Subject: + mm-hwpoison-fix-race-against-poison-thp.patch added to -mm tree
To: liwanp@xxxxxxxxxxxxxxxxxx,andi@xxxxxxxxxxxxxx,n-horiguchi@xxxxxxxxxxxxx,tony.luck@xxxxxxxxx
From: akpm@xxxxxxxxxxxxxxxxxxxx
Date: Mon, 26 Aug 2013 14:42:39 -0700
The patch titled
Subject: mm/hwpoison: fix race against poison thp
has been added to the -mm tree. Its filename is
mm-hwpoison-fix-race-against-poison-thp.patch
This patch should soon appear at
http://ozlabs.org/~akpm/mmots/broken-out/mm-hwpoison-fix-race-against-poison-thp.patch
and later at
http://ozlabs.org/~akpm/mmotm/broken-out/mm-hwpoison-fix-race-against-poison-thp.patch
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From: Wanpeng Li <liwanp@xxxxxxxxxxxxxxxxxx>
Subject: mm/hwpoison: fix race against poison thp
There is a race between hwpoison page and unpoison page, memory_failure
set the page hwpoison and increase num_poisoned_pages without hold page
lock, and one page count will be accounted against thp for
num_poisoned_pages. However, unpoison can occur before memory_failure
hold page lock and split transparent hugepage, unpoison will decrease
num_poisoned_pages by 1 << compound_order since memory_failure has not yet
split transparent hugepage with page lock held. That means we account one
page for hwpoison and 1 << compound_order for unpoison. This patch fix it
by inserting a PageTransHuge check before doing TestClearPageHWPoison,
unpoison failed without clearing PageHWPoison and decreasing
num_poisoned_pages.
A B
memory_failue
TestSetPageHWPoison(p);
if (PageHuge(p))
nr_pages = 1 << compound_order(hpage);
else
nr_pages = 1;
atomic_long_add(nr_pages, &num_poisoned_pages);
unpoison_memory
nr_pages = 1<< compound_trans_order(page);
if(TestClearPageHWPoison(p))
atomic_long_sub(nr_pages, &num_poisoned_pages);
lock page
if (!PageHWPoison(p))
unlock page and return
hwpoison_user_mappings
if (PageTransHuge(hpage))
split_huge_page(hpage);
Signed-off-by: Wanpeng Li <liwanp@xxxxxxxxxxxxxxxxxx>
Suggested-by: Naoya Horiguchi <n-horiguchi@xxxxxxxxxxxxx>
Cc: Andi Kleen <andi@xxxxxxxxxxxxxx>
Cc: Tony Luck <tony.luck@xxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
mm/memory-failure.c | 10 ++++++++++
1 file changed, 10 insertions(+)
diff -puN mm/memory-failure.c~mm-hwpoison-fix-race-against-poison-thp mm/memory-failure.c
--- a/mm/memory-failure.c~mm-hwpoison-fix-race-against-poison-thp
+++ a/mm/memory-failure.c
@@ -1339,6 +1339,16 @@ int unpoison_memory(unsigned long pfn)
return 0;
}
+ /*
+ * unpoison_memory() can encounter thp only when the thp is being
+ * worked by memory_failure() and the page lock is not held yet.
+ * In such case, we yield to memory_failure() and make unpoison fail.
+ */
+ if (PageTransHuge(page)) {
+ pr_info("MCE: Memory failure is now running on %#lx\n", pfn);
+ return 0;
+ }
+
nr_pages = 1 << compound_order(page);
if (!get_page_unless_zero(page)) {
_
Patches currently in -mm which might be from liwanp@xxxxxxxxxxxxxxxxxx are
mm-zswapc-get-swapper-address_space-by-using-macro.patch
mm-fix-potential-null-pointer-dereference.patch
mm-hugetlb-move-up-the-code-which-check-availability-of-free-huge-page.patch
mm-hugetlb-trivial-commenting-fix.patch
mm-hugetlb-clean-up-alloc_huge_page.patch
mm-hugetlb-fix-and-clean-up-node-iteration-code-to-alloc-or-free.patch
mm-hugetlb-remove-redundant-list_empty-check-in-gather_surplus_pages.patch
mm-hugetlb-do-not-use-a-page-in-page-cache-for-cow-optimization.patch
mm-hugetlb-add-vm_noreserve-check-in-vma_has_reserves.patch
mm-hugetlb-remove-decrement_hugepage_resv_vma.patch
mm-hugetlb-decrement-reserve-count-if-vm_noreserve-alloc-page-cache.patch
mm-vmalloc-remove-useless-variable-in-vmap_block.patch
mm-vmalloc-use-well-defined-find_last_bit-func.patch
mm-hotplug-verify-hotplug-memory-range.patch
mm-hotplug-verify-hotplug-memory-range-fix.patch
mm-hotplug-remove-stop_machine-from-try_offline_node.patch
mm-hugetlb-protect-reserved-pages-when-soft-offlining-a-hugepage.patch
mm-hugetlb-change-variable-name-reservations-to-resv.patch
mm-hugetlb-fix-subpool-accounting-handling.patch
mm-hugetlb-remove-useless-check-about-mapping-type.patch
mm-hugetlb-grab-a-page_table_lock-after-page_cache_release.patch
mm-hugetlb-return-a-reserved-page-to-a-reserved-pool-if-failed.patch
mm-migrate-make-core-migration-code-aware-of-hugepage.patch
mm-soft-offline-use-migrate_pages-instead-of-migrate_huge_page.patch
migrate-add-hugepage-migration-code-to-migrate_pages.patch
mm-migrate-add-hugepage-migration-code-to-move_pages.patch
mm-mbind-add-hugepage-migration-code-to-mbind.patch
mm-migrate-remove-vm_hugetlb-from-vma-flag-check-in-vma_migratable.patch
mm-memory-hotplug-enable-memory-hotplug-to-handle-hugepage.patch
mm-migrate-check-movability-of-hugepage-in-unmap_and_move_huge_page.patch
mm-prepare-to-remove-proc-sys-vm-hugepages_treat_as_movable.patch
mm-prepare-to-remove-proc-sys-vm-hugepages_treat_as_movable-v2.patch
mm-mempolicy-rename-check_range-to-queue_pages_range.patch
mm-sparse-introduce-alloc_usemap_and_memmap.patch
mm-writeback-make-writeback_inodes_wb-static.patch
mm-vmalloc-use-wrapper-function-get_vm_area_size-to-caculate-size-of-vm-area.patch
hwpoison-always-unset-migrate_isolate-before-returning-from-soft_offline_page.patch
mm-hwpoison-fix-loss-of-pg_dirty-for-errors-on-mlocked-pages.patch
mm-hwpoison-dont-need-to-hold-compound-lock-for-hugetlbfs-page.patch
mm-hwpoison-fix-race-against-poison-thp.patch
mm-hwpoison-replace-atomic_long_sub-with-atomic_long_dec.patch
mm-hwpoison-dont-set-migration-type-twice-to-avoid-holding-heavily-contend-zone-lock.patch
mm-hwpoison-drop-forward-reference-declarations-__soft_offline_page.patch
mm-hwpoison-add-to-madvise_hwpoison.patch
mm-hwpoison-fix-memory-failure-still-holding-reference-count-after-unpoisoning-empty-zero-page.patch
linux-next.patch
mm-drop-actor-argument-of-do_generic_file_read.patch
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