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authorMel Gorman <mgorman@suse.de>2013-10-07 11:28:46 +0100
committerIngo Molnar <mingo@kernel.org>2013-10-29 11:38:05 +0100
commit3f926ab945b60a5824369d21add7710622a2eac0 (patch)
treec3098df81f687abec56d42d864a07c214ff7f017 /mm/mprotect.c
parentc61109e34f60f6e85bb43c5a1cd51c0e3db40847 (diff)
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mm: Close races between THP migration and PMD numa clearing
THP migration uses the page lock to guard against parallel allocations but there are cases like this still open Task A Task B --------------------- --------------------- do_huge_pmd_numa_page do_huge_pmd_numa_page lock_page mpol_misplaced == -1 unlock_page goto clear_pmdnuma lock_page mpol_misplaced == 2 migrate_misplaced_transhuge pmd = pmd_mknonnuma set_pmd_at During hours of testing, one crashed with weird errors and while I have no direct evidence, I suspect something like the race above happened. This patch extends the page lock to being held until the pmd_numa is cleared to prevent migration starting in parallel while the pmd_numa is being cleared. It also flushes the old pmd entry and orders pagetable insertion before rmap insertion. Signed-off-by: Mel Gorman <mgorman@suse.de> Reviewed-by: Rik van Riel <riel@redhat.com> Cc: Andrea Arcangeli <aarcange@redhat.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Srikar Dronamraju <srikar@linux.vnet.ibm.com> Cc: <stable@kernel.org> Signed-off-by: Peter Zijlstra <peterz@infradead.org> Link: http://lkml.kernel.org/r/1381141781-10992-9-git-send-email-mgorman@suse.de Signed-off-by: Ingo Molnar <mingo@kernel.org>
Diffstat (limited to 'mm/mprotect.c')
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