<feed xmlns='http://www.w3.org/2005/Atom'>
<title>kernel/linux.git/include/trace/events/mmflags.h, branch v6.19.11</title>
<subtitle>Linux kernel stable tree (mirror)</subtitle>
<id>https://git.radix-linux.su/kernel/linux.git/atom?h=v6.19.11</id>
<link rel='self' href='https://git.radix-linux.su/kernel/linux.git/atom?h=v6.19.11'/>
<link rel='alternate' type='text/html' href='https://git.radix-linux.su/kernel/linux.git/'/>
<updated>2025-11-20T21:43:58+00:00</updated>
<entry>
<title>mm: introduce VM_MAYBE_GUARD and make visible in /proc/$pid/smaps</title>
<updated>2025-11-20T21:43:58+00:00</updated>
<author>
<name>Lorenzo Stoakes</name>
<email>lorenzo.stoakes@oracle.com</email>
</author>
<published>2025-11-18T10:17:43+00:00</published>
<link rel='alternate' type='text/html' href='https://git.radix-linux.su/kernel/linux.git/commit/?id=5dba5cc2e0ffa76f2f6c8922a04469dc9602c396'/>
<id>urn:sha1:5dba5cc2e0ffa76f2f6c8922a04469dc9602c396</id>
<content type='text'>
Patch series "introduce VM_MAYBE_GUARD and make it sticky", v4.

Currently, guard regions are not visible to users except through
/proc/$pid/pagemap, with no explicit visibility at the VMA level.

This makes the feature less useful, as it isn't entirely apparent which
VMAs may have these entries present, especially when performing actions
which walk through memory regions such as those performed by CRIU.

This series addresses this issue by introducing the VM_MAYBE_GUARD flag
which fulfils this role, updating the smaps logic to display an entry for
these.

The semantics of this flag are that a guard region MAY be present if set
(we cannot be sure, as we can't efficiently track whether an
MADV_GUARD_REMOVE finally removes all the guard regions in a VMA) - but if
not set the VMA definitely does NOT have any guard regions present.

It's problematic to establish this flag without further action, because
that means that VMAs with guard regions in them become non-mergeable with
adjacent VMAs for no especially good reason.

To work around this, this series also introduces the concept of 'sticky'
VMA flags - that is flags which:

a. if set in one VMA and not in another still permit those VMAs to be
   merged (if otherwise compatible).

b. When they are merged, the resultant VMA must have the flag set.

The VMA logic is updated to propagate these flags correctly.

Additionally, VM_MAYBE_GUARD being an explicit VMA flag allows us to solve
an issue with file-backed guard regions - previously these established an
anon_vma object for file-backed mappings solely to have vma_needs_copy()
correctly propagate guard region mappings to child processes.

We introduce a new flag alias VM_COPY_ON_FORK (which currently only
specifies VM_MAYBE_GUARD) and update vma_needs_copy() to check explicitly
for this flag and to copy page tables if it is present, which resolves
this issue.

Additionally, we add the ability for allow-listed VMA flags to be
atomically writable with only mmap/VMA read locks held.

The only flag we allow so far is VM_MAYBE_GUARD, which we carefully ensure
does not cause any races by being allowed to do so.

This allows us to maintain guard region installation as a read-locked
operation and not endure the overhead of obtaining a write lock here.

Finally we introduce extensive VMA userland tests to assert that the
sticky VMA logic behaves correctly as well as guard region self tests to
assert that smaps visibility is correctly implemented.


This patch (of 9):

Currently, if a user needs to determine if guard regions are present in a
range, they have to scan all VMAs (or have knowledge of which ones might
have guard regions).

Since commit 8e2f2aeb8b48 ("fs/proc/task_mmu: add guard region bit to
pagemap") and the related commit a516403787e0 ("fs/proc: extend the
PAGEMAP_SCAN ioctl to report guard regions"), users can use either
/proc/$pid/pagemap or the PAGEMAP_SCAN functionality to perform this
operation at a virtual address level.

This is not ideal, and it gives no visibility at a /proc/$pid/smaps level
that guard regions exist in ranges.

This patch remedies the situation by establishing a new VMA flag,
VM_MAYBE_GUARD, to indicate that a VMA may contain guard regions (it is
uncertain because we cannot reasonably determine whether a
MADV_GUARD_REMOVE call has removed all of the guard regions in a VMA, and
additionally VMAs may change across merge/split).

We utilise 0x800 for this flag which makes it available to 32-bit
architectures also, a flag that was previously used by VM_DENYWRITE, which
was removed in commit 8d0920bde5eb ("mm: remove VM_DENYWRITE") and hasn't
bee reused yet.

We also update the smaps logic and documentation to identify these VMAs.

Another major use of this functionality is that we can use it to identify
that we ought to copy page tables on fork.

We do not actually implement usage of this flag in mm/madvise.c yet as we
need to allow some VMA flags to be applied atomically under mmap/VMA read
lock in order to avoid the need to acquire a write lock for this purpose.

Link: https://lkml.kernel.org/r/cover.1763460113.git.lorenzo.stoakes@oracle.com
Link: https://lkml.kernel.org/r/cf8ef821eba29b6c5b5e138fffe95d6dcabdedb9.1763460113.git.lorenzo.stoakes@oracle.com
Signed-off-by: Lorenzo Stoakes &lt;lorenzo.stoakes@oracle.com&gt;
Reviewed-by: Pedro Falcato &lt;pfalcato@suse.de&gt;
Reviewed-by: Vlastimil Babka &lt;vbabka@suse.cz&gt;
Acked-by: David Hildenbrand (Red Hat) &lt;david@kernel.org&gt;
Reviewed-by: Lance Yang &lt;lance.yang@linux.dev&gt;
Cc: Andrei Vagin &lt;avagin@gmail.com&gt;
Cc: Baolin Wang &lt;baolin.wang@linux.alibaba.com&gt;
Cc: Barry Song &lt;baohua@kernel.org&gt;
Cc: Dev Jain &lt;dev.jain@arm.com&gt;
Cc: Jann Horn &lt;jannh@google.com&gt;
Cc: Jonathan Corbet &lt;corbet@lwn.net&gt;
Cc: Liam Howlett &lt;liam.howlett@oracle.com&gt;
Cc: "Masami Hiramatsu (Google)" &lt;mhiramat@kernel.org&gt;
Cc: Mathieu Desnoyers &lt;mathieu.desnoyers@efficios.com&gt;
Cc: Michal Hocko &lt;mhocko@suse.com&gt;
Cc: Mike Rapoport &lt;rppt@kernel.org&gt;
Cc: Nico Pache &lt;npache@redhat.com&gt;
Cc: Ryan Roberts &lt;ryan.roberts@arm.com&gt;
Cc: Steven Rostedt &lt;rostedt@goodmis.org&gt;
Cc: Suren Baghdasaryan &lt;surenb@google.com&gt;
Cc: Zi Yan &lt;ziy@nvidia.com&gt;
Signed-off-by: Andrew Morton &lt;akpm@linux-foundation.org&gt;
</content>
</entry>
<entry>
<title>mm: remove VM_PAT</title>
<updated>2025-05-22T21:55:37+00:00</updated>
<author>
<name>David Hildenbrand</name>
<email>david@redhat.com</email>
</author>
<published>2025-05-12T12:34:19+00:00</published>
<link rel='alternate' type='text/html' href='https://git.radix-linux.su/kernel/linux.git/commit/?id=cba4dbeb7bfcf8b69d491288c3bf877ead883214'/>
<id>urn:sha1:cba4dbeb7bfcf8b69d491288c3bf877ead883214</id>
<content type='text'>
It's unused, so let's remove it.

Link: https://lkml.kernel.org/r/20250512123424.637989-7-david@redhat.com
Signed-off-by: David Hildenbrand &lt;david@redhat.com&gt;
Reviewed-by: Lorenzo Stoakes &lt;lorenzo.stoakes@oracle.com&gt;
Acked-by: Ingo Molnar &lt;mingo@kernel.org&gt;	[x86 bits]
Reviewed-by: Liam R. Howlett &lt;Liam.Howlett@oracle.com&gt;
Cc: Andy Lutomirski &lt;luto@kernel.org&gt;
Cc: Borislav Betkov &lt;bp@alien8.de&gt;
Cc: Dave Airlie &lt;airlied@gmail.com&gt;
Cc: "H. Peter Anvin" &lt;hpa@zytor.com&gt;
Cc: Jani Nikula &lt;jani.nikula@linux.intel.com&gt;
Cc: Jann Horn &lt;jannh@google.com&gt;
Cc: Jonas Lahtinen &lt;joonas.lahtinen@linux.intel.com&gt;
Cc: "Masami Hiramatsu (Google)" &lt;mhiramat@kernel.org&gt;
Cc: Mathieu Desnoyers &lt;mathieu.desnoyers@efficios.com&gt;
Cc: Peter Xu &lt;peterx@redhat.com&gt;
Cc: Peter Zijlstra &lt;peterz@infradead.org&gt;
Cc: Rodrigo Vivi &lt;rodrigo.vivi@intel.com&gt;
Cc: Steven Rostedt &lt;rostedt@goodmis.org&gt;
Cc: Thomas Gleinxer &lt;tglx@linutronix.de&gt;
Cc: Tvrtko Ursulin &lt;tursulin@ursulin.net&gt;
Cc: Vlastimil Babka &lt;vbabka@suse.cz&gt;
Signed-off-by: Andrew Morton &lt;akpm@linux-foundation.org&gt;
</content>
</entry>
<entry>
<title>tracing: gfp: vsprintf: Do not print "none" when using %pGg printf format</title>
<updated>2025-03-22T09:15:44+00:00</updated>
<author>
<name>Petr Mladek</name>
<email>pmladek@suse.com</email>
</author>
<published>2025-03-14T14:13:11+00:00</published>
<link rel='alternate' type='text/html' href='https://git.radix-linux.su/kernel/linux.git/commit/?id=c1657640a8b3f7023675511d4857aff4f32f3a51'/>
<id>urn:sha1:c1657640a8b3f7023675511d4857aff4f32f3a51</id>
<content type='text'>
The commit ca29a0bf122145 ("tracing: gfp: Remove duplication of recording
GFP flags") caused the following regression in printf_test selftest:

[   46.208199] test_printf: kvasprintf(..., "%pGg", ...) returned 'none|0xfc000000', expected '0xfc000000'
[   46.208209] test_printf: kvasprintf(..., "%pGg", ...) returned '__GFP_HIGH|none|0xfc000000', expected '__GFP_HIGH|0xfc000000'

The problem is the new '{ 0, "none" }' entry in __def_gfpflag_names macro
and the following code:

char *format_flags(char *buf, char *end, unsigned long flags,
					const struct trace_print_flags *names)
{
[...]
		if ((flags &amp; mask) != mask)
			continue;
[...]
}

The purpose of the code is to print the name of a mask instead of bits,
for example, printk "GFP_ZONEMASK", instead of
"__GFP_DMA|__GFP_HIGHMEM|__GFP_DMA32|__GFP_MOVABLE".

