kernel/linux.git/mm/memcontrol.c, branch v6.18.21

memcg: fix slab accounting in refill_obj_stock() trylock path

2026-03-19T15:08:39+00:00

commit dccd5ee2625d50239510bcd73ed78559005e00a3 upstream. In the trylock path of refill_obj_stock(), mod_objcg_mlstate() should use the real alloc/free bytes (i.e., nr_acct) for accounting, rather than nr_bytes. The user-visible impact is that the NR_SLAB_RECLAIMABLE_B and NR_SLAB_UNRECLAIMABLE_B stats can end up being incorrect. For example, if a user allocates a 6144-byte object, then before this fix efill_obj_stock() calls mod_objcg_mlstate(..., nr_bytes=2048), even though it should account for 6144 bytes (i.e., nr_acct). When the user later frees the same object with kfree(), refill_obj_stock() calls mod_objcg_mlstate(..., nr_bytes=6144). This ends up adding 6144 to the stats, but it should be applying -6144 (i.e., nr_acct) since the object is being freed. Link: https://lkml.kernel.org/r/20260226115145.62903-1-hao.li@linux.dev Fixes: 200577f69f29 ("memcg: objcg stock trylock without irq disabling") Signed-off-by: Hao Li Acked-by: Shakeel Butt Acked-by: Johannes Weiner Cc: Michal Hocko Cc: Muchun Song Cc: Roman Gushchin Cc: Vlastimil Babka Cc: Signed-off-by: Andrew Morton Signed-off-by: Greg Kroah-Hartman

mm/vmscan: fix demotion targets checks in reclaim/demotion

2026-03-04T12:21:29+00:00

[ Upstream commit 1aceed565ff172fc0331dd1d5e7e65139b711139 ] Patch series "mm/vmscan: fix demotion targets checks in reclaim/demotion", v9. This patch series addresses two issues in demote_folio_list(), can_demote(), and next_demotion_node() in reclaim/demotion. 1. demote_folio_list() and can_demote() do not correctly check demotion target against cpuset.mems_effective, which will cause (a) pages to be demoted to not-allowed nodes and (b) pages fail demotion even if the system still has allowed demotion nodes. Patch 1 fixes this bug by updating cpuset_node_allowed() and mem_cgroup_node_allowed() to return effective_mems, allowing directly logic-and operation against demotion targets. 2. next_demotion_node() returns a preferred demotion target, but it does not check the node against allowed nodes. Patch 2 ensures that next_demotion_node() filters against the allowed node mask and selects the closest demotion target to the source node. This patch (of 2): Fix two bugs in demote_folio_list() and can_demote() due to incorrect demotion target checks against cpuset.mems_effective in reclaim/demotion. Commit 7d709f49babc ("vmscan,cgroup: apply mems_effective to reclaim") introduces the cpuset.mems_effective check and applies it to can_demote(). However: 1. It does not apply this check in demote_folio_list(), which leads to situations where pages are demoted to nodes that are explicitly excluded from the task's cpuset.mems. 2. It checks only the nodes in the immediate next demotion hierarchy and does not check all allowed demotion targets in can_demote(). This can cause pages to never be demoted if the nodes in the next demotion hierarchy are not set in mems_effective. These bugs break resource isolation provided by cpuset.mems. This is visible from userspace because pages can either fail to be demoted entirely or are demoted to nodes that are not allowed in multi-tier memory systems. To address these bugs, update cpuset_node_allowed() and mem_cgroup_node_allowed() to return effective_mems, allowing directly logic-and operation against demotion targets. Also update can_demote() and demote_folio_list() accordingly. Bug 1 reproduction: Assume a system with 4 nodes, where nodes 0-1 are top-tier and nodes 2-3 are far-tier memory. All nodes have equal capacity. Test script: echo 1 > /sys/kernel/mm/numa/demotion_enabled mkdir /sys/fs/cgroup/test echo +cpuset > /sys/fs/cgroup/cgroup.subtree_control echo "0-2" > /sys/fs/cgroup/test/cpuset.mems echo $$ > /sys/fs/cgroup/test/cgroup.procs swapoff -a # Expectation: Should respect node 0-2 limit. # Observation: Node 3 shows significant allocation (MemFree drops) stress-ng --oomable --vm 1 --vm-bytes 150% --mbind 0,1 Bug 2 reproduction: Assume a system with 6 nodes, where nodes 0-2 are top-tier, node 3 is a far-tier node, and nodes 4-5 are the farthest-tier nodes. All nodes have equal capacity. Test script: echo 1 > /sys/kernel/mm/numa/demotion_enabled mkdir /sys/fs/cgroup/test echo +cpuset > /sys/fs/cgroup/cgroup.subtree_control echo "0-2,4-5" > /sys/fs/cgroup/test/cpuset.mems echo $$ > /sys/fs/cgroup/test/cgroup.procs swapoff -a # Expectation: Pages are demoted to Nodes 4-5 # Observation: No pages are demoted before oom. stress-ng --oomable --vm 1 --vm-bytes 150% --mbind 0,1,2 Link: https://lkml.kernel.org/r/20260114205305.2869796-1-bingjiao@google.com Link: https://lkml.kernel.org/r/20260114205305.2869796-2-bingjiao@google.com Fixes: 7d709f49babc ("vmscan,cgroup: apply mems_effective to reclaim") Signed-off-by: Bing Jiao Acked-by: Shakeel Butt Cc: Axel Rasmussen Cc: David Hildenbrand Cc: Gregory Price Cc: Johannes Weiner Cc: Joshua Hahn Cc: Liam Howlett Cc: Lorenzo Stoakes Cc: Michal Hocko Cc: Mike Rapoport Cc: Muchun Song Cc: Qi Zheng Cc: Roman Gushchin Cc: Suren Baghdasaryan Cc: Tejun Heo Cc: Vlastimil Babka Cc: Waiman Long Cc: Wei Xu Cc: Yuanchu Xie Cc: Signed-off-by: Andrew Morton Signed-off-by: Sasha Levin

