From: Andrew Morton <akpm@zip.com.au>
To: Daniel Phillips <phillips@arcor.de>
Cc: Marcelo Tosatti <marcelo@conectiva.com.br>, linux-kernel@vger.kernel.org
Subject: Re: Race in shrink_cache
Date: Wed, 04 Sep 2002 23:36:20 -0700 [thread overview]
Message-ID: <3D76FB64.7AAB215F@zip.com.au> (raw)
In-Reply-To: <E17mooe-00064m-00@starship>
Daniel Phillips wrote:
>
> Hi Marcelo,
>
> This looks really suspicious, vmscan.c#435:
>
> spin_unlock(&pagemap_lru_lock);
> if (put_page_testzero(page))
> __free_pages_ok(page, 0);
> /* avoid to free a locked page */
> page_cache_get(page);
>
> /* whoops, double free coming */
>
> I suggest you bump the page count before releasing the lru lock. The race
> shown above may not in fact be possible, but the current code is fragile.
>
That's OK. The page has a ref because of nonzero ->buffers And it
is locked, which pins page->buffers.
next prev parent reply other threads:[~2002-09-05 6:19 UTC|newest]
Thread overview: 12+ messages / expand[flat|nested] mbox.gz Atom feed top
2002-09-05 5:04 Daniel Phillips
2002-09-05 6:36 ` Andrew Morton [this message]
2002-09-05 6:36 ` Daniel Phillips
2002-09-05 7:07 ` Andrew Morton
2002-09-05 7:28 ` Daniel Phillips
2002-09-05 7:53 ` Andrew Morton
2002-09-05 18:41 ` Daniel Phillips
2002-09-05 18:51 ` Andrew Morton
2002-09-05 19:08 ` Daniel Phillips
2002-09-05 19:22 ` Andrew Morton
2002-09-05 20:00 ` Daniel Phillips
2002-09-05 13:33 ` Rik van Riel
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