Skip to content

L
linux

xiphi1978 / linux

通知 2
Star 0
Fork 0
L
linux

体验新版 GitCode，发现更多精彩内容 >>

切换分支/标签
  1. 31 8月, 2019 2 次提交
    • R
      mm, memcg: partially revert "mm/memcontrol.c: keep local VM counters in sync... · b4c46484
      由 Roman Gushchin 提交于 
      mm, memcg: partially revert "mm/memcontrol.c: keep local VM counters in sync with the hierarchical ones"

Commit 766a4c19 ("mm/memcontrol.c: keep local VM counters in sync
with the hierarchical ones") effectively decreased the precision of
per-memcg vmstats_local and per-memcg-per-node lruvec percpu counters.

That's good for displaying in memory.stat, but brings a serious
regression into the reclaim process.

One issue I've discovered and debugged is the following:
lruvec_lru_size() can return 0 instead of the actual number of pages in
the lru list, preventing the kernel to reclaim last remaining pages.
Result is yet another dying memory cgroups flooding.  The opposite is
also happening: scanning an empty lru list is the waste of cpu time.

Also, inactive_list_is_low() can return incorrect values, preventing the
active lru from being scanned and freed.  It can fail both because the
size of active and inactive lists are inaccurate, and because the number
of workingset refaults isn't precise.  In other words, the result is
pretty random.

I'm not sure, if using the approximate number of slab pages in
count_shadow_number() is acceptable, but issues described above are
enough to partially revert the patch.

Let's keep per-memcg vmstat_local batched (they are only used for
displaying stats to the userspace), but keep lruvec stats precise.  This
change fixes the dead memcg flooding on my setup.

Link: http://lkml.kernel.org/r/20190817004726.2530670-1-guro@fb.com
Fixes: 766a4c19 ("mm/memcontrol.c: keep local VM counters in sync with the hierarchical ones")
Signed-off-by: NRoman Gushchin <guro@fb.com>
Acked-by: NYafang Shao <laoar.shao@gmail.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Michal Hocko <mhocko@kernel.org>
Cc: <stable@vger.kernel.org>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
      b4c46484
    • R
      mm: memcontrol: flush percpu slab vmstats on kmem offlining · bee07b33
      由 Roman Gushchin 提交于 
      I've noticed that the "slab" value in memory.stat is sometimes 0, even
if some children memory cgroups have a non-zero "slab" value.  The
following investigation showed that this is the result of the kmem_cache
reparenting in combination with the per-cpu batching of slab vmstats.

At the offlining some vmstat value may leave in the percpu cache, not
being propagated upwards by the cgroup hierarchy.  It means that stats
on ancestor levels are lower than actual.  Later when slab pages are
released, the precise number of pages is substracted on the parent
level, making the value negative.  We don't show negative values, 0 is
printed instead.

To fix this issue, let's flush percpu slab memcg and lruvec stats on
memcg offlining.  This guarantees that numbers on all ancestor levels
are accurate and match the actual number of outstanding slab pages.

Link: http://lkml.kernel.org/r/20190819202338.363363-3-guro@fb.com
Fixes: fb2f2b0a ("mm: memcg/slab: reparent memcg kmem_caches on cgroup removal")
Signed-off-by: NRoman Gushchin <guro@fb.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Michal Hocko <mhocko@kernel.org>
Cc: Vladimir Davydov <vdavydov.dev@gmail.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
      bee07b33
  3. 25 8月, 2019 2 次提交
    • R
      mm: memcontrol: flush percpu vmevents before releasing memcg · bb65f89b
      由 Roman Gushchin 提交于 
      Similar to vmstats, percpu caching of local vmevents leads to an
accumulation of errors on non-leaf levels.  This happens because some
leftovers may remain in percpu caches, so that they are never propagated
up by the cgroup tree and just disappear into nonexistence with on
releasing of the memory cgroup.

To fix this issue let's accumulate and propagate percpu vmevents values
before releasing the memory cgroup similar to what we're doing with
vmstats.

Since on cpu hotplug we do flush percpu vmstats anyway, we can iterate
only over online cpus.

Link: http://lkml.kernel.org/r/20190819202338.363363-4-guro@fb.com
Fixes: 42a30035 ("mm: memcontrol: fix recursive statistics correctness & scalabilty")
Signed-off-by: NRoman Gushchin <guro@fb.com>
Acked-by: NMichal Hocko <mhocko@suse.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Vladimir Davydov <vdavydov.dev@gmail.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
      bb65f89b
    • R
      mm: memcontrol: flush percpu vmstats before releasing memcg · c350a99e
      由 Roman Gushchin 提交于 
      Percpu caching of local vmstats with the conditional propagation by the
cgroup tree leads to an accumulation of errors on non-leaf levels.

Let's imagine two nested memory cgroups A and A/B.  Say, a process
belonging to A/B allocates 100 pagecache pages on the CPU 0.  The percpu
cache will spill 3 times, so that 32*3=96 pages will be accounted to A/B
and A atomic vmstat counters, 4 pages will remain in the percpu cache.

Imagine A/B is nearby memory.max, so that every following allocation
triggers a direct reclaim on the local CPU.  Say, each such attempt will
free 16 pages on a new cpu.  That means every percpu cache will have -16
pages, except the first one, which will have 4 - 16 = -12.  A/B and A
atomic counters will not be touched at all.

Now a user removes A/B.  All percpu caches are freed and corresponding
vmstat numbers are forgotten.  A has 96 pages more than expected.

As memory cgroups are created and destroyed, errors do accumulate.  Even
1-2 pages differences can accumulate into large numbers.

To fix this issue let's accumulate and propagate percpu vmstat values
before releasing the memory cgroup.  At this point these numbers are
stable and cannot be changed.

