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2024-11-23Merge tag 'mm-stable-2024-11-18-19-27' of ↵Linus Torvalds
git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm Pull MM updates from Andrew Morton: - The series "zram: optimal post-processing target selection" from Sergey Senozhatsky improves zram's post-processing selection algorithm. This leads to improved memory savings. - Wei Yang has gone to town on the mapletree code, contributing several series which clean up the implementation: - "refine mas_mab_cp()" - "Reduce the space to be cleared for maple_big_node" - "maple_tree: simplify mas_push_node()" - "Following cleanup after introduce mas_wr_store_type()" - "refine storing null" - The series "selftests/mm: hugetlb_fault_after_madv improvements" from David Hildenbrand fixes this selftest for s390. - The series "introduce pte_offset_map_{ro|rw}_nolock()" from Qi Zheng implements some rationaizations and cleanups in the page mapping code. - The series "mm: optimize shadow entries removal" from Shakeel Butt optimizes the file truncation code by speeding up the handling of shadow entries. - The series "Remove PageKsm()" from Matthew Wilcox completes the migration of this flag over to being a folio-based flag. - The series "Unify hugetlb into arch_get_unmapped_area functions" from Oscar Salvador implements a bunch of consolidations and cleanups in the hugetlb code. - The series "Do not shatter hugezeropage on wp-fault" from Dev Jain takes away the wp-fault time practice of turning a huge zero page into small pages. Instead we replace the whole thing with a THP. More consistent cleaner and potentiall saves a large number of pagefaults. - The series "percpu: Add a test case and fix for clang" from Andy Shevchenko enhances and fixes the kernel's built in percpu test code. - The series "mm/mremap: Remove extra vma tree walk" from Liam Howlett optimizes mremap() by avoiding doing things which we didn't need to do. - The series "Improve the tmpfs large folio read performance" from Baolin Wang teaches tmpfs to copy data into userspace at the folio size rather than as individual pages. A 20% speedup was observed. - The series "mm/damon/vaddr: Fix issue in damon_va_evenly_split_region()" fro Zheng Yejian fixes DAMON splitting. - The series "memcg-v1: fully deprecate charge moving" from Shakeel Butt removes the long-deprecated memcgv2 charge moving feature. - The series "fix error handling in mmap_region() and refactor" from Lorenzo Stoakes cleanup up some of the mmap() error handling and addresses some potential performance issues. - The series "x86/module: use large ROX pages for text allocations" from Mike Rapoport teaches x86 to use large pages for read-only-execute module text. - The series "page allocation tag compression" from Suren Baghdasaryan is followon maintenance work for the new page allocation profiling feature. - The series "page->index removals in mm" from Matthew Wilcox remove most references to page->index in mm/. A slow march towards shrinking struct page. - The series "damon/{self,kunit}tests: minor fixups for DAMON debugfs interface tests" from Andrew Paniakin performs maintenance work for DAMON's self testing code. - The series "mm: zswap swap-out of large folios" from Kanchana Sridhar improves zswap's batching of compression and decompression. It is a step along the way towards using Intel IAA hardware acceleration for this zswap operation. - The series "kasan: migrate the last module test to kunit" from Sabyrzhan Tasbolatov completes the migration of the KASAN built-in tests over to the KUnit framework. - The series "implement lightweight guard pages" from Lorenzo Stoakes permits userapace to place fault-generating guard pages within a single VMA, rather than requiring that multiple VMAs be created for this. Improved efficiencies for userspace memory allocators are expected. - The series "memcg: tracepoint for flushing stats" from JP Kobryn uses tracepoints to provide increased visibility into memcg stats flushing activity. - The series "zram: IDLE flag handling fixes" from Sergey Senozhatsky fixes a zram buglet which potentially affected performance. - The series "mm: add more kernel parameters to control mTHP" from Maíra Canal enhances our ability to control/configuremultisize THP from the kernel boot command line. - The series "kasan: few improvements on kunit tests" from Sabyrzhan Tasbolatov has a couple of fixups for the KASAN KUnit tests. - The series "mm/list_lru: Split list_lru lock into per-cgroup scope" from Kairui Song optimizes list_lru memory utilization when lockdep is enabled. * tag 'mm-stable-2024-11-18-19-27' of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm: (215 commits) cma: enforce non-zero pageblock_order during cma_init_reserved_mem() mm/kfence: add a new kunit test test_use_after_free_read_nofault() zram: fix NULL pointer in comp_algorithm_show() memcg/hugetlb: add hugeTLB counters to memcg vmstat: call fold_vm_zone_numa_events() before show per zone NUMA event mm: mmap_lock: check trace_mmap_lock_$type_enabled() instead of regcount zram: ZRAM_DEF_COMP should depend on ZRAM MAINTAINERS/MEMORY MANAGEMENT: add document files for mm Docs/mm/damon: recommend academic papers to read and/or cite mm: define general function pXd_init() kmemleak: iommu/iova: fix transient kmemleak false positive mm/list_lru: simplify the list_lru walk callback function mm/list_lru: split the lock to per-cgroup scope mm/list_lru: simplify reparenting and initial allocation mm/list_lru: code clean up for reparenting mm/list_lru: don't export list_lru_add mm/list_lru: don't pass unnecessary key parameters kasan: add kunit tests for kmalloc_track_caller, kmalloc_node_track_caller kasan: change kasan_atomics kunit test as KUNIT_CASE_SLOW kasan: use EXPORT_SYMBOL_IF_KUNIT to export symbols ...
