From 9ae47aa6db989e462944e931d31a1c6e66fe5385 Mon Sep 17 00:00:00 2001 From: Leonid Yegoshin Date: Fri, 10 May 2013 09:57:03 +1000 Subject: [PATCH] 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 Cc: Leonid Yegoshin Cc: Rik van Riel Cc: Michal Hocko Cc: Mel Gorman Cc: Ralf Baechle Cc: Russell King Cc: David Miller Cc: Signed-off-by: Andrew Morton --- mm/migrate.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/mm/migrate.c b/mm/migrate.c index 27ed22579fd9..b1f57501de9c 100644 --- a/mm/migrate.c +++ b/mm/migrate.c @@ -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); } #endif - flush_cache_page(vma, addr, pte_pfn(pte)); + flush_dcache_page(new); set_pte_at(mm, addr, ptep, pte); if (PageHuge(new)) { -- 2.39.5