Since on cpu hotplug we do flush percpu vmstats anyway, we can iterate
only over online cpus.

Link: http://lkml.kernel.org/r/20190819202338.363363-2-guro@fb.com
Fixes: 42a30035 ("mm: memcontrol: fix recursive statistics correctness & scalabilty")
Signed-off-by: NRoman Gushchin <guro@fb.com>
Acked-by: NMichal Hocko <mhocko@suse.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Vladimir Davydov <vdavydov.dev@gmail.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
      c350a99e
  5. 14 8月, 2019 2 次提交
    • R
      mm: workingset: fix vmstat counters for shadow nodes · ec9f0238
      由 Roman Gushchin 提交于 
      Memcg counters for shadow nodes are broken because the memcg pointer is
obtained in a wrong way. The following approach is used:
        virt_to_page(xa_node)->mem_cgroup

Since commit 4d96ba35 ("mm: memcg/slab: stop setting
page->mem_cgroup pointer for slab pages") page->mem_cgroup pointer isn't
set for slab pages, so memcg_from_slab_page() should be used instead.

Also I doubt that it ever worked correctly: virt_to_head_page() should
be used instead of virt_to_page().  Otherwise objects residing on tail
pages are not accounted, because only the head page contains a valid
mem_cgroup pointer.  That was a case since the introduction of these
counters by the commit 68d48e6a ("mm: workingset: add vmstat counter
for shadow nodes").

Link: http://lkml.kernel.org/r/20190801233532.138743-1-guro@fb.com
Fixes: 4d96ba35 ("mm: memcg/slab: stop setting page->mem_cgroup pointer for slab pages")
Signed-off-by: NRoman Gushchin <guro@fb.com>
Acked-by: NJohannes Weiner <hannes@cmpxchg.org>
Cc: Vladimir Davydov <vdavydov.dev@gmail.com>
Cc: Shakeel Butt <shakeelb@google.com>
Cc: Michal Hocko <mhocko@suse.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
      ec9f0238
    • M
      mm/memcontrol.c: fix use after free in mem_cgroup_iter() · 54a83d6b
      由 Miles Chen 提交于 
      This patch is sent to report an use after free in mem_cgroup_iter()
after merging commit be2657752e9e ("mm: memcg: fix use after free in
mem_cgroup_iter()").

I work with android kernel tree (4.9 & 4.14), and commit be2657752e9e
("mm: memcg: fix use after free in mem_cgroup_iter()") has been merged
to the trees.  However, I can still observe use after free issues
addressed in the commit be2657752e9e.  (on low-end devices, a few times
this month)

backtrace:
        css_tryget <- crash here
        mem_cgroup_iter
        shrink_node
        shrink_zones
        do_try_to_free_pages
        try_to_free_pages
        __perform_reclaim
        __alloc_pages_direct_reclaim
        __alloc_pages_slowpath
        __alloc_pages_nodemask

To debug, I poisoned mem_cgroup before freeing it:

  static void __mem_cgroup_free(struct mem_cgroup *memcg)
        for_each_node(node)
        free_mem_cgroup_per_node_info(memcg, node);
        free_percpu(memcg->stat);
  +     /* poison memcg before freeing it */
  +     memset(memcg, 0x78, sizeof(struct mem_cgroup));
        kfree(memcg);
  }

The coredump shows the position=0xdbbc2a00 is freed.

  (gdb) p/x ((struct mem_cgroup_per_node *)0xe5009e00)->iter[8]
  $13 = {position = 0xdbbc2a00, generation = 0x2efd}

  0xdbbc2a00:     0xdbbc2e00      0x00000000      0xdbbc2800      0x00000100
  0xdbbc2a10:     0x00000200      0x78787878      0x00026218      0x00000000
  0xdbbc2a20:     0xdcad6000      0x00000001      0x78787800      0x00000000
  0xdbbc2a30:     0x78780000      0x00000000      0x0068fb84      0x78787878
  0xdbbc2a40:     0x78787878      0x78787878      0x78787878      0xe3fa5cc0
  0xdbbc2a50:     0x78787878      0x78787878      0x00000000      0x00000000
  0xdbbc2a60:     0x00000000      0x00000000      0x00000000      0x00000000
  0xdbbc2a70:     0x00000000      0x00000000      0x00000000      0x00000000
  0xdbbc2a80:     0x00000000      0x00000000      0x00000000      0x00000000
  0xdbbc2a90:     0x00000001      0x00000000      0x00000000      0x00100000
  0xdbbc2aa0:     0x00000001      0xdbbc2ac8      0x00000000      0x00000000
  0xdbbc2ab0:     0x00000000      0x00000000      0x00000000      0x00000000
  0xdbbc2ac0:     0x00000000      0x00000000      0xe5b02618      0x00001000
  0xdbbc2ad0:     0x00000000      0x78787878      0x78787878      0x78787878
  0xdbbc2ae0:     0x78787878      0x78787878      0x78787878      0x78787878
  0xdbbc2af0:     0x78787878      0x78787878      0x78787878      0x78787878
  0xdbbc2b00:     0x78787878      0x78787878      0x78787878      0x78787878
  0xdbbc2b10:     0x78787878      0x78787878      0x78787878      0x78787878
  0xdbbc2b20:     0x78787878      0x78787878      0x78787878      0x78787878
  0xdbbc2b30:     0x78787878      0x78787878      0x78787878      0x78787878
  0xdbbc2b40:     0x78787878      0x78787878      0x78787878      0x78787878
  0xdbbc2b50:     0x78787878      0x78787878      0x78787878      0x78787878
  0xdbbc2b60:     0x78787878      0x78787878      0x78787878      0x78787878
  0xdbbc2b70:     0x78787878      0x78787878      0x78787878      0x78787878
  0xdbbc2b80:     0x78787878      0x78787878      0x00000000      0x78787878
  0xdbbc2b90:     0x78787878      0x78787878      0x78787878      0x78787878
  0xdbbc2ba0:     0x78787878      0x78787878      0x78787878      0x78787878

In the reclaim path, try_to_free_pages() does not setup
sc.target_mem_cgroup and sc is passed to do_try_to_free_pages(), ...,
shrink_node().

