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| author | Vishal Moola (Oracle) <vishal.moola@gmail.com> | 2024-04-15 14:17:47 -0700 |
|---|---|---|
| committer | Andrew Morton <akpm@linux-foundation.org> | 2024-04-24 19:34:26 -0700 |
| commit | 37641efaa3faa4b8292aba4bbd7d71c0b703a239 (patch) | |
| tree | ba4426bd53e97e37951e37cfbe757ddd7998ecfe | |
| parent | 682886ec69d22363819a83ddddd5d66cb5c791e1 (diff) | |
| download | linux-37641efaa3faa4b8292aba4bbd7d71c0b703a239.tar.gz | |
hugetlb: check for anon_vma prior to folio allocation
Commit 9acad7ba3e25 ("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: 9acad7ba3e25 ("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>
| -rw-r--r-- | mm/hugetlb.c | 11 |
1 files changed, 7 insertions, 4 deletions
diff --git a/mm/hugetlb.c b/mm/hugetlb.c index 4553241f0fb284..05371bf54f96d3 100644 --- a/mm/hugetlb.c +++ b/mm/hugetlb.c @@ -6261,6 +6261,12 @@ static vm_fault_t hugetlb_no_page(struct mm_struct *mm, VM_UFFD_MISSING); } + if (!(vma->vm_flags & VM_MAYSHARE)) { + ret = vmf_anon_prepare(vmf); + if (unlikely(ret)) + goto out; + } + folio = alloc_hugetlb_folio(vma, haddr, 0); if (IS_ERR(folio)) { /* @@ -6297,15 +6303,12 @@ static vm_fault_t hugetlb_no_page(struct mm_struct *mm, */ restore_reserve_on_error(h, vma, haddr, folio); folio_put(folio); + ret = VM_FAULT_SIGBUS; goto out; } new_pagecache_folio = true; } else { folio_lock(folio); - - ret = vmf_anon_prepare(vmf); - if (unlikely(ret)) - goto backout_unlocked; anon_rmap = 1; } } else { |