memcg: skip cgroup_file_notify if spinning is not allowed

2025-10-07T21:01:11+00:00

Generally memcg charging is allowed from all the contexts including NMI where even spinning on spinlock can cause locking issues. However one call chain was missed during the addition of memcg charging from any context support. That is try_charge_memcg() -> memcg_memory_event() -> cgroup_file_notify(). The possible function call tree under cgroup_file_notify() can acquire many different spin locks in spinning mode. Some of them are cgroup_file_kn_lock, kernfs_notify_lock, pool_workqeue's lock. So, let's just skip cgroup_file_notify() from memcg charging if the context does not allow spinning. Alternative approach was also explored where instead of skipping cgroup_file_notify(), we defer the memcg event processing to irq_work [1]. However it adds complexity and it was decided to keep things simple until we need more memcg events with !allow_spinning requirement. Link: https://lore.kernel.org/all/5qi2llyzf7gklncflo6gxoozljbm4h3tpnuv4u4ej4ztysvi6f@x44v7nz2wdzd/ [1] Link: https://lkml.kernel.org/r/20250922220203.261714-1-shakeel.butt@linux.dev Fixes: 3ac4638a734a ("memcg: make memcg_rstat_updated nmi safe") Signed-off-by: Shakeel Butt Acked-by: Michal Hocko Closes: https://lore.kernel.org/all/20250905061919.439648-1-yepeilin@google.com/ Cc: Alexei Starovoitov Cc: Johannes Weiner Cc: Kumar Kartikeya Dwivedi Cc: Muchun Song Cc: Peilin Ye Cc: Roman Gushchin Cc: Tejun Heo Cc: Signed-off-by: Andrew Morton

Merge tag 'mm-stable-2025-10-01-19-00' of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm

2025-10-03T01:18:33+00:00

Pull MM updates from Andrew Morton: - "mm, swap: improve cluster scan strategy" from Kairui Song improves performance and reduces the failure rate of swap cluster allocation - "support large align and nid in Rust allocators" from Vitaly Wool permits Rust allocators to set NUMA node and large alignment when perforning slub and vmalloc reallocs - "mm/damon/vaddr: support stat-purpose DAMOS" from Yueyang Pan extend DAMOS_STAT's handling of the DAMON operations sets for virtual address spaces for ops-level DAMOS filters - "execute PROCMAP_QUERY ioctl under per-vma lock" from Suren Baghdasaryan reduces mmap_lock contention during reads of /proc/pid/maps - "mm/mincore: minor clean up for swap cache checking" from Kairui Song performs some cleanup in the swap code - "mm: vm_normal_page*() improvements" from David Hildenbrand provides code cleanup in the pagemap code - "add persistent huge zero folio support" from Pankaj Raghav provides a block layer speedup by optionalls making the huge_zero_pagepersistent, instead of releasing it when its refcount falls to zero - "kho: fixes and cleanups" from Mike Rapoport adds a few touchups to the recently added Kexec Handover feature - "mm: make mm->flags a bitmap and 64-bit on all arches" from Lorenzo Stoakes turns mm_struct.flags into a bitmap. To end the constant struggle with space shortage on 32-bit conflicting with 64-bit's needs - "mm/swapfile.c and swap.h cleanup" from Chris Li cleans up some swap code - "selftests/mm: Fix false positives and skip unsupported tests" from Donet Tom fixes a few things in our selftests code - "prctl: extend PR_SET_THP_DISABLE to only provide THPs when advised" from David Hildenbrand "allows individual processes to opt-out of THP=always into THP=madvise, without affecting other workloads on the system". It's a long story - the [1/N] changelog spells out the considerations - "Add and use memdesc_flags_t" from Matthew Wilcox gets us started on the memdesc project. Please see https://kernelnewbies.org/MatthewWilcox/Memdescs and https://blogs.oracle.com/linux/post/introducing-memdesc - "Tiny optimization for large read operations" from Chi Zhiling improves the efficiency of the pagecache read path - "Better split_huge_page_test result check" from Zi Yan improves our folio splitting selftest code - "test that rmap behaves as expected" from Wei Yang adds some rmap selftests - "remove write_cache_pages()" from Christoph Hellwig removes that function and converts its two remaining callers - "selftests/mm: uffd-stress fixes" from Dev Jain fixes some UFFD selftests issues - "introduce kernel file mapped folios" from Boris Burkov introduces the concept of "kernel file pages". Using these permits btrfs to account its metadata pages to the root cgroup, rather than to the cgroups of random inappropriate tasks - "mm/pageblock: improve readability of some pageblock handling" from Wei Yang provides some readability improvements to the page allocator code - "mm/damon: support ARM32 with LPAE" from SeongJae Park teaches DAMON to understand arm32 highmem - "tools: testing: Use existing atomic.h for vma/maple tests" from Brendan Jackman performs some code cleanups and deduplication under tools/testing/ - "maple_tree: Fix testing for 32bit compiles" from Liam Howlett fixes a couple of 32-bit issues in tools/testing/radix-tree.c - "kasan: unify kasan_enabled() and remove arch-specific implementations" from Sabyrzhan Tasbolatov moves KASAN arch-specific initialization code into a common arch-neutral implementation - "mm: remove zpool" from Johannes Weiner removes zspool - an indirection layer which now only redirects to a single thing (zsmalloc) - "mm: task_stack: Stack handling cleanups" from Pasha Tatashin makes a couple of cleanups in the fork code - "mm: remove nth_page()" from David Hildenbrand makes rather a lot of adjustments at various nth_page() callsites, eventually permitting the removal of that undesirable helper function - "introduce kasan.write_only option in hw-tags" from Yeoreum Yun creates a KASAN read-only mode for ARM, using that architecture's memory tagging feature. It is felt that a read-only mode KASAN is suitable for use in production systems rather than debug-only - "mm: hugetlb: cleanup hugetlb folio allocation" from Kefeng Wang does some tidying in the hugetlb folio allocation code - "mm: establish const-correctness for pointer parameters" from Max Kellermann makes quite a number of the MM API functions more accurate about the constness of their arguments. This was getting in the way of subsystems (in this case CEPH) when they attempt to improving their own const/non-const accuracy - "Cleanup free_pages() misuse" from Vishal Moola fixes a number of code sites which were confused over when to use free_pages() vs __free_pages() - "Add Rust abstraction for Maple Trees" from Alice Ryhl makes the mapletree code accessible to Rust. Required by nouveau and by its forthcoming successor: the new Rust Nova driver - "selftests/mm: split_huge_page_test: split_pte_mapped_thp improvements" from David Hildenbrand adds a fix and some cleanups to the thp selftesting code - "mm, swap: introduce swap table as swap cache (phase I)" from Chris Li and Kairui Song is the first step along the path to implementing "swap tables" - a new approach to swap allocation and state tracking which is expected to yield speed and space improvements. This patchset itself yields a 5-20% performance benefit in some situations - "Some ptdesc cleanups" from Matthew Wilcox utilizes the new memdesc layer to clean up the ptdesc code a little - "Fix va_high_addr_switch.sh test failure" from Chunyu Hu fixes some issues in our 5-level pagetable selftesting code - "Minor fixes for memory allocation profiling" from Suren Baghdasaryan addresses a couple of minor issues in relatively new memory allocation profiling feature - "Small cleanups" from Matthew Wilcox has a few cleanups in preparation for more memdesc work - "mm/damon: add addr_unit for DAMON_LRU_SORT and DAMON_RECLAIM" from Quanmin Yan makes some changes to DAMON in furtherance of supporting arm highmem - "selftests/mm: Add -Wunreachable-code and fix warnings" from Muhammad Anjum adds that compiler check to selftests code and fixes the fallout, by removing dead code - "Improvements to Victim Process Thawing and OOM Reaper Traversal Order" from zhongjinji makes a number of improvements in the OOM killer: mainly thawing a more appropriate group of victim threads so they can release resources - "mm/damon: misc fixups and improvements for 6.18" from SeongJae Park is a bunch of small and unrelated fixups for DAMON - "mm/damon: define and use DAMON initialization check function" from SeongJae Park implement reliability and maintainability improvements to a recently-added bug fix - "mm/damon/stat: expose auto-tuned intervals and non-idle ages" from SeongJae Park provides additional transparency to userspace clients of the DAMON_STAT information - "Expand scope of khugepaged anonymous collapse" from Dev Jain removes some constraints on khubepaged's collapsing of anon VMAs. It also increases the success rate of MADV_COLLAPSE against an anon vma - "mm: do not assume file == vma->vm_file in compat_vma_mmap_prepare()" from Lorenzo Stoakes moves us further towards removal of file_operations.mmap(). This patchset concentrates upon clearing up the treatment of stacked filesystems - "mm: Improve mlock tracking for large folios" from Kiryl Shutsemau provides some fixes and improvements to mlock's tracking of large folios. /proc/meminfo's "Mlocked" field became more accurate - "mm/ksm: Fix incorrect accounting of KSM counters during fork" from Donet Tom fixes several user-visible KSM stats inaccuracies across forks and adds selftest code to verify these counters - "mm_slot: fix the usage of mm_slot_entry" from Wei Yang addresses some potential but presently benign issues in KSM's mm_slot handling * tag 'mm-stable-2025-10-01-19-00' of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm: (372 commits) mm: swap: check for stable address space before operating on the VMA mm: convert folio_page() back to a macro mm/khugepaged: use start_addr/addr for improved readability hugetlbfs: skip VMAs without shareable locks in hugetlb_vmdelete_list alloc_tag: fix boot failure due to NULL pointer dereference mm: silence data-race in update_hiwater_rss mm/memory-failure: don't select MEMORY_ISOLATION mm/khugepaged: remove definition of struct khugepaged_mm_slot mm/ksm: get mm_slot by mm_slot_entry() when slot is !NULL hugetlb: increase number of reserving hugepages via cmdline selftests/mm: add fork inheritance test for ksm_merging_pages counter mm/ksm: fix incorrect KSM counter handling in mm_struct during fork drivers/base/node: fix double free in register_one_node() mm: remove PMD alignment constraint in execmem_vmalloc() mm/memory_hotplug: fix typo 'esecially' -> 'especially' mm/rmap: improve mlock tracking for large folios mm/filemap: map entire large folio faultaround mm/fault: try to map the entire file folio in finish_fault() mm/rmap: mlock large folios in try_to_unmap_one() mm/rmap: fix a mlock race condition in folio_referenced_one() ...

mm/hwpoison: decouple hwpoison_filter from mm/memory-failure.c

2025-09-21T21:22:21+00:00

mm/memory-failure.c defines and uses hwpoison_filter_* parameters but the values of those parameters can only be modified via mm/hwpoison-inject.c from userspace. They have a potentially different life time. Decouple those parameters from mm/memory-failure.c to fix this broken layering. Link: https://lkml.kernel.org/r/20250904062258.3336092-1-linmiaohe@huawei.com Signed-off-by: Miaohe Lin Suggested-by: Michal Hocko Cc: David Hildenbrand Cc: Naoya Horiguchi Signed-off-by: Andrew Morton

memcg: optimize exit to user space

2025-09-13T23:55:01+00:00

memcg uses TIF_NOTIFY_RESUME to handle reclaiming on exit to user space. TIF_NOTIFY_RESUME is a multiplexing TIF bit, which is utilized by other entities as well. This results in a unconditional mem_cgroup_handle_over_high() call for every invocation of resume_user_mode_work(), which is a pointless exercise as most of the time there is no reclaim work to do. Especially since RSEQ is used by glibc, TIF_NOTIFY_RESUME is raised quite frequently and the empty calls show up in exit path profiling. Optimize this by doing a quick check of the reclaim condition before invoking it. [akpm@linux-foundation.org: remove now-unneeded test of memcg_nr_pages_over_high==0, per Shakeel] Link: https://lkml.kernel.org/r/87tt2b6zgs.ffs@tglx Signed-off-by: Thomas Gleixner Reviewed-by: Roman Gushchin Acked-by: Johannes Weiner Acked-by: Shakeel Butt Cc: Michal Hocko Cc: Muchun Song Cc: Peter Zijlstra Signed-off-by: Andrew Morton

net-memcg: Pass struct sock to mem_cgroup_sk_(un)?charge().

2025-08-20T02:20:59+00:00

We will store a flag in the lowest bit of sk->sk_memcg. Then, we cannot pass the raw pointer to mem_cgroup_charge_skmem() and mem_cgroup_uncharge_skmem(). Let's pass struct sock to the functions. While at it, they are renamed to match other functions starting with mem_cgroup_sk_. Signed-off-by: Kuniyuki Iwashima Reviewed-by: Eric Dumazet Acked-by: Roman Gushchin Acked-by: Shakeel Butt Link: https://patch.msgid.link/20250815201712.1745332-9-kuniyu@google.com Signed-off-by: Jakub Kicinski

net-memcg: Introduce mem_cgroup_from_sk().

2025-08-20T02:20:59+00:00

We will store a flag in the lowest bit of sk->sk_memcg. Then, directly dereferencing sk->sk_memcg will be illegal, and we do not want to allow touching the raw sk->sk_memcg in many places. Let's introduce mem_cgroup_from_sk(). Other places accessing the raw sk->sk_memcg will be converted later. Note that we cannot define the helper as an inline function in memcontrol.h as we cannot access any fields of struct sock there due to circular dependency, so it is placed in sock.h. Signed-off-by: Kuniyuki Iwashima Reviewed-by: Eric Dumazet Acked-by: Roman Gushchin Acked-by: Shakeel Butt Link: https://patch.msgid.link/20250815201712.1745332-7-kuniyu@google.com Signed-off-by: Jakub Kicinski

mptcp: Fix up subflow's memcg when CONFIG_SOCK_CGROUP_DATA=n.

2025-08-20T02:20:58+00:00

When sk_alloc() allocates a socket, mem_cgroup_sk_alloc() sets sk->sk_memcg based on the current task. MPTCP subflow socket creation is triggered from userspace or an in-kernel worker. In the latter case, sk->sk_memcg is not what we want. So, we fix it up from the parent socket's sk->sk_memcg in mptcp_attach_cgroup(). Although the code is placed under #ifdef CONFIG_MEMCG, it is buried under #ifdef CONFIG_SOCK_CGROUP_DATA. The two configs are orthogonal. If CONFIG_MEMCG is enabled without CONFIG_SOCK_CGROUP_DATA, the subflow's memory usage is not charged correctly. Let's move the code out of the wrong ifdef guard. Note that sk->sk_memcg is freed in sk_prot_free() and the parent sk holds the refcnt of memcg->css here, so we don't need to use css_tryget(). Fixes: 3764b0c5651e3 ("mptcp: attach subflow socket to parent cgroup") Signed-off-by: Kuniyuki Iwashima Reviewed-by: Eric Dumazet Acked-by: Matthieu Baerts (NGI0) Acked-by: Shakeel Butt Link: https://patch.msgid.link/20250815201712.1745332-2-kuniyu@google.com Signed-off-by: Jakub Kicinski

Merge tag 'cgroup-for-6.17' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/cgroup

2025-07-31T23:04:19+00:00

Pull cgroup updates from Tejun Heo: - Allow css_rstat_updated() in NMI context to enable memory accounting for allocations in NMI context. - /proc/cgroups doesn't contain useful information for cgroup2 and was updated to only show v1 controllers. This unfortunately broke something in the wild. Add an option to bring back the old behavior to ease transition. - selftest updates and other cleanups. * tag 'cgroup-for-6.17' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/cgroup: cgroup: Add compatibility option for content of /proc/cgroups selftests/cgroup: fix cpu.max tests cgroup: llist: avoid memory tears for llist_node selftests: cgroup: Fix missing newline in test_zswap_writeback_one selftests: cgroup: Allow longer timeout for kmem_dead_cgroups cleanup memcg: cgroup: call css_rstat_updated irrespective of in_nmi() cgroup: remove per-cpu per-subsystem locks cgroup: make css_rstat_updated nmi safe cgroup: support to enable nmi-safe css_rstat_updated selftests: cgroup: Fix compilation on pre-cgroupns kernels selftests: cgroup: Optionally set up v1 environment selftests: cgroup: Add support for named v1 hierarchies in test_core selftests: cgroup_util: Add helpers for testing named v1 hierarchies Documentation: cgroup: add section explaining controller availability cgroup: Drop sock_cgroup_classid() dummy implementation