In mem_cgroup_iter(), root is set to root_mem_cgroup because
sc->target_mem_cgroup is NULL.  It is possible to assign a memcg to
root_mem_cgroup.nodeinfo.iter in mem_cgroup_iter().

        try_to_free_pages
        	struct scan_control sc = {...}, target_mem_cgroup is 0x0;
        do_try_to_free_pages
        shrink_zones
        shrink_node
        	 mem_cgroup *root = sc->target_mem_cgroup;
        	 memcg = mem_cgroup_iter(root, NULL, &reclaim);
        mem_cgroup_iter()
        	if (!root)
        		root = root_mem_cgroup;
        	...

        	css = css_next_descendant_pre(css, &root->css);
        	memcg = mem_cgroup_from_css(css);
        	cmpxchg(&iter->position, pos, memcg);

My device uses memcg non-hierarchical mode.  When we release a memcg:
invalidate_reclaim_iterators() reaches only dead_memcg and its parents.
If non-hierarchical mode is used, invalidate_reclaim_iterators() never
reaches root_mem_cgroup.

  static void invalidate_reclaim_iterators(struct mem_cgroup *dead_memcg)
  {
        struct mem_cgroup *memcg = dead_memcg;

        for (; memcg; memcg = parent_mem_cgroup(memcg)
        ...
  }

So the use after free scenario looks like:

  CPU1						CPU2

  try_to_free_pages
  do_try_to_free_pages
  shrink_zones
  shrink_node
  mem_cgroup_iter()
      if (!root)
      	root = root_mem_cgroup;
      ...
      css = css_next_descendant_pre(css, &root->css);
      memcg = mem_cgroup_from_css(css);
      cmpxchg(&iter->position, pos, memcg);

        				invalidate_reclaim_iterators(memcg);
        				...
        				__mem_cgroup_free()
        					kfree(memcg);

  try_to_free_pages
  do_try_to_free_pages
  shrink_zones
  shrink_node
  mem_cgroup_iter()
      if (!root)
      	root = root_mem_cgroup;
      ...
      mz = mem_cgroup_nodeinfo(root, reclaim->pgdat->node_id);
      iter = &mz->iter[reclaim->priority];
      pos = READ_ONCE(iter->position);
      css_tryget(&pos->css) <- use after free

To avoid this, we should also invalidate root_mem_cgroup.nodeinfo.iter
in invalidate_reclaim_iterators().

[cai@lca.pw: fix -Wparentheses compilation warning]
  Link: http://lkml.kernel.org/r/1564580753-17531-1-git-send-email-cai@lca.pw
Link: http://lkml.kernel.org/r/20190730015729.4406-1-miles.chen@mediatek.com
Fixes: 5ac8fb31 ("mm: memcontrol: convert reclaim iterator to simple css refcounting")
Signed-off-by: NMiles Chen <miles.chen@mediatek.com>
Signed-off-by: NQian Cai <cai@lca.pw>
Acked-by: NMichal Hocko <mhocko@suse.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Vladimir Davydov <vdavydov.dev@gmail.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
      54a83d6b
  7. 17 7月, 2019 1 次提交
  9. 13 7月, 2019 10 次提交
    • S
      mm, oom: remove redundant task_in_mem_cgroup() check · 6ba749ee
      由 Shakeel Butt 提交于 
      oom_unkillable_task() can be called from three different contexts i.e.
global OOM, memcg OOM and oom_score procfs interface.  At the moment
oom_unkillable_task() does a task_in_mem_cgroup() check on the given
process.  Since there is no reason to perform task_in_mem_cgroup()
check for global OOM and oom_score procfs interface, those contexts
provide NULL memcg and skips the task_in_mem_cgroup() check.  However
for memcg OOM context, the oom_unkillable_task() is always called from
mem_cgroup_scan_tasks() and thus task_in_mem_cgroup() check becomes
redundant and effectively dead code.  So, just remove the
task_in_mem_cgroup() check altogether.

Link: http://lkml.kernel.org/r/20190624212631.87212-2-shakeelb@google.comSigned-off-by: NShakeel Butt <shakeelb@google.com>
Signed-off-by: NTetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>
Acked-by: NRoman Gushchin <guro@fb.com>
Acked-by: NMichal Hocko <mhocko@suse.com>
Cc: David Rientjes <rientjes@google.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Cc: Nick Piggin <npiggin@suse.de>
Cc: Paul Jackson <pj@sgi.com>
Cc: Vladimir Davydov <vdavydov.dev@gmail.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
      6ba749ee
    • T
      mm: memcontrol: use CSS_TASK_ITER_PROCS at mem_cgroup_scan_tasks() · f168a9a5
      由 Tetsuo Handa 提交于 
      Since commit c03cd773 ("cgroup: Include dying leaders with live
threads in PROCS iterations") corrected how CSS_TASK_ITER_PROCS works,
mem_cgroup_scan_tasks() can use CSS_TASK_ITER_PROCS in order to check
only one thread from each thread group.

