Merge misc updates from Andrew Morton:
"173 patches.
Subsystems affected by this series: ia64, ocfs2, block, and mm (debug,
pagecache, gup, swap, shmem, memcg, selftests, pagemap, mremap,
bootmem, sparsemem, vmalloc, kasan, pagealloc, memory-failure,
hugetlb, userfaultfd, vmscan, compaction, mempolicy, memblock,
oom-kill, migration, ksm, percpu, vmstat, and madvise)"
* emailed patches from Andrew Morton <akpm@linux-foundation.org>: (173 commits)
mm/madvise: add MADV_WILLNEED to process_madvise()
mm/vmstat: remove unneeded return value
mm/vmstat: simplify the array size calculation
mm/vmstat: correct some wrong comments
mm/percpu,c: remove obsolete comments of pcpu_chunk_populated()
selftests: vm: add COW time test for KSM pages
selftests: vm: add KSM merging time test
mm: KSM: fix data type
selftests: vm: add KSM merging across nodes test
selftests: vm: add KSM zero page merging test
selftests: vm: add KSM unmerge test
selftests: vm: add KSM merge test
mm/migrate: correct kernel-doc notation
mm: wire up syscall process_mrelease
mm: introduce process_mrelease system call
memblock: make memblock_find_in_range method private
mm/mempolicy.c: use in_task() in mempolicy_slab_node()
mm/mempolicy: unify the create() func for bind/interleave/prefer-many policies
mm/mempolicy: advertise new MPOL_PREFERRED_MANY
mm/hugetlb: add support for mempolicy MPOL_PREFERRED_MANY
...
At the moment memcg stats are read in four contexts:
1. memcg stat user interfaces
2. dirty throttling
3. page fault
4. memory reclaim
Currently the kernel flushes the stats for first two cases. Flushing the
stats for remaining two casese may have performance impact. Always
flushing the memcg stats on the page fault code path may negatively
impacts the performance of the applications. In addition flushing in the
memory reclaim code path, though treated as slowpath, can become the
source of contention for the global lock taken for stat flushing because
when system or memcg is under memory pressure, many tasks may enter the
reclaim path.
This patch uses following mechanisms to solve these challenges:
1. Periodically flush the stats from root memcg every 2 seconds. This
will time limit the out of sync stats.
2. Asynchronously flush the stats after fixed number of stat updates.
In the worst case the stat can be out of sync by O(nr_cpus * BATCH) for
2 seconds.
3. For avoiding thundering herd to flush the stats particularly from
the memory reclaim context, introduce memcg local spinlock and let only
one flusher active at a time. This could have been done through
cgroup_rstat_lock lock but that lock is used by other subsystem and for
userspace reading memcg stats. So, it is better to keep flushers
introduced by this patch decoupled from cgroup_rstat_lock. However we
would have to use irqsafe version of rstat flush but that is fine as
this code path will be flushing for whole tree and do the work for
everyone. No one will be waiting for that worker.
[shakeelb@google.com: fix sleep-in-wrong context bug]
Link: https://lkml.kernel.org/r/20210716212137.1391164-2-shakeelb@google.com
Link: https://lkml.kernel.org/r/20210714013948.270662-2-shakeelb@google.com
Signed-off-by: Shakeel Butt <shakeelb@google.com>
Tested-by: Marek Szyprowski <m.szyprowski@samsung.com>
Cc: Hillf Danton <hdanton@sina.com>
Cc: Huang Ying <ying.huang@intel.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Michal Hocko <mhocko@kernel.org>
Cc: Michal Koutný <mkoutny@suse.com>
Cc: Muchun Song <songmuchun@bytedance.com>
Cc: Roman Gushchin <guro@fb.com>
Cc: Tejun Heo <tj@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
The commit 2d146aa3aa ("mm: memcontrol: switch to rstat") switched memcg
stats to rstat infrastructure but skipped the conversion of the lruvec
stats as such stats are read in the performance critical code paths and
flushing stats may have impacted the performances of the applications.