2024-11-18Merge tag 'pull-fd' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfsLinus Torvalds
Pull 'struct fd' class updates from Al Viro: "The bulk of struct fd memory safety stuff Making sure that struct fd instances are destroyed in the same scope where they'd been created, getting rid of reassignments and passing them by reference, converting to CLASS(fd{,_pos,_raw}). We are getting very close to having the memory safety of that stuff trivial to verify" * tag 'pull-fd' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs: (28 commits) deal with the last remaing boolean uses of fd_file() css_set_fork(): switch to CLASS(fd_raw, ...) memcg_write_event_control(): switch to CLASS(fd) assorted variants of irqfd setup: convert to CLASS(fd) do_pollfd(): convert to CLASS(fd) convert do_select() convert vfs_dedupe_file_range(). convert cifs_ioctl_copychunk() convert media_request_get_by_fd() convert spu_run(2) switch spufs_calls_{get,put}() to CLASS() use convert cachestat(2) convert do_preadv()/do_pwritev() fdget(), more trivial conversions fdget(), trivial conversions privcmd_ioeventfd_assign(): don't open-code eventfd_ctx_fdget() o2hb_region_dev_store(): avoid goto around fdget()/fdput() introduce "fd_pos" class, convert fdget_pos() users to it. fdget_raw() users: switch to CLASS(fd_raw) convert vmsplice() to CLASS(fd) ...
2024-11-06memcg-v1: remove memcg move locking codeShakeel Butt
The memcg v1's charge move feature has been deprecated. All the places using the memcg move lock, have stopped using it as they don't need the protection any more. Let's proceed to remove all the locking code related to charge moving. Link: https://lkml.kernel.org/r/20241025012304.2473312-7-shakeel.butt@linux.dev Signed-off-by: Shakeel Butt <shakeel.butt@linux.dev> Acked-by: Michal Hocko <mhocko@suse.com> Reviewed-by: Roman Gushchin <roman.gushchin@linux.dev> Acked-by: Johannes Weiner <hannes@cmpxchg.org> Cc: Hugh Dickins <hughd@google.com> Cc: Muchun Song <muchun.song@linux.dev> Cc: Yosry Ahmed <yosryahmed@google.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
2024-11-06memcg-v1: remove charge move codeShakeel Butt
The memcg-v1 charge move feature has been deprecated completely and let's remove the relevant code as well. Link: https://lkml.kernel.org/r/20241025012304.2473312-3-shakeel.butt@linux.dev Signed-off-by: Shakeel Butt <shakeel.butt@linux.dev> Acked-by: Michal Hocko <mhocko@suse.com> Reviewed-by: Roman Gushchin <roman.gushchin@linux.dev> Acked-by: Johannes Weiner <hannes@cmpxchg.org> Cc: Hugh Dickins <hughd@google.com> Cc: Muchun Song <muchun.song@linux.dev> Cc: Yosry Ahmed <yosryahmed@google.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
2024-11-06memcg-v1: fully deprecate move_charge_at_immigrateShakeel Butt
Patch series "memcg-v1: fully deprecate charge moving". The memcg v1's charge moving feature has been deprecated for almost 2 years and the kernel warns if someone try to use it. This warning has been backported to all stable kernel and there have not been any report of the warning or the request to support this feature anymore. Let's proceed to fully deprecate this feature. This patch (of 6): Proceed with the complete deprecation of memcg v1's charge moving feature. The deprecation warning has been in the kernel for almost two years and has been ported to all stable kernel since. Now is the time to fully deprecate this feature. Link: https://lkml.kernel.org/r/20241025012304.2473312-1-shakeel.butt@linux.dev Link: https://lkml.kernel.org/r/20241025012304.2473312-2-shakeel.butt@linux.dev Signed-off-by: Shakeel Butt <shakeel.butt@linux.dev> Reviewed-by: Roman Gushchin <roman.gushchin@linux.dev> Acked-by: Michal Hocko <mhocko@suse.com> Acked-by: Johannes Weiner <hannes@cmpxchg.org> Cc: Hugh Dickins <hughd@google.com> Cc: Muchun Song <muchun.song@linux.dev> Cc: Yosry Ahmed <yosryahmed@google.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
2024-11-05mm/thp: fix deferred split unqueue naming and lockingHugh Dickins
Recent changes are putting more pressure on THP deferred split queues: under load revealing long-standing races, causing list_del corruptions, "Bad page state"s and worse (I keep BUGs in both of those, so usually don't get to see how badly they end up without). The relevant recent changes being 6.8's mTHP, 6.10's mTHP swapout, and 6.12's mTHP swapin, improved swap allocation, and underused THP splitting. Before fixing locking: rename misleading folio_undo_large_rmappable(), which does not undo large_rmappable, to folio_unqueue_deferred_split(), which is what it does. But that and its out-of-line __callee are mm internals of very limited usability: add comment and WARN_ON_ONCEs to check usage; and return a bool to say if a deferred split was unqueued, which can then be used in WARN_ON_ONCEs around safety checks (sparing callers the arcane conditionals in __folio_unqueue_deferred_split()). Just omit the folio_unqueue_deferred_split() from free_unref_folios(), all of whose callers now call it beforehand (and if any forget then bad_page() will tell) - except for its caller put_pages_list(), which itself no longer has any callers (and will be deleted separately). Swapout: mem_cgroup_swapout() has been resetting folio->memcg_data 0 without checking and unqueueing a THP folio from deferred split list; which is unfortunate, since the split_queue_lock depends on the memcg (when memcg is enabled); so swapout has been unqueueing such THPs later, when freeing the folio, using the pgdat's lock instead: potentially corrupting the memcg's list. __remove_mapping() has frozen refcount to 0 here, so no problem with calling folio_unqueue_deferred_split() before resetting memcg_data. That goes back to 5.4 commit 87eaceb3faa5 ("mm: thp: make deferred split shrinker memcg aware"): which included a check on swapcache before adding to deferred queue, but no check on deferred queue before adding THP to swapcache. That worked fine with the usual sequence of events in reclaim (though there were a couple of rare ways in which a THP on deferred queue could have been swapped out), but 6.12 commit dafff3f4c850 ("mm: split underused THPs") avoids