From: Oleg Nesterov <oleg@redhat.com>
To: Vasiliy Kulikov <segoon@openwall.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>,
Andrew Morton <akpm@linux-foundation.org>,
Manuel Lauss <manuel.lauss@googlemail.com>,
Richard Weinberger <richard@nod.at>,
Marc Zyngier <marc.zyngier@arm.com>,
linux-kernel@vger.kernel.org
Subject: Re: [PATCH] shm: optimize exit_shm()
Date: Wed, 3 Aug 2011 21:39:06 +0200 [thread overview]
Message-ID: <20110803193906.GA2921@redhat.com> (raw)
In-Reply-To: <20110803193457.GA6734@albatros>
On 08/03, Vasiliy Kulikov wrote:
>
> On Wed, Aug 03, 2011 at 21:21 +0200, Oleg Nesterov wrote:
> > > we should check .in_use once again after
> > > down_write().
> >
> > Why?
>
> https://lkml.org/lkml/2011/8/3/277
>
> "No, as I said in the comment above, other task may be holding the mutex and
> deleting the last shm segment.
This is obvious,
> "Should" == additional check might speed the things, so it worth checking.
and this is not.
I was confused, the changelog looks as if we _have to_ recheck
or something bad can happen.
But as I said, the patch looks correct anyway. I am not
sure the 2nd optimization really makes sense (this is very
unlikely case) but it doesn't hurt.
Oleg.
next prev parent reply other threads:[~2011-08-03 19:42 UTC|newest]
Thread overview: 13+ messages / expand[flat|nested] mbox.gz Atom feed top
2011-08-03 14:04 + shm-fix-a-race-between-shm_exit-and-shm_init.patch added to -mm tree Oleg Nesterov
2011-08-03 18:24 ` Vasiliy Kulikov
2011-08-03 18:26 ` [PATCH] shm: fix wrong tests Vasiliy Kulikov
2011-08-03 18:28 ` [PATCH] shm: optimize exit_shm() Vasiliy Kulikov
2011-08-03 19:08 ` Manuel Lauss
2011-08-03 19:16 ` Vasiliy Kulikov
2011-08-03 19:29 ` Oleg Nesterov
2011-08-03 19:41 ` Vasiliy Kulikov
2011-08-03 19:43 ` Oleg Nesterov
2011-08-03 19:21 ` Oleg Nesterov
2011-08-03 19:34 ` Vasiliy Kulikov
2011-08-03 19:39 ` Oleg Nesterov [this message]
2011-08-03 19:18 ` + shm-fix-a-race-between-shm_exit-and-shm_init.patch added to -mm tree Oleg Nesterov
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