
#
# # start DAMON_RECLAIM
# echo Y > enabled
# ps -ef | grep kdamond
root 806 2 0 17:53 ? 00:00:00 [kdamond.0]
root 808 803 0 17:53 pts/4 00:00:00 grep kdamond
#
# # commit wrong input to stop kdamond withou explicit stop request
# echo 3 > addr_unit
# echo Y > commit_inputs
bash: echo: write error: Invalid argument
#
# # confirm kdamond is stopped
# ps -ef | grep kdamond
root 811 803 0 17:53 pts/4 00:00:00 grep kdamond
#
# # users casn now show stable status
# cat enabled
Y
# cat kdamond_pid
806
#
# # even after fixing the wrong parameter,
# # kdamond cannot be restarted.
# echo 1 > addr_unit
# echo Y > enabled
# ps -ef | grep kdamond
root 815 803 0 17:54 pts/4 00:00:00 grep kdamond
The problem will only rarely happen in real and common setups for the
following reasons. The allocation failures are unlikely in such setups
since those allocations are arguably too small to fail. Also sane users
on real production environments may not commit wrong input parameters.
But once it happens, the consequence is quite bad. And the bug is a bug.
The issue stems from the fact that there are multiple events that can
change the status, and following all the events is challenging.
Dynamically detect and use the fresh status for the parameters when those
are requested.
Link: https://lore.kernel.org/20260419161003.79176-1-sj@kernel.org
Link: https://lore.kernel.org/20260419161003.79176-2-sj@kernel.org
Fixes: e035c280f6df ("mm/damon/reclaim: support online inputs update")
Co-developed-by: Liew Rui Yan <aethernet65535@gmail.com>
Signed-off-by: Liew Rui Yan <aethernet65535@gmail.com>
Signed-off-by: SeongJae Park <sj@kernel.org>
Cc: <stable@vger.kernel.org> # 5.19.x
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: SeongJae Park <sj@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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commit b98b7ff6025ae82570d4915e083f0cbd8d48b3cf upstream.
DAMON_LRU_SORT updates 'enabled' and 'kdamond_pid' parameter values, which
represents the running status of its kdamond, when the user explicitly
requests start/stop of the kdamond. The kdamond can, however, be stopped
in events other than the explicit user request in the following three
events.
1. ctx->regions_score_histogram allocation failure at beginning of the
execution,
2. damon_commit_ctx() failure due to invalid user input, and
3. damon_commit_ctx() failure due to its internal allocation failures.
Hence, if the kdamond is stopped by the above three events, the values of
the status parameters can be stale. Users could show the stale values and
be confused. This is already bad, but the real consequence is worse.
DAMON_LRU_SORT avoids unnecessary damon_start() and damon_stop() calls
based on the 'enabled' parameter value. And the update of 'enabled'
parameter value depends on the damon_start() and damon_stop() call
results. Hence, once the kdamond has stopped by the unintentional events,
the user cannot restart the kdamond before the system reboot. For
example, the issue can be reproduced via below steps.
# cd /sys/module/damon_lru_sort/parameters
#
# # start DAMON_LRU_SORT
# echo Y > enabled
# ps -ef | grep kdamond
root 806 2 0 17:53 ? 00:00:00 [kdamond.0]
root 808 803 0 17:53 pts/4 00:00:00 grep kdamond
#
# # commit wrong input to stop kdamond withou explicit stop request
# echo 3 > addr_unit
# echo Y > commit_inputs
bash: echo: write error: Invalid argument
#
# # confirm kdamond is stopped
# ps -ef | grep kdamond
root 811 803 0 17:53 pts/4 00:00:00 grep kdamond
#
# # users casn now show stable status
# cat enabled
Y
# cat kdamond_pid
806
#
# # even after fixing the wrong parameter,
# # kdamond cannot be restarted.
# echo 1 > addr_unit
# echo Y > enabled
# ps -ef | grep kdamond
root 815 803 0 17:54 pts/4 00:00:00 grep kdamond
The problem will only rarely happen in real and common setups for the
following reasons. The allocation failures are unlikely in such setups
since those allocations are arguably too small to fail. Also sane users
on real production environments may not commit wrong input parameters.
But once it happens, the consequence is quite bad. And the bug is a bug.
The issue stems from the fact that there are multiple events that can
change the status, and following all the events is challenging.
Dynamically detect and use the fresh status for the parameters when those
are requested.
Link: https://lore.kernel.org/20260419161003.79176-3-sj@kernel.org
Fixes: 40e983cca927 ("mm/damon: introduce DAMON-based LRU-lists Sorting")
Co-developed-by: Liew Rui Yan <aethernet65535@gmail.com>
Signed-off-by: Liew Rui Yan <aethernet65535@gmail.com>
Signed-off-by: SeongJae Park <sj@kernel.org>
Cc: <stable@vger.kernel.org> # 6.0.x
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: SeongJae Park <sj@kernel.org>
(port parts of 42b7491af14c ("mm/damon/core: introduce damon_call()")
and d2b5be741a50 ("mm/damon/sysfs: use DAMON core API
damon_is_running()") for damon_is_running() dependency)
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
|
|
commit 4262c53236977de3ceaa3bf2aefdf772c9b874dd upstream.
Patch series "mm/damon: hide kdamond and kdamond_lock from API callers".
'kdamond' and 'kdamond_lock' fields initially exposed to DAMON API callers
for flexible synchronization and use cases. As DAMON API became somewhat
complicated compared to the early days, Keeping those exposed could only
encourage the API callers to invent more creative but complicated and
difficult-to-debug use cases.
Fortunately DAMON API callers didn't invent that many creative use cases.
There exist only two use cases of 'kdamond' and 'kdamond_lock'. Finding
whether the kdamond is actively running, and getting the pid of the
kdamond. For the first use case, a dedicated API function, namely
'damon_is_running()' is provided, and all DAMON API callers are using the
function for the use case. Hence only the second use case is where the
fields are directly being used by DAMON API callers.
To prevent future invention of complicated and erroneous use cases of the
fields, hide the fields from the API callers. For that, provide new
dedicated DAMON API functions for the remaining use case, namely
damon_kdamond_pid(), migrate DAMON API callers to use the new function,
and mark the fields as private fields.
This patch (of 5):
'kdamond' and 'kdamond_lock' are directly being used by DAMON API callers
for getting the pid of the corresponding kdamond. To discourage invention
of creative but complicated and erroneous new usages of the fields that
require careful synchronization, implement a new API function that can
simply be used without the manual synchronizations.
Link: https://lkml.kernel.org/r/20260115152047.68415-1-sj@kernel.org
Link: https://lkml.kernel.org/r/20260115152047.68415-2-sj@kernel.org
Signed-off-by: SeongJae Park <sj@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: SeongJae Park <sj@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
|
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commit 8bbde987c2b84f80da0853f739f0a920386f8b99 upstream.
When the throughput of a DAMOS scheme is very slow, DAMOS time quota can
make the effective size quota smaller than damon_ctx->min_region_sz. In
the case, damos_apply_scheme() will skip applying the action, because the
action is tried at region level, which requires >=min_region_sz size.
That is, the quota is effectively exceeded for the quota charge window.
Because no action will be applied, the total_charged_sz and
total_charged_ns are also not updated. damos_set_effective_quota() will
try to update the effective size quota before starting the next charge
window. However, because the total_charged_sz and total_charged_ns have
not updated, the throughput and effective size quota are also not changed.
Since effective size quota can only be decreased, other effective size
quota update factors including DAMOS quota goals and size quota cannot
make any change, either.
As a result, the scheme is unexpectedly deactivated until the user notices
and mitigates the situation. The users can mitigate this situation by
changing the time quota online or re-install the scheme. While the
mitigation is somewhat straightforward, finding the situation would be
challenging, because DAMON is not providing good observabilities for that.
Even if such observability is provided, doing the additional monitoring
and the mitigation is somewhat cumbersome and not aligned to the intention
of the time quota. The time quota was intended to help reduce the user's
administration overhead.
Fix the problem by setting time quota-modified effective size quota be at
least min_region_sz always.
The issue was discovered [1] by sashiko.
Link: https://lore.kernel.org/20260407003153.79589-1-sj@kernel.org
Link: https://lore.kernel.org/20260405192504.110014-1-sj@kernel.org [1]
Fixes: 1cd243030059 ("mm/damon/schemes: implement time quota")
Signed-off-by: SeongJae Park <sj@kernel.org>
Cc: <stable@vger.kernel.org> # 5.16.x
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: SeongJae Park <sj@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
|
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[ Upstream commit 8f5ce56b76303c55b78a87af996e2e0f8535f979 ]
When the user requests a total hugetlb CMA size without per-node
specification, hugetlb_cma_reserve() computes per_node from
hugetlb_cma_size and the number of nodes that have memory
per_node = DIV_ROUND_UP(hugetlb_cma_size,
nodes_weight(hugetlb_bootmem_nodes));
The reservation loop later computes
size = round_up(min(per_node, hugetlb_cma_size - reserved),
PAGE_SIZE << order);
So the actually reserved per_node size is multiple of (PAGE_SIZE <<
order), but the logged per_node is not rounded up, so it may be smaller
than the actual reserved size.
For example, as the existing comment describes, if a 3 GB area is
requested on a machine with 4 NUMA nodes that have memory, 1 GB is
allocated on the first three nodes, but the printed log is
hugetlb_cma: reserve 3072 MiB, up to 768 MiB per node
Round per_node up to (PAGE_SIZE << order) before logging so that the
printed log always matches the actual reserved size. No functional change
to the actual reservation size, as the following case analysis shows
1. remaining (hugetlb_cma_size - reserved) >= rounded per_node
- AS-IS: min() picks unrounded per_node;
round_up() returns rounded per_node
- TO-BE: min() picks rounded per_node;
round_up() returns rounded per_node (no-op)
2. remaining < unrounded per_node
- AS-IS: min() picks remaining;
round_up() returns round_up(remaining)
- TO-BE: min() picks remaining;
round_up() returns round_up(remaining)
3. unrounded per_node <= remaining < rounded per_node
- AS-IS: min() picks unrounded per_node;
round_up() returns rounded per_node
- TO-BE: min() picks remaining;
round_up() returns round_up(remaining) equals rounded per_node
Link: https://lore.kernel.org/20260422143353.852257-1-ekffu200098@gmail.com
Fixes: cf11e85fc08c ("mm: hugetlb: optionally allocate gigantic hugepages using cma") # 5.7
Signed-off-by: Sang-Heon Jeon <ekffu200098@gmail.com>
Reviewed-by: Muchun Song <muchun.song@linux.dev>
Cc: David Hildenbrand <david@kernel.org>
Cc: Oscar Salvador <osalvador@suse.de>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
[ applied the single-line addition to mm/hugetlb.c since mm/hugetlb_cma.c didn't exist yet in 6.12 ]
Signed-off-by: Sasha Levin <sashal@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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commit 1e68eb96e8beb1abefd12dd22c5637795d8a877e upstream.
Patch series "mm/damon/sysfs-schemes: fix use-after-free for [memcg_]path".
Reads of 'memcg_path' and 'path' files in DAMON sysfs interface could race
with their writes, results in use-after-free. Fix those.
This patch (of 2):
damon_sysfs_scheme_filter->mmecg_path can be read and written by users,
via DAMON sysfs memcg_path file. It can also be indirectly read, for the
parameters {on,off}line committing to DAMON. The reads for parameters
committing are protected by damon_sysfs_lock to avoid the sysfs files
being destroyed while any of the parameters are being read. But the
user-driven direct reads and writes are not protected by any lock, while
the write is deallocating the memcg_path-pointing buffer. As a result,
the readers could read the already freed buffer (user-after-free). Note
that the user-reads don't race when the same open file is used by the
writer, due to kernfs's open file locking. Nonetheless, doing the reads
and writes with separate open files would be common. Fix it by protecting
both the user-direct reads and writes with damon_sysfs_lock.