splitting underused THPs in reclaim, which makes swapcache THPs on deferred queue commonplace. Keep the check on swapcache before adding to deferred queue? Yes: it is no longer essential, but preserves the existing behaviour, and is likely to be a worthwhile optimization (vmstat showed much more traffic on the queue under swapping load if the check was removed); update its comment. Memcg-v1 move (deprecated): mem_cgroup_move_account() has been changing folio->memcg_data without checking and unqueueing a THP folio from the deferred list, sometimes corrupting "from" memcg's list, like swapout. Refcount is non-zero here, so folio_unqueue_deferred_split() can only be used in a WARN_ON_ONCE to validate the fix, which must be done earlier: mem_cgroup_move_charge_pte_range() first try to split the THP (splitting of course unqueues), or skip it if that fails. Not ideal, but moving charge has been requested, and khugepaged should repair the THP later: nobody wants new custom unqueueing code just for this deprecated case. The 87eaceb3faa5 commit did have the code to move from one deferred list to another (but was not conscious of its unsafety while refcount non-0); but that was removed by 5.6 commit fac0516b5534 ("mm: thp: don't need care deferred split queue in memcg charge move path"), which argued that the existence of a PMD mapping guarantees that the THP cannot be on a deferred list. As above, false in rare cases, and now commonly false. Backport to 6.11 should be straightforward. Earlier backports must take care that other _deferred_list fixes and dependencies are included. There is not a strong case for backports, but they can fix cornercases. Link: https://lkml.kernel.org/r/8dc111ae-f6db-2da7-b25c-7a20b1effe3b@google.com Fixes: 87eaceb3faa5 ("mm: thp: make deferred split shrinker memcg aware") Fixes: dafff3f4c850 ("mm: split underused THPs") Signed-off-by: Hugh Dickins <hughd@google.com> Acked-by: David Hildenbrand <david@redhat.com> Reviewed-by: Yang Shi <shy828301@gmail.com> Cc: Baolin Wang <baolin.wang@linux.alibaba.com> Cc: Barry Song <baohua@kernel.org> Cc: Chris Li <chrisl@kernel.org> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Kefeng Wang <wangkefeng.wang@huawei.com> Cc: Kirill A. Shutemov <kirill.shutemov@linux.intel.com> Cc: Matthew Wilcox (Oracle) <willy@infradead.org> Cc: Nhat Pham <nphamcs@gmail.com> Cc: Ryan Roberts <ryan.roberts@arm.com> Cc: Shakeel Butt <shakeel.butt@linux.dev> Cc: Usama Arif <usamaarif642@gmail.com> Cc: Wei Yang <richard.weiyang@gmail.com> Cc: Zi Yan <ziy@nvidia.com> Cc: <stable@vger.kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
2024-11-03memcg_write_event_control(): switch to CLASS(fd)Al Viro
some reordering required - take both fdget() to the point before the allocations, with matching move of fdput() to the very end of failure exit(s); after that it converts trivially. simplify the cleanups that involve css_put(), while we are at it... Reviewed-by: Christian Brauner <brauner@kernel.org> Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2024-09-23Merge tag 'pull-stable-struct_fd' of ↵Linus Torvalds
git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs Pull 'struct fd' updates from Al Viro: "Just the 'struct fd' layout change, with conversion to accessor helpers" * tag 'pull-stable-struct_fd' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs: add struct fd constructors, get rid of __to_fd() struct fd: representation change introduce fd_file(), convert all accessors to it.
2024-09-01memcg: initiate deprecation of pressure_levelShakeel Butt
The pressure_level in memcg v1 provides memory pressure notifications to the user space. At the moment it provides notifications for three levels of memory pressure i.e. low, medium and critical, which are defined based on internal memory reclaim implementation details. More specifically the ratio of scanned and reclaimed pages during a memory reclaim. However this is not robust as there are workloads with mostly unreclaimable user memory or kernel memory. For v2, the users can use PSI for memory pressure status of the system or the cgroup. Let's start the deprecation process for pressure_level and add warnings to gather the info on how the current users are using this interface and how they can be used to PSI. Link: https://lkml.kernel.org/r/20240814220021.3208384-5-shakeel.butt@linux.dev Signed-off-by: Shakeel Butt <shakeel.butt@linux.dev> Reviewed-by: T.J. Mercier <tjmercier@google.com> Acked-by: Michal Hocko <mhocko@suse.com> Acked-by: Roman Gushchin <roman.gushchin@linux.dev> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Muchun Song <muchun.song@linux.dev> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
2024-09-01memcg: initiate deprecation of oom_controlShakeel Butt
The oom_control provides functionality to disable memcg oom-killer, notifications on oom-kill and reading the stats regarding oom-kills. This interface was mainly introduced to provide functionality for userspace oom-killers. However it is not robust enough and only supports OOM handling in the page fault path. For v2, the users can use the combination of memory.events notifications, memory.high and PSI to provide userspace OOM-killing functionality. Actually LMKD in Android and OOMd in systemd and Meta infrastructure already use PSI in combination with other stats to implement userspace OOM-killing. Let's start the deprecation process for v1 and gather the info on how the current users are using this interface and work on providing a more robust functionality in v2. Link: https://lkml.kernel.org/r/20240814220021.3208384-4-shakeel.butt@linux.dev Signed-off-by: Shakeel Butt <shakeel.butt@linux.dev> Reviewed-by: T.J. Mercier <tjmercier@google.com> Acked-by: Michal Hocko <mhocko@suse.com> Acked-by: Roman Gushchin <roman.gushchin@linux.dev> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Muchun Song <muchun.song@linux.dev> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
2024-09-01memcg: initiate deprecation of v1 soft limitShakeel Butt
