Re: [PATCH v2 3/3] NFS: Fix a memory leak in nfs_readdir

[Rik van Riel]

On 12/01/2010 11:47 AM, Linus Torvalds wrote:
> On Wed, Dec 1, 2010 at 8:35 AM, Rik van Riel<riel@xxxxxxxxxx>  wrote:
> > Surely somebody can have just looked up the page and
> > gotten a reference count, right before your ->freepage
> > call is invoked?
>
> No.
>
> The removal from the page cache is atomic, even in the presence of the
> lockless lookup.
>
> The page cache lookup does a "get_page_unless_zero()" on the count, so
> when __remove_mapping() has removed the page using
> "page_freeze_refs()", it's really gone, and cannot be looked up.

Doh, you're right.  I forgot to look at all the stuff that
__remove_mapping does nowadays and remembered some very old
code from vmscan.c instead.

Acked-by: Rik van Riel <riel@xxxxxxxxxx>

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