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From: Alex Shi <alex.shi@linux.alibaba.com>
To: linux-kernel@vger.kernel.org, akpm@linux-foundation.org,
	hannes@cmpxchg.org, hughd@google.com, linux-mm@kvack.org,
	mhocko@suse.com, mm-commits@vger.kernel.org, shakeelb@google.com,
	stable@vger.kernel.org, torvalds@linux-foundation.org
Subject: Re: [patch 06/15] mm/memcg: fix refcount error while moving and swapping
Date: Fri, 24 Jul 2020 21:41:07 +0800
Message-ID: <e22a1ccb-6b5a-d448-e3ff-3045e93e4f09@linux.alibaba.com> (raw)
In-Reply-To: <20200724041524.eAqB5zPs6%akpm@linux-foundation.org>



在 2020/7/24 下午12:15, Andrew Morton 写道:
> From: Hugh Dickins <hughd@google.com>
> Subject: mm/memcg: fix refcount error while moving and swapping
> 
> It was hard to keep a test running, moving tasks between memcgs with
> move_charge_at_immigrate, while swapping: mem_cgroup_id_get_many()'s
> refcount is discovered to be 0 (supposedly impossible), so it is then
> forced to REFCOUNT_SATURATED, and after thousands of warnings in quick
> succession, the test is at last put out of misery by being OOM killed.
> 
> This is because of the way moved_swap accounting was saved up until the
> task move gets completed in __mem_cgroup_clear_mc(), deferred from when
> mem_cgroup_move_swap_account() actually exchanged old and new ids. 
> Concurrent activity can free up swap quicker than the task is scanned,
> bringing id refcount down 0 (which should only be possible when
> offlining).
> 
> Just skip that optimization: do that part of the accounting immediately.
> 
> Link: http://lkml.kernel.org/r/alpine.LSU.2.11.2007071431050.4726@eggly.anvils
> Fixes: 615d66c37c75 ("mm: memcontrol: fix memcg id ref counter on swap charge move")
> Signed-off-by: Hugh Dickins <hughd@google.com>
> Cc: Johannes Weiner <hannes@cmpxchg.org>
> Cc: Alex Shi <alex.shi@linux.alibaba.com>
> Cc: Shakeel Butt <shakeelb@google.com>
> Cc: Michal Hocko <mhocko@suse.com>
> Cc: <stable@vger.kernel.org>
> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
> ---

Reviewed-by: Alex Shi <alex.shi@linux.alibaba.com>

> 
>  mm/memcontrol.c |    4 ++--
>  1 file changed, 2 insertions(+), 2 deletions(-)
> 
> --- a/mm/memcontrol.c~mm-memcg-fix-refcount-error-while-moving-and-swapping
> +++ a/mm/memcontrol.c
> @@ -5669,7 +5669,6 @@ static void __mem_cgroup_clear_mc(void)
>  		if (!mem_cgroup_is_root(mc.to))
>  			page_counter_uncharge(&mc.to->memory, mc.moved_swap);
>  
> -		mem_cgroup_id_get_many(mc.to, mc.moved_swap);
>  		css_put_many(&mc.to->css, mc.moved_swap);
>  
>  		mc.moved_swap = 0;
> @@ -5860,7 +5859,8 @@ put:			/* get_mctgt_type() gets the page
>  			ent = target.ent;
>  			if (!mem_cgroup_move_swap_account(ent, mc.from, mc.to)) {
>  				mc.precharge--;
> -				/* we fixup refcnts and charges later. */
> +				mem_cgroup_id_get_many(mc.to, 1);
> +				/* we fixup other refcnts and charges later. */
>  				mc.moved_swap++;
>  			}
>  			break;
> _
> 