Memcg v1 provides soft limit functionality for the best effort memory sharing between multiple workloads on a system. It is usually triggered through kswapd and at the moment does not reclaim kernel memory. Memcg v2 provides more straightforward best effort (memory.low) and hard protection (memory.min) functionalities. Let's initiate the deprecation of soft limit from v1 and gather if v2 needs something more to move the existing v1 users to v2 regarding soft limit. Link: https://lkml.kernel.org/r/20240814220021.3208384-3-shakeel.butt@linux.dev Signed-off-by: Shakeel Butt <shakeel.butt@linux.dev> Reviewed-by: T.J. Mercier <tjmercier@google.com> Acked-by: Michal Hocko <mhocko@suse.com> Acked-by: Roman Gushchin <roman.gushchin@linux.dev> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Muchun Song <muchun.song@linux.dev> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
2024-09-01memcg: initiate deprecation of v1 tcp accountingShakeel Butt
Patch series "memcg: initiate deprecation of v1 features", v2. Start the deprecation process of the memcg v1 features which we discussed during LSFMMBPF 2024 [1]. For now add the warnings to collect the information on how the current users are using these features. Next we will work on providing better alternatives in v2 (if needed) and fully deprecate these features. Link: https://lwn.net/Articles/974575 [1] This patch (of 4): Memcg v1 provides opt-in TCP memory accounting feature. However it is mostly unused due to its performance impact on the network traffic. In v2, the TCP memory is accounted in the regular memory usage and is transparent to the users but they can observe the TCP memory usage through memcg stats. Let's initiate the deprecation process of memcg v1's tcp accounting functionality and add warnings to gather if there are any users and if there are, collect how they are using it and plan to provide them better alternative in v2. Link: https://lkml.kernel.org/r/20240814220021.3208384-1-shakeel.butt@linux.dev Link: https://lkml.kernel.org/r/20240814220021.3208384-2-shakeel.butt@linux.dev Signed-off-by: Shakeel Butt <shakeel.butt@linux.dev> Reviewed-by: T.J. Mercier <tjmercier@google.com> Acked-by: Michal Hocko <mhocko@suse.com> Acked-by: Roman Gushchin <roman.gushchin@linux.dev> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Muchun Song <muchun.song@linux.dev> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
2024-09-01memcg: allocate v1 event percpu only on v1 deploymentShakeel Butt
Currently memcg->events_percpu gets allocated on v2 deployments. Let's move the allocation to v1 only codebase. This is not needed in v2. Link: https://lkml.kernel.org/r/20240815050453.1298138-7-shakeel.butt@linux.dev Signed-off-by: Shakeel Butt <shakeel.butt@linux.dev> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Michal Hocko <mhocko@kernel.org> Cc: Muchun Song <muchun.song@linux.dev> Cc: Roman Gushchin <roman.gushchin@linux.dev> Cc: T.J. Mercier <tjmercier@google.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
2024-09-01memcg: make v1 only functions staticShakeel Butt
The functions memcg1_charge_statistics() and memcg1_check_events() are never used outside of v1 source file. So, make them static. Link: https://lkml.kernel.org/r/20240815050453.1298138-6-shakeel.butt@linux.dev Signed-off-by: Shakeel Butt <shakeel.butt@linux.dev> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Michal Hocko <mhocko@kernel.org> Cc: Muchun Song <muchun.song@linux.dev> Cc: Roman Gushchin <roman.gushchin@linux.dev> Cc: T.J. Mercier <tjmercier@google.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
2024-09-01memcg: move v1 events and statistics code to v1 fileShakeel Butt
Currently the common code path for charge commit, swapout and batched uncharge are executing v1 only code which is completely useless for the v2 deployments where CONFIG_MEMCG_V1 is disabled. In addition, it is mucking with IRQs which might be slow on some architectures. Let's move all of this code to v1 only code and remove them from v2 only deployments. Link: https://lkml.kernel.org/r/20240815050453.1298138-5-shakeel.butt@linux.dev Signed-off-by: Shakeel Butt <shakeel.butt@linux.dev> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Michal Hocko <mhocko@kernel.org> Cc: Muchun Song <muchun.song@linux.dev> Cc: Roman Gushchin <roman.gushchin@linux.dev> Cc: T.J. Mercier <tjmercier@google.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
2024-09-01memcg: move mem_cgroup_charge_statistics to v1 codeShakeel Butt
There are no callers of mem_cgroup_charge_statistics() in the v2 code base, so move it to the v1 only code and rename it to memcg1_charge_statistics(). Link: https://lkml.kernel.org/r/20240815050453.1298138-4-shakeel.butt@linux.dev Signed-off-by: Shakeel Butt <shakeel.butt@linux.dev> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Michal Hocko <mhocko@kernel.org> Cc: Muchun Song <muchun.song@linux.dev> Cc: Roman Gushchin <roman.gushchin@linux.dev> Cc: T.J. Mercier <tjmercier@google.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
2024-09-01memcg: move mem_cgroup_event_ratelimit to v1 codeShakeel Butt
There are no callers of mem_cgroup_event_ratelimit() in the v2 code. Move it to v1 only code and rename it to memcg1_event_ratelimit(). Link: https://lkml.kernel.org/r/20240815050453.1298138-3-shakeel.butt@linux.dev Signed-off-by: Shakeel Butt <shakeel.butt@linux.dev> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Michal Hocko <mhocko@kernel.org> Cc: Muchun Song <muchun.song@linux.dev> Cc: Roman Gushchin <roman.gushchin@linux.dev> Cc: T.J. Mercier <tjmercier@google.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
2024-08-12introduce fd_file(), convert all accessors to it.Al Viro
