Commit 50814c7f authored by Roman Gushchin's avatar Roman Gushchin Committed by Cai Xinchen
Browse files

mm: memcontrol: do not miss MEMCG_MAX events for enforced allocations 

mainline inclusion
from mainline-v6.0-rc1
commit d6e103a7
category: bugfix
bugzilla: https://gitee.com/openeuler/kernel/issues/I9ORR4

Reference: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=d6e103a757fa7876e7ded76128d5dffe12402ab9

--------------------------------

Yafang Shao reported an issue related to the accounting of bpf memory:
if a bpf map is charged indirectly for memory consumed from an
interrupt context and allocations are enforced, MEMCG_MAX events are
not raised.

It's not/less of an issue in a generic case because consequent
allocations from a process context will trigger the direct reclaim and
MEMCG_MAX events will be raised.  However a bpf map can belong to a
dying/abandoned memory cgroup, so there will be no allocations from a
process context and no MEMCG_MAX events will be triggered.

Link: https://lkml.kernel.org/r/20220702033521.64630-1-roman.gushchin@linux.dev


Signed-off-by: default avatarRoman Gushchin <roman.gushchin@linux.dev>
Reported-by: default avatarYafang Shao <laoar.shao@gmail.com>
Acked-by: default avatarShakeel Butt <shakeelb@google.com>
Acked-by: default avatarMichal Hocko <mhocko@suse.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Muchun Song <songmuchun@bytedance.com>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Conflicts:
	mm/memcontrol.c
[There are context conflicts bacause commit c5c8b16b("mm: memcontrol: fix root_mem_cgroup charging")
is not merged. And we merge commit 789303ae("mm: vmpressure: don't count proactive reclaim in vmpressure")]
Signed-off-by: default avatarCai Xinchen <caixinchen1@huawei.com>
parent 0982dad0

mm/memcontrol.c

+9 −0
Original line number Diff line number Diff line
@@ -2674,6 +2674,7 @@ static int try_charge(struct mem_cgroup *memcg, gfp_t gfp_mask, 
	bool passed_oom = false;

	unsigned int reclaim_options = MEMCG_RECLAIM_MAY_SWAP;

	bool drained = false;

	bool raised_max_event = false;

	unsigned long pflags;



	if (mem_cgroup_is_root(memcg))
@@ -2724,6 +2725,7 @@ static int try_charge(struct mem_cgroup *memcg, gfp_t gfp_mask, 
		goto nomem;



	memcg_memory_event(mem_over_limit, MEMCG_MAX);

	raised_max_event = true;

#ifdef CONFIG_PSI_FINE_GRAINED

	pflags = PSI_MEMCG_RECLAIM;

#endif
@@ -2787,6 +2789,13 @@ static int try_charge(struct mem_cgroup *memcg, gfp_t gfp_mask, 
	if (!(gfp_mask & __GFP_NOFAIL))

		return -ENOMEM;

force:

	/*

	 * If the allocation has to be enforced, don't forget to raise

	 * a MEMCG_MAX event.

	 */

	if (!raised_max_event)

		memcg_memory_event(mem_over_limit, MEMCG_MAX);



	/*

	 * The allocation either can't fail or will lead to more memory

	 * being freed very soon.  Allow memory usage go over the limit