This patch converts the lruvec stats to rstat and later patches add
mechanisms to keep the performance impact to minimum.
The rstat conversion comes with the price i.e. memory cost. Effectively
this patch reverts the savings done by the commit f3344adf38 ("mm:
memcontrol: optimize per-lruvec stats counter memory usage"). However
this cost is justified due to negative impact of the inaccurate lruvec
stats on many heuristics. One such case is reported in [1].
The memory reclaim code is filled with plethora of heuristics and many of
those heuristics reads the lruvec stats. So, inaccurate stats can make
such heuristics ineffective. [1] reports the impact of inaccurate lruvec
stats on the "cache trim mode" heuristic. Inaccurate lruvec stats can
impact the deactivation and aging anon heuristics as well.
[1] https://lore.kernel.org/linux-mm/20210311004449.1170308-1-ying.huang@intel.com/
Link: https://lkml.kernel.org/r/20210716212137.1391164-1-shakeelb@google.com
Link: https://lkml.kernel.org/r/20210714013948.270662-1-shakeelb@google.com
Signed-off-by: Shakeel Butt <shakeelb@google.com>
Cc: Tejun Heo <tj@kernel.org>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Muchun Song <songmuchun@bytedance.com>
Cc: Michal Hocko <mhocko@kernel.org>
Cc: Roman Gushchin <guro@fb.com>
Cc: Huang Ying <ying.huang@intel.com>
Cc: Hillf Danton <hdanton@sina.com>
Cc: Michal Koutný <mkoutny@suse.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Currently cgroup_writeback_by_id calls mem_cgroup_wb_stats() to get dirty
pages for a memcg. However mem_cgroup_wb_stats() does a lot more than
just get the number of dirty pages. Just directly get the number of dirty
pages instead of calling mem_cgroup_wb_stats(). Also
cgroup_writeback_by_id() is only called for best-effort dirty flushing, so
remove the unused 'nr' parameter and no need to explicitly flush memcg
stats.
Link: https://lkml.kernel.org/r/20210722182627.2267368-1-shakeelb@google.com
Signed-off-by: Shakeel Butt <shakeelb@google.com>
Reviewed-by: Jan Kara <jack@suse.cz>
Cc: Tejun Heo <tj@kernel.org>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
We've noticed occasional OOM killing when memory.low settings are in
effect for cgroups. This is unexpected and undesirable as memory.low is
supposed to express non-OOMing memory priorities between cgroups.
The reason for this is proportional memory.low reclaim. When cgroups
are below their memory.low threshold, reclaim passes them over in the
first round, and then retries if it couldn't find pages anywhere else.
But when cgroups are slightly above their memory.low setting, page scan
force is scaled down and diminished in proportion to the overage, to the
point where it can cause reclaim to fail as well - only in that case we
currently don't retry, and instead trigger OOM.
To fix this, hook proportional reclaim into the same retry logic we have
in place for when cgroups are skipped entirely. This way if reclaim
fails and some cgroups were scanned with diminished pressure, we'll try
another full-force cycle before giving up and OOMing.
[akpm@linux-foundation.org: coding-style fixes]
Link: https://lkml.kernel.org/r/20210817180506.220056-1-hannes@cmpxchg.org
Fixes: 9783aa9917 ("mm, memcg: proportional memory.{low,min} reclaim")
Signed-off-by: Johannes Weiner <hannes@cmpxchg.org>
Reported-by: Leon Yang <lnyng@fb.com>
Reviewed-by: Rik van Riel <riel@surriel.com>
Reviewed-by: Shakeel Butt <shakeelb@google.com>
Acked-by: Roman Gushchin <guro@fb.com>
Acked-by: Chris Down <chris@chrisdown.name>
Acked-by: Michal Hocko <mhocko@suse.com>
Cc: <stable@vger.kernel.org> [5.4+]
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Add gfp_t mask as an input parameter to mem_cgroup_charge_skmem(),
to give more control to the networking stack and enable it to change
memcg charging behavior. In the future, the networking stack may decide
to avoid oom-kills when fallbacks are more appropriate.
