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authorJin Dongming <jin.dongming@np.css.fujitsu.com>2011-02-02 00:52:40 +0100
committerLinus Torvalds <torvalds@linux-foundation.org>2011-02-03 01:03:19 +0100
commita6d30dddae4648837be5a0c0cb2c0ae9ad0377db (patch)
treef04020b0442b8bfce45e159bde01a61f01c39c30 /mm/huge_memory.c
parentthp: fix splitting of hwpoisoned hugepages (diff)
downloadlinux-a6d30dddae4648837be5a0c0cb2c0ae9ad0377db.tar.xz
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thp: fix the wrong reported address of hwpoisoned hugepages
When the tail page of THP is poisoned, the head page will be poisoned too. And the wrong address, address of head page, will be sent with sigbus always. So when the poisoned page is used by Guest OS which is running on KVM, after the address changing(hva->gpa) by qemu, the unexpected process on Guest OS will be killed by sigbus. What we expected is that the process using the poisoned tail page could be killed on Guest OS, but not that the process using the healthy head page is killed. Since it is not good to poison the healthy page, avoid poisoning other than the page which is really poisoned. (While we poison all pages in a huge page in case of hugetlb, we can do this for THP thanks to split_huge_page().) Here we fix two parts: 1. Isolate the poisoned page only to make sure the reported address is the address of poisoned page. 2. make the poisoned page work as the poisoned regular page. [akpm@linux-foundation.org: fix spello in comment] Signed-off-by: Jin Dongming <jin.dongming@np.css.fujitsu.com> Reviewed-by: Hidetoshi Seto <seto.hidetoshi@jp.fujitsu.com> Cc: Andrea Arcangeli <aarcange@redhat.com> Cc: Andi Kleen <andi@firstfloor.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'mm/huge_memory.c')
-rw-r--r--mm/huge_memory.c7
1 files changed, 6 insertions, 1 deletions
diff --git a/mm/huge_memory.c b/mm/huge_memory.c
index e187454d82f6..b6c1ce3c53b5 100644
--- a/mm/huge_memory.c
+++ b/mm/huge_memory.c
@@ -1162,7 +1162,12 @@ static void __split_huge_page_refcount(struct page *page)
/* after clearing PageTail the gup refcount can be released */
smp_mb();
- page_tail->flags &= ~PAGE_FLAGS_CHECK_AT_PREP;
+ /*
+ * retain hwpoison flag of the poisoned tail page:
+ * fix for the unsuitable process killed on Guest Machine(KVM)
+ * by the memory-failure.
+ */
+ page_tail->flags &= ~PAGE_FLAGS_CHECK_AT_PREP | __PG_HWPOISON;
page_tail->flags |= (page->flags &
((1L << PG_referenced) |
(1L << PG_swapbacked) |