Unfortunately, the mask "0" pass this check and "none" is always
printed.

A solution would be to move TRACE_GFP_FLAGS up so that it is not
the last entry. But it breaks the rule that named masks must
be defined before names of single bytes. Otherwise, it would
print the names of the bytes instead of the mask.

Instead, replace '{ 0, "none" }' with '{ 0, NULL }'. It works because
__def_gfpflag_names defines a standalone array and this is the standard
trailing entry. The code processing these arrays always ends the cycle
when flag-&gt;name == NULL.

Cc: Masami Hiramatsu &lt;mhiramat@kernel.org&gt;
Cc: Mathieu Desnoyers &lt;mathieu.desnoyers@efficios.com&gt;
Cc: Andrew Morton &lt;akpm@linux-foundation.org&gt;
Cc: Michael Petlan &lt;mpetlan@redhat.com&gt;
Cc: Veronika Molnarova &lt;vmolnaro@redhat.com&gt;
Cc: Suren Baghdasaryan &lt;surenb@google.com&gt;
Cc: Rasmus Villemoes &lt;linux@rasmusvillemoes.dk&gt;
Cc: Andy Shevchenko &lt;andriy.shevchenko@linux.intel.com&gt;
Cc: Tamir Duberstein &lt;tamird@gmail.com&gt;
Cc: Linus Torvalds &lt;torvalds@linux-foundation.org&gt;
Link: https://lore.kernel.org/Z9Q5d11ZbA3CNMZm@pathway.suse.cz
Fixes: ca29a0bf122145 ("tracing: gfp: Remove duplication of recording GFP flags")
Signed-off-by: Petr Mladek &lt;pmladek@suse.com&gt;
Signed-off-by: Steven Rostedt (Google) &lt;rostedt@goodmis.org&gt;
</content>
</entry>
<entry>
<title>tracing: gfp: Remove duplication of recording GFP flags</title>
<updated>2025-03-06T18:35:26+00:00</updated>
<author>
<name>Steven Rostedt</name>
<email>rostedt@goodmis.org</email>
</author>
<published>2025-02-25T18:56:11+00:00</published>
<link rel='alternate' type='text/html' href='https://git.radix-linux.su/kernel/linux.git/commit/?id=ca29a0bf1221451f566f19999f2eda8adf116ff9'/>
<id>urn:sha1:ca29a0bf1221451f566f19999f2eda8adf116ff9</id>
<content type='text'>
The gfp_flags when recorded in the trace require being converted from
their numbers to values. Various macros are used to help facilitate this,
but there's two sets of macros that need to keep track of the same GFP
flags to stay in sync.

Commit 60295b944ff68 ("tracing: gfp: Fix the GFP enum values shown for
user space tracing tools") added a TRACE_GFP_FLAGS macro that holds the
enum ___GFP_*_BIT defined bits, and creates the TRACE_DEFINE_ENUM()
wrapper around them.

The __def_gfpflag_names() macro creates the mapping of various flags or
multiple flags to give them human readable names via the __print_flags()
tracing helper macro.

As the TRACE_GFP_FLAGS is a subset of the __def_gfpflags_names(), it can
be used to cover the individual bit names, by redefining the internal
macro TRACE_GFP_EM():

  #undef TRACE_GFP_EM
  #define TRACE_GFP_EM(a) gfpflag_string(__GFP_##a),

This will remove the bits that are duplicate between the two macros. If a
new bit is created, only the TRACE_GFP_FLAGS needs to be updated and that
will also update the __def_gfpflags_names() macro.

Cc: Masami Hiramatsu &lt;mhiramat@kernel.org&gt;
Cc: Mathieu Desnoyers &lt;mathieu.desnoyers@efficios.com&gt;
Cc: Andrew Morton &lt;akpm@linux-foundation.org&gt;
Cc: Michael Petlan &lt;mpetlan@redhat.com&gt;
Cc: Veronika Molnarova &lt;vmolnaro@redhat.com&gt;
Cc: Suren Baghdasaryan &lt;surenb@google.com&gt;
Cc: Linus Torvalds &lt;torvalds@linux-foundation.org&gt;
Link: https://lore.kernel.org/20250225135611.1942b65c@gandalf.local.home
Signed-off-by: Steven Rostedt (Google) &lt;rostedt@goodmis.org&gt;
</content>
</entry>
<entry>
<title>Merge tag 'mm-stable-2025-01-26-14-59' of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm</title>
<updated>2025-01-27T02:36:23+00:00</updated>
<author>
<name>Linus Torvalds</name>
<email>torvalds@linux-foundation.org</email>
</author>
<published>2025-01-27T02:36:23+00:00</published>
<link rel='alternate' type='text/html' href='https://git.radix-linux.su/kernel/linux.git/commit/?id=9c5968db9e625019a0ee5226c7eebef5519d366a'/>
<id>urn:sha1:9c5968db9e625019a0ee5226c7eebef5519d366a</id>
<content type='text'>
Pull MM updates from Andrew Morton:
 "The various patchsets are summarized below. Plus of course many
  indivudual patches which are described in their changelogs.

