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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