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authorNaoya Horiguchi <n-horiguchi@ah.jp.nec.com>2015-08-06 15:47:04 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2015-08-07 04:39:41 +0300
commit98ed2b0052e68420f1bad6c81e3f2600d25023e7 (patch)
tree6cd4c68bc6b5ff247305b802d402113df3d494ff /mm/memory-failure.c
parenta209ef09af0dc921311d0cc4a1d4f926321d91b8 (diff)
downloadlinux-stericsson-98ed2b0052e68420f1bad6c81e3f2600d25023e7.tar.gz
mm/memory-failure: give up error handling for non-tail-refcounted thp
"non anonymous thp" case is still racy with freeing thp, which causes panic due to put_page() for refcount-0 page. It seems that closing up this race might be hard (and/or not worth doing,) so let's give up the error handling for this case. Signed-off-by: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com> Cc: Andi Kleen <andi@firstfloor.org> Cc: Dean Nelson <dnelson@redhat.com> Cc: Tony Luck <tony.luck@intel.com> Cc: "Kirill A. Shutemov" <kirill@shutemov.name> Cc: Hugh Dickins <hughd@google.com> Cc: David Rientjes <rientjes@google.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'mm/memory-failure.c')
-rw-r--r--mm/memory-failure.c21
1 files changed, 12 insertions, 9 deletions
diff --git a/mm/memory-failure.c b/mm/memory-failure.c
index f72d2fad0b90..cd985530f102 100644
--- a/mm/memory-failure.c
+++ b/mm/memory-failure.c
@@ -909,6 +909,18 @@ int get_hwpoison_page(struct page *page)
* directly for tail pages.
*/
if (PageTransHuge(head)) {
+ /*
+ * Non anonymous thp exists only in allocation/free time. We
+ * can't handle such a case correctly, so let's give it up.
+ * This should be better than triggering BUG_ON when kernel
+ * tries to touch the "partially handled" page.
+ */
+ if (!PageAnon(head)) {
+ pr_err("MCE: %#lx: non anonymous thp\n",
+ page_to_pfn(page));
+ return 0;
+ }
+
if (get_page_unless_zero(head)) {
if (PageTail(page))
get_page(page);
@@ -1134,15 +1146,6 @@ int memory_failure(unsigned long pfn, int trapno, int flags)
}
if (!PageHuge(p) && PageTransHuge(hpage)) {
- if (!PageAnon(hpage)) {
- pr_err("MCE: %#lx: non anonymous thp\n", pfn);
- if (TestClearPageHWPoison(p))
- atomic_long_sub(nr_pages, &num_poisoned_pages);
- put_page(p);
- if (p != hpage)
- put_page(hpage);
- return -EBUSY;
- }
if (unlikely(split_huge_page(hpage))) {
pr_err("MCE: %#lx: thp split failed\n", pfn);
if (TestClearPageHWPoison(p))