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Date: Sat, 23 Aug 2014 15:30:01 +0200 From: Oleg Nesterov <oleg@...hat.com> To: Cyrill Gorcunov <gorcunov@...il.com> Cc: Kees Cook <keescook@...omium.org>, Tejun Heo <tj@...nel.org>, Andrew Vagin <avagin@...nvz.org>, "Eric W. Biederman" <ebiederm@...ssion.com>, "H. Peter Anvin" <hpa@...or.com>, Serge Hallyn <serge.hallyn@...onical.com>, Pavel Emelyanov <xemul@...allels.com>, Vasiliy Kulikov <segoon@...nwall.com>, KAMEZAWA Hiroyuki <kamezawa.hiroyu@...fujitsu.com>, Michael Kerrisk <mtk.manpages@...il.com>, Julien Tinnes <jln@...gle.com>, Andrew Morton <akpm@...ux-foundation.org>, linux-kernel@...r.kernel.org Subject: Re: + prctl-pr_set_mm-introduce-pr_set_mm_map-operation-v3.patch added to -mm tree forgot to mention, On 08/23, Oleg Nesterov wrote: > > On 08/23, Cyrill Gorcunov wrote: > > > Looks like I need > > to use cred_guard_mutex instead of task_lock here, no? > > Please don't. First of all, it can't help because proc_pid_auxv() doesn't hold > this lock. It does mm_access() which drops this lock after return. And to remind, > we are going to remove mm_access/lock_trace from sys_read() paths in proc. Besides, it can't help anyway. cred_guard_mutex is per-process (not per-thread), suppose that a vfork()'ed child does prctl() while another thread reads the parent's /proc/pid/auxv. Cyrill, I am sorry, but I am starting to think that this patch should be dropped and replaced by another version. Or do you think it would be better to send the fixes on top? Oleg. -- 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/
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