From: Oleg Nesterov <oleg@redhat.com>
To: Andrew Morton <akpm@linux-foundation.org>
Cc: Zhen Ni <zhen.ni@easystack.cn>,
viro@zeniv.linux.org.uk, catalin.marinas@arm.com,
brauner@kernel.org, zev@bewilderbeest.net,
linux-kernel@vger.kernel.org,
linux-security-module@vger.kernel.org
Subject: Re: [PATCH] kernel/sys: Optimize do_prlimit lock scope to reduce contention
Date: Thu, 28 Nov 2024 09:08:11 +0100 [thread overview]
Message-ID: <20241128080811.GC10998@redhat.com> (raw)
In-Reply-To: <20241128073911.GB10998@redhat.com>
On 11/28, Oleg Nesterov wrote:
>
> On 11/28, Oleg Nesterov wrote:
> >
> > The problem is that task_lock(tsk->group_leader) doesn't look right with or
> > without this patch. I'll try to make a fix on weekend.
> >
> > If the caller is sys_prlimit64() and tsk != current, then ->group_leader is
> > not stable, do_prlimit() can race with mt exec and take the wrong lock.
>
> ... and task_unlock(tsk->group_leader) is simply unsafe.
>
> perhaps something like below,
No, this is wrong too,
> I'll try to think more.
Yes...
Oleg.
prev parent reply other threads:[~2024-11-28 8:08 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <20241120132156.207250-1-zhen.ni@easystack.cn>
2024-11-28 1:45 ` [PATCH] kernel/sys: Optimize do_prlimit lock scope to reduce contention Andrew Morton
2024-11-28 7:13 ` Oleg Nesterov
2024-11-28 7:39 ` Oleg Nesterov
2024-11-28 8:08 ` Oleg Nesterov [this message]
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