Link: https://lore.kernel.org/20260423150253.111520-1-sj@kernel.org
Link: https://lore.kernel.org/20260423150253.111520-2-sj@kernel.org
Fixes: 4f489fe6afb3 ("mm/damon/sysfs-schemes: free old damon_sysfs_scheme_filter->memcg_path on write")
Co-developed-by: Junxi Qian <qjx1298677004@gmail.com>
Signed-off-by: Junxi Qian <qjx1298677004@gmail.com>
Signed-off-by: SeongJae Park <sj@kernel.org>
Cc: <stable@vger.kernel.org> # 6.16.x
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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commit 049a57421dd67a28c45ae7e92c36df758033e5fa upstream.
damos_adjust_quota() uses time_after_eq() to show if it is time to start a
new quota charge window, comparing the current jiffies and the scheduled
next charge window start time. If it is, the next charge window start
time is updated and the new charge window starts.
The time check and next window start time update is skipped while the
scheme is deactivated by the watermarks. Let's suppose the deactivation
is kept more than LONG_MAX jiffies (assuming CONFIG_HZ of 250, more than
99 days in 32 bit systems and more than one billion years in 64 bit
systems), resulting in having the jiffies larger than the next charge
window start time + LONG_MAX. Then, the time_after_eq() call can return
false until another LONG_MAX jiffies are passed.
This means the scheme can continue working after being reactivated by the
watermarks. But, soon, the quota will be exceeded and the scheme will
again effectively stop working until the next charge window starts.
Because the current charge window is extended to up to LONG_MAX jiffies,
however, it will look like it stopped unexpectedly and indefinitely, from
the user's perspective.
Fix this by using !time_in_range_open() instead.
The issue was discovered [1] by sashiko.
Link: https://lore.kernel.org/20260329152306.45796-1-sj@kernel.org
Link: https://lore.kernel.org/20260324040722.57944-1-sj@kernel.org [1]
Fixes: ee801b7dd782 ("mm/damon/schemes: activate schemes based on a watermarks mechanism")
Signed-off-by: SeongJae Park <sj@kernel.org>
Cc: <stable@vger.kernel.org> # 5.16.x
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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commit 8f5857be99f1ed1fa80991c72449541f634626ee upstream.
cgwb_release_workfn() calls css_put(wb->blkcg_css) and then later accesses
wb->blkcg_css again via blkcg_unpin_online(). If css_put() drops the last
reference, the blkcg can be freed asynchronously (css_free_rwork_fn ->
blkcg_css_free -> kfree) before blkcg_unpin_online() dereferences the
pointer to access blkcg->online_pin, resulting in a use-after-free:
BUG: KASAN: slab-use-after-free in blkcg_unpin_online (./include/linux/instrumented.h:112 ./include/linux/atomic/atomic-instrumented.h:400 ./include/linux/refcount.h:389 ./include/linux/refcount.h:432 ./include/linux/refcount.h:450 block/blk-cgroup.c:1367)
Write of size 4 at addr ff11000117aa6160 by task kworker/71:1/531
Workqueue: cgwb_release cgwb_release_workfn
Call Trace:
<TASK>
blkcg_unpin_online (./include/linux/instrumented.h:112 ./include/linux/atomic/atomic-instrumented.h:400 ./include/linux/refcount.h:389 ./include/linux/refcount.h:432 ./include/linux/refcount.h:450 block/blk-cgroup.c:1367)
cgwb_release_workfn (mm/backing-dev.c:629)
process_scheduled_works (kernel/workqueue.c:3278 kernel/workqueue.c:3385)
Freed by task 1016:
kfree (./include/linux/kasan.h:235 mm/slub.c:2689 mm/slub.c:6246 mm/slub.c:6561)
css_free_rwork_fn (kernel/cgroup/cgroup.c:5542)
process_scheduled_works (kernel/workqueue.c:3302 kernel/workqueue.c:3385)
** Stack based on commit 66672af7a095 ("Add linux-next specific files
for 20260410")
I am seeing this crash sporadically in Meta fleet across multiple kernel
versions. A full reproducer is available at:
https://github.com/leitao/debug/blob/main/reproducers/repro_blkcg_uaf.sh
(The race window is narrow. To make it easily reproducible, inject a
msleep(100) between css_put() and blkcg_unpin_online() in
cgwb_release_workfn(). With that delay and a KASAN-enabled kernel, the
reproducer triggers the splat reliably in less than a second.)
Fix this by moving blkcg_unpin_online() before css_put(), so the
cgwb's CSS reference keeps the blkcg alive while blkcg_unpin_online()
accesses it.
Link: https://lore.kernel.org/20260413-blkcg-v1-1-35b72622d16c@debian.org
Fixes: 59b57717fff8 ("blkcg: delay blkg destruction until after writeback has finished")
Signed-off-by: Breno Leitao <leitao@debian.org>
Reviewed-by: Dennis Zhou <dennis@kernel.org>
Reviewed-by: Shakeel Butt <shakeel.butt@linux.dev>
Cc: David Hildenbrand <david@kernel.org>
Cc: Jens Axboe <axboe@kernel.dk>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Josef Bacik <josef@toxicpanda.com>
Cc: JP Kobryn <inwardvessel@gmail.com>
Cc: Liam Howlett <liam.howlett@oracle.com>
Cc: Lorenzo Stoakes (Oracle) <ljs@kernel.org>
Cc: Martin KaFai Lau <martin.lau@linux.dev>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Mike Rapoport <rppt@kernel.org>
Cc: Suren Baghdasaryan <surenb@google.com>
Cc: Tejun Heo <tj@kernel.org>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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commit 51d8c78be0c27ddb91bc2c0263941d8b30a47d3b upstream.
kasan_free_pxd() assumes the page table is always struct page aligned.
But that's not always the case for all architectures. E.g. In case of
powerpc with 64K pagesize, PUD table (of size 4096) comes from slab cache
named pgtable-2^9. Hence instead of page_to_virt(pxd_page()) let's just
directly pass the start of the pxd table which is passed as the 1st
argument.