   - "Allocate and free frozen pages" from Matthew Wilcox reorganizes
     the page allocator so we end up with the ability to allocate and
     free zero-refcount pages. So that callers (ie, slab) can avoid a
     refcount inc &amp; dec

   - "Support large folios for tmpfs" from Baolin Wang teaches tmpfs to
     use large folios other than PMD-sized ones

   - "Fix mm/rodata_test" from Petr Tesarik performs some maintenance
     and fixes for this small built-in kernel selftest

   - "mas_anode_descend() related cleanup" from Wei Yang tidies up part
     of the mapletree code

   - "mm: fix format issues and param types" from Keren Sun implements a
     few minor code cleanups

   - "simplify split calculation" from Wei Yang provides a few fixes and
     a test for the mapletree code

   - "mm/vma: make more mmap logic userland testable" from Lorenzo
     Stoakes continues the work of moving vma-related code into the
     (relatively) new mm/vma.c

   - "mm/page_alloc: gfp flags cleanups for alloc_contig_*()" from David
     Hildenbrand cleans up and rationalizes handling of gfp flags in the
     page allocator

   - "readahead: Reintroduce fix for improper RA window sizing" from Jan
     Kara is a second attempt at fixing a readahead window sizing issue.
     It should reduce the amount of unnecessary reading

   - "synchronously scan and reclaim empty user PTE pages" from Qi Zheng
     addresses an issue where "huge" amounts of pte pagetables are
     accumulated:

       https://lore.kernel.org/lkml/cover.1718267194.git.zhengqi.arch@bytedance.com/

     Qi's series addresses this windup by synchronously freeing PTE
     memory within the context of madvise(MADV_DONTNEED)

   - "selftest/mm: Remove warnings found by adding compiler flags" from
     Muhammad Usama Anjum fixes some build warnings in the selftests
     code when optional compiler warnings are enabled

   - "mm: don't use __GFP_HARDWALL when migrating remote pages" from
     David Hildenbrand tightens the allocator's observance of
     __GFP_HARDWALL

   - "pkeys kselftests improvements" from Kevin Brodsky implements
     various fixes and cleanups in the MM selftests code, mainly
     pertaining to the pkeys tests

   - "mm/damon: add sample modules" from SeongJae Park enhances DAMON to
     estimate application working set size

   - "memcg/hugetlb: Rework memcg hugetlb charging" from Joshua Hahn
     provides some cleanups to memcg's hugetlb charging logic

   - "mm/swap_cgroup: remove global swap cgroup lock" from Kairui Song
     removes the global swap cgroup lock. A speedup of 10% for a
     tmpfs-based kernel build was demonstrated

   - "zram: split page type read/write handling" from Sergey Senozhatsky
     has several fixes and cleaups for zram in the area of
     zram_write_page(). A watchdog softlockup warning was eliminated

   - "move pagetable_*_dtor() to __tlb_remove_table()" from Kevin
     Brodsky cleans up the pagetable destructor implementations. A rare
     use-after-free race is fixed

   - "mm/debug: introduce and use VM_WARN_ON_VMG()" from Lorenzo Stoakes
     simplifies and cleans up the debugging code in the VMA merging
     logic

   - "Account page tables at all levels" from Kevin Brodsky cleans up
     and regularizes the pagetable ctor/dtor handling. This results in
     improvements in accounting accuracy

   - "mm/damon: replace most damon_callback usages in sysfs with new
     core functions" from SeongJae Park cleans up and generalizes
     DAMON's sysfs file interface logic

   - "mm/damon: enable page level properties based monitoring" from
     SeongJae Park increases the amount of information which is
     presented in response to DAMOS actions

   - "mm/damon: remove DAMON debugfs interface" from SeongJae Park
     removes DAMON's long-deprecated debugfs interfaces. Thus the
     migration to sysfs is completed

   - "mm/hugetlb: Refactor hugetlb allocation resv accounting" from
     Peter Xu cleans up and generalizes the hugetlb reservation
     accounting

   - "mm: alloc_pages_bulk: small API refactor" from Luiz Capitulino
     removes a never-used feature of the alloc_pages_bulk() interface

   - "mm/damon: extend DAMOS filters for inclusion" from SeongJae Park
     extends DAMOS filters to support not only exclusion (rejecting),
     but also inclusion (allowing) behavior

   - "Add zpdesc memory descriptor for zswap.zpool" from Alex Shi
     introduces a new memory descriptor for zswap.zpool that currently
     overlaps with struct page for now. This is part of the effort to
     reduce the size of struct page and to enable dynamic allocation of
     memory descriptors

   - "mm, swap: rework of swap allocator locks" from Kairui Song redoes
     and simplifies the swap allocator locking. A speedup of 400% was
     demonstrated for one workload. As was a 35% reduction for kernel
     build time with swap-on-zram

   - "mm: update mips to use do_mmap(), make mmap_region() internal"
     from Lorenzo Stoakes reworks MIPS's use of mmap_region() so that
     mmap_region() can be made MM-internal

   - "mm/mglru: performance optimizations" from Yu Zhao fixes a few
     MGLRU regressions and otherwise improves MGLRU performance

   - "Docs/mm/damon: add tuning guide and misc updates" from SeongJae
     Park updates DAMON documentation