[penguin-kernel@I-love.SAKURA.ne.jp: remove thread group leader check in oom_evaluate_task()]
  Link: http://lkml.kernel.org/r/1560853257-14934-1-git-send-email-penguin-kernel@I-love.SAKURA.ne.jp
Link: http://lkml.kernel.org/r/c763afc8-f0ae-756a-56a7-395f625b95fc@i-love.sakura.ne.jpSigned-off-by: NTetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>
Acked-by: NMichal Hocko <mhocko@suse.com>
Reviewed-by: NShakeel Butt <shakeelb@google.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Tejun Heo <tj@kernel.org>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
      f168a9a5
    • R
      mm: memcg/slab: reparent memcg kmem_caches on cgroup removal · fb2f2b0a
      由 Roman Gushchin 提交于 
      Let's reparent non-root kmem_caches on memcg offlining.  This allows us to
release the memory cgroup without waiting for the last outstanding kernel
object (e.g.  dentry used by another application).

Since the parent cgroup is already charged, everything we need to do is to
splice the list of kmem_caches to the parent's kmem_caches list, swap the
memcg pointer, drop the css refcounter for each kmem_cache and adjust the
parent's css refcounter.

Please, note that kmem_cache->memcg_params.memcg isn't a stable pointer
anymore.  It's safe to read it under rcu_read_lock(), cgroup_mutex held,
or any other way that protects the memory cgroup from being released.

We can race with the slab allocation and deallocation paths.  It's not a
big problem: parent's charge and slab global stats are always correct, and
we don't care anymore about the child usage and global stats.  The child
cgroup is already offline, so we don't use or show it anywhere.

Local slab stats (NR_SLAB_RECLAIMABLE and NR_SLAB_UNRECLAIMABLE) aren't
used anywhere except count_shadow_nodes().  But even there it won't break
anything: after reparenting "nodes" will be 0 on child level (because
we're already reparenting shrinker lists), and on parent level page stats
always were 0, and this patch won't change anything.

[guro@fb.com: properly handle kmem_caches reparented to root_mem_cgroup]
  Link: http://lkml.kernel.org/r/20190620213427.1691847-1-guro@fb.com
Link: http://lkml.kernel.org/r/20190611231813.3148843-11-guro@fb.comSigned-off-by: NRoman Gushchin <guro@fb.com>
Acked-by: NVladimir Davydov <vdavydov.dev@gmail.com>
Reviewed-by: NShakeel Butt <shakeelb@google.com>
Acked-by: NDavid Rientjes <rientjes@google.com>
Cc: Christoph Lameter <cl@linux.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Waiman Long <longman@redhat.com>
Cc: David Rientjes <rientjes@google.com>
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Cc: Pekka Enberg <penberg@kernel.org>
Cc: Andrei Vagin <avagin@gmail.com>
Cc: Qian Cai <cai@lca.pw>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
      fb2f2b0a
    • R
      mm: memcg/slab: stop setting page->mem_cgroup pointer for slab pages · 4d96ba35
      由 Roman Gushchin 提交于 
      Every slab page charged to a non-root memory cgroup has a pointer to the
memory cgroup and holds a reference to it, which protects a non-empty
memory cgroup from being released.  At the same time the page has a
pointer to the corresponding kmem_cache, and also hold a reference to the
kmem_cache.  And kmem_cache by itself holds a reference to the cgroup.

So there is clearly some redundancy, which allows to stop setting the
page->mem_cgroup pointer and rely on getting memcg pointer indirectly via
kmem_cache.  Further it will allow to change this pointer easier, without
a need to go over all charged pages.

So let's stop setting page->mem_cgroup pointer for slab pages, and stop
using the css refcounter directly for protecting the memory cgroup from
going away.  Instead rely on kmem_cache as an intermediate object.

Make sure that vmstats and shrinker lists are working as previously, as
well as /proc/kpagecgroup interface.

Link: http://lkml.kernel.org/r/20190611231813.3148843-10-guro@fb.comSigned-off-by: NRoman Gushchin <guro@fb.com>
Acked-by: NVladimir Davydov <vdavydov.dev@gmail.com>
Reviewed-by: NShakeel Butt <shakeelb@google.com>
Cc: Christoph Lameter <cl@linux.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Waiman Long <longman@redhat.com>
Cc: David Rientjes <rientjes@google.com>
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Cc: Pekka Enberg <penberg@kernel.org>
Cc: Andrei Vagin <avagin@gmail.com>
Cc: Qian Cai <cai@lca.pw>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
      4d96ba35
    • R
      mm: memcg/slab: rework non-root kmem_cache lifecycle management · f0a3a24b
      由 Roman Gushchin 提交于 
      Currently each charged slab page holds a reference to the cgroup to which
it's charged.  Kmem_caches are held by the memcg and are released all
together with the memory cgroup.  It means that none of kmem_caches are
released unless at least one reference to the memcg exists, which is very
far from optimal.

Let's rework it in a way that allows releasing individual kmem_caches as
soon as the cgroup is offline, the kmem_cache is empty and there are no
pending allocations.

To make it possible, let's introduce a new percpu refcounter for non-root
kmem caches.  The counter is initialized to the percpu mode, and is
switched to the atomic mode during kmem_cache deactivation.  The counter
is bumped for every charged page and also for every running allocation.
So the kmem_cache can't be released unless all allocations complete.

To shutdown non-active empty kmem_caches, let's reuse the work queue,
previously used for the kmem_cache deactivation.  Once the reference
counter reaches 0, let's schedule an asynchronous kmem_cache release.

