[026/141] mm compaction: fix of improper cache flush in migration code

Steven Rostedt
2013-07-03T18:52:38Z

[-- Attachment #1: 0026-mm-compaction-fix-of-improper-cache-flush-in-migrati.patch --]
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3.6.11.6 stable review patch.
If anyone has any objections, please let me know.

------------------

From: Leonid Yegoshin <Leonid.Yegoshin@imgtec.com>

[ Upstream commit c2cc499c5bcf9040a738f49e8051b42078205748 ]

Page 'new' during MIGRATION can't be flushed with flush_cache_page().
Using flush_cache_page(vma, addr, pfn) is justified only if the page is
already placed in process page table, and that is done right after
flush_cache_page(). But without it the arch function has no knowledge
of process PTE and does nothing.

Besides that, flush_cache_page() flushes an application cache page, but
the kernel has a different page virtual address and dirtied it.

Replace it with flush_dcache_page(new) which is the proper usage.

The old page is flushed in try_to_unmap_one() before migration.

This bug takes place in Sead3 board with M14Kc MIPS CPU without cache
aliasing (but Harvard arch - separate I and D cache) in tight memory
environment (128MB) each 1-3days on SOAK test. It fails in cc1 during
kernel build (SIGILL, SIGBUS, SIGSEG) if CONFIG_COMPACTION is switched
ON.

Signed-off-by: Leonid Yegoshin <Leonid.Yegoshin@imgtec.com>
Cc: Leonid Yegoshin <yegoshin@mips.com>
Acked-by: Rik van Riel <riel@redhat.com>
Cc: Michal Hocko <mhocko@suse.cz>
Acked-by: Mel Gorman <mgorman@suse.de>
Cc: Ralf Baechle <ralf@linux-mips.org>
Cc: Russell King <rmk@arm.linux.org.uk>
Cc: David Miller <davem@davemloft.net>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
---
mm/migrate.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/mm/migrate.c b/mm/migrate.c
index 77ed2d7..a303524 100644
--- a/mm/migrate.c
+++ b/mm/migrate.c
@@ -146,7 +146,7 @@ static int remove_migration_pte(struct page *new, struct vm_area_struct *vma,
if (PageHuge(new))
pte = pte_mkhuge(pte);
#endif
- flush_cache_page(vma, addr, pte_pfn(pte));
+ flush_dcache_page(new);
set_pte_at(mm, addr, ptep, pte);

if (PageHuge(new)) {
--
1.7.10.4