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authorWanpeng Li <wanpeng.li@hotmail.com>2015-08-14 15:35:08 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2015-08-14 15:56:32 -0700
commit7f6bf39bbdd1dcccd103ba7dce8496a8e72e7df4 (patch)
treea8f540d29959b512e21d79aa0111bb1ac7519208
parenta97955844807e327df11aa33869009d14d6b7de0 (diff)
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mm/hwpoison: fix panic due to split huge zero page
Bug: ------------[ cut here ]------------ kernel BUG at mm/huge_memory.c:1957! invalid opcode: 0000 [#1] SMP Modules linked in: snd_hda_codec_hdmi i915 rpcsec_gss_krb5 snd_hda_codec_realtek snd_hda_codec_generic nfsv4 dns_re CPU: 2 PID: 2576 Comm: test_huge Not tainted 4.2.0-rc5-mm1+ #27 Hardware name: Dell Inc. OptiPlex 7020/0F5C5X, BIOS A03 01/08/2015 task: ffff880204e3d600 ti: ffff8800db16c000 task.ti: ffff8800db16c000 RIP: split_huge_page_to_list+0xdb/0x120 Call Trace: memory_failure+0x32e/0x7c0 madvise_hwpoison+0x8b/0x160 SyS_madvise+0x40/0x240 ? do_page_fault+0x37/0x90 entry_SYSCALL_64_fastpath+0x12/0x71 Code: ff f0 41 ff 4c 24 30 74 0d 31 c0 48 83 c4 08 5b 41 5c 41 5d c9 c3 4c 89 e7 e8 e2 58 fd ff 48 83 c4 08 31 c0 RIP split_huge_page_to_list+0xdb/0x120 RSP <ffff8800db16fde8> ---[ end trace aee7ce0df8e44076 ]--- Testcase: #define _GNU_SOURCE #include <stdlib.h> #include <stdio.h> #include <sys/mman.h> #include <unistd.h> #include <fcntl.h> #include <sys/types.h> #include <errno.h> #include <string.h> #define MB 1024*1024 int main(void) { char *mem; posix_memalign((void **)&mem, 2 * MB, 200 * MB); madvise(mem, 200 * MB, MADV_HWPOISON); free(mem); return 0; } Huge zero page is allocated if page fault w/o FAULT_FLAG_WRITE flag. The get_user_pages_fast() which called in madvise_hwpoison() will get huge zero page if the page is not allocated before. Huge zero page is a tranparent huge page, however, it is not an anonymous page. memory_failure will split the huge zero page and trigger BUG_ON(is_huge_zero_page(page)); After commit 98ed2b0052e6 ("mm/memory-failure: give up error handling for non-tail-refcounted thp"), memory_failure will not catch non anon thp from madvise_hwpoison path and this bug occur. Fix it by catching non anon thp in memory_failure in order to not split huge zero page in madvise_hwpoison path. After this patch: Injecting memory failure for page 0x202800 at 0x7fd8ae800000 MCE: 0x202800: non anonymous thp [...] [akpm@linux-foundation.org: remove second split, per Wanpeng] Signed-off-by: Wanpeng Li <wanpeng.li@hotmail.com> Acked-by: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
-rw-r--r--mm/memory-failure.c7
1 files changed, 5 insertions, 2 deletions
diff --git a/mm/memory-failure.c b/mm/memory-failure.c
index dba52ee31bd4..1f4446a90cef 100644
--- a/mm/memory-failure.c
+++ b/mm/memory-failure.c
@@ -1146,8 +1146,11 @@ int memory_failure(unsigned long pfn, int trapno, int flags)
}
if (!PageHuge(p) && PageTransHuge(hpage)) {
- if (unlikely(split_huge_page(hpage))) {
- pr_err("MCE: %#lx: thp split failed\n", pfn);
+ if (!PageAnon(hpage) || unlikely(split_huge_page(hpage))) {
+ if (!PageAnon(hpage))
+ pr_err("MCE: %#lx: non anonymous thp\n", pfn);
+ else
+ pr_err("MCE: %#lx: thp split failed\n", pfn);
if (TestClearPageHWPoison(p))
atomic_long_sub(nr_pages, &num_poisoned_pages);
put_page(p);