Messages in this thread Patch in this message | | | Subject | [PATCH] COMPACTION: bugfix of improper cache flush in MIGRATION code. | From | Leonid Yegoshin <> | Date | Wed, 8 May 2013 17:18:21 -0700 |
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Page 'new' during MIGRATION can't be flushed by flush_cache_page(). Using flush_cache_page(vma, addr, pfn) is justified only if 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, kernel has a different page virtual address and dirtied it.
Replace it with flush_dcache_page(new) which is a proper usage.
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.
Author: Leonid Yegoshin <yegoshin@mips.com> Signed-off-by: Leonid Yegoshin <Leonid.Yegoshin@imgtec.com> --- mm/migrate.c | 2 +- 1 files changed, 1 insertions(+), 1 deletions(-)
diff --git a/mm/migrate.c b/mm/migrate.c index 2fd8b4a..4c6250a 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)) {
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