This fixes the below double free kasan issue seen with PMEM:
radix-mmu: Mapped 0x0000047d10000000-0x0000047f90000000 with 2.00 MiB pages
==================================================================
BUG: KASAN: double-free in kasan_remove_zero_shadow+0x9c4/0xa20
Free of addr c0000003c38e0000 by task ndctl/2164
CPU: 34 UID: 0 PID: 2164 Comm: ndctl Not tainted 6.19.0-rc1-00048-gea1013c15392 #157 VOLUNTARY
Hardware name: IBM,9080-HEX POWER10 (architected) 0x800200 0xf000006 of:IBM,FW1060.00 (NH1060_012) hv:phyp pSeries
Call Trace:
dump_stack_lvl+0x88/0xc4 (unreliable)
print_report+0x214/0x63c
kasan_report_invalid_free+0xe4/0x110
check_slab_allocation+0x100/0x150
kmem_cache_free+0x128/0x6e0
kasan_remove_zero_shadow+0x9c4/0xa20
memunmap_pages+0x2b8/0x5c0
devm_action_release+0x54/0x70
release_nodes+0xc8/0x1a0
devres_release_all+0xe0/0x140
device_unbind_cleanup+0x30/0x120
device_release_driver_internal+0x3e4/0x450
unbind_store+0xfc/0x110
drv_attr_store+0x78/0xb0
sysfs_kf_write+0x114/0x140
kernfs_fop_write_iter+0x264/0x3f0
vfs_write+0x3bc/0x7d0
ksys_write+0xa4/0x190
system_call_exception+0x190/0x480
system_call_vectored_common+0x15c/0x2ec
---- interrupt: 3000 at 0x7fff93b3d3f4
NIP: 00007fff93b3d3f4 LR: 00007fff93b3d3f4 CTR: 0000000000000000
REGS: c0000003f1b07e80 TRAP: 3000 Not tainted (6.19.0-rc1-00048-gea1013c15392)
MSR: 800000000280f033 <SF,VEC,VSX,EE,PR,FP,ME,IR,DR,RI,LE> CR: 48888208 XER: 00000000
<...>
NIP [00007fff93b3d3f4] 0x7fff93b3d3f4
LR [00007fff93b3d3f4] 0x7fff93b3d3f4
---- interrupt: 3000
The buggy address belongs to the object at c0000003c38e0000
which belongs to the cache pgtable-2^9 of size 4096
The buggy address is located 0 bytes inside of
4096-byte region [c0000003c38e0000, c0000003c38e1000)
The buggy address belongs to the physical page:
page: refcount:0 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x3c38c
head: order:2 mapcount:0 entire_mapcount:0 nr_pages_mapped:0 pincount:0
memcg:c0000003bfd63e01
flags: 0x63ffff800000040(head|node=6|zone=0|lastcpupid=0x7ffff)
page_type: f5(slab)
raw: 063ffff800000040 c000000140058980 5deadbeef0000122 0000000000000000
raw: 0000000000000000 0000000080200020 00000000f5000000 c0000003bfd63e01
head: 063ffff800000040 c000000140058980 5deadbeef0000122 0000000000000000
head: 0000000000000000 0000000080200020 00000000f5000000 c0000003bfd63e01
head: 063ffff800000002 c00c000000f0e301 00000000ffffffff 00000000ffffffff
head: ffffffffffffffff 0000000000000000 00000000ffffffff 0000000000000004
page dumped because: kasan: bad access detected
[ 138.953636] [ T2164] Memory state around the buggy address:
[ 138.953643] [ T2164] c0000003c38dff00: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
[ 138.953652] [ T2164] c0000003c38dff80: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
[ 138.953661] [ T2164] >c0000003c38e0000: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
[ 138.953669] [ T2164] ^
[ 138.953675] [ T2164] c0000003c38e0080: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
[ 138.953684] [ T2164] c0000003c38e0100: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
[ 138.953692] [ T2164] ==================================================================
[ 138.953701] [ T2164] Disabling lock debugging due to kernel taint
Link: https://lkml.kernel.org/r/2f9135c7866c6e0d06e960993b8a5674a9ebc7ec.1771938394.git.ritesh.list@gmail.com
Fixes: 0207df4fa1a8 ("kernel/memremap, kasan: make ZONE_DEVICE with work with KASAN")
Signed-off-by: Ritesh Harjani (IBM) <ritesh.list@gmail.com>
Reported-by: Venkat Rao Bagalkote <venkat88@linux.ibm.com>
Reviewed-by: Alexander Potapenko <glider@google.com>
Cc: Andrey Konovalov <andreyknvl@gmail.com>
Cc: Andrey Ryabinin <ryabinin.a.a@gmail.com>
Cc: Dmitry Vyukov <dvyukov@google.com>
Cc: "Ritesh Harjani (IBM)" <ritesh.list@gmail.com>
Cc: Vincenzo Frascino <vincenzo.frascino@arm.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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commit f58df566524ebcdfa394329c64f47e3c9257516e upstream.
When running stress-ng on my Arm64 machine with v7.0-rc3 kernel, I
encountered some very strange crash issues showing up as "Bad page state":
"
[ 734.496287] BUG: Bad page state in process stress-ng-env pfn:415735fb
[ 734.496427] page: refcount:0 mapcount:1 mapping:0000000000000000 index:0x4cf316 pfn:0x415735fb
[ 734.496434] flags: 0x57fffe000000800(owner_2|node=1|zone=2|lastcpupid=0x3ffff)
[ 734.496439] raw: 057fffe000000800 0000000000000000 dead000000000122 0000000000000000
[ 734.496440] raw: 00000000004cf316 0000000000000000 0000000000000000 0000000000000000
[ 734.496442] page dumped because: nonzero mapcount
"
After analyzing this page’s state, it is hard to understand why the
mapcount is not 0 while the refcount is 0, since this page is not where
the issue first occurred. By enabling the CONFIG_DEBUG_VM config, I can
reproduce the crash as well and captured the first warning where the issue
appears:
"
[ 734.469226] page: refcount:33 mapcount:0 mapping:00000000bef2d187 index:0x81a0 pfn:0x415735c0
[ 734.469304] head: order:5 mapcount:0 entire_mapcount:0 nr_pages_mapped:0 pincount:0
[ 734.469315] memcg:ffff000807a8ec00
[ 734.469320] aops:ext4_da_aops ino:100b6f dentry name(?):"stress-ng-mmaptorture-9397-0-2736200540"
[ 734.469335] flags: 0x57fffe400000069(locked|uptodate|lru|head|node=1|zone=2|lastcpupid=0x3ffff)
......
