From: Johannes Weiner <hannes@cmpxchg.org>
To: Yosry Ahmed <yosry.ahmed@linux.dev>
Cc: "Greg Thelen" <gthelen@google.com>, "Tejun Heo" <tj@kernel.org>,
"Michal Koutný" <mkoutny@suse.com>,
"Andrew Morton" <akpm@linux-foundation.org>,
cgroups@vger.kernel.org, linux-mm@kvack.org,
linux-kernel@vger.kernel.org,
"Eric Dumazet" <edumazet@google.com>
Subject: Re: [PATCH] cgroup/rstat: avoid disabling irqs for O(num_cpu)
Date: Wed, 19 Mar 2025 15:46:10 -0400 [thread overview]
Message-ID: <20250319194610.GF1876369@cmpxchg.org> (raw)
In-Reply-To: <20250319191638.GD1876369@cmpxchg.org>
On Wed, Mar 19, 2025 at 03:16:42PM -0400, Johannes Weiner wrote:
> On Wed, Mar 19, 2025 at 06:35:02PM +0000, Yosry Ahmed wrote:
> > On Wed, Mar 19, 2025 at 02:06:43PM -0400, Johannes Weiner wrote:
> > > (btw, why do we not have any locking around the root stats in
> > > cgroup_base_stat_cputime_show()? There isn't anything preventing a
> > > reader from seeing all zeroes if another reader runs the memset() on
> > > cgrp->bstat, is there? Or double times...)
> >
> > (I think root_cgroup_cputime() operates on a stack allocated bstat, not
> > cgrp->bstat)
>
> That was the case until:
>
> commit b824766504e49f3fdcbb8c722e70996a78c3636e
> Author: Chen Ridong <chenridong@huawei.com>
> Date: Thu Jul 4 14:01:19 2024 +0000
Nevermind, Tejun pointed me to the follow-up fix he's got already
queued up:
https://web.git.kernel.org/pub/scm/linux/kernel/git/tj/cgroup.git/commit/?id=c4af66a95aa3bc1d4f607ebd4eea524fb58946e3
That brings it all back on the stack.
next prev parent reply other threads:[~2025-03-19 19:46 UTC|newest]
Thread overview: 24+ messages / expand[flat|nested] mbox.gz Atom feed top
2025-03-19 7:13 [PATCH] cgroup/rstat: avoid disabling irqs for O(num_cpu) Greg Thelen
2025-03-19 7:17 ` Greg Thelen
2025-03-19 10:20 ` Michal Koutný
2025-03-19 10:47 ` Mateusz Guzik
2025-03-19 17:18 ` Yosry Ahmed
2025-03-27 14:38 ` Mateusz Guzik
2025-03-27 17:17 ` Yosry Ahmed
2025-03-27 17:47 ` Mateusz Guzik
2025-04-01 15:00 ` Michal Koutný
2025-04-01 15:46 ` Mateusz Guzik
2025-04-01 16:59 ` Michal Koutný
2025-03-19 17:26 ` Tejun Heo
2025-03-26 23:57 ` Mateusz Guzik
2025-03-19 17:16 ` Yosry Ahmed
2025-03-19 18:06 ` Johannes Weiner
2025-03-19 18:35 ` Yosry Ahmed
2025-03-19 19:10 ` Tejun Heo
2025-03-19 19:16 ` Johannes Weiner
2025-03-19 19:46 ` Johannes Weiner [this message]
2025-03-19 17:26 ` Tejun Heo
2025-03-19 17:35 ` Johannes Weiner
2025-03-19 17:53 ` Shakeel Butt
2025-03-19 18:37 ` Eric Dumazet
2025-03-20 14:43 ` Greg Thelen
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