* I used the following simple approach to test the performance
(stolen from another patchset by T. Harding):

    time find / -name fname-no-exist
    echo 2 > /proc/sys/vm/drop_caches
    repeat 10 times

Results:

        orig		patched

real	0m1.455s	real	0m1.355s
user	0m0.206s	user	0m0.219s
sys	0m0.855s	sys	0m0.807s

real	0m1.487s	real	0m1.699s
user	0m0.221s	user	0m0.256s
sys	0m0.806s	sys	0m0.948s

real	0m1.515s	real	0m1.505s
user	0m0.183s	user	0m0.215s
sys	0m0.876s	sys	0m0.858s

real	0m1.291s	real	0m1.380s
user	0m0.193s	user	0m0.198s
sys	0m0.843s	sys	0m0.786s

real	0m1.364s	real	0m1.374s
user	0m0.180s	user	0m0.182s
sys	0m0.868s	sys	0m0.806s

real	0m1.352s	real	0m1.312s
user	0m0.201s	user	0m0.212s
sys	0m0.820s	sys	0m0.761s

real	0m1.302s	real	0m1.349s
user	0m0.205s	user	0m0.203s
sys	0m0.803s	sys	0m0.792s

real	0m1.334s	real	0m1.301s
user	0m0.194s	user	0m0.201s
sys	0m0.806s	sys	0m0.779s

real	0m1.426s	real	0m1.434s
user	0m0.216s	user	0m0.181s
sys	0m0.824s	sys	0m0.864s

real	0m1.350s	real	0m1.295s
user	0m0.200s	user	0m0.190s
sys	0m0.842s	sys	0m0.811s

So it looks like the difference is not noticeable in this test.

[cai@lca.pw: fix an use-after-free in kmemcg_workfn()]
  Link: http://lkml.kernel.org/r/1560977573-10715-1-git-send-email-cai@lca.pw
Link: http://lkml.kernel.org/r/20190611231813.3148843-9-guro@fb.comSigned-off-by: NRoman Gushchin <guro@fb.com>
Signed-off-by: NQian Cai <cai@lca.pw>
Acked-by: NVladimir Davydov <vdavydov.dev@gmail.com>
Cc: Christoph Lameter <cl@linux.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Shakeel Butt <shakeelb@google.com>
Cc: Waiman Long <longman@redhat.com>
Cc: David Rientjes <rientjes@google.com>
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Cc: Pekka Enberg <penberg@kernel.org>
Cc: Andrei Vagin <avagin@gmail.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
      f0a3a24b
    • R
      mm: memcg/slab: introduce __memcg_kmem_uncharge_memcg() · 49a18eae
      由 Roman Gushchin 提交于 
      Let's separate the page counter modification code out of
__memcg_kmem_uncharge() in a way similar to what
__memcg_kmem_charge() and __memcg_kmem_charge_memcg() work.

This will allow to reuse this code later using a new
memcg_kmem_uncharge_memcg() wrapper, which calls
__memcg_kmem_uncharge_memcg() if memcg_kmem_enabled()
check is passed.

Link: http://lkml.kernel.org/r/20190611231813.3148843-5-guro@fb.comSigned-off-by: NRoman Gushchin <guro@fb.com>
Reviewed-by: NShakeel Butt <shakeelb@google.com>
Acked-by: NVladimir Davydov <vdavydov.dev@gmail.com>
Cc: Christoph Lameter <cl@linux.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Waiman Long <longman@redhat.com>
Cc: David Rientjes <rientjes@google.com>
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Cc: Pekka Enberg <penberg@kernel.org>
Cc: Andrei Vagin <avagin@gmail.com>
Cc: Qian Cai <cai@lca.pw>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
      49a18eae
    • J
      mm: memcontrol: dump memory.stat during cgroup OOM · c8713d0b
      由 Johannes Weiner 提交于 
      The current cgroup OOM memory info dump doesn't include all the memory
we are tracking, nor does it give insight into what the VM tried to do
leading up to the OOM. All that useful info is in memory.stat.

Furthermore, the recursive printing for every child cgroup can
generate absurd amounts of data on the console for larger cgroup
trees, and it's not like we provide a per-cgroup breakdown during
global OOM kills.

When an OOM kill is triggered, print one set of recursive memory.stat
items at the level whose limit triggered the OOM condition.

Example output:

    stress invoked oom-killer: gfp_mask=0x100cca(GFP_HIGHUSER_MOVABLE), order=0, oom_score_adj=0
    CPU: 2 PID: 210 Comm: stress Not tainted 5.2.0-rc2-mm1-00247-g47d49835983c #135
    Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.12.0-20181126_142135-anatol 04/01/2014
    Call Trace:
     dump_stack+0x46/0x60
     dump_header+0x4c/0x2d0
     oom_kill_process.cold.10+0xb/0x10
     out_of_memory+0x200/0x270
     ? try_to_free_mem_cgroup_pages+0xdf/0x130
     mem_cgroup_out_of_memory+0xb7/0xc0
     try_charge+0x680/0x6f0
     mem_cgroup_try_charge+0xb5/0x160
     __add_to_page_cache_locked+0xc6/0x300
     ? list_lru_destroy+0x80/0x80
     add_to_page_cache_lru+0x45/0xc0
     pagecache_get_page+0x11b/0x290
     filemap_fault+0x458/0x6d0
     ext4_filemap_fault+0x27/0x36
     __do_fault+0x2f/0xb0
     __handle_mm_fault+0x9c5/0x1140
     ? apic_timer_interrupt+0xa/0x20
     handle_mm_fault+0xc5/0x180
     __do_page_fault+0x1ab/0x440
     ? page_fault+0x8/0x30
     page_fault+0x1e/0x30
    RIP: 0033:0x55c32167fc10
    Code: Bad RIP value.
    RSP: 002b:00007fff1d031c50 EFLAGS: 00010206
    RAX: 000000000dc00000 RBX: 00007fd2db000010 RCX: 00007fd2db000010
    RDX: 0000000000000000 RSI: 0000000010001000 RDI: 0000000000000000
    RBP: 000055c321680a54 R08: 00000000ffffffff R09: 0000000000000000
    R10: 0000000000000022 R11: 0000000000000246 R12: ffffffffffffffff
    R13: 0000000000000002 R14: 0000000000001000 R15: 0000000010000000
    memory: usage 1024kB, limit 1024kB, failcnt 75131
    swap: usage 0kB, limit 9007199254740988kB, failcnt 0
    Memory cgroup stats for /foo:
    anon 0
    file 0
    kernel_stack 36864
    slab 274432
    sock 0
    shmem 0
    file_mapped 0
    file_dirty 0
    file_writeback 0
    anon_thp 0
    inactive_anon 126976
    active_anon 0
    inactive_file 0
    active_file 0
    unevictable 0
    slab_reclaimable 0
    slab_unreclaimable 274432
    pgfault 59466
    pgmajfault 1617
    workingset_refault 2145
    workingset_activate 0
    workingset_nodereclaim 0
    pgrefill 98952
    pgscan 200060
    pgsteal 59340
    pgactivate 40095
    pgdeactivate 96787
    pglazyfree 0
    pglazyfreed 0
    thp_fault_alloc 0
    thp_collapse_alloc 0
    Tasks state (memory values in pages):
    [  pid  ]   uid  tgid total_vm      rss pgtables_bytes swapents oom_score_adj name
    [    200]     0   200     1121      884    53248       29             0 bash
    [    209]     0   209      905      246    45056       19             0 stress
    [    210]     0   210    66442       56   499712    56349             0 stress
    oom-kill:constraint=CONSTRAINT_NONE,nodemask=(null),oom_memcg=/foo,task_memcg=/foo,task=stress,pid=210,uid=0
    Memory cgroup out of memory: Killed process 210 (stress) total-vm:265768kB, anon-rss:0kB, file-rss:224kB, shmem-rss:0kB
    oom_reaper: reaped process 210 (stress), now anon-rss:0kB, file-rss:0kB, shmem-rss:0kB

[hannes@cmpxchg.org: s/kvmalloc/kmalloc/ per Michal]
  Link: http://lkml.kernel.org/r/20190605161133.GA12453@cmpxchg.org
Link: http://lkml.kernel.org/r/20190604210509.9744-1-hannes@cmpxchg.orgSigned-off-by: NJohannes Weiner <hannes@cmpxchg.org>
Acked-by: NMichal Hocko <mhocko@suse.com>
Cc: Vladimir Davydov <vdavydov.dev@gmail.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
      c8713d0b
    • S
      mm, memcg: introduce memory.events.local · 1e577f97
      由 Shakeel Butt 提交于 
      The memory controller in cgroup v2 exposes memory.events file for each
memcg which shows the number of times events like low, high, max, oom
and oom_kill have happened for the whole tree rooted at that memcg.
Users can also poll or register notification to monitor the changes in
that file.  Any event at any level of the tree rooted at memcg will
notify all the listeners along the path till root_mem_cgroup.  There are
existing users which depend on this behavior.

However there are users which are only interested in the events
happening at a specific level of the memcg tree and not in the events in
the underlying tree rooted at that memcg.  One such use-case is a
centralized resource monitor which can dynamically adjust the limits of
the jobs running on a system.  The jobs can create their sub-hierarchy
for their own sub-tasks.  The centralized monitor is only interested in
the events at the top level memcgs of the jobs as it can then act and
adjust the limits of the jobs.  Using the current memory.events for such
centralized monitor is very inconvenient.  The monitor will keep
receiving events which it is not interested and to find if the received
event is interesting, it has to read memory.event files of the next
level and compare it with the top level one.  So, let's introduce
memory.events.local to the memcg which shows and notify for the events
at the memcg level.

Now, does memory.stat and memory.pressure need their local versions.  IMHO
no due to the no internal process contraint of the cgroup v2.  The
memory.stat file of the top level memcg of a job shows the stats and
vmevents of the whole tree.  The local stats or vmevents of the top level
memcg will only change if there is a process running in that memcg but v2
does not allow that.  Similarly for memory.pressure there will not be any
process in the internal nodes and thus no chance of local pressure.

Link: http://lkml.kernel.org/r/20190527174643.209172-1-shakeelb@google.comSigned-off-by: NShakeel Butt <shakeelb@google.com>
Reviewed-by: NRoman Gushchin <guro@fb.com>
Acked-by: NJohannes Weiner <hannes@cmpxchg.org>
Acked-by: NMichal Hocko <mhocko@suse.com>
Cc: Vladimir Davydov <vdavydov.dev@gmail.com>
Cc: Chris Down <chris@chrisdown.name>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
      1e577f97
    • S
      memcg, oom: no oom-kill for __GFP_RETRY_MAYFAIL · 38d38493
      由 Shakeel Butt 提交于 
      The documentation of __GFP_RETRY_MAYFAIL clearly mentioned that the OOM
killer will not be triggered and indeed the page alloc does not invoke OOM
killer for such allocations.  However we do trigger memcg OOM killer for
__GFP_RETRY_MAYFAIL.  Fix that.  This flag will used later to not trigger
oom-killer in the charging path for fanotify and inotify event
allocations.

Link: http://lkml.kernel.org/r/20190514212259.156585-1-shakeelb@google.comSigned-off-by: NShakeel Butt <shakeelb@google.com>
Acked-by: NMichal Hocko <mhocko@suse.com>
Cc: Amir Goldstein <amir73il@gmail.com>
Cc: Jan Kara <jack@suse.cz>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Roman Gushchin <guro@fb.com>
Cc: Vladimir Davydov <vdavydov.dev@gmail.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
      38d38493
    • Y
      mm/memcontrol: fix wrong statistics in memory.stat · dd923990
      由 Yafang Shao 提交于 
      When we calculate total statistics for memcg1_stats and memcg1_events,
we use the the index 'i' in the for loop as the events index.  Actually
we should use memcg1_stats[i] and memcg1_events[i] as the events index.

