From: Andi Kleen <ak@suse.de>
To: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Cc: Andrew Morton <akpm@osdl.org>,
ebiederm@xmission.com, pj@sgi.com,
saito.tadashi@soft.fujitsu.com, linux-kernel@vger.kernel.org
Subject: Re: [RFC][PATCH] ps command race fix take2 [4/4] proc_pid_readdir
Date: 22 Aug 2006 13:11:30 +0200 [thread overview]
Message-ID: <p733bbp81p9.fsf@verdi.suse.de> (raw)
In-Reply-To: <20060822174302.e97f23d1.kamezawa.hiroyu@jp.fujitsu.com>
KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> writes:
> proc_pid_readdir() by list_token.
>
> Remember 'where we are reading' by inserting a token in the list.
> It seems a bit complicated because of RCU but what we do is very simple.
>
What happens when you have multiple readers at the same time? Can't
the tokens then be mixed up?
>+ /* this small kmalloc() can fail in rare case, but readdir()
>+ * is not allowed to return ENOMEM. retrying is reasonable. */
Who disallows this? Such retry loops are normally discouraged
because they can lead to deadlocks in OOM situations.
I think it would be better to just return ENOMEM.
-Andi
next prev parent reply other threads:[~2006-08-22 11:11 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2006-08-22 8:43 [RFC][PATCH] ps command race fix take2 [4/4] proc_pid_readdir KAMEZAWA Hiroyuki
2006-08-22 9:38 ` KAMEZAWA Hiroyuki
2006-08-22 11:11 ` Andi Kleen [this message]
2006-08-22 11:39 ` KAMEZAWA Hiroyuki
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