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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 05:17:16 -0700	[thread overview]
Message-ID: <Z/UTzPoI7+LElhEE@gmail.com> (raw)
In-Reply-To: <Z_UI2AHtkIGS4bZR@gpd3>

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.

Thanks for the review,
--breno

  reply	other threads:[~2025-04-08 12:17 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 [this message]
2025-04-08 13:12     ` Andrea Righi
2025-04-08 13:40       ` Breno Leitao

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