linux-kernel - Re: [PATCH] sched: Fix migration_cpu

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 for Android: free password hash cracker in your pocket

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

Message-Id: <5962011401880725@web26h.yandex.ru>
Date:	Wed, 04 Jun 2014 15:18:45 +0400
From:	Kirill Tkhai <tkhai@...dex.ru>
To:	Peter Zijlstra <peterz@...radead.org>,
	"riel@...hat.com" <riel@...hat.com>,
	"laijs@...fujitsu.com" <laijs@...fujitsu.com>
Cc:	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	"mingo@...nel.org" <mingo@...nel.org>
Subject: Re: [PATCH] sched: Fix migration_cpu_stop() return value

Hi, Peter,

04.06.2014, 14:41, "Peter Zijlstra" <peterz@...radead.org>:
>  A while ago I did a similar patch for some debugging, but looking at it
>  again today I realized we should probably fix this anyway.
>
>  ---
>  Subject: sched: Fix migration_cpu_stop() return value
>
>  There are a number of migration_cpu_stop() users; and some actually care
>  about the success of the migration. So report this.
>
>  In particular migrate_task_to() as used from task_numa_migrate()
>  actually tests this return value.
>
>  Also change set_cpus_allowed_ptr() to propagate this return value, since
>  it already returns other errors.
>
>  Cc: Lai Jiangshan <laijs@...fujitsu.com>
>  Cc: Ingo Molnar <mingo@...hat.com>
>  Signed-off-by: Peter Zijlstra <peterz@...radead.org>
>  ---
>   kernel/sched/core.c |   15 +++++++++++----
>   1 file changed, 11 insertions(+), 4 deletions(-)
(snipped everything because of bad email editor)

In set_cpus_allowed_ptr() p->on_rq branch can not fail.

We've changed affinity and released rq's lock, so task can migrate
on allowed cpu only (even if migration_cpu_stop fails).

And it's a little ambiguously how user should react on this EAGAIN.

Regards,
Kirill.
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/