For any changes of struct fd representation we need to turn existing accesses to fields into calls of wrappers. Accesses to struct fd::flags are very few (3 in linux/file.h, 1 in net/socket.c, 3 in fs/overlayfs/file.c and 3 more in explicit initializers). Those can be dealt with in the commit converting to new layout; accesses to struct fd::file are too many for that. This commit converts (almost) all of f.file to fd_file(f). It's not entirely mechanical ('file' is used as a member name more than just in struct fd) and it does not even attempt to distinguish the uses in pointer context from those in boolean context; the latter will be eventually turned into a separate helper (fd_empty()). NOTE: mass conversion to fd_empty(), tempting as it might be, is a bad idea; better do that piecewise in commit that convert from fdget...() to CLASS(...). [conflicts in fs/fhandle.c, kernel/bpf/syscall.c, mm/memcontrol.c caught by git; fs/stat.c one got caught by git grep] [fs/xattr.c conflict] Reviewed-by: Christian Brauner <brauner@kernel.org> Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2024-08-12memcg_write_event_control(): fix a user-triggerable oopsAl Viro
we are *not* guaranteed that anything past the terminating NUL is mapped (let alone initialized with anything sane). Fixes: 0dea116876ee ("cgroup: implement eventfd-based generic API for notifications") Cc: stable@vger.kernel.org Cc: Andrew Morton <akpm@linux-foundation.org> Acked-by: Michal Hocko <mhocko@suse.com> Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2024-07-17mm: memcg1: convert charge move flags to unsigned long longRoman Gushchin
Currently MOVE_ANON and MOVE_FILE flags are defined as integers and it leads to the following Smatch static checker warning: mm/memcontrol-v1.c:609 mem_cgroup_move_charge_write() warn: was expecting a 64 bit value instead of '~(1 | 2)' Fix this be redefining them as unsigned long long. Even though the issue allows to set high 32 bits of mc.flags to an arbitrary number, these bits are never used, so it doesn't have any significant consequences. Link: https://lkml.kernel.org/r/ZpF8Q9zBsIY7d2P9@google.com Signed-off-by: Roman Gushchin <roman.gushchin@linux.dev> Reported-by: Dan Carpenter <dan.carpenter@linaro.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
2024-07-10mm: remove CONFIG_MEMCG_KMEMJohannes Weiner
CONFIG_MEMCG_KMEM used to be a user-visible option for whether slab tracking is enabled. It has been default-enabled and equivalent to CONFIG_MEMCG for almost a decade. We've only grown more kernel memory accounting sites since, and there is no imaginable cgroup usecase going forward that wants to track user pages but not the multitude of user-drivable kernel allocations. Link: https://lkml.kernel.org/r/20240701153148.452230-1-hannes@cmpxchg.org Signed-off-by: Johannes Weiner <hannes@cmpxchg.org> Acked-by: Roman Gushchin <roman.gushchin@linux.dev> Acked-by: Michal Hocko <mhocko@suse.com> Acked-by: Shakeel Butt <shakeel.butt@linux.dev> Acked-by: David Hildenbrand <david@redhat.com> Cc: Muchun Song <muchun.song@linux.dev> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
2024-07-04mm: memcg: gather memcg1-specific fields initialization in memcg1_memcg_init()Roman Gushchin
Gather all memcg1-specific struct mem_cgroup's members initialization in a new memcg1_memcg_init() function, defined in mm/memcontrol-v1.c. Obviously, if CONFIG_MEMCG_V1 is not set, there is no need to initialize these fields, so the function becomes trivial. Link: https://lkml.kernel.org/r/20240628210317.272856-5-roman.gushchin@linux.dev Signed-off-by: Roman Gushchin <roman.gushchin@linux.dev> Acked-by: Shakeel Butt <shakeel.butt@linux.dev> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Michal Hocko <mhocko@kernel.org> Cc: Muchun Song <muchun.song@linux.dev> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
2024-07-04mm: memcg: factor out legacy socket memory accounting codeRoman Gushchin
Move out the legacy cgroup v1 socket memory accounting code into mm/memcontrol-v1.c. This commit introduces three new functions: memcg1_tcpmem_active(), memcg1_charge_skmem() and memcg1_uncharge_skmem(), which contain all cgroup v1-specific code and become trivial if CONFIG_MEMCG_V1 isn't set. Note, that !!memcg->tcpmem_pressure check in mem_cgroup_under_socket_pressure() can't be easily moved into memcontrol-v1.h without including memcontrol-v1.h from memcontrol.h which isn't a good idea, so it's better to just #ifdef it. Link: https://lkml.kernel.org/r/20240628210317.272856-3-roman.gushchin@linux.dev Signed-off-by: Roman Gushchin <roman.gushchin@linux.dev> Acked-by: Shakeel Butt <shakeel.butt@linux.dev> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Michal Hocko <mhocko@kernel.org> Cc: Muchun Song <muchun.song@linux.dev> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
2024-07-04mm: memcg: move memcg_account_kmem() to memcontrol-v1.cRoman Gushchin
Patch series "mm: memcg: put cgroup v1-specific memcg data under CONFIG_MEMCG_V1". This patchset puts all cgroup v1's members of struct mem_cgroup, struct mem_cgroup_per_node and struct task_struct under the CONFIG_MEMCG_V1 config option. If cgroup v1 support is not required (and it's true for many cgroup users these days), it allows to save a bit of memory and compile out some code, some of which is on relatively hot paths. It also structures the code a bit better by grouping cgroup v1-specific stuff in one place. This patch (of 9): memcg_account_kmem() consists of a trivial statistics change via mod_memcg_state() call and a relatively large memcg1-specific part. Let's factor out the mod_memcg_state() call and move the rest into the mm/memcontrol-v1.c file. Also rename memcg_account_kmem() into memcg1_account_kmem() for consistency. Link: https://lkml.kernel.org/r/20240628210317.272856-1-roman.gushchin@linux.dev Link: https://lkml.kernel.org/r/20240628210317.272856-2-roman.gushchin@linux.dev Signed-off-by: Roman Gushchin <roman.gushchin@linux.dev> Acked-by: Shakeel Butt <shakeel.butt@linux.dev> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Michal Hocko <mhocko@kernel.org> Cc: Muchun Song <muchun.song@linux.dev> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
2024-07-04mm: add swappiness= arg to memory.reclaimDan Schatzberg
