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authorMichal Hocko <mhocko@suse.com>2018-02-01 01:21:03 +0100
committerLinus Torvalds <torvalds@linux-foundation.org>2018-02-01 02:18:40 +0100
commit389c8178d0904f944887ccca2256ff9d79c12e8e (patch)
treeb4b089a0b4406d0215237ecc28f4f34c14958a70 /mm/percpu-vm.c
parenthugetlb, mempolicy: fix the mbind hugetlb migration (diff)
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hugetlb, mbind: fall back to default policy if vma is NULL
Dan Carpenter has noticed that mbind migration callback (new_page) can get a NULL vma pointer and choke on it inside alloc_huge_page_vma which relies on the VMA to get the hstate. We used to BUG_ON this case but the BUG_+ON has been removed recently by "hugetlb, mempolicy: fix the mbind hugetlb migration". The proper way to handle this is to get the hstate from the migrated page and rely on huge_node (resp. get_vma_policy) do the right thing with null VMA. We are currently falling back to the default mempolicy in that case which is in line what THP path is doing here. Link: http://lkml.kernel.org/r/20180110104712.GR1732@dhcp22.suse.cz Signed-off-by: Michal Hocko <mhocko@suse.com> Reported-by: Dan Carpenter <dan.carpenter@oracle.com> Cc: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com> Cc: Mike Kravetz <mike.kravetz@oracle.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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