Commit c2cc499c authored by Leonid Yegoshin's avatar Leonid Yegoshin Committed by Linus Torvalds
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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
Signed-off-by: default avatarLeonid Yegoshin <>
Cc: Leonid Yegoshin <>
Acked-by: default avatarRik van Riel <>
Cc: Michal Hocko <>
Acked-by: default avatarMel Gorman <>
Cc: Ralf Baechle <>
Cc: Russell King <>
Cc: David Miller <>
Cc: <>
Signed-off-by: default avatarAndrew Morton <>
Signed-off-by: default avatarLinus Torvalds <>
parent 1ccc819d
......@@ -165,7 +165,7 @@ static int remove_migration_pte(struct page *new, struct vm_area_struct *vma,
pte = arch_make_huge_pte(pte, vma, new, 0);
flush_cache_page(vma, addr, pte_pfn(pte));
set_pte_at(mm, addr, ptep, pte);
if (PageHuge(new)) {
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