  reply index

Thread overview: 69+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-07-24  4:14 incoming Andrew Morton
2020-07-24  4:15 ` [patch 01/15] mm/memory.c: avoid access flag update TLB flush for retried page fault Andrew Morton
2020-07-24  4:38   ` Yang Shi
2020-07-24  4:56     ` Andrew Morton
2020-07-24 19:27   ` Linus Torvalds
2020-07-24 20:22     ` Linus Torvalds
2020-07-25  0:36       ` Yang Shi
2020-07-25  1:29         ` Linus Torvalds
2020-07-25 15:58           ` Catalin Marinas
2020-07-28  9:22             ` Will Deacon
2020-07-28  9:39               ` Catalin Marinas
2020-07-28 10:07                 ` Yu Xu
2020-07-28 11:46                   ` Catalin Marinas
2020-07-28 10:21                 ` Will Deacon
2020-07-28 18:28                 ` Linus Torvalds
2020-07-27 17:52           ` Yang Shi
2020-07-27 18:04             ` Linus Torvalds
2020-07-27 18:42               ` Catalin Marinas
2020-07-27 20:56                 ` Linus Torvalds
2020-07-27 22:34               ` Yang Shi
2020-07-27  7:31       ` Yu Xu
2020-07-27 11:05         ` Catalin Marinas
2020-07-27 17:01           ` Linus Torvalds
2020-07-28 11:19             ` Catalin Marinas
2020-07-27 17:12           ` Yu Xu
2020-07-27 18:04             ` Yang Shi
2020-07-27 18:37               ` Linus Torvalds
2020-07-27 22:43                 ` Yang Shi
2020-07-28  0:38                   ` Linus Torvalds
2020-07-28  0:13                 ` Yu Xu
2020-07-28 10:53                 ` Nicholas Piggin
2020-07-28 19:02                   ` Linus Torvalds
2020-07-28 22:53                     ` Nicholas Piggin
2020-07-29 13:58                       ` Michael Ellerman
2020-07-28  6:41             ` Yu Xu
2020-07-24  4:15 ` [patch 02/15] mm/mmap.c: close race between munmap() and expand_upwards()/downwards() Andrew Morton
2020-07-24  4:15 ` [patch 03/15] vfs/xattr: mm/shmem: kernfs: release simple xattr entry in a right way Andrew Morton
2020-07-24  4:15 ` [patch 04/15] mm: initialize return of vm_insert_pages Andrew Morton
2020-07-24  4:15 ` [patch 05/15] mm/memcontrol: fix OOPS inside mem_cgroup_get_nr_swap_pages() Andrew Morton
2020-07-24  4:15 ` [patch 06/15] mm/memcg: fix refcount error while moving and swapping Andrew Morton
2020-07-24 13:41   ` Alex Shi [this message]
2020-07-24  4:15 ` [patch 07/15] mm: memcg/slab: fix memory leak at non-root kmem_cache destroy Andrew Morton
2020-07-24  4:15 ` [patch 08/15] mm/hugetlb: avoid hardcoding while checking if cma is enabled Andrew Morton
2020-07-24  4:15 ` [patch 09/15] khugepaged: fix null-pointer dereference due to race Andrew Morton
2020-07-24  4:15 ` [patch 10/15] mailmap: add entry for Mike Rapoport Andrew Morton
2020-07-24  4:15 ` [patch 11/15] squashfs: fix length field overlap check in metadata reading Andrew Morton
2020-07-24  4:15 ` [patch 12/15] scripts/decode_stacktrace: strip basepath from all paths Andrew Morton
2020-07-24  4:15 ` [patch 13/15] io-mapping: indicate mapping failure Andrew Morton
2020-07-24  4:15 ` [patch 14/15] MAINTAINERS: add KCOV section Andrew Morton
2020-07-24  4:15 ` [patch 15/15] scripts/gdb: fix lx-symbols 'gdb.error' while loading modules Andrew Morton
2020-07-28  1:19 ` mmotm 2020-07-27-18-18 uploaded Andrew Morton
2020-07-28  2:14   ` Stephen Rothwell
2020-07-28  3:22   ` mmotm 2020-07-27-18-18 uploaded (drivers/scsi/ufs/: SCSI_UFS_EXYNOS) Randy Dunlap
2020-07-28  8:23     ` Alim Akhtar
2020-07-28 12:33   ` mmotm 2020-07-27-18-18 uploaded (mm/page_alloc.c) Randy Dunlap
2020-07-28 21:55     ` Andrew Morton
2020-07-28 22:20       ` Stephen Rothwell
2020-07-28 22:31         ` Andrew Morton
2020-07-29 14:18           ` Michael S. Tsirkin
2020-07-29 14:38             ` David Hildenbrand
2020-07-29 16:14               ` David Hildenbrand
2020-07-29 17:29                 ` Randy Dunlap
2020-07-28 22:39       ` Randy Dunlap
2020-07-29  1:43         ` Nathan Chancellor
2020-07-29  1:44         ` Andrew Morton
2020-07-29  2:04           ` Randy Dunlap
2020-07-29 14:09           ` make oldconfig (Re: mmotm 2020-07-27-18-18 uploaded (mm/page_alloc.c)) Alexey Dobriyan
2020-07-31 23:46 ` mmotm 2020-07-31-16-45 uploaded Andrew Morton
2020-08-01  5:24   ` mmotm 2020-07-31-16-45 uploaded (drivers/staging/vc04_services/) Randy Dunlap

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