| Date | Thu, 18 Nov 2010 17:13:39 +0000 | From | Mel Gorman <> | Subject | Re: [PATCH 02 of 66] mm, migration: Fix race between shift_arg_pages and rmap_walk by guaranteeing rmap_walk finds PTEs created within the temporary stack |
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On Thu, Nov 18, 2010 at 11:13:49AM +0000, Mel Gorman wrote: > > This patch fixes the problem by using two VMAs - one which covers the temporary > > stack and the other which covers the new location. This guarantees that rmap > > can always find the migration PTE even if it is copied while rmap_walk is > > taking place. > > > > Signed-off-by: Andrea Arcangeli <aarcange@redhat.com> > > This old chestnut. IIRC, this was the more complete solution to a fix that made > it into mainline. The patch still looks reasonable. It does add a kmalloc() > but I can't remember if we decided we were ok with it or not. Can you remind > me? More importantly, it appears to be surviving the original testcase that > this bug was about (20 minutes so far but will leave it a few hours). Assuming > the test does not crash; >
Incidentally, after 6.5 hours this still hasn't crashed. Previously a worst case reproduction scenario for the bug was around 35 minutes.
-- Mel Gorman Part-time Phd Student Linux Technology Center University of Limerick IBM Dublin Software Lab
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