The quilt patch titled
Subject: mm: prevent userfaults to be handled under per-vma lock
has been removed from the -mm tree. Its filename was
mm-prevent-userfaults-to-be-handled-under-per-vma-lock.patch
This patch was dropped because it was merged into the mm-stable branch
of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm
------------------------------------------------------
From: Suren Baghdasaryan <surenb@xxxxxxxxxx>
Subject: mm: prevent userