linux-kernel - Re: [PATCH v4] sched/topology: Enable topology_span

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <xhsmhwmd2ds0o.mognet@vschneid-thinkpadt14sgen2i.remote.csb>
Date: Thu, 06 Mar 2025 17:48:39 +0100
From: Valentin Schneider <vschneid@...hat.com>
To: Naman Jain <namjain@...ux.microsoft.com>, Ingo Molnar
 <mingo@...hat.com>, Peter Zijlstra <peterz@...radead.org>, Juri Lelli
 <juri.lelli@...hat.com>, Vincent Guittot <vincent.guittot@...aro.org>,
 Dietmar Eggemann <dietmar.eggemann@....com>, Steven Rostedt
 <rostedt@...dmis.org>, Ben Segall <bsegall@...gle.com>, Mel Gorman
 <mgorman@...e.de>
Cc: stable@...r.kernel.org, linux-kernel@...r.kernel.org, Steve Wahl
 <steve.wahl@....com>, Saurabh Singh Sengar <ssengar@...ux.microsoft.com>,
 srivatsa@...il.mit.edu, K Prateek Nayak <kprateek.nayak@....com>, Michael
 Kelley <mhklinux@...look.com>, Naman Jain <namjain@...ux.microsoft.com>,
 Shrikanth Hegde <sshegde@...ux.ibm.com>
Subject: Re: [PATCH v4] sched/topology: Enable topology_span_sane check only
 for debug builds

On 06/03/25 11:23, Naman Jain wrote:
> diff --git a/kernel/sched/topology.c b/kernel/sched/topology.c
> index c49aea8c1025..666f0a18cc6c 100644
> --- a/kernel/sched/topology.c
> +++ b/kernel/sched/topology.c
> @@ -2359,6 +2359,13 @@ static bool topology_span_sane(struct sched_domain_topology_level *tl,
>  {
>       int i = cpu + 1;
>
> +	/* Skip the topology sanity check for non-debug, as it is a time-consuming operation */
> +	if (!sched_debug()) {
> +		pr_info_once("%s: Skipping topology span sanity check. Use `sched_verbose` boot parameter to enable it.\n",
> +			     __func__);

FWIW I'm not against this change, however if you want to add messaging
about sched_verbose I'd put that in e.g. sched_domain_debug() (as a print
once like you've done here) with something along the lines of:

  "Scheduler topology debugging disabled, add 'sched_verbose' to the cmdline to enable it"

> +		return true;
> +	}
> +
>       /* NUMA levels are allowed to overlap */
>       if (tl->flags & SDTL_OVERLAP)
>               return true;
> --
> 2.34.1