From: Leonid Yegoshin <Leonid.Yegoshin@xxxxxxxxxx>
Subject: mm compaction: fix of improper cache flush in migration code
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@xxxxxxxxxx>
Cc: Leonid Yegoshin <yegoshin@xxxxxxxx>
Acked-by: Rik van Riel <riel@xxxxxxxxxx>
Cc: Michal Hocko <mhocko@xxxxxxx>
Acked-by: Mel Gorman <mgorman@xxxxxxx>
Cc: Ralf Baechle <ralf@xxxxxxxxxxxxxx>
Cc: Russell King <rmk@xxxxxxxxxxxxxxxx>
Cc: David Miller <davem@xxxxxxxxxxxxx>
Cc: <stable@xxxxxxxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
mm/migrate.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff -puN mm/migrate.c~mm-compaction-fix-of-improper-cache-flush-in-migration-code mm/migrate.c
--- a/mm/migrate.c~mm-compaction-fix-of-improper-cache-flush-in-migration-code
+++ a/mm/migrate.c
@@ -165,7 +165,7 @@ static int remove_migration_pte(struct p
pte = arch_make_huge_pte(pte, vma, new, 0);
}
#endif
- flush_cache_page(vma, addr, pte_pfn(pte));
+ flush_dcache_page(new);
set_pte_at(mm, addr, ptep, pte);
if (PageHuge(new)) {
_
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