Allow proactive reclaimers to submit an additional swappiness=<val> argument to memory.reclaim. This overrides the global or per-memcg swappiness setting for that reclaim attempt. For example: echo "2M swappiness=0" > /sys/fs/cgroup/memory.reclaim will perform reclaim on the rootcg with a swappiness setting of 0 (no swap) regardless of the vm.swappiness sysctl setting. Userspace proactive reclaimers use the memory.reclaim interface to trigger reclaim. The memory.reclaim interface does not allow for any way to effect the balance of file vs anon during proactive reclaim. The only approach is to adjust the vm.swappiness setting. However, there are a few reasons we look to control the balance of file vs anon during proactive reclaim, separately from reactive reclaim: * Swapout should be limited to manage SSD write endurance. In near-OOM situations we are fine with lots of swap-out to avoid OOMs. As these are typically rare events, they have relatively little impact on write endurance. However, proactive reclaim runs continuously and so its impact on SSD write endurance is more significant. Therefore it is desireable to control swap-out for proactive reclaim separately from reactive reclaim * Some userspace OOM killers like systemd-oomd[1] support OOM killing on swap exhaustion. This makes sense if the swap exhaustion is triggered due to reactive reclaim but less so if it is triggered due to proactive reclaim (e.g. one could see OOMs when free memory is ample but anon is just particularly cold). Therefore, it's desireable to have proactive reclaim reduce or stop swap-out before the threshold at which OOM killing occurs. In the case of Meta's Senpai proactive reclaimer, we adjust vm.swappiness before writes to memory.reclaim[2]. This has been in production for nearly two years and has addressed our needs to control proactive vs reactive reclaim behavior but is still not ideal for a number of reasons: * vm.swappiness is a global setting, adjusting it can race/interfere with other system administration that wishes to control vm.swappiness. In our case, we need to disable Senpai before adjusting vm.swappiness. * vm.swappiness is stateful - so a crash or restart of Senpai can leave a misconfigured setting. This requires some additional management to record the "desired" setting and ensure Senpai always adjusts to it. With this patch, we avoid these downsides of adjusting vm.swappiness globally. [1]https://www.freedesktop.org/software/systemd/man/latest/systemd-oomd.service.html [2]https://github.com/facebookincubator/oomd/blob/main/src/oomd/plugins/Senpai.cpp#L585-L598 Link: https://lkml.kernel.org/r/20240103164841.2800183-3-schatzberg.dan@gmail.com Signed-off-by: Dan Schatzberg <schatzberg.dan@gmail.com> Suggested-by: Yosry Ahmed <yosryahmed@google.com> Acked-by: Michal Hocko <mhocko@suse.com> Acked-by: David Rientjes <rientjes@google.com> Acked-by: Chris Li <chrisl@kernel.org> Cc: David Hildenbrand <david@redhat.com> Cc: Hugh Dickins <hughd@google.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Jonathan Corbet <corbet@lwn.net> Cc: Kefeng Wang <wangkefeng.wang@huawei.com> Cc: Matthew Wilcox (Oracle) <willy@infradead.org> Cc: Muchun Song <muchun.song@linux.dev> Cc: Roman Gushchin <roman.gushchin@linux.dev> Cc: Shakeel Butt <shakeel.butt@linux.dev> Cc: Shakeel Butt <shakeelb@google.com> Cc: Tejun Heo <tj@kernel.org> Cc: Yue Zhao <findns94@gmail.com> Cc: Zefan Li <lizefan.x@bytedance.com> Cc: Nhat Pham <nphamcs@gmail.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
2024-07-04mm: add defines for min/max swappinessDan Schatzberg
Patch series "Add swappiness argument to memory.reclaim", v6. This patch proposes augmenting the memory.reclaim interface with a swappiness=<val> argument that overrides the swappiness value for that instance of proactive reclaim. Userspace proactive reclaimers use the memory.reclaim interface to trigger reclaim. The memory.reclaim interface does not allow for any way to effect the balance of file vs anon during proactive reclaim. The only approach is to adjust the vm.swappiness setting. However, there are a few reasons we look to control the balance of file vs anon during proactive reclaim, separately from reactive reclaim: * Swapout should be limited to manage SSD write endurance. In near-OOM situations we are fine with lots of swap-out to avoid OOMs. As these are typically rare events, they have relatively little impact on write endurance. However, proactive reclaim runs continuously and so its impact on SSD write endurance is more significant. Therefore it is desireable to control swap-out for proactive reclaim separately from reactive reclaim * Some userspace OOM killers like systemd-oomd[1] support OOM killing on swap exhaustion. This makes sense if the swap exhaustion is triggered due to reactive reclaim but less so if it is triggered due to proactive reclaim (e.g. one could see OOMs when free memory is ample but anon is just particularly cold). Therefore, it's desireable to have proactive reclaim reduce or stop swap-out before the threshold at which OOM killing occurs. In the case of Meta's Senpai proactive reclaimer, we adjust vm.swappiness before writes to memory.reclaim[2]. This has been in production for nearly two years and has addressed our needs to control proactive vs reactive reclaim behavior but is still not ideal for a number of reasons: * vm.swappiness is a global setting, adjusting it can race/interfere with other system administration that wishes to control vm.swappiness. In our case, we need to disable Senpai before adjusting vm.swappiness. * vm.swappiness is stateful - so a crash or restart of Senpai can leave a misconfigured setting. This requires some additional management to record the "desired" setting and ensure Senpai always adjusts to it. With this patch, we avoid these downsides of adjusting vm.swappiness globally. Previously, this exact interface addition was proposed by Yosry[3]. In response, Roman proposed instead an interface to specify precise file/anon/slab reclaim amounts[4]. More recently Huan also proposed this as well[5] and others similarly questioned if this was the proper interface. Previous proposals sought to use this to allow proactive reclaimers to effectively perform a custom reclaim algorithm by issuing proactive reclaim with different settings to control file vs anon reclaim (e.g. to only reclaim anon from some applications). Responses argued that adjusting swappiness is a poor interface for custom reclaim. In contrast, I argue in favor of a swappiness setting not as a way to implement custom reclaim algorithms