One behavior change in mem_cgroup_charge_skmem() by this patch is to
avoid force charging by default and let the caller decide when and if
force charging is needed through the presence or absence of
__GFP_NOFAIL.
Signed-off-by: Wei Wang <weiwan@google.com>
Reviewed-by: Shakeel Butt <shakeelb@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Pull percpu updates from Dennis Zhou:
- percpu chunk depopulation - depopulate backing pages for chunks with
empty pages when we exceed a global threshold without those pages.
This lets us reclaim a portion of memory that would previously be
lost until the full chunk would be freed (possibly never).
- memcg accounting cleanup - previously separate chunks were managed
for normal allocations and __GFP_ACCOUNT allocations. These are now
consolidated which cleans up the code quite a bit.
- a few misc clean ups for clang warnings
* 'for-5.14' of git://git.kernel.org/pub/scm/linux/kernel/git/dennis/percpu:
percpu: optimize locking in pcpu_balance_workfn()
percpu: initialize best_upa variable
percpu: rework memcg accounting
mm, memcg: introduce mem_cgroup_kmem_disabled()
mm, memcg: mark cgroup_memory_nosocket, nokmem and noswap as __ro_after_init
percpu: make symbol 'pcpu_free_slot' static
percpu: implement partial chunk depopulation
percpu: use pcpu_free_slot instead of pcpu_nr_slots - 1
percpu: factor out pcpu_check_block_hint()
percpu: split __pcpu_balance_workfn()
percpu: fix a comment about the chunks ordering
Introduce a new mem_cgroup_kmem_disabled() helper, similar to
mem_cgroup_disabled(), to check whether the kernel memory accounting
is off. A user could disable it using a boot option to eliminate
some associated costs.
The helper can be used outside of memcontrol.c to dynamically disable
the kmem-related code. The returned value is stable after the kernel
initialization is finished.
Signed-off-by: Roman Gushchin <guro@fb.com>
Signed-off-by: Dennis Zhou <dennis@kernel.org>
Currently the number of deferred objects are per shrinker, but some
slabs, for example, vfs inode/dentry cache are per memcg, this would
result in poor isolation among memcgs.
The deferred objects typically are generated by __GFP_NOFS allocations,
one memcg with excessive __GFP_NOFS allocations may blow up deferred
objects, then other innocent memcgs may suffer from over shrink,
excessive reclaim latency, etc.
For example, two workloads run in memcgA and memcgB respectively,
workload in B is vfs heavy workload. Workload in A generates excessive
deferred objects, then B's vfs cache might be hit heavily (drop half of
caches) by B's limit reclaim or global reclaim.
We observed this hit in our production environment which was running vfs
heavy workload shown as the below tracing log:
<...>-409454 [016] .... 28286961.747146: mm_shrink_slab_start: super_cache_scan+0x0/0x1a0 ffff9a83046f3458:
nid: 1 objects to shrink 3641681686040 gfp_flags GFP_HIGHUSER_MOVABLE|__GFP_ZERO pgs_scanned 1 lru_pgs 15721
cache items 246404277 delta 31345 total_scan 123202138
<...>-409454 [022] .... 28287105.928018: mm_shrink_slab_end: super_cache_scan+0x0/0x1a0 ffff9a83046f3458:
nid: 1 unused scan count 3641681686040 new scan count 3641798379189 total_scan 602
last shrinker return val 123186855
The vfs cache and page cache ratio was 10:1 on this machine, and half of
caches were dropped. This also resulted in significant amount of page
caches were dropped due to inodes eviction.
Make nr_deferred per memcg for memcg aware shrinkers would solve the
unfairness and bring better isolation.
