linux-toradex.git/mm/memcontrol.c, branch v5.16

mm/memcg: relocate mod_objcg_mlstate(), get_obj_stock() and put_obj_stock()

2021-12-11T01:10:56+00:00

All the calls to mod_objcg_mlstate(), get_obj_stock() and
put_obj_stock() are done by functions defined within the same "#ifdef
CONFIG_MEMCG_KMEM" compilation block.  When CONFIG_MEMCG_KMEM isn't
defined, the following compilation warnings will be issued [1] and [2].

  mm/memcontrol.c:785:20: warning: unused function 'mod_objcg_mlstate'
  mm/memcontrol.c:2113:33: warning: unused function 'get_obj_stock'

Fix these warning by moving those functions to under the same
CONFIG_MEMCG_KMEM compilation block.  There is no functional change.

[1] https://lore.kernel.org/lkml/202111272014.WOYNLUV6-lkp@intel.com/
[2] https://lore.kernel.org/lkml/202111280551.LXsWYt1T-lkp@intel.com/

Link: https://lkml.kernel.org/r/20211129161140.306488-1-longman@redhat.com
Fixes: 559271146efc ("mm/memcg: optimize user context object stock access")
Fixes: 68ac5b3c8db2 ("mm/memcg: cache vmstat data in percpu memcg_stock_pcp")
Signed-off-by: Waiman Long 
Reported-by: kernel test robot 
Reviewed-by: Shakeel Butt 
Acked-by: Roman Gushchin 
Reviewed-by: Muchun Song 
Cc: Johannes Weiner 
Cc: Michal Hocko 
Cc: Vladimir Davydov 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

mm: Rename folio_test_multi to folio_test_large

2021-11-17T15:36:35+00:00

This is a better name.  Also add kernel-doc.

Signed-off-by: Matthew Wilcox (Oracle)

mm: unexport {,un}lock_page_memcg

2021-11-11T17:34:35+00:00

These are only used in built-in core mm code.

Link: https://lkml.kernel.org/r/20210820095815.445392-3-hch@lst.de
Signed-off-by: Christoph Hellwig 
Acked-by: Johannes Weiner 
Cc: Michal Hocko 
Cc: Vladimir Davydov 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

mm: unexport folio_memcg_{,un}lock

2021-11-11T17:34:35+00:00

Patch series "unexport memcg locking helpers".

Neither the old page-based nor the new folio-based memcg locking helpers
are used in modular code at all, so drop the exports.

This patch (of 2):

folio_memcg_{,un}lock are only used in built-in core mm code.

Link: https://lkml.kernel.org/r/20210820095815.445392-1-hch@lst.de
Link: https://lkml.kernel.org/r/20210820095815.445392-2-hch@lst.de
Signed-off-by: Christoph Hellwig 
Cc: Johannes Weiner 
Cc: Michal Hocko 
Cc: Vladimir Davydov 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

Merge branch 'akpm' (patches from Andrew)

2021-11-06T21:08:17+00:00

Merge misc updates from Andrew Morton:
 "257 patches.

  Subsystems affected by this patch series: scripts, ocfs2, vfs, and
  mm (slab-generic, slab, slub, kconfig, dax, kasan, debug, pagecache,
  gup, swap, memcg, pagemap, mprotect, mremap, iomap, tracing, vmalloc,
  pagealloc, memory-failure, hugetlb, userfaultfd, vmscan, tools,
  memblock, oom-kill, hugetlbfs, migration, thp, readahead, nommu, ksm,
  vmstat, madvise, memory-hotplug, rmap, zsmalloc, highmem, zram,
  cleanups, kfence, and damon)"

* emailed patches from Andrew Morton : (257 commits)
  mm/damon: remove return value from before_terminate callback
  mm/damon: fix a few spelling mistakes in comments and a pr_debug message
  mm/damon: simplify stop mechanism
  Docs/admin-guide/mm/pagemap: wordsmith page flags descriptions
  Docs/admin-guide/mm/damon/start: simplify the content
  Docs/admin-guide/mm/damon/start: fix a wrong link
  Docs/admin-guide/mm/damon/start: fix wrong example commands
  mm/damon/dbgfs: add adaptive_targets list check before enable monitor_on
  mm/damon: remove unnecessary variable initialization
  Documentation/admin-guide/mm/damon: add a document for DAMON_RECLAIM
  mm/damon: introduce DAMON-based Reclamation (DAMON_RECLAIM)
  selftests/damon: support watermarks
  mm/damon/dbgfs: support watermarks
  mm/damon/schemes: activate schemes based on a watermarks mechanism
  tools/selftests/damon: update for regions prioritization of schemes
  mm/damon/dbgfs: support prioritization weights
  mm/damon/vaddr,paddr: support pageout prioritization
  mm/damon/schemes: prioritize regions within the quotas
  mm/damon/selftests: support schemes quotas
  mm/damon/dbgfs: support quotas of schemes
  ...

mm/vmscan: throttle reclaim when no progress is being made

2021-11-06T20:30:40+00:00

Memcg reclaim throttles on congestion if no reclaim progress is made.
This makes little sense, it might be due to writeback or a host of other
factors.

For !memcg reclaim, it's messy.  Direct reclaim primarily is throttled
in the page allocator if it is failing to make progress.  Kswapd
throttles if too many pages are under writeback and marked for immediate
reclaim.

This patch explicitly throttles if reclaim is failing to make progress.

