Messages in this thread | | | Date | Tue, 01 Feb 2011 11:48:20 -0500 | From | Rik van Riel <> | Subject | Re: [PATCH 1/2] Allow GUP to fail instead of waiting on a page. |
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On 02/01/2011 06:21 AM, Gleb Natapov wrote: > GUP user may want to try to acquire a reference to a page if it is already > in memory, but not if IO, to bring it in, is needed. For example KVM may > tell vcpu to schedule another guest process if current one is trying to > access swapped out page. Meanwhile, the page will be swapped in and the > guest process, that depends on it, will be able to run again. > > This patch adds FAULT_FLAG_RETRY_NOWAIT (suggested by Linus) and > FOLL_NOWAIT follow_page flags. FAULT_FLAG_RETRY_NOWAIT, when used in > conjunction with VM_FAULT_ALLOW_RETRY, indicates to handle_mm_fault that > it shouldn't drop mmap_sem and wait on a page, but return VM_FAULT_RETRY > instead. > > Signed-off-by: Gleb Natapov<gleb@redhat.com> > CC: Linus Torvalds<torvalds@linux-foundation.org> > CC: Rik van Riel<riel@redhat.com> > CC: Hugh Dickins<hughd@google.com> > CC: Andrew Morton<akpm@linux-foundation.org>
Acked-by: Rik van Riel <riel@redhat.com>
-- All rights reversed
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