The patch titled
Subject: userfaultfd: fix deadlock warning when locking src and dst VMAs
has been added to the -mm mm-nonmm-unstable branch. Its filename is
userfaultfd-fix-deadlock-warning-when-locking-src-and-dst-vmas.patch
This patch will shortly appear at
https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches/userfaultfd-fix-deadlock-warning-when-locking-src-and-dst-vmas.patch
This patch will later appear in the mm-nonmm-unstable branch at
git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm
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------------------------------------------------------
From: Lokesh Gidra <lokeshgidra@xxxxxxxxxx>
Subject: userfaultfd: fix deadlock warning when locking src and dst VMAs
Date: Thu, 21 Mar 2024 16:58:18 -0700
Use down_read_nested() to avoid the warning.
Link: https://lkml.kernel.org/r/20240321235818.125118-1-lokeshgidra@xxxxxxxxxx
Fixes: 867a43a34ff8a ("userfaultfd: use per-vma locks in userfaultfd operations")
Reported-by: syzbot+49056626fe41e01f2ba7@xxxxxxxxxxxxxxxxxxxxxxxxx
Signed-off-by: Lokesh Gidra <lokeshgidra@xxxxxxxxxx>
Cc: Andrea Arcangeli <aarcange@xxxxxxxxxx>
Cc: Axel Rasmussen <axelrasmussen@xxxxxxxxxx>
Cc: Brian Geffon <bgeffon@xxxxxxxxxx>
Cc: David Hildenbrand <david@xxxxxxxxxx>
Cc: Hillf Danton <hdanton@xxxxxxxx>
Cc: Jann Horn <jannh@xxxxxxxxxx> [Bug #2]
Cc: Kalesh Singh <kaleshsingh@xxxxxxxxxx>
Cc: Lokesh Gidra <lokeshgidra@xxxxxxxxxx>
Cc: Mike Rapoport (IBM) <rppt@xxxxxxxxxx>
Cc: Nicolas Geoffray <ngeoffray@xxxxxxxxxx>
Cc: Peter Xu <peterx@xxxxxxxxxx>
Cc: Suren Baghdasaryan <surenb@xxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
mm/userfaultfd.c | 3 ++-
1 file changed, 2 insertions(+), 1 deletion(-)
--- a/mm/userfaultfd.c~userfaultfd-fix-deadlock-warning-when-locking-src-and-dst-vmas
+++ a/mm/userfaultfd.c
@@ -1479,7 +1479,8 @@ static int uffd_move_lock(struct mm_stru
*/
down_read(&(*dst_vmap)->vm_lock->lock);
if (*dst_vmap != *src_vmap)
- down_read(&(*src_vmap)->vm_lock->lock);
+ down_read_nested(&(*src_vmap)->vm_lock->lock,
+ SINGLE_DEPTH_NESTING);
}
mmap_read_unlock(mm);
return err;
_
Patches currently in -mm which might be from lokeshgidra@xxxxxxxxxx are
userfaultfd-fix-deadlock-warning-when-locking-src-and-dst-vmas.patch
