From: Yosry Ahmed <yosryahmed@google.com>
To: "Tejun Heo" <tj@kernel.org>, "Josef Bacik" <josef@toxicpanda.com>,
"Jens Axboe" <axboe@kernel.dk>,
"Zefan Li" <lizefan.x@bytedance.com>,
"Johannes Weiner" <hannes@cmpxchg.org>,
"Michal Hocko" <mhocko@kernel.org>,
"Roman Gushchin" <roman.gushchin@linux.dev>,
"Shakeel Butt" <shakeelb@google.com>,
"Muchun Song" <muchun.song@linux.dev>,
"Andrew Morton" <akpm@linux-foundation.org>,
"Michal Koutný" <mkoutny@suse.com>
Cc: Vasily Averin <vasily.averin@linux.dev>,
cgroups@vger.kernel.org, linux-block@vger.kernel.org,
linux-kernel@vger.kernel.org, linux-mm@kvack.org,
bpf@vger.kernel.org, Yosry Ahmed <yosryahmed@google.com>
Subject: [PATCH v2 4/9] cgroup: rstat: add WARN_ON_ONCE() if flushing outside task context
Date: Tue, 28 Mar 2023 22:16:39 +0000 [thread overview]
Message-ID: <20230328221644.803272-5-yosryahmed@google.com> (raw)
In-Reply-To: <20230328221644.803272-1-yosryahmed@google.com>
rstat flushing is too expensive to perform in irq context.
The previous patch removed the only context that may invoke an rstat
flush from irq context, add a WARN_ON_ONCE() to detect future
violations, or those that we are not aware of.
Ideally, we wouldn't flush with irqs disabled either, but we have one
context today that does so in mem_cgroup_usage(). Forbid callers from
irq context for now, and hopefully we can also forbid callers with irqs
disabled in the future when we can get rid of this callsite.
Signed-off-by: Yosry Ahmed <yosryahmed@google.com>
Reviewed-by: Shakeel Butt <shakeelb@google.com>
---
kernel/cgroup/rstat.c | 2 ++
1 file changed, 2 insertions(+)
diff --git a/kernel/cgroup/rstat.c b/kernel/cgroup/rstat.c
index d3252b0416b6..c2571939139f 100644
--- a/kernel/cgroup/rstat.c
+++ b/kernel/cgroup/rstat.c
@@ -176,6 +176,8 @@ static void cgroup_rstat_flush_locked(struct cgroup *cgrp, bool may_sleep)
{
int cpu;
+ /* rstat flushing is too expensive for irq context */
+ WARN_ON_ONCE(!in_task());
lockdep_assert_held(&cgroup_rstat_lock);
for_each_possible_cpu(cpu) {
--
2.40.0.348.gf938b09366-goog
next prev parent reply other threads:[~2023-03-28 22:17 UTC|newest]
Thread overview: 40+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-03-28 22:16 [PATCH v2 0/9] memcg: make rstat flushing irq and sleep Yosry Ahmed
2023-03-28 22:16 ` [PATCH v2 1/9] cgroup: rename cgroup_rstat_flush_"irqsafe" to "atomic" Yosry Ahmed
2023-03-28 22:16 ` [PATCH v2 2/9] memcg: rename mem_cgroup_flush_stats_"delayed" to "ratelimited" Yosry Ahmed
2023-03-29 11:56 ` Michal Hocko
2023-03-28 22:16 ` [PATCH v2 3/9] memcg: do not flush stats in irq context Yosry Ahmed
2023-03-29 11:58 ` Michal Hocko
2023-03-28 22:16 ` Yosry Ahmed [this message]
2023-03-29 11:22 ` [PATCH v2 4/9] cgroup: rstat: add WARN_ON_ONCE() if flushing outside task context Michal Hocko
2023-03-29 18:41 ` Yosry Ahmed
2023-03-29 19:20 ` Shakeel Butt
2023-03-30 7:06 ` Michal Hocko
2023-03-30 7:13 ` Yosry Ahmed
2023-03-30 7:49 ` Michal Hocko
2023-03-30 8:06 ` Yosry Ahmed
2023-03-30 8:14 ` Michal Hocko
2023-03-30 8:19 ` Yosry Ahmed
2023-03-30 8:39 ` Michal Hocko
2023-03-30 8:53 ` Yosry Ahmed
2023-03-31 11:02 ` Michal Hocko
2023-03-31 19:03 ` Yosry Ahmed
2023-04-03 8:38 ` Michal Hocko
2023-04-03 20:39 ` Yosry Ahmed
2023-03-28 22:16 ` [PATCH v2 5/9] memcg: replace stats_flush_lock with an atomic Yosry Ahmed
2023-03-28 22:22 ` Shakeel Butt
2023-03-29 15:58 ` Michal Hocko
2023-03-29 18:45 ` Yosry Ahmed
2023-03-28 22:16 ` [PATCH v2 6/9] memcg: sleep during flushing stats in safe contexts Yosry Ahmed
2023-03-30 7:35 ` Michal Hocko
2023-03-28 22:16 ` [PATCH v2 7/9] workingset: memcg: sleep when flushing stats in workingset_refault() Yosry Ahmed
2023-03-30 7:39 ` Michal Hocko
2023-03-30 7:42 ` Yosry Ahmed
2023-03-30 7:50 ` Michal Hocko
2023-03-30 7:55 ` Yosry Ahmed
2023-03-28 22:16 ` [PATCH v2 8/9] vmscan: memcg: sleep when flushing stats during reclaim Yosry Ahmed
2023-03-30 7:40 ` Michal Hocko
2023-03-30 7:44 ` Yosry Ahmed
2023-03-30 7:52 ` Michal Hocko
2023-03-30 7:54 ` Yosry Ahmed
2023-03-28 22:16 ` [PATCH v2 9/9] memcg: do not modify rstat tree for zero updates Yosry Ahmed
2023-03-30 7:43 ` Michal Hocko
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