   - "Cleanup for memfd_create()" from Isaac Manjarres does that thing

   - "mm: hugetlb+THP folio and migration cleanups" from David
     Hildenbrand provides various cleanups in the areas of hugetlb
     folios, THP folios and migration

   - "Uncached buffered IO" from Jens Axboe implements the new
     RWF_DONTCACHE flag which provides synchronous dropbehind for
     pagecache reading and writing. To permite userspace to address
     issues with massive buildup of useless pagecache when
     reading/writing fast devices

   - "selftests/mm: virtual_address_range: Reduce memory" from Thomas
     Weißschuh fixes and optimizes some of the MM selftests"

* tag 'mm-stable-2025-01-26-14-59' of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm: (321 commits)
  mm/compaction: fix UBSAN shift-out-of-bounds warning
  s390/mm: add missing ctor/dtor on page table upgrade
  kasan: sw_tags: use str_on_off() helper in kasan_init_sw_tags()
  tools: add VM_WARN_ON_VMG definition
  mm/damon/core: use str_high_low() helper in damos_wmark_wait_us()
  seqlock: add missing parameter documentation for raw_seqcount_try_begin()
  mm/page-writeback: consolidate wb_thresh bumping logic into __wb_calc_thresh
  mm/page_alloc: remove the incorrect and misleading comment
  zram: remove zcomp_stream_put() from write_incompressible_page()
  mm: separate move/undo parts from migrate_pages_batch()
  mm/kfence: use str_write_read() helper in get_access_type()
  selftests/mm/mkdirty: fix memory leak in test_uffdio_copy()
  kasan: hw_tags: Use str_on_off() helper in kasan_init_hw_tags()
  selftests/mm: virtual_address_range: avoid reading from VM_IO mappings
  selftests/mm: vm_util: split up /proc/self/smaps parsing
  selftests/mm: virtual_address_range: unmap chunks after validation
  selftests/mm: virtual_address_range: mmap() without PROT_WRITE
  selftests/memfd/memfd_test: fix possible NULL pointer dereference
  mm: add FGP_DONTCACHE folio creation flag
  mm: call filemap_fdatawrite_range_kick() after IOCB_DONTCACHE issue
  ...
</content>
</entry>
<entry>
<title>mm: add PG_dropbehind folio flag</title>
<updated>2025-01-26T04:22:42+00:00</updated>
<author>
<name>Jens Axboe</name>
<email>axboe@kernel.dk</email>
</author>
<published>2024-12-20T15:47:42+00:00</published>
<link rel='alternate' type='text/html' href='https://git.radix-linux.su/kernel/linux.git/commit/?id=cceba6f7e46c48deca433030d80fc34599fb9fd8'/>
<id>urn:sha1:cceba6f7e46c48deca433030d80fc34599fb9fd8</id>
<content type='text'>
Add a folio flag that file IO can use to indicate that the cached IO being
done should be dropped from the page cache upon completion.

Link: https://lkml.kernel.org/r/20241220154831.1086649-5-axboe@kernel.dk
Signed-off-by: Jens Axboe &lt;axboe@kernel.dk&gt;
Reviewed-by: Kirill A. Shutemov &lt;kirill.shutemov@linux.intel.com&gt;
Cc: Brian Foster &lt;bfoster@redhat.com&gt;
Cc: Chris Mason &lt;clm@meta.com&gt;
Cc: Christoph Hellwig &lt;hch@lst.de&gt;
Cc: Johannes Weiner &lt;hannes@cmpxchg.org&gt;
Cc: Matthew Wilcox (Oracle) &lt;willy@infradead.org&gt;
Signed-off-by: Andrew Morton &lt;akpm@linux-foundation.org&gt;
</content>
</entry>
<entry>
<title>tracing: gfp: Fix the GFP enum values shown for user space tracing tools</title>
<updated>2025-01-17T21:15:39+00:00</updated>
<author>
<name>Steven Rostedt</name>
<email>rostedt@goodmis.org</email>
</author>
<published>2025-01-16T21:41:24+00:00</published>
<link rel='alternate' type='text/html' href='https://git.radix-linux.su/kernel/linux.git/commit/?id=60295b944ff6805e677c48ae4178532b207d43be'/>
<id>urn:sha1:60295b944ff6805e677c48ae4178532b207d43be</id>
<content type='text'>
Tracing tools like perf and trace-cmd read the /sys/kernel/tracing/events/*/*/format
files to know how to parse the data and also how to print it. For the
"print fmt" portion of that file, if anything uses an enum that is not
exported to the tracing system, user space will not be able to parse it.

The GFP flags use to be defines, and defines get translated in the print
fmt sections. But now they are converted to use enums, which is not.

The mm_page_alloc trace event format use to have:

  print fmt: "page=%p pfn=0x%lx order=%d migratetype=%d gfp_flags=%s",
    REC-&gt;pfn != -1UL ? (((struct page *)vmemmap_base) + (REC-&gt;pfn)) : ((void
    *)0), REC-&gt;pfn != -1UL ? REC-&gt;pfn : 0, REC-&gt;order, REC-&gt;migratetype,
    (REC-&gt;gfp_flags) ? __print_flags(REC-&gt;gfp_flags, "|", {( unsigned
    long)(((((((( gfp_t)(0x400u|0x800u)) | (( gfp_t)0x40u) | (( gfp_t)0x80u) |
    (( gfp_t)0x100000u)) | (( gfp_t)0x02u)) | (( gfp_t)0x08u) | (( gfp_t)0)) |
    (( gfp_t)0x40000u) | (( gfp_t)0x80000u) | (( gfp_t)0x2000u)) &amp; ~((
    gfp_t)(0x400u|0x800u))) | (( gfp_t)0x400u)), "GFP_TRANSHUGE"}, {( unsigned
    long)((((((( gfp_t)(0x400u|0x800u)) | (( gfp_t)0x40u) | (( gfp_t)0x80u) |
    (( gfp_t)0x100000u)) | (( gfp_t)0x02u)) | (( gfp_t)0x08u) | (( gfp_t)0)) ...

