linux-kernel - Re: [PATCH v3] 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] [day] [month] [year] [list]

Message-ID: <6d436d56-20f7-4106-bedc-e9d146427fa9@amd.com>
Date: Fri, 7 Feb 2025 08:14:10 +0530
From: K Prateek Nayak <kprateek.nayak@....com>
To: Valentin Schneider <vschneid@...hat.com>, Peter Zijlstra
	<peterz@...radead.org>
CC: Naman Jain <namjain@...ux.microsoft.com>, Ingo Molnar <mingo@...hat.com>,
	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>, <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>, Michael
 Kelley <mhklinux@...look.com>
Subject: Re: [PATCH v3] sched/topology: Enable topology_span_sane check only
 for debug builds

Hello Valentin,

On 2/6/2025 8:54 PM, Valentin Schneider wrote:
> [..snip..]
>> So circling back to my original question around "SDTL_ARCH_VERIFIED",
>> would folks be okay to an early bailout from topology_span_sane() on:
>>
>>       if (!sched_debug() && (tl->flags & SDTL_ARCH_VERIFIED))
>>        return;
>>
>> and more importantly, do folks care enough about topology_span_sane()
>> to have it run on other architectures and not just have it guarded
>> behind just "sched_debug()" which starts off as false by default?
>>
> 
> If/when possible I prefer to have sanity checks run unconditionally, as
> long as they don't noticeably impact runtime. Unfortunately this does show
> up in the boot time, though Steve had a promising improvement for that.
> 
> Anyway, if someone gets one of those hangs on a
> 
>    do { } while (group != sd->groups)
> 
> they'll quickly turn on sched_verbose (or be told to) and the sanity check
> will holler at them, so I'm not entirely against it.

If you're game, I'm too!

I just put it out there in case folks had any strong feelings against
this on other arch but that doesn't seem to be the case and we all love
a simple solution :)

> 
>> (Sorry for the long answer explaining my thought process.)
>>
>>>
>>> That I can't remember, sorry :/
>>
>> --
>> Thanks and Regards,
>> Prateek
> 

-- 
Thanks and Regards,
Prateek