Re: [PATCH 0/2] Reintroduce picky __compound_tail_refcounted()

From: Kirill A. Shutemov
Date: Tue May 05 2015 - 03:30:24 EST


On Tue, Apr 28, 2015 at 07:24:56PM +0300, Kirill A. Shutemov wrote:
> Hi Andrew,
>
> My patch 8d63d99a5dfb which was merged during 4.1 merge window caused
> regression:
>
> page:ffffea0010a15040 count:0 mapcount:1 mapping: (null) index:0x0
> flags: 0x8000000000008014(referenced|dirty|tail)
> page dumped because: VM_BUG_ON_PAGE(page_mapcount(page) != 0)
> ------------[ cut here ]------------
> kernel BUG at mm/swap.c:134!
>
> The patch was reverted by Linus.
>
> This VM_BUG_ON_PAGE() is bogus. The first patch explains why the assert is
> wrong and removes it. The second re-introduces original patch.
>
> Kirill A. Shutemov (2):
> mm: drop bogus VM_BUG_ON_PAGE assert in put_page() codepath
> mm: avoid tail page refcounting on non-THP compound pages
>
> include/linux/mm.h | 2 +-
> mm/swap.c | 1 -
> 2 files changed, 1 insertion(+), 2 deletions(-)

Ping?

--
Kirill A. Shutemov
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