Where the GFP values are shown and not their names. But after the GFP
flags were converted to use enums, it has:

  print fmt: "page=%p pfn=0x%lx order=%d migratetype=%d gfp_flags=%s",
    REC-&gt;pfn != -1UL ? (vmemmap + (REC-&gt;pfn)) : ((void *)0), REC-&gt;pfn != -1UL
    ? REC-&gt;pfn : 0, REC-&gt;order, REC-&gt;migratetype, (REC-&gt;gfp_flags) ?
    __print_flags(REC-&gt;gfp_flags, "|", {( unsigned long)((((((((
    gfp_t)(((((1UL))) &lt;&lt; (___GFP_DIRECT_RECLAIM_BIT))|((((1UL))) &lt;&lt;
    (___GFP_KSWAPD_RECLAIM_BIT)))) | (( gfp_t)((((1UL))) &lt;&lt; (___GFP_IO_BIT)))
    | (( gfp_t)((((1UL))) &lt;&lt; (___GFP_FS_BIT))) | (( gfp_t)((((1UL))) &lt;&lt;
    (___GFP_HARDWALL_BIT)))) | (( gfp_t)((((1UL))) &lt;&lt; (___GFP_HIGHMEM_BIT))))
    | (( gfp_t)((((1UL))) &lt;&lt; (___GFP_MOVABLE_BIT))) | (( gfp_t)0)) | ((
    gfp_t)((((1UL))) &lt;&lt; (___GFP_COMP_BIT))) ...

Where the enums names like ___GFP_KSWAPD_RECLAIM_BIT are shown and not their
values. User space has no way to convert these names to their values and
the output will fail to parse. What is shown is now:

  mm_page_alloc:  page=0xffffffff981685f3 pfn=0x1d1ac1 order=0 migratetype=1 gfp_flags=0x140cca

The TRACE_DEFINE_ENUM() macro was created to handle enums in the print fmt
files. This causes them to be replaced at boot up with the numbers, so
that user space tooling can parse it. By using this macro, the output is
back to the human readable:

  mm_page_alloc: page=0xffffffff981685f3 pfn=0x122233 order=0 migratetype=1 gfp_flags=GFP_HIGHUSER_MOVABLE|__GFP_COMP

Cc: stable@vger.kernel.org
Cc: Masami Hiramatsu &lt;mhiramat@kernel.org&gt;
Cc: Mark Rutland &lt;mark.rutland@arm.com&gt;
Cc: Mathieu Desnoyers &lt;mathieu.desnoyers@efficios.com&gt;
Cc: Andrew Morton &lt;akpm@linux-foundation.org&gt;
Cc: Veronika  Molnarova &lt;vmolnaro@redhat.com&gt;
Cc: Suren Baghdasaryan &lt;surenb@google.com&gt;
Cc: Linus Torvalds &lt;torvalds@linux-foundation.org&gt;
Link: https://lore.kernel.org/20250116214438.749504792@goodmis.org
Reported-by: Michael Petlan &lt;mpetlan@redhat.com&gt;
Closes: https://lore.kernel.org/all/87be5f7c-1a0-dad-daa0-54e342efaea7@redhat.com/
Fixes: 772dd0342727c ("mm: enumerate all gfp flags")
Signed-off-by: Steven Rostedt (Google) &lt;rostedt@goodmis.org&gt;
</content>
</entry>
<entry>
<title>Merge tag 'mm-stable-2024-09-20-02-31' of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm</title>
<updated>2024-09-21T14:29:05+00:00</updated>
<author>
<name>Linus Torvalds</name>
<email>torvalds@linux-foundation.org</email>
</author>
<published>2024-09-21T14:29:05+00:00</published>
<link rel='alternate' type='text/html' href='https://git.radix-linux.su/kernel/linux.git/commit/?id=617a814f14b8914271f7a70366d72c6196d17663'/>
<id>urn:sha1:617a814f14b8914271f7a70366d72c6196d17663</id>
<content type='text'>
Pull MM updates from Andrew Morton:
 "Along with the usual shower of singleton patches, notable patch series
  in this pull request are:

   - "Align kvrealloc() with krealloc()" from Danilo Krummrich. Adds
     consistency to the APIs and behaviour of these two core allocation
     functions. This also simplifies/enables Rustification.

   - "Some cleanups for shmem" from Baolin Wang. No functional changes -
     mode code reuse, better function naming, logic simplifications.

   - "mm: some small page fault cleanups" from Josef Bacik. No
     functional changes - code cleanups only.

   - "Various memory tiering fixes" from Zi Yan. A small fix and a
     little cleanup.

   - "mm/swap: remove boilerplate" from Yu Zhao. Code cleanups and
     simplifications and .text shrinkage.