Link: http://lkml.kernel.org/r/1562116978-19539-1-git-send-email-laoar.shao@gmail.com
Fixes: 42a30035 ("mm: memcontrol: fix recursive statistics correctness & scalabilty").
Signed-off-by: Yafang Shao <laoar.shao@gmail.com
Reviewed-by: NShakeel Butt <shakeelb@google.com>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Yafang Shao <shaoyafang@didiglobal.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
      dd923990
  11. 03 7月, 2019 1 次提交
  13. 14 6月, 2019 1 次提交
    • J
      mm: memcontrol: don't batch updates of local VM stats and events · 815744d7
      由 Johannes Weiner 提交于 
      The kernel test robot noticed a 26% will-it-scale pagefault regression
from commit 42a30035 ("mm: memcontrol: fix recursive statistics
correctness & scalabilty").  This appears to be caused by bouncing the
additional cachelines from the new hierarchical statistics counters.

We can fix this by getting rid of the batched local counters instead.

Originally, there were *only* group-local counters, and they were fully
maintained per cpu.  A reader of a stats file high up in the cgroup tree
would have to walk the entire subtree and collect each level's per-cpu
counters to get the recursive view.  This was prohibitively expensive,
and so we switched to per-cpu batched updates of the local counters
during a983b5eb ("mm: memcontrol: fix excessive complexity in
memory.stat reporting"), reducing the complexity from nr_subgroups *
nr_cpus to nr_subgroups.

With growing machines and cgroup trees, the tree walk itself became too
expensive for monitoring top-level groups, and this is when the culprit
patch added hierarchy counters on each cgroup level.  When the per-cpu
batch size would be reached, both the local and the hierarchy counters
would get batch-updated from the per-cpu delta simultaneously.

This makes local and hierarchical counter reads blazingly fast, but it
unfortunately makes the write-side too cache line intense.

Since local counter reads were never a problem - we only centralized
them to accelerate the hierarchy walk - and use of the local counters
are becoming rarer due to replacement with hierarchical views (ongoing
rework in the page reclaim and workingset code), we can make those local
counters unbatched per-cpu counters again.

The scheme will then be as such:

   when a memcg statistic changes, the writer will:
   - update the local counter (per-cpu)
   - update the batch counter (per-cpu). If the batch is full:
   - spill the batch into the group's atomic_t
   - spill the batch into all ancestors' atomic_ts
   - empty out the batch counter (per-cpu)

   when a local memcg counter is read, the reader will:
   - collect the local counter from all cpus

   when a hiearchy memcg counter is read, the reader will:
   - read the atomic_t

We might be able to simplify this further and make the recursive
counters unbatched per-cpu counters as well (batch upward propagation,
but leave per-cpu collection to the readers), but that will require a
more in-depth analysis and testing of all the callsites.  Deal with the
immediate regression for now.

Link: http://lkml.kernel.org/r/20190521151647.GB2870@cmpxchg.org
Fixes: 42a30035 ("mm: memcontrol: fix recursive statistics correctness & scalabilty")
Signed-off-by: NJohannes Weiner <hannes@cmpxchg.org>
Reported-by: Nkernel test robot <rong.a.chen@intel.com>
Tested-by: Nkernel test robot <rong.a.chen@intel.com>
Cc: Michal Hocko <mhocko@kernel.org>
Cc: Shakeel Butt <shakeelb@google.com>
Cc: Roman Gushchin <guro@fb.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
      815744d7
  15. 31 5月, 2019 1 次提交
    • T
      treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 157 · c942fddf
      由 Thomas Gleixner 提交于 
      Based on 3 normalized pattern(s):

  this program is free software you can redistribute it and or modify
  it under the terms of the gnu general public license as published by
  the free software foundation either version 2 of the license or at
  your option any later version this program is distributed in the
  hope that it will be useful but without any warranty without even
  the implied warranty of merchantability or fitness for a particular
  purpose see the gnu general public license for more details

  this program is free software you can redistribute it and or modify
  it under the terms of the gnu general public license as published by
  the free software foundation either version 2 of the license or at
  your option any later version [author] [kishon] [vijay] [abraham]
  [i] [kishon]@[ti] [com] this program is distributed in the hope that
  it will be useful but without any warranty without even the implied
  warranty of merchantability or fitness for a particular purpose see
  the gnu general public license for more details

  this program is free software you can redistribute it and or modify
  it under the terms of the gnu general public license as published by
  the free software foundation either version 2 of the license or at
  your option any later version [author] [graeme] [gregory]
  [gg]@[slimlogic] [co] [uk] [author] [kishon] [vijay] [abraham] [i]
  [kishon]@[ti] [com] [based] [on] [twl6030]_[usb] [c] [author] [hema]
  [hk] [hemahk]@[ti] [com] this program is distributed in the hope
  that it will be useful but without any warranty without even the
  implied warranty of merchantability or fitness for a particular
  purpose see the gnu general public license for more details

extracted by the scancode license scanner the SPDX license identifier

  GPL-2.0-or-later

has been chosen to replace the boilerplate/reference in 1105 file(s).
Signed-off-by: NThomas Gleixner <tglx@linutronix.de>
Reviewed-by: NAllison Randal <allison@lohutok.net>
Reviewed-by: NRichard Fontana <rfontana@redhat.com>
Reviewed-by: NKate Stewart <kstewart@linuxfoundation.org>
Cc: linux-spdx@vger.kernel.org
Link: https://lkml.kernel.org/r/20190527070033.202006027@linutronix.deSigned-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>
      c942fddf
  17. 15 5月, 2019 10 次提交
  19. 06 4月, 2019 1 次提交
    • G
      mm: writeback: use exact memcg dirty counts · 0b3d6e6f
      由 Greg Thelen 提交于 
      Since commit a983b5eb ("mm: memcontrol: fix excessive complexity in
memory.stat reporting") memcg dirty and writeback counters are managed
as:

 1) per-memcg per-cpu values in range of [-32..32]

 2) per-memcg atomic counter

When a per-cpu counter cannot fit in [-32..32] it's flushed to the
atomic.  Stat readers only check the atomic.  Thus readers such as
balance_dirty_pages() may see a nontrivial error margin: 32 pages per
cpu.