but rather to bias the balance of anon vs file due to differences of proactive vs reactive reclaim. In this context, swappiness is the existing interface for controlling this balance and this patch simply allows for it to be configured differently for proactive vs reactive reclaim. Specifying explicit amounts of anon vs file pages to reclaim feels inappropriate for this prupose. Proactive reclaimers are un-aware of the relative age of file vs anon for a cgroup which makes it difficult to manage proactive reclaim of different memory pools. A proactive reclaimer would need some amount of anon reclaim attempts separate from the amount of file reclaim attempts which seems brittle given that it's difficult to observe the impact. [1]https://www.freedesktop.org/software/systemd/man/latest/systemd-oomd.service.html [2]https://github.com/facebookincubator/oomd/blob/main/src/oomd/plugins/Senpai.cpp#L585-L598 [3]https://lore.kernel.org/linux-mm/CAJD7tkbDpyoODveCsnaqBBMZEkDvshXJmNdbk51yKSNgD7aGdg@mail.gmail.com/ [4]https://lore.kernel.org/linux-mm/YoPHtHXzpK51F%2F1Z@carbon/ [5]https://lore.kernel.org/lkml/20231108065818.19932-1-link@vivo.com/ This patch (of 2): We use the constants 0 and 200 in a few places in the mm code when referring to the min and max swappiness. This patch adds MIN_SWAPPINESS and MAX_SWAPPINESS #defines to improve clarity. There are no functional changes. Link: https://lkml.kernel.org/r/20240103164841.2800183-1-schatzberg.dan@gmail.com Link: https://lkml.kernel.org/r/20240103164841.2800183-2-schatzberg.dan@gmail.com Signed-off-by: Dan Schatzberg <schatzberg.dan@gmail.com> Acked-by: David Rientjes <rientjes@google.com> Acked-by: Chris Li <chrisl@kernel.org> Reviewed-by: Nhat Pham <nphamcs@gmail.com> Cc: David Hildenbrand <david@redhat.com> Cc: Hugh Dickins <hughd@google.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Jonathan Corbet <corbet@lwn.net> Cc: Kefeng Wang <wangkefeng.wang@huawei.com> Cc: Matthew Wilcox (Oracle) <willy@infradead.org> Cc: Michal Hocko <mhocko@suse.com> Cc: Muchun Song <muchun.song@linux.dev> Cc: Roman Gushchin <roman.gushchin@linux.dev> Cc: Shakeel Butt <shakeelb@google.com> Cc: Shakeel Butt <shakeel.butt@linux.dev> Cc: Tejun Heo <tj@kernel.org> Cc: Yosry Ahmed <yosryahmed@google.com> Cc: Yue Zhao <findns94@gmail.com> Cc: Zefan Li <lizefan.x@bytedance.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
2024-07-04mm: memcg: make memcg1_update_tree() staticRoman Gushchin
memcg1_update_tree() is not used outside of mm/memcontrol-v1.c anymore, define it as static and remove the declaration from the header file. Link: https://lkml.kernel.org/r/20240625005906.106920-12-roman.gushchin@linux.dev Signed-off-by: Roman Gushchin <roman.gushchin@linux.dev> Acked-by: Michal Hocko <mhocko@suse.com> Acked-by: Shakeel Butt <shakeel.butt@linux.dev> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Matthew Wilcox (Oracle) <willy@infradead.org> Cc: Muchun Song <muchun.song@linux.dev> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
2024-07-04mm: memcg: move cgroup v1 interface files to memcontrol-v1.cRoman Gushchin
Move legacy cgroup v1 memory controller interfaces and corresponding code into memcontrol-v1.c. [roman.gushchin@linux.dev: move two functions] Link: https://lkml.kernel.org/r/20240704002712.2077812-1-roman.gushchin@linux.dev Link: https://lkml.kernel.org/r/20240625005906.106920-11-roman.gushchin@linux.dev Signed-off-by: Roman Gushchin <roman.gushchin@linux.dev> Acked-by: Michal Hocko <mhocko@suse.com> Acked-by: Shakeel Butt <shakeel.butt@linux.dev> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Matthew Wilcox (Oracle) <willy@infradead.org> Cc: Muchun Song <muchun.song@linux.dev> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
2024-07-04mm: memcg: rename memcg_oom_recover()Roman Gushchin
Rename memcg_oom_recover() into memcg1_oom_recover() for consistency with other memory cgroup v1-related functions. Move the declaration in mm/memcontrol-v1.h to be nearby other memcg v1 oom handling functions. Link: https://lkml.kernel.org/r/20240625005906.106920-10-roman.gushchin@linux.dev Signed-off-by: Roman Gushchin <roman.gushchin@linux.dev> Acked-by: Michal Hocko <mhocko@suse.com> Acked-by: Shakeel Butt <shakeel.butt@linux.dev> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Matthew Wilcox (Oracle) <willy@infradead.org> Cc: Muchun Song <muchun.song@linux.dev> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
2024-07-04mm: memcg: move cgroup v1 oom handling code into memcontrol-v1.cRoman Gushchin
Cgroup v1 supports a complicated OOM handling in userspace mechanism, which is not supported by cgroup v2. Let's move the corresponding code into memcontrol-v1.c. Aside from mechanical code movement this patch introduces two new functions: memcg1_oom_prepare() and memcg1_oom_finish(). Those are implementing cgroup v1-specific parts of the common memcg OOM handling path. Link: https://lkml.kernel.org/r/20240625005906.106920-9-roman.gushchin@linux.dev Signed-off-by: Roman Gushchin <roman.gushchin@linux.dev> Acked-by: Michal Hocko <mhocko@suse.com> Acked-by: Shakeel Butt <shakeel.butt@linux.dev> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Matthew Wilcox (Oracle) <willy@infradead.org> Cc: Muchun Song <muchun.song@linux.dev> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
2024-07-04mm: memcg: rename memcg_check_events()Roman Gushchin
Rename memcg_check_events() into memcg1_check_events() for consistency with other cgroup v1-specific functions. Link: https://lkml.kernel.org/r/20240625005906.106920-8-roman.gushchin@linux.dev Signed-off-by: Roman Gushchin <roman.gushchin@linux.dev> Acked-by: Michal Hocko <mhocko@suse.com> Acked-by: Shakeel Butt <shakeel.butt@linux.dev> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Matthew Wilcox (Oracle) <willy@infradead.org> Cc: Muchun Song <muchun.song@linux.dev> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
2024-07-04mm: memcg: move legacy memcg event code into memcontrol-v1.cRoman Gushchin