   - "Kernel stack usage histogram" from Pasha Tatashin and Shakeel
     Butt. This is a feature, it adds new feilds to /proc/vmstat such as

       $ grep kstack /proc/vmstat
       kstack_1k 3
       kstack_2k 188
       kstack_4k 11391
       kstack_8k 243
       kstack_16k 0

     which tells us that 11391 processes used 4k of stack while none at
     all used 16k. Useful for some system tuning things, but
     partivularly useful for "the dynamic kernel stack project".

   - "kmemleak: support for percpu memory leak detect" from Pavel
     Tikhomirov. Teaches kmemleak to detect leaksage of percpu memory.

   - "mm: memcg: page counters optimizations" from Roman Gushchin. "3
     independent small optimizations of page counters".

   - "mm: split PTE/PMD PT table Kconfig cleanups+clarifications" from
     David Hildenbrand. Improves PTE/PMD splitlock detection, makes
     powerpc/8xx work correctly by design rather than by accident.

   - "mm: remove arch_make_page_accessible()" from David Hildenbrand.
     Some folio conversions which make arch_make_page_accessible()
     unneeded.

   - "mm, memcg: cg2 memory{.swap,}.peak write handlers" fro David
     Finkel. Cleans up and fixes our handling of the resetting of the
     cgroup/process peak-memory-use detector.

   - "Make core VMA operations internal and testable" from Lorenzo
     Stoakes. Rationalizaion and encapsulation of the VMA manipulation
     APIs. With a view to better enable testing of the VMA functions,
     even from a userspace-only harness.

   - "mm: zswap: fixes for global shrinker" from Takero Funaki. Fix
     issues in the zswap global shrinker, resulting in improved
     performance.

   - "mm: print the promo watermark in zoneinfo" from Kaiyang Zhao. Fill
     in some missing info in /proc/zoneinfo.

   - "mm: replace follow_page() by folio_walk" from David Hildenbrand.
     Code cleanups and rationalizations (conversion to folio_walk())
     resulting in the removal of follow_page().

   - "improving dynamic zswap shrinker protection scheme" from Nhat
     Pham. Some tuning to improve zswap's dynamic shrinker. Significant
     reductions in swapin and improvements in performance are shown.

   - "mm: Fix several issues with unaccepted memory" from Kirill
     Shutemov. Improvements to the new unaccepted memory feature,

   - "mm/mprotect: Fix dax puds" from Peter Xu. Implements mprotect on
     DAX PUDs. This was missing, although nobody seems to have notied
     yet.

   - "Introduce a store type enum for the Maple tree" from Sidhartha
     Kumar. Cleanups and modest performance improvements for the maple
     tree library code.

   - "memcg: further decouple v1 code from v2" from Shakeel Butt. Move
     more cgroup v1 remnants away from the v2 memcg code.

   - "memcg: initiate deprecation of v1 features" from Shakeel Butt.
     Adds various warnings telling users that memcg v1 features are
     deprecated.

   - "mm: swap: mTHP swap allocator base on swap cluster order" from
     Chris Li. Greatly improves the success rate of the mTHP swap
     allocation.

   - "mm: introduce numa_memblks" from Mike Rapoport. Moves various
     disparate per-arch implementations of numa_memblk code into generic
     code.

   - "mm: batch free swaps for zap_pte_range()" from Barry Song. Greatly
     improves the performance of munmap() of swap-filled ptes.

   - "support large folio swap-out and swap-in for shmem" from Baolin
     Wang. With this series we no longer split shmem large folios into
     simgle-page folios when swapping out shmem.

   - "mm/hugetlb: alloc/free gigantic folios" from Yu Zhao. Nice
     performance improvements and code reductions for gigantic folios.

   - "support shmem mTHP collapse" from Baolin Wang. Adds support for
     khugepaged's collapsing of shmem mTHP folios.

   - "mm: Optimize mseal checks" from Pedro Falcato. Fixes an mprotect()
     performance regression due to the addition of mseal().

   - "Increase the number of bits available in page_type" from Matthew
     Wilcox. Increases the number of bits available in page_type!

   - "Simplify the page flags a little" from Matthew Wilcox. Many legacy
     page flags are now folio flags, so the page-based flags and their
     accessors/mutators can be removed.

   - "mm: store zero pages to be swapped out in a bitmap" from Usama
     Arif. An optimization which permits us to avoid writing/reading
     zero-filled zswap pages to backing store.

   - "Avoid MAP_FIXED gap exposure" from Liam Howlett. Fixes a race
     window which occurs when a MAP_FIXED operqtion is occurring during
     an unrelated vma tree walk.

   - "mm: remove vma_merge()" from Lorenzo Stoakes. Major rotorooting of
     the vma_merge() functionality, making ot cleaner, more testable and
     better tested.

   - "misc fixups for DAMON {self,kunit} tests" from SeongJae Park.
     Minor fixups of DAMON selftests and kunit tests.

   - "mm: memory_hotplug: improve do_migrate_range()" from Kefeng Wang.
     Code cleanups and folio conversions.

   - "Shmem mTHP controls and stats improvements" from Ryan Roberts.
     Cleanups for shmem controls and stats.

   - "mm: count the number of anonymous THPs per size" from Barry Song.
     Expose additional anon THP stats to userspace for improved tuning.

   - "mm: finish isolate/putback_lru_page()" from Kefeng Wang: more
     folio conversions and removal of now-unused page-based APIs.

   - "replace per-quota region priorities histogram buffer with
     per-context one" from SeongJae Park. DAMON histogram
     rationalization.