Assuming 100 cpus:
   4k x86 page_size:  13 MiB error per memcg
  64k ppc page_size: 200 MiB error per memcg

Considering that dirty+writeback are used together for some decisions the
errors double.

This inaccuracy can lead to undeserved oom kills.  One nasty case is
when all per-cpu counters hold positive values offsetting an atomic
negative value (i.e.  per_cpu[*]=32, atomic=n_cpu*-32).
balance_dirty_pages() only consults the atomic and does not consider
throttling the next n_cpu*32 dirty pages.  If the file_lru is in the
13..200 MiB range then there's absolutely no dirty throttling, which
burdens vmscan with only dirty+writeback pages thus resorting to oom
kill.

It could be argued that tiny containers are not supported, but it's more
subtle.  It's the amount the space available for file lru that matters.
If a container has memory.max-200MiB of non reclaimable memory, then it
will also suffer such oom kills on a 100 cpu machine.

The following test reliably ooms without this patch.  This patch avoids
oom kills.

  $ cat test
  mount -t cgroup2 none /dev/cgroup
  cd /dev/cgroup
  echo +io +memory > cgroup.subtree_control
  mkdir test
  cd test
  echo 10M > memory.max
  (echo $BASHPID > cgroup.procs && exec /memcg-writeback-stress /foo)
  (echo $BASHPID > cgroup.procs && exec dd if=/dev/zero of=/foo bs=2M count=100)

  $ cat memcg-writeback-stress.c
  /*
   * Dirty pages from all but one cpu.
   * Clean pages from the non dirtying cpu.
   * This is to stress per cpu counter imbalance.
   * On a 100 cpu machine:
   * - per memcg per cpu dirty count is 32 pages for each of 99 cpus
   * - per memcg atomic is -99*32 pages
   * - thus the complete dirty limit: sum of all counters 0
   * - balance_dirty_pages() only sees atomic count -99*32 pages, which
   *   it max()s to 0.
   * - So a workload can dirty -99*32 pages before balance_dirty_pages()
   *   cares.
   */
  #define _GNU_SOURCE
  #include <err.h>
  #include <fcntl.h>
  #include <sched.h>
  #include <stdlib.h>
  #include <stdio.h>
  #include <sys/stat.h>
  #include <sys/sysinfo.h>
  #include <sys/types.h>
  #include <unistd.h>

  static char *buf;
  static int bufSize;

  static void set_affinity(int cpu)
  {
  	cpu_set_t affinity;

  	CPU_ZERO(&affinity);
  	CPU_SET(cpu, &affinity);
  	if (sched_setaffinity(0, sizeof(affinity), &affinity))
  		err(1, "sched_setaffinity");
  }

  static void dirty_on(int output_fd, int cpu)
  {
  	int i, wrote;

  	set_affinity(cpu);
  	for (i = 0; i < 32; i++) {
  		for (wrote = 0; wrote < bufSize; ) {
  			int ret = write(output_fd, buf+wrote, bufSize-wrote);
  			if (ret == -1)
  				err(1, "write");
  			wrote += ret;
  		}
  	}
  }

  int main(int argc, char **argv)
  {
  	int cpu, flush_cpu = 1, output_fd;
  	const char *output;

  	if (argc != 2)
  		errx(1, "usage: output_file");

  	output = argv[1];
  	bufSize = getpagesize();
  	buf = malloc(getpagesize());
  	if (buf == NULL)
  		errx(1, "malloc failed");

  	output_fd = open(output, O_CREAT|O_RDWR);
  	if (output_fd == -1)
  		err(1, "open(%s)", output);

  	for (cpu = 0; cpu < get_nprocs(); cpu++) {
  		if (cpu != flush_cpu)
  			dirty_on(output_fd, cpu);
  	}

  	set_affinity(flush_cpu);
  	if (fsync(output_fd))
  		err(1, "fsync(%s)", output);
  	if (close(output_fd))
  		err(1, "close(%s)", output);
  	free(buf);
  }

Make balance_dirty_pages() and wb_over_bg_thresh() work harder to
collect exact per memcg counters.  This avoids the aforementioned oom
kills.

This does not affect the overhead of memory.stat, which still reads the
single atomic counter.

Why not use percpu_counter? memcg already handles cpus going offline, so
no need for that overhead from percpu_counter.  And the percpu_counter
spinlocks are more heavyweight than is required.

It probably also makes sense to use exact dirty and writeback counters
in memcg oom reports.  But that is saved for later.

Link: http://lkml.kernel.org/r/20190329174609.164344-1-gthelen@google.comSigned-off-by: NGreg Thelen <gthelen@google.com>
Reviewed-by: NRoman Gushchin <guro@fb.com>
Acked-by: NJohannes Weiner <hannes@cmpxchg.org>
Cc: Michal Hocko <mhocko@kernel.org>
Cc: Vladimir Davydov <vdavydov.dev@gmail.com>
Cc: Tejun Heo <tj@kernel.org>
Cc: <stable@vger.kernel.org>	[4.16+]
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
      0b3d6e6f
  21. 06 3月, 2019 9 次提交