hugetlb: check for anon_vma prior to folio allocation

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Commit 9acad7ba3e ("hugetlb: use vmf_anon_prepare() instead of
anon_vma_prepare()") may bailout after allocating a folio if we do not
hold the mmap lock.  When this occurs, vmf_anon_prepare() will release the
vma lock.  Hugetlb then attempts to call restore_reserve_on_error(), which
depends on the vma lock being held.

We can move vmf_anon_prepare() prior to the folio allocation in order to
avoid calling restore_reserve_on_error() without the vma lock.

Link: https://lkml.kernel.org/r/ZiFqSrSRLhIV91og@fedora
Fixes: 9acad7ba3e ("hugetlb: use vmf_anon_prepare() instead of anon_vma_prepare()")
Reported-by: syzbot+ad1b592fc4483655438b@syzkaller.appspotmail.com
Signed-off-by: Vishal Moola (Oracle) <vishal.moola@gmail.com>
Cc: Muchun Song <muchun.song@linux.dev>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

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Vishal Moola (Oracle) 2024-04-15 14:17:47 -07:00 • committed by Andrew Morton

parent 682886ec69

commit 37641efaa3

1 changed files with 7 additions and 4 deletions

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mm/hugetlb.c

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