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4e31635c36
Building under memory pressure, with KSM on 2.6.36-rc5, collapsed with an internal compiler error: typically indicating an error in swapping. Perhaps there's a timing issue which makes it now more likely, perhaps it's just a long time since I tried for so long: this bug goes back to KSM swapping in 2.6.33. Notice how reuse_swap_page() allows an exclusive page to be reused, but only does SetPageDirty if it can delete it from swap cache right then - if it's currently under Writeback, it has to be left in cache and we don't SetPageDirty, but the page can be reused. Fine, the dirty bit will get set in the pte; but notice how zap_pte_range() does not bother to transfer pte_dirty to page_dirty when unmapping a PageAnon. If KSM chooses to share such a page, it will look like a clean copy of swapcache, and not be written out to swap when its memory is needed; then stale data read back from swap when it's needed again. We could fix this in reuse_swap_page() (or even refuse to reuse a page under writeback), but it's more honest to fix my oversight in KSM's write_protect_page(). Several days of testing on three machines confirms that this fixes the issue they showed. Signed-off-by: Hugh Dickins <hughd@google.com> Cc: Andrew Morton <akpm@linux-foundation.org> Cc: Andrea Arcangeli <aarcange@redhat.com> Cc: stable@kernel.org Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> |
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| .. | ||
| backing-dev.c | ||
| bootmem.c | ||
| bounce.c | ||
| compaction.c | ||
| debug-pagealloc.c | ||
| dmapool.c | ||
| fadvise.c | ||
| failslab.c | ||
| filemap_xip.c | ||
| filemap.c | ||
| fremap.c | ||
| highmem.c | ||
| hugetlb.c | ||
| hwpoison-inject.c | ||
| init-mm.c | ||
| internal.h | ||
| Kconfig | ||
| Kconfig.debug | ||
| kmemcheck.c | ||
| kmemleak-test.c | ||
| kmemleak.c | ||
| ksm.c | ||
| maccess.c | ||
| madvise.c | ||
| Makefile | ||
| memblock.c | ||
| memcontrol.c | ||
| memory_hotplug.c | ||
| memory-failure.c | ||
| memory.c | ||
| mempolicy.c | ||
| mempool.c | ||
| migrate.c | ||
| mincore.c | ||
| mlock.c | ||
| mm_init.c | ||
| mmap.c | ||
| mmu_context.c | ||
| mmu_notifier.c | ||
| mmzone.c | ||
| mprotect.c | ||
| mremap.c | ||
| msync.c | ||
| nommu.c | ||
| oom_kill.c | ||
| page_alloc.c | ||
| page_cgroup.c | ||
| page_io.c | ||
| page_isolation.c | ||
| page-writeback.c | ||
| pagewalk.c | ||
| percpu_up.c | ||
| percpu-km.c | ||
| percpu-vm.c | ||
| percpu.c | ||
| prio_tree.c | ||
| quicklist.c | ||
| readahead.c | ||
| rmap.c | ||
| shmem.c | ||
| slab.c | ||
| slob.c | ||
| slub.c | ||
| sparse-vmemmap.c | ||
| sparse.c | ||
| swap_state.c | ||
| swap.c | ||
| swapfile.c | ||
| thrash.c | ||
| truncate.c | ||
| util.c | ||
| vmalloc.c | ||
| vmscan.c | ||
| vmstat.c | ||