[ 734.469364] page dumped because: VM_WARN_ON_FOLIO((_Generic((page + nr_pages - 1),
const struct page *: (const struct folio *)_compound_head(page + nr_pages - 1), struct page *:
(struct folio *)_compound_head(page + nr_pages - 1))) != folio)
[ 734.469390] ------------[ cut here ]------------
[ 734.469393] WARNING: ./include/linux/rmap.h:351 at folio_add_file_rmap_ptes+0x3b8/0x468,
CPU#90: stress-ng-mlock/9430
[ 734.469551] folio_add_file_rmap_ptes+0x3b8/0x468 (P)
[ 734.469555] set_pte_range+0xd8/0x2f8
[ 734.469566] filemap_map_folio_range+0x190/0x400
[ 734.469579] filemap_map_pages+0x348/0x638
[ 734.469583] do_fault_around+0x140/0x198
......
[ 734.469640] el0t_64_sync+0x184/0x188
"
The code that triggers the warning is: "VM_WARN_ON_FOLIO(page_folio(page +
nr_pages - 1) != folio, folio)", which indicates that set_pte_range()
tried to map beyond the large folio’s size.
By adding more debug information, I found that 'nr_pages' had overflowed
in filemap_map_pages(), causing set_pte_range() to establish mappings for
a range exceeding the folio size, potentially corrupting fields of pages
that do not belong to this folio (e.g., page->_mapcount).
After above analysis, I think the possible race is as follows:
CPU 0 CPU 1
filemap_map_pages() ext4_setattr()
//get and lock folio with old inode->i_size
next_uptodate_folio()
.......
//shrink the inode->i_size
i_size_write(inode, attr->ia_size);
//calculate the end_pgoff with the new inode->i_size
file_end = DIV_ROUND_UP(i_size_read(mapping->host), PAGE_SIZE) - 1;
end_pgoff = min(end_pgoff, file_end);
......
//nr_pages can be overflowed, cause xas.xa_index > end_pgoff
end = folio_next_index(folio) - 1;
nr_pages = min(end, end_pgoff) - xas.xa_index + 1;
......
//map large folio
filemap_map_folio_range()
......
//truncate folios
truncate_pagecache(inode, inode->i_size);
To fix this issue, move the 'end_pgoff' calculation before
next_uptodate_folio(), so the retrieved folio stays consistent with the
file end to avoid 'nr_pages' calculation overflow. After this patch, the
crash issue is gone.
Link: https://lkml.kernel.org/r/1cf1ac59018fc647a87b0dad605d4056a71c14e4.1773739704.git.baolin.wang@linux.alibaba.com
Fixes: 743a2753a02e ("filemap: cap PTE range to be created to allowed zero fill in folio_map_range()")
Signed-off-by: Baolin Wang <baolin.wang@linux.alibaba.com>
Reported-by: Yuanhe Shu <xiangzao@linux.alibaba.com>
Tested-by: Yuanhe Shu <xiangzao@linux.alibaba.com>
Acked-by: Kiryl Shutsemau (Meta) <kas@kernel.org>
Acked-by: David Hildenbrand (Arm) <david@kernel.org>
Cc: Christian Brauner <brauner@kernel.org>
Cc: Daniel Gomez <da.gomez@samsung.com>
Cc: "Darrick J. Wong" <djwong@kernel.org>
Cc: Dave Chinner <dchinner@redhat.com>
Cc: David Howells <dhowells@redhat.com>
Cc: Hannes Reinecke <hare@suse.de>
Cc: Lorenzo Stoakes (Oracle) <ljs@kernel.org>
Cc: Luis Chamberalin <mcgrof@kernel.org>
Cc: Matthew Wilcox (Oracle) <willy@infradead.org>
Cc: Pankaj Raghav <p.raghav@samsung.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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commit 1bfe9fb5ed2667fb075682408b776b5273162615 upstream.
Multiple sysfs command paths dereference contexts_arr[0] without first
verifying that kdamond->contexts->nr == 1. A user can set nr_contexts to
0 via sysfs while DAMON is running, causing NULL pointer dereferences.
In more detail, the issue can be triggered by privileged users like
below.
First, start DAMON and make contexts directory empty
(kdamond->contexts->nr == 0).
# damo start
# cd /sys/kernel/mm/damon/admin/kdamonds/0
# echo 0 > contexts/nr_contexts
Then, each of below commands will cause the NULL pointer dereference.
# echo update_schemes_stats > state
# echo update_schemes_tried_regions > state
# echo update_schemes_tried_bytes > state
# echo update_schemes_effective_quotas > state
# echo update_tuned_intervals > state
Guard all commands (except OFF) at the entry point of
damon_sysfs_handle_cmd().
Link: https://lkml.kernel.org/r/20260321175427.86000-3-sj@kernel.org
Fixes: 0ac32b8affb5 ("mm/damon/sysfs: support DAMOS stats")
Signed-off-by: Josh Law <objecting@objecting.org>
Reviewed-by: SeongJae Park <sj@kernel.org>
Signed-off-by: SeongJae Park <sj@kernel.org>
Cc: <stable@vger.kernel.org> [5.18+]
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: SeongJae Park <sj@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
|
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The backport of commit 091c1dd2d4df ("mm/mempolicy: fix migrate_to_node()
assuming there is at least one VMA in a MM") contains an error:
migrate_to_node() does not lock the mmap_lock itself, that is handled by
the caller instead.
So let's drop the wrong mmap_read_unlock(). Fortunately, this path is
very hard to hit in practice.
Fixes: a13b2b9b0b0b ("mm/mempolicy: fix migrate_to_node() assuming there is at least one VMA in a MM")
Reported-by: Li Ying <liying3@sungrowpower.com>
Closes: https://lore.kernel.org/r/aaZgUNxAyKC2IwuG@casper.infradead.org
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Christoph Lameter <cl@linux.com>
Cc: <stable@vger.kernel.org>
Reviewed-by: Gregory Price <gourry@gourry.net>
Reviewed-by: Liam R. Howlett <Liam.Howlett@Oracle.com>
Signed-off-by: David Hildenbrand (Arm) <david@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
|
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[ Upstream commit d155aab90fffa00f93cea1f107aef0a3d548b2ff ]
When KASAN hardware tags are enabled, re-enabling KFENCE late (via
/sys/module/kfence/parameters/sample_interval) causes KASAN faults.
This happens because the KFENCE pool and metadata are allocated via the
page allocator, which tags the memory, while KFENCE continues to access it
using untagged pointers during initialization.
Use __GFP_SKIP_KASAN for late KFENCE pool and metadata allocations to
ensure the memory remains untagged, consistent with early allocations from
memblock. To support this, add __GFP_SKIP_KASAN to the allowlist in
__alloc_contig_verify_gfp_mask().
Link: https://lkml.kernel.org/r/20260220144940.2779209-1-glider@google.com
Fixes: 0ce20dd84089 ("mm: add Kernel Electric-Fence infrastructure")
Signed-off-by: Alexander Potapenko <glider@google.com>
Suggested-by: Ernesto Martinez Garcia <ernesto.martinezgarcia@tugraz.at>
Cc: Andrey Konovalov <andreyknvl@gmail.com>
Cc: Andrey Ryabinin <ryabinin.a.a@gmail.com>
Cc: Dmitry Vyukov <dvyukov@google.com>
Cc: Greg KH <gregkh@linuxfoundation.org>
Cc: Kees Cook <kees@kernel.org>
Cc: Marco Elver <elver@google.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
[ dropped page_alloc.c hunk adding __GFP_SKIP_KASAN ]
Signed-off-by: Sasha Levin <sashal@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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commit 09833d99db36d74456a4d13eb29c32d56ff8f2b6 upstream.
KFENCE does not currently support KASAN hardware tags. As a result, the
two features are incompatible when enabled simultaneously.
Given that MTE provides deterministic protection and KFENCE is a
sampling-based debugging tool, prioritize the stronger hardware
protections. Disable KFENCE initialization and free the pre-allocated
pool if KASAN hardware tags are detected to ensure the system maintains
the security guarantees provided by MTE.
Link: https://lkml.kernel.org/r/20260213095410.1862978-1-glider@google.com
Fixes: 0ce20dd84089 ("mm: add Kernel Electric-Fence infrastructure")
Signed-off-by: Alexander Potapenko <glider@google.com>
Suggested-by: Marco Elver <elver@google.com>
Reviewed-by: Marco Elver <elver@google.com>
Cc: Andrey Konovalov <andreyknvl@gmail.com>
Cc: Andrey Ryabinin <ryabinin.a.a@gmail.com>
Cc: Dmitry Vyukov <dvyukov@google.com>
Cc: Ernesto Martinez Garcia <ernesto.martinezgarcia@tugraz.at>
Cc: Greg KH <gregkh@linuxfoundation.org>
Cc: Kees Cook <kees@kernel.org>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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[ Upstream commit 94350fe6cad77b46c3dcb8c96543bef7647efbc0 ]
This changes fixes following build error which is a miss from ef6e06b2ef87
("highmem: fix kmap_to_page() for kmap_local_page() addresses").
mm/highmem.c:184:66: error: 'pteval' undeclared (first use in this
function); did you mean 'pte_val'?
184 | idx = arch_kmap_local_map_idx(i, pte_pfn(pteval));
In __kmap_to_page(), pteval is used but does not exist in the function.
(akpm: affects xtensa only)
Link: https://lkml.kernel.org/r/SJ0PR07MB86317E00EC0C59DA60935FDCD18DA@SJ0PR07MB8631.namprd07.prod.outlook.com
Fixes: ef6e06b2ef87 ("highmem: fix kmap_to_page() for kmap_local_page() addresses")
Signed-off-by: William Tambe <williamt@cadence.com>
Reviewed-by: Max Filippov <jcmvbkbc@gmail.com>
Cc: Chris Zankel <chris@zankel.net>
Cc: Max Filippov <jcmvbkbc@gmail.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
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[ Upstream commit 9c9828d3ead69416d731b1238802af31760c823e ]
Since commit cc638f329ef6 ("mm, thp: tweak reclaim/compaction effort of
local-only and all-node allocations"), THP page fault allocations have
settled on the following scheme (from the commit log):
1. local node only THP allocation with no reclaim, just compaction.
2. for madvised VMA's or when synchronous compaction is enabled always - THP
allocation from any node with effort determined by global defrag setting
and VMA madvise
3. fallback to base pages on any node
Recent customer reports however revealed we have a gap in step 1 above.
What we have seen is excessive reclaim due to THP page faults on a NUMA
node that's close to its high watermark, while other nodes have plenty of
free memory.
The problem with step 1 is that it promises no reclaim after the
compaction attempt, however reclaim is only avoided for certain compaction
outcomes (deferred, or skipped due to insufficient free base pages), and
not e.g. when compaction is actually performed but fails (we did see
compact_fail vmstat counter increasing).
THP page faults can therefore exhibit a zone_reclaim_mode-like behavior,
which is not the intention.
Thus add a check for __GFP_THISNODE that corresponds to this exact
situation and prevents continuing with reclaim/compaction once the initial
compaction attempt isn't successful in allocating the page.
Note that commit cc638f329ef6 has not introduced this over-reclaim
possibility; it appears to exist in some form since commit 2f0799a0ffc0
("mm, thp: restore node-local hugepage allocations"). Followup commits
b39d0ee2632d ("mm, page_alloc: avoid expensive reclaim when compaction may
not succeed") and cc638f329ef6 have moved in the right direction, but left
the abovementioned gap.
Link: https://lkml.kernel.org/r/20251219-costly-noretry-thisnode-fix-v1-1-e1085a4a0c34@suse.cz
Fixes: 2f0799a0ffc0 ("mm, thp: restore node-local hugepage allocations")
Signed-off-by: Vlastimil Babka <vbabka@suse.cz>
Acked-by: Michal Hocko <mhocko@suse.com>
Acked-by: Johannes Weiner <hannes@cmpxchg.org>
Acked-by: Pedro Falcato <pfalcato@suse.de>
Acked-by: Zi Yan <ziy@nvidia.com>
Cc: Brendan Jackman <jackmanb@google.com>
Cc: "David Hildenbrand (Red Hat)" <david@kernel.org>
Cc: David Rientjes <rientjes@google.com>
Cc: Joshua Hahn <joshua.hahnjy@gmail.com>
Cc: Liam Howlett <liam.howlett@oracle.com>
Cc: Lorenzo Stoakes <lorenzo.stoakes@oracle.com>
Cc: Mike Rapoport <rppt@kernel.org>
Cc: Suren Baghdasaryan <surenb@google.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
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mmu_gather
commit 8ce720d5bd91e9dc16db3604aa4b1bf76770a9a1 upstream.
