[PATCH 0/2] Reintroduce picky __compound_tail_refcounted()

From: Kirill A. Shutemov
Date: Tue Apr 28 2015 - 12:26:08 EST


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(-)

--
2.1.4

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