Messages in this thread Patch in this message | | | From | Hillf Danton <> | Subject | Re: [syzbot] [mm?] possible deadlock in move_pages | Date | Wed, 20 Mar 2024 18:45:54 +0800 |
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On Tue, 19 Mar 2024 02:52:16 -0700 > syzbot found the following issue on: > > HEAD commit: e5eb28f6d1af Merge tag 'mm-nonmm-stable-2024-03-14-09-36' .. > git tree: upstream > C reproducer: https://syzkaller.appspot.com/x/repro.c?x=173b7ac9180000
#syz test https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git e5eb28f6d1af
--- x/mm/userfaultfd.c +++ y/mm/userfaultfd.c @@ -1442,9 +1442,9 @@ static int uffd_move_lock(struct mm_stru * See comment in lock_vma() as to why not using * vma_start_read() here. */ - down_read(&(*dst_vmap)->vm_lock->lock); + down_read_nested(&(*dst_vmap)->vm_lock->lock, 1); if (*dst_vmap != *src_vmap) - down_read(&(*src_vmap)->vm_lock->lock); + down_read_nested(&(*src_vmap)->vm_lock->lock, 2); } mmap_read_unlock(mm); return err; --
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