   - "Docs/damon: update GitHub repo URLs and maintainer-profile" from
     SeongJae Park. DAMON documentation updates.

   - "mm/vdpa: correct misuse of non-direct-reclaim __GFP_NOFAIL and
     improve related doc and warn" from Jason Wang: fixes usage of page
     allocator __GFP_NOFAIL and GFP_ATOMIC flags.

   - "mm: split underused THPs" from Yu Zhao. Improve THP=always policy.
     This was overprovisioning THPs in sparsely accessed memory areas.

   - "zram: introduce custom comp backends API" frm Sergey Senozhatsky.
     Add support for zram run-time compression algorithm tuning.

   - "mm: Care about shadow stack guard gap when getting an unmapped
     area" from Mark Brown. Fix up the various arch_get_unmapped_area()
     implementations to better respect guard areas.

   - "Improve mem_cgroup_iter()" from Kinsey Ho. Improve the reliability
     of mem_cgroup_iter() and various code cleanups.

   - "mm: Support huge pfnmaps" from Peter Xu. Extends the usage of huge
     pfnmap support.

   - "resource: Fix region_intersects() vs add_memory_driver_managed()"
     from Huang Ying. Fix a bug in region_intersects() for systems with
     CXL memory.

   - "mm: hwpoison: two more poison recovery" from Kefeng Wang. Teaches
     a couple more code paths to correctly recover from the encountering
     of poisoned memry.

   - "mm: enable large folios swap-in support" from Barry Song. Support
     the swapin of mTHP memory into appropriately-sized folios, rather
     than into single-page folios"

* tag 'mm-stable-2024-09-20-02-31' of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm: (416 commits)
  zram: free secondary algorithms names
  uprobes: turn xol_area-&gt;pages[2] into xol_area-&gt;page
  uprobes: introduce the global struct vm_special_mapping xol_mapping
  Revert "uprobes: use vm_special_mapping close() functionality"
  mm: support large folios swap-in for sync io devices
  mm: add nr argument in mem_cgroup_swapin_uncharge_swap() helper to support large folios
  mm: fix swap_read_folio_zeromap() for large folios with partial zeromap
  mm/debug_vm_pgtable: Use pxdp_get() for accessing page table entries
  set_memory: add __must_check to generic stubs
  mm/vma: return the exact errno in vms_gather_munmap_vmas()
  memcg: cleanup with !CONFIG_MEMCG_V1
  mm/show_mem.c: report alloc tags in human readable units
  mm: support poison recovery from copy_present_page()
  mm: support poison recovery from do_cow_fault()
  resource, kunit: add test case for region_intersects()
  resource: make alloc_free_mem_region() works for iomem_resource
  mm: z3fold: deprecate CONFIG_Z3FOLD
  vfio/pci: implement huge_fault support
  mm/arm64: support large pfn mappings
  mm/x86: support large pfn mappings
  ...
</content>
</entry>
<entry>
<title>mm: Define VM_DROPPABLE for powerpc/32</title>
<updated>2024-09-13T15:28:36+00:00</updated>
<author>
<name>Christophe Leroy</name>
<email>christophe.leroy@csgroup.eu</email>
</author>
<published>2024-09-02T19:17:18+00:00</published>
<link rel='alternate' type='text/html' href='https://git.radix-linux.su/kernel/linux.git/commit/?id=d175ee98fe545d2c56df22751314584cce228307'/>
<id>urn:sha1:d175ee98fe545d2c56df22751314584cce228307</id>
<content type='text'>
Commit 9651fcedf7b9 ("mm: add MAP_DROPPABLE for designating always
lazily freeable mappings") only adds VM_DROPPABLE for 64 bits
architectures.

In order to also use the getrandom vDSO implementation on powerpc/32,
use VM_ARCH_1 for VM_DROPPABLE on powerpc/32. This is possible because
VM_ARCH_1 is used for VM_SAO on powerpc and VM_SAO is only for
powerpc/64. It is used in combination with PROT_SAO in some parts of
code that are restricted to CONFIG_PPC64 through #ifdefs, it is
therefore possible to define VM_SAO for CONFIG_PPC64 only.

Signed-off-by: Christophe Leroy &lt;christophe.leroy@csgroup.eu&gt;
Acked-by: Michael Ellerman &lt;mpe@ellerman.id.au&gt;
Signed-off-by: Jason A. Donenfeld &lt;Jason@zx2c4.com&gt;
</content>
</entry>
<entry>
<title>x86: remove PG_uncached</title>
<updated>2024-09-04T04:15:46+00:00</updated>
<author>
<name>Matthew Wilcox (Oracle)</name>
<email>willy@infradead.org</email>
</author>
<published>2024-08-21T19:34:43+00:00</published>
<link rel='alternate' type='text/html' href='https://git.radix-linux.su/kernel/linux.git/commit/?id=7a87225ae2c6c317c7b80cf599e5cf0eee699196'/>
<id>urn:sha1:7a87225ae2c6c317c7b80cf599e5cf0eee699196</id>
<content type='text'>
Convert x86 to use PG_arch_2 instead of PG_uncached and remove
PG_uncached.

Link: https://lkml.kernel.org/r/20240821193445.2294269-11-willy@infradead.org
Signed-off-by: Matthew Wilcox (Oracle) &lt;willy@infradead.org&gt;
Signed-off-by: Andrew Morton &lt;akpm@linux-foundation.org&gt;
</content>
</entry>
</feed>