The following patch will add nr_deferred to parent memcg when memcg
offline. To preserve nr_deferred when reparenting memcgs to root, root
memcg needs shrinker_info allocated too.
When memcg is not enabled (!CONFIG_MEMCG or memcg disabled), the
shrinker's nr_deferred would be used. And non memcg aware shrinkers use
shrinker's nr_deferred all the time.
Link: https://lkml.kernel.org/r/20210311190845.9708-10-shy828301@gmail.com
Signed-off-by: Yang Shi <shy828301@gmail.com>
Acked-by: Roman Gushchin <guro@fb.com>
Acked-by: Kirill Tkhai <ktkhai@virtuozzo.com>
Reviewed-by: Shakeel Butt <shakeelb@google.com>
Cc: Dave Chinner <david@fromorbit.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Since Roman's series "The new cgroup slab memory controller" applied.
All slab objects are charged via the new APIs of obj_cgroup. The new
APIs introduce a struct obj_cgroup to charge slab objects. It prevents
long-living objects from pinning the original memory cgroup in the
memory. But there are still some corner objects (e.g. allocations
larger than order-1 page on SLUB) which are not charged via the new
APIs. Those objects (include the pages which are allocated from buddy
allocator directly) are charged as kmem pages which still hold a
reference to the memory cgroup.
We want to reuse the obj_cgroup APIs to charge the kmem pages. If we do
that, we should store an object cgroup pointer to page->memcg_data for
the kmem pages.
Finally, page->memcg_data will have 3 different meanings.
1) For the slab pages, page->memcg_data points to an object cgroups
vector.
2) For the kmem pages (exclude the slab pages), page->memcg_data
points to an object cgroup.
3) For the user pages (e.g. the LRU pages), page->memcg_data points
to a memory cgroup.
We do not change the behavior of page_memcg() and page_memcg_rcu(). They
are also suitable for LRU pages and kmem pages. Why?
Because memory allocations pinning memcgs for a long time - it exists at a
larger scale and is causing recurring problems in the real world: page
cache doesn't get reclaimed for a long time, or is used by the second,
third, fourth, ... instance of the same job that was restarted into a new
cgroup every time. Unreclaimable dying cgroups pile up, waste memory, and
make page reclaim very inefficient.
We can convert LRU pages and most other raw memcg pins to the objcg
direction to fix this problem, and then the page->memcg will always point
to an object cgroup pointer. At that time, LRU pages and kmem pages will
be treated the same. The implementation of page_memcg() will remove the
kmem page check.
This patch aims to charge the kmem pages by using the new APIs of
obj_cgroup. Finally, the page->memcg_data of the kmem page points to an
object cgroup. We can use the __page_objcg() to get the object cgroup
associated with a kmem page. Or we can use page_memcg() to get the memory
cgroup associated with a kmem page, but caller must ensure that the
returned memcg won't be released (e.g. acquire the rcu_read_lock or
css_set_lock).
Link: https://lkml.kernel.org/r/20210401030141.37061-1-songmuchun@bytedance.com
Link: https://lkml.kernel.org/r/20210319163821.20704-6-songmuchun@bytedance.com
Signed-off-by: Muchun Song <songmuchun@bytedance.com>
Acked-by: Johannes Weiner <hannes@cmpxchg.org>
Reviewed-by: Shakeel Butt <shakeelb@google.com>
Acked-by: Roman Gushchin <guro@fb.com>
Reviewed-by: Miaohe Lin <linmiaohe@huawei.com>
Cc: Michal Hocko <mhocko@kernel.org>
Cc: Vladimir Davydov <vdavydov.dev@gmail.com>
Cc: Xiongchun Duan <duanxiongchun@bytedance.com>
Cc: Christian Borntraeger <borntraeger@de.ibm.com>
[songmuchun@bytedance.com: fix forget to obtain the ref to objcg in split_page_memcg]
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