Cgroup v1's memory controller contains a pretty complicated event notifications mechanism which is not used on cgroup v2. Let's move the corresponding code into memcontrol-v1.c. Please, note, that mem_cgroup_event_ratelimit() remains in memcontrol.c, otherwise it would require exporting too many details on memcg stats outside of memcontrol.c. Link: https://lkml.kernel.org/r/20240625005906.106920-7-roman.gushchin@linux.dev Signed-off-by: Roman Gushchin <roman.gushchin@linux.dev> Acked-by: Michal Hocko <mhocko@suse.com> Acked-by: Shakeel Butt <shakeel.butt@linux.dev> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Matthew Wilcox (Oracle) <willy@infradead.org> Cc: Muchun Song <muchun.song@linux.dev> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
2024-07-04mm: memcg: rename charge move-related functionsRoman Gushchin
Rename exported function related to the charge move to have the memcg1_ prefix. Link: https://lkml.kernel.org/r/20240625005906.106920-6-roman.gushchin@linux.dev Signed-off-by: Roman Gushchin <roman.gushchin@linux.dev> Acked-by: Michal Hocko <mhocko@suse.com> Acked-by: Shakeel Butt <shakeel.butt@linux.dev> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Matthew Wilcox (Oracle) <willy@infradead.org> Cc: Muchun Song <muchun.song@linux.dev> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
2024-07-04mm: memcg: move charge migration code to memcontrol-v1.cRoman Gushchin
Unlike the legacy cgroup v1 memory controller, cgroup v2 memory controller doesn't support moving charged pages between cgroups. It's a fairly large and complicated code which created a number of problems in the past. Let's move this code into memcontrol-v1.c. It shaves off 1k lines from memcontrol.c. It's also another step towards making the legacy memory controller code optionally compiled. Link: https://lkml.kernel.org/r/20240625005906.106920-5-roman.gushchin@linux.dev Signed-off-by: Roman Gushchin <roman.gushchin@linux.dev> Acked-by: Michal Hocko <mhocko@suse.com> Acked-by: Shakeel Butt <shakeel.butt@linux.dev> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Matthew Wilcox (Oracle) <willy@infradead.org> Cc: Muchun Song <muchun.song@linux.dev> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
2024-07-04mm: memcg: rename soft limit reclaim-related functionsRoman Gushchin
Rename exported function related to the softlimit reclaim to have memcg1_ prefix. Link: https://lkml.kernel.org/r/20240625005906.106920-4-roman.gushchin@linux.dev Signed-off-by: Roman Gushchin <roman.gushchin@linux.dev> Acked-by: Michal Hocko <mhocko@suse.com> Acked-by: Shakeel Butt <shakeel.butt@linux.dev> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Matthew Wilcox (Oracle) <willy@infradead.org> Cc: Muchun Song <muchun.song@linux.dev> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
2024-07-04mm: memcg: move soft limit reclaim code to memcontrol-v1.cRoman Gushchin
Soft limits are cgroup v1-specific and are not supported by cgroup v2, so let's move the corresponding code into memcontrol-v1.c. Aside from simple moving the code, this commits introduces a trivial memcg1_soft_limit_reset() function to reset soft limits and also moves the global soft limit tree initialization code into a new memcg1_init() function. It also moves corresponding declarations shared between memcontrol.c and memcontrol-v1.c into mm/memcontrol-v1.h. Link: https://lkml.kernel.org/r/20240625005906.106920-3-roman.gushchin@linux.dev Signed-off-by: Roman Gushchin <roman.gushchin@linux.dev> Acked-by: Michal Hocko <mhocko@suse.com> Acked-by: Shakeel Butt <shakeel.butt@linux.dev> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Matthew Wilcox (Oracle) <willy@infradead.org> Cc: Muchun Song <muchun.song@linux.dev> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
2024-07-04mm: memcg: introduce memcontrol-v1.cRoman Gushchin
Patch series "mm: memcg: separate legacy cgroup v1 code and put under config option", v2. Cgroups v2 have been around for a while and many users have fully adopted them, so they never use cgroups v1 features and functionality. Yet they have to "pay" for the cgroup v1 support anyway: 1) the kernel binary contains an unused cgroup v1 code, 2) some code paths have additional checks which are not needed, 3) some common structures like task_struct and mem_cgroup contain unused cgroup v1-specific members. Cgroup v1's memory controller has a number of features that are not supported by cgroup v2 and their implementation is pretty much self contained. Most notably, these features are: soft limit reclaim, oom handling in userspace, complicated event notification system, charge migration. Cgroup v1-specific code in memcontrol.c is close to 4k lines in size and it's intervened with generic and cgroup v2-specific code. It's a burden on developers and maintainers. This patchset aims to solve these problems by: 1) moving cgroup v1-specific memcg code to the new mm/memcontrol-v1.c file, 2) putting definitions shared by memcontrol.c and memcontrol-v1.c into the mm/memcontrol-v1.h header, 3) introducing the CONFIG_MEMCG_V1 config option, turned off by default, 4) making memcontrol-v1.c to compile only if CONFIG_MEMCG_V1 is set. If CONFIG_MEMCG_V1 is not set, cgroup v1 memory controller is still available for mounting, however no memory-specific control knobs are present. This patch (of 14): This patch introduces the mm/memcontrol-v1.c source file which will be used for all legacy (cgroup v1) memory cgroup code. It also introduces mm/memcontrol-v1.h to keep declarations shared between mm/memcontrol.c and mm/memcontrol-v1.c. As of now, let's compile it if CONFIG_MEMCG is set, similar to mm/memcontrol.c. Later on it can be switched to use a separate config option, so that the legacy code won't be compiled if not required. Link: https://lkml.kernel.org/r/20240625005906.106920-1-roman.gushchin@linux.dev Link: https://lkml.kernel.org/r/20240625005906.106920-2-roman.gushchin@linux.dev Signed-off-by: Roman Gushchin <roman.gushchin@linux.dev> Acked-by: Michal Hocko <mhocko@suse.com> Acked-by: Shakeel Butt <shakeel.butt@linux.dev> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Matthew Wilcox (Oracle) <willy@infradead.org> Cc: Muchun Song <muchun.song@linux.dev> Cc: Roman Gushchin <roman.gushchin@linux.dev> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>