[vbabka@suse.cz: Remove redundant code]

Link: https://lkml.kernel.org/r/20211022144651.19914-4-mgorman@techsingularity.net
Signed-off-by: Mel Gorman 
Acked-by: Vlastimil Babka 
Cc: Andreas Dilger 
Cc: "Darrick J . Wong" 
Cc: Dave Chinner 
Cc: Johannes Weiner 
Cc: Jonathan Corbet 
Cc: Matthew Wilcox 
Cc: Michal Hocko 
Cc: NeilBrown 
Cc: Rik van Riel 
Cc: "Theodore Ts'o" 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

memcg: prohibit unconditional exceeding the limit of dying tasks

2021-11-06T20:30:35+00:00

Memory cgroup charging allows killed or exiting tasks to exceed the hard
limit.  It is assumed that the amount of the memory charged by those
tasks is bound and most of the memory will get released while the task
is exiting.  This is resembling a heuristic for the global OOM situation
when tasks get access to memory reserves.  There is no global memory
shortage at the memcg level so the memcg heuristic is more relieved.

The above assumption is overly optimistic though.  E.g.  vmalloc can
scale to really large requests and the heuristic would allow that.  We
used to have an early break in the vmalloc allocator for killed tasks
but this has been reverted by commit b8c8a338f75e ("Revert "vmalloc:
back off when the current task is killed"").  There are likely other
similar code paths which do not check for fatal signals in an
allocation&charge loop.  Also there are some kernel objects charged to a
memcg which are not bound to a process life time.

It has been observed that it is not really hard to trigger these
bypasses and cause global OOM situation.

One potential way to address these runaways would be to limit the amount
of excess (similar to the global OOM with limited oom reserves).  This
is certainly possible but it is not really clear how much of an excess
is desirable and still protects from global OOMs as that would have to
consider the overall memcg configuration.

This patch is addressing the problem by removing the heuristic
altogether.  Bypass is only allowed for requests which either cannot
fail or where the failure is not desirable while excess should be still
limited (e.g.  atomic requests).  Implementation wise a killed or dying
task fails to charge if it has passed the OOM killer stage.  That should
give all forms of reclaim chance to restore the limit before the failure
(ENOMEM) and tell the caller to back off.

In addition, this patch renames should_force_charge() helper to
task_is_dying() because now its use is not associated witch forced
charging.

This patch depends on pagefault_out_of_memory() to not trigger
out_of_memory(), because then a memcg failure can unwind to VM_FAULT_OOM
and cause a global OOM killer.

Link: https://lkml.kernel.org/r/8f5cebbb-06da-4902-91f0-6566fc4b4203@virtuozzo.com
Signed-off-by: Vasily Averin 
Suggested-by: Michal Hocko 
Acked-by: Michal Hocko 
Cc: Johannes Weiner 
Cc: Vladimir Davydov 
Cc: Roman Gushchin 
Cc: Uladzislau Rezki 
Cc: Vlastimil Babka 
Cc: Shakeel Butt 
Cc: Mel Gorman 
Cc: Tetsuo Handa 
Cc: 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

mm: memcontrol: remove the kmem states

2021-11-06T20:30:35+00:00

Now the kmem states is only used to indicate whether the kmem is
offline.  However, we can set ->kmemcg_id to -1 to indicate whether the
kmem is offline.  Finally, we can remove the kmem states to simplify the
code.

Link: https://lkml.kernel.org/r/20211025125259.56624-1-songmuchun@bytedance.com
Signed-off-by: Muchun Song 
Acked-by: Roman Gushchin 
Cc: Michal Hocko 
Cc: Shakeel Butt 
Cc: Matthew Wilcox (Oracle) 
Cc: Johannes Weiner 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

mm: memcontrol: remove kmemcg_id reparenting

2021-11-06T20:30:35+00:00

Since slab objects and kmem pages are charged to object cgroup instead
of memory cgroup, memcg_reparent_objcgs() will reparent this cgroup and
all its descendants to its parent cgroup.  This already makes further
list_lru_add()'s add elements to the parent's list.  So it is
unnecessary to change kmemcg_id of an offline cgroup to its parent's id.
It just wastes CPU cycles.  Just remove the redundant code.

Link: https://lkml.kernel.org/r/20211025125102.56533-1-songmuchun@bytedance.com
Signed-off-by: Muchun Song 
Acked-by: Roman Gushchin 
Cc: Johannes Weiner 
Cc: Matthew Wilcox (Oracle) 
Cc: Michal Hocko 
Cc: Shakeel Butt 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

memcg, kmem: further deprecate kmem.limit_in_bytes

2021-11-06T20:30:35+00:00

The deprecation process of kmem.limit_in_bytes started with the commit
0158115f702 ("memcg, kmem: deprecate kmem.limit_in_bytes") which also
explains in detail the motivation behind the deprecation.  To summarize,
it is the unexpected behavior on hitting the kmem limit.  This patch
moves the deprecation process to the next stage by disallowing to set
the kmem limit.  In future we might just remove the kmem.limit_in_bytes
file completely.

[akpm@linux-foundation.org: s/ENOTSUPP/EOPNOTSUPP/]
[arnd@arndb.de: mark cancel_charge() inline]
  Link: https://lkml.kernel.org/r/20211022070542.679839-1-arnd@kernel.org

Link: https://lkml.kernel.org/r/20211019153408.2916808-1-shakeelb@google.com
Signed-off-by: Shakeel Butt 
Signed-off-by: Arnd Bergmann 
Acked-by: Roman Gushchin 
Acked-by: Michal Hocko 
Reviewed-by: Muchun Song 
Cc: Vasily Averin 
Cc: Johannes Weiner 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds