Re: [PATCH] mm/hwpoison: fix panic due to split huge zero page

From: Wanpeng Li
Date: Tue Aug 11 2015 - 18:20:45 EST

On 8/12/15 5:14 AM, Andrew Morton wrote:
On Tue, 11 Aug 2015 18:47:57 +0800 Wanpeng Li <> wrote:


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 (98ed2b0: 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.
So I'm assuming this patch is needed for 4.2 but not in earlier

I think so. :-) Btw, how about my other hwpoison patches?

Wanpeng Li

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