As reported, ever since commit 1013af4f585f ("mm/hugetlb: fix
huge_pmd_unshare() vs GUP-fast race") we can end up in some situations
where we perform so many IPI broadcasts when unsharing hugetlb PMD page
tables that it severely regresses some workloads.
In particular, when we fork()+exit(), or when we munmap() a large
area backed by many shared PMD tables, we perform one IPI broadcast per
unshared PMD table.
There are two optimizations to be had:
(1) When we process (unshare) multiple such PMD tables, such as during
exit(), it is sufficient to send a single IPI broadcast (as long as
we respect locking rules) instead of one per PMD table.
Locking prevents that any of these PMD tables could get reused before
we drop the lock.
(2) When we are not the last sharer (> 2 users including us), there is
no need to send the IPI broadcast. The shared PMD tables cannot
become exclusive (fully unshared) before an IPI will be broadcasted
by the last sharer.
Concurrent GUP-fast could walk into a PMD table just before we
unshared it. It could then succeed in grabbing a page from the
shared page table even after munmap() etc succeeded (and supressed
an IPI). But there is not difference compared to GUP-fast just
sleeping for a while after grabbing the page and re-enabling IRQs.
Most importantly, GUP-fast will never walk into page tables that are
no-longer shared, because the last sharer will issue an IPI
broadcast.
(if ever required, checking whether the PUD changed in GUP-fast
after grabbing the page like we do in the PTE case could handle
this)
So let's rework PMD sharing TLB flushing + IPI sync to use the mmu_gather
infrastructure so we can implement these optimizations and demystify the
code at least a bit. Extend the mmu_gather infrastructure to be able to
deal with our special hugetlb PMD table sharing implementation.
To make initialization of the mmu_gather easier when working on a single
VMA (in particular, when dealing with hugetlb), provide
tlb_gather_mmu_vma().
We'll consolidate the handling for (full) unsharing of PMD tables in
tlb_unshare_pmd_ptdesc() and tlb_flush_unshared_tables(), and track
in "struct mmu_gather" whether we had (full) unsharing of PMD tables.
Because locking is very special (concurrent unsharing+reuse must be
prevented), we disallow deferring flushing to tlb_finish_mmu() and instead
require an explicit earlier call to tlb_flush_unshared_tables().
From hugetlb code, we call huge_pmd_unshare_flush() where we make sure
that the expected lock protecting us from concurrent unsharing+reuse is
still held.
Check with a VM_WARN_ON_ONCE() in tlb_finish_mmu() that
tlb_flush_unshared_tables() was properly called earlier.
Document it all properly.
Notes about tlb_remove_table_sync_one() interaction with unsharing:
There are two fairly tricky things:
(1) tlb_remove_table_sync_one() is a NOP on architectures without
CONFIG_MMU_GATHER_RCU_TABLE_FREE.
Here, the assumption is that the previous TLB flush would send an
IPI to all relevant CPUs. Careful: some architectures like x86 only
send IPIs to all relevant CPUs when tlb->freed_tables is set.
The relevant architectures should be selecting
MMU_GATHER_RCU_TABLE_FREE, but x86 might not do that in stable
kernels and it might have been problematic before this patch.
Also, the arch flushing behavior (independent of IPIs) is different
when tlb->freed_tables is set. Do we have to enlighten them to also
take care of tlb->unshared_tables? So far we didn't care, so
hopefully we are fine. Of course, we could be setting
tlb->freed_tables as well, but that might then unnecessarily flush
too much, because the semantics of tlb->freed_tables are a bit
fuzzy.
This patch changes nothing in this regard.
(2) tlb_remove_table_sync_one() is not a NOP on architectures with
CONFIG_MMU_GATHER_RCU_TABLE_FREE that actually don't need a sync.
Take x86 as an example: in the common case (!pv, !X86_FEATURE_INVLPGB)
we still issue IPIs during TLB flushes and don't actually need the
second tlb_remove_table_sync_one().
This optimized can be implemented on top of this, by checking e.g., in
tlb_remove_table_sync_one() whether we really need IPIs. But as
described in (1), it really must honor tlb->freed_tables then to
send IPIs to all relevant CPUs.
Notes on TLB flushing changes:
(1) Flushing for non-shared PMD tables
We're converting from flush_hugetlb_tlb_range() to
tlb_remove_huge_tlb_entry(). Given that we properly initialize the
MMU gather in tlb_gather_mmu_vma() to be hugetlb aware, similar to
__unmap_hugepage_range(), that should be fine.
(2) Flushing for shared PMD tables
We're converting from various things (flush_hugetlb_tlb_range(),
tlb_flush_pmd_range(), flush_tlb_range()) to tlb_flush_pmd_range().
tlb_flush_pmd_range() achieves the same that
tlb_remove_huge_tlb_entry() would achieve in these scenarios.
Note that tlb_remove_huge_tlb_entry() also calls
__tlb_remove_tlb_entry(), however that is only implemented on
powerpc, which does not support PMD table sharing.
Similar to (1), tlb_gather_mmu_vma() should make sure that TLB
flushing keeps on working as expected.
Further, note that the ptdesc_pmd_pts_dec() in huge_pmd_share() is not a
concern, as we are holding the i_mmap_lock the whole time, preventing
concurrent unsharing. That ptdesc_pmd_pts_dec() usage will be removed
separately as a cleanup later.
There are plenty more cleanups to be had, but they have to wait until
this is fixed.
