From: Breno Leitao <leitao@debian.org>
To: Andrea Righi <arighi@nvidia.com>
Cc: Tejun Heo <tj@kernel.org>, David Vernet <void@manifault.com>,
Changwoo Min <changwoo@igalia.com>,
Ingo Molnar <mingo@redhat.com>,
Peter Zijlstra <peterz@infradead.org>,
Juri Lelli <juri.lelli@redhat.com>,
Vincent Guittot <vincent.guittot@linaro.org>,
Dietmar Eggemann <dietmar.eggemann@arm.com>,
Steven Rostedt <rostedt@goodmis.org>,
Ben Segall <bsegall@google.com>, Mel Gorman <mgorman@suse.de>,
Valentin Schneider <vschneid@redhat.com>,
linux-kernel@vger.kernel.org, christophe.jaillet@wanadoo.fr,
kernel-team@meta.com, stable@vger.kernel.org,
Rik van Riel <riel@surriel.com>
Subject: Re: [PATCH v2] sched_ext: Use kvzalloc for large exit_dump allocation
Date: Tue, 8 Apr 2025 06:40:42 -0700 [thread overview]
Message-ID: <Z/UnWnvmUVy8jilG@gmail.com> (raw)
In-Reply-To: <Z_Ugy6NDFBscP9Ef@gpd3>
On Tue, Apr 08, 2025 at 03:12:43PM +0200, Andrea Righi wrote:
> On Tue, Apr 08, 2025 at 05:17:16AM -0700, Breno Leitao wrote:
> > Hello Andrea,
> >
> > On Tue, Apr 08, 2025 at 01:30:32PM +0200, Andrea Righi wrote:
> > > Hi Breno,
> > >
> > > I already acked even the buggy version, so this one looks good. :)
> > >
> > > On Tue, Apr 08, 2025 at 04:09:02AM -0700, Breno Leitao wrote:
> > > > Replace kzalloc with kvzalloc for the exit_dump buffer allocation, which
> > > > can require large contiguous memory (up to order=9) depending on the
> > >
> > > BTW, from where this order=9 is coming from? exit_dump_len is 32K by
> > > default, but a BPF scheduler can arbitrarily set it to any value via
> > > ops->exit_dump_len, so it could be even bigger than an order 9 allocation.
> >
> > You are absolutely correct, this allocation could be of any size.
> >
> > I've got this problem because I was monitoring the Meta fleet, and saw
> > a bunch of allocation failures and decided to investigate. In this case
> > specifically, the users were using order=9 (512 pages), but, again, this
> > could be even bigger.
>
> I see, makes sense. Maybe we can rephrase this part to not mention the
> order=9 allocation and avoid potential confusion.
Sure! I will send a v3 later today, then.
prev parent reply other threads:[~2025-04-08 13:40 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2025-04-08 11:09 [PATCH v2] sched_ext: Use kvzalloc for large exit_dump allocation Breno Leitao
2025-04-08 11:30 ` Andrea Righi
2025-04-08 12:17 ` Breno Leitao
2025-04-08 13:12 ` Andrea Righi
2025-04-08 13:40 ` Breno Leitao [this message]
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