[merged mm-stable] mm-memcontrol-do-not-miss-memcg_max-events-for-enforced-allocations.patch removed from -mm tree

[merged mm-stable] mm-memcontrol-do-not-miss-memcg_max-events-for-enforced-allocations.patch removed from -mm tree

[Andrew Morton]

The quilt patch titled
     Subject: mm: memcontrol: do not miss MEMCG_MAX events for enforced allocations
has been removed from the -mm tree.  Its filename was
     mm-memcontrol-do-not-miss-memcg_max-events-for-enforced-allocations.patch

This patch was dropped because it was merged into the mm-stable branch
of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm

------------------------------------------------------
From: Roman Gushchin <roman.gushchin@linux.dev>
Subject: mm: memcontrol: do not miss MEMCG_MAX events for enforced allocations
Date: Fri, 1 Jul 2022 20:35:21 -0700

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: Roman Gushchin <roman.gushchin@linux.dev>
Reported-by: Yafang Shao <laoar.shao@gmail.com>
Acked-by: Shakeel Butt <shakeelb@google.com>
Acked-by: Michal Hocko <mhocko@suse.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Muchun Song <songmuchun@bytedance.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---

 mm/memcontrol.c |    9 +++++++++
 1 file changed, 9 insertions(+)

--- a/mm/memcontrol.c~mm-memcontrol-do-not-miss-memcg_max-events-for-enforced-allocations
+++ a/mm/memcontrol.c
@@ -2577,6 +2577,7 @@ static int try_charge_memcg(struct mem_c
 	bool passed_oom = false;
 	bool may_swap = true;
 	bool drained = false;
+	bool raised_max_event = false;
 	unsigned long pflags;
 
 retry:
@@ -2616,6 +2617,7 @@ retry:
 		goto nomem;
 
 	memcg_memory_event(mem_over_limit, MEMCG_MAX);
+	raised_max_event = true;
 
 	psi_memstall_enter(&pflags);
 	nr_reclaimed = try_to_free_mem_cgroup_pages(mem_over_limit, nr_pages,
@@ -2683,6 +2685,13 @@ nomem:
 		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
 	 * temporarily by force charging it.
_

Patches currently in -mm which might be from roman.gushchin@linux.dev are