[david@kernel.org: fix kerneldoc]
Link: https://lkml.kernel.org/r/f223dd74-331c-412d-93fc-69e360a5006c@kernel.org
Link: https://lkml.kernel.org/r/20251223214037.580860-5-david@kernel.org
Fixes: 1013af4f585f ("mm/hugetlb: fix huge_pmd_unshare() vs GUP-fast race")
Signed-off-by: David Hildenbrand (Red Hat) <david@kernel.org>
Reported-by: "Uschakow, Stanislav" <suschako@amazon.de>
Closes: https://lore.kernel.org/all/4d3878531c76479d9f8ca9789dc6485d@amazon.de/
Tested-by: Laurence Oberman <loberman@redhat.com>
Acked-by: Harry Yoo <harry.yoo@oracle.com>
Reviewed-by: Lorenzo Stoakes <lorenzo.stoakes@oracle.com>
Cc: Lance Yang <lance.yang@linux.dev>
Cc: Liu Shixin <liushixin2@huawei.com>
Cc: Oscar Salvador <osalvador@suse.de>
Cc: Rik van Riel <riel@surriel.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: David Hildenbrand (Arm) <david@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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commit 3937027caecb4f8251e82dd857ba1d749bb5a428 upstream.
Ever since we stopped using the page count to detect shared PMD page
tables, these comments are outdated.
The only reason we have to flush the TLB early is because once we drop the
i_mmap_rwsem, the previously shared page table could get freed (to then
get reallocated and used for other purpose). So we really have to flush
the TLB before that could happen.
So let's simplify the comments a bit.
The "If we unshared PMDs, the TLB flush was not recorded in mmu_gather."
part introduced as in commit a4a118f2eead ("hugetlbfs: flush TLBs
correctly after huge_pmd_unshare") was confusing: sure it is recorded in
the mmu_gather, otherwise tlb_flush_mmu_tlbonly() wouldn't do anything.
So let's drop that comment while at it as well.
We'll centralize these comments in a single helper as we rework the code
next.
Link: https://lkml.kernel.org/r/20251223214037.580860-3-david@kernel.org
Fixes: 59d9094df3d7 ("mm: hugetlb: independent PMD page table shared count")
Signed-off-by: David Hildenbrand (Red Hat) <david@kernel.org>
Reviewed-by: Rik van Riel <riel@surriel.com>
Tested-by: Laurence Oberman <loberman@redhat.com>
Reviewed-by: Lorenzo Stoakes <lorenzo.stoakes@oracle.com>
Acked-by: Oscar Salvador <osalvador@suse.de>
Reviewed-by: Harry Yoo <harry.yoo@oracle.com>
Cc: Liu Shixin <liushixin2@huawei.com>
Cc: Lance Yang <lance.yang@linux.dev>
Cc: "Uschakow, Stanislav" <suschako@amazon.de>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: David Hildenbrand (Arm) <david@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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commit 14967a9c7d247841b0312c48dcf8cd29e55a4cc8 upstream.
commit 59d9094df3d79 ("mm: hugetlb: independent PMD page table shared
count") introduced ->pt_share_count dedicated to hugetlb PMD share count
tracking, but omitted fixing copy_hugetlb_page_range(), leaving the
function relying on page_count() for tracking that no longer works.
When lazy page table copy for hugetlb is disabled, that is, revert commit
bcd51a3c679d ("hugetlb: lazy page table copies in fork()") fork()'ing with
hugetlb PMD sharing quickly lockup -
[ 239.446559] watchdog: BUG: soft lockup - CPU#75 stuck for 27s!
[ 239.446611] RIP: 0010:native_queued_spin_lock_slowpath+0x7e/0x2e0
[ 239.446631] Call Trace:
[ 239.446633] <TASK>
[ 239.446636] _raw_spin_lock+0x3f/0x60
[ 239.446639] copy_hugetlb_page_range+0x258/0xb50
[ 239.446645] copy_page_range+0x22b/0x2c0
[ 239.446651] dup_mmap+0x3e2/0x770
[ 239.446654] dup_mm.constprop.0+0x5e/0x230
[ 239.446657] copy_process+0xd17/0x1760
[ 239.446660] kernel_clone+0xc0/0x3e0
[ 239.446661] __do_sys_clone+0x65/0xa0
[ 239.446664] do_syscall_64+0x82/0x930
[ 239.446668] ? count_memcg_events+0xd2/0x190
[ 239.446671] ? syscall_trace_enter+0x14e/0x1f0
[ 239.446676] ? syscall_exit_work+0x118/0x150
[ 239.446677] ? arch_exit_to_user_mode_prepare.constprop.0+0x9/0xb0
[ 239.446681] ? clear_bhb_loop+0x30/0x80
[ 239.446684] ? clear_bhb_loop+0x30/0x80
[ 239.446686] entry_SYSCALL_64_after_hwframe+0x76/0x7e
There are two options to resolve the potential latent issue:
1. warn against PMD sharing in copy_hugetlb_page_range(),
2. fix it.
This patch opts for the second option.
While at it, simplify the comment, the details are not actually relevant
anymore.
Link: https://lkml.kernel.org/r/20250916004520.1604530-1-jane.chu@oracle.com
Fixes: 59d9094df3d7 ("mm: hugetlb: independent PMD page table shared count")
Signed-off-by: Jane Chu <jane.chu@oracle.com>
Reviewed-by: Harry Yoo <harry.yoo@oracle.com>
Acked-by: Oscar Salvador <osalvador@suse.de>
Acked-by: David Hildenbrand <david@redhat.com>
Cc: Jann Horn <jannh@google.com>
Cc: Liu Shixin <liushixin2@huawei.com>
Cc: Muchun Song <muchun.song@linux.dev>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: David Hildenbrand (Arm) <david@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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commit 870ff19251bf3910dda7a7245da826924045fedd upstream.
Randomize the KFENCE freelist during pool initialization to make
allocation patterns less predictable. This is achieved by shuffling the
order in which metadata objects are added to the freelist using
get_random_u32_below().
Additionally, ensure the error path correctly calculates the address range
to be reset if initialization fails, as the address increment logic has
been moved to a separate loop.
Link: https://lkml.kernel.org/r/20260120161510.3289089-1-pimyn@google.com
Fixes: 0ce20dd84089 ("mm: add Kernel Electric-Fence infrastructure")
Signed-off-by: Pimyn Girgis <pimyn@google.com>
Reviewed-by: Alexander Potapenko <glider@google.com>
Cc: Dmitry Vyukov <dvyukov@google.com>
Cc: Marco Elver <elver@google.com>
Cc: Ernesto Martnez Garca <ernesto.martinezgarcia@tugraz.at>
Cc: Greg KH <gregkh@linuxfoundation.org>
Cc: Kees Cook <kees@kernel.org>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Pimyn Girgis <pimyn@google.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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