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mm/memory-failure: give up error handling for non-tail-refcounted thp

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"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>
This commit is contained in:
Naoya Horiguchi 2015-08-06 15:47:04 -07:00 committed by Linus Torvalds
parent a209ef09af
commit 98ed2b0052
1 changed files with 12 additions and 9 deletions
repo.diff.show_diff_stats Download patch file Download diff file Expand all files Collapse all files

21
mm/memory-failure.c
View file

@ -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))