linux-kernel - Re: [PATCH v2] mm: correctly synchronize rss-counters at exit/exec

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: <20120410191059.GA5678@redhat.com>
Date:	Tue, 10 Apr 2012 21:10:59 +0200
From:	Oleg Nesterov <oleg@...hat.com>
To:	Konstantin Khlebnikov <khlebnikov@...nvz.org>
Cc:	Andrew Morton <akpm@...ux-foundation.org>,
	Hugh Dickins <hughd@...gle.com>, linux-kernel@...r.kernel.org,
	linux-mm@...ck.org, Markus Trippelsdorf <markus@...ppelsdorf.de>,
	KAMEZAWA Hiroyuki <kamezawa.hiroyu@...fujitsu.com>
Subject: Re: [PATCH v2] mm: correctly synchronize rss-counters at exit/exec

On 04/10, Konstantin Khlebnikov wrote:
>
> This patch moves sync_mm_rss() into mm_release(), and moves mm_release() out of
> do_exit() and calls it earlier. After mm_release() there should be no page-faults.

Can't prove, but I feel there should be a simpler fix...

Anyway, this patch is not exactly correct.

> @@ -959,9 +959,10 @@ void do_exit(long code)
>  				preempt_count());
>
>  	acct_update_integrals(tsk);
> -	/* sync mm's RSS info before statistics gathering */
> -	if (tsk->mm)
> -		sync_mm_rss(tsk->mm);
> +
> +	/* Release mm and sync mm's RSS info before statistics gathering */
> +	mm_release(tsk, tsk->mm);

This breaks kthread_stop() at least.

The exiting kthread shouldn't do complete_vfork_done() until it
sets ->exit_code.

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/