From 389c8178d0904f944887ccca2256ff9d79c12e8e Mon Sep 17 00:00:00 2001 From: Michal Hocko Date: Wed, 31 Jan 2018 16:21:03 -0800 Subject: 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 Reported-by: Dan Carpenter Cc: Naoya Horiguchi Cc: Mike Kravetz Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- mm/hugetlb.c | 5 ++--- 1 file changed, 2 insertions(+), 3 deletions(-) (limited to 'mm/hugetlb.c') diff --git a/mm/hugetlb.c b/mm/hugetlb.c index 742a929f2311..7c204e3d132b 100644 --- a/mm/hugetlb.c +++ b/mm/hugetlb.c @@ -1675,16 +1675,15 @@ struct page *alloc_huge_page_nodemask(struct hstate *h, int preferred_nid, } /* mempolicy aware migration callback */ -struct page *alloc_huge_page_vma(struct vm_area_struct *vma, unsigned long address) +struct page *alloc_huge_page_vma(struct hstate *h, struct vm_area_struct *vma, + unsigned long address) { struct mempolicy *mpol; nodemask_t *nodemask; struct page *page; - struct hstate *h; gfp_t gfp_mask; int node; - h = hstate_vma(vma); gfp_mask = htlb_alloc_mask(h); node = huge_node(vma, address, gfp_mask, &mpol, &nodemask); page = alloc_huge_page_nodemask(h, node, nodemask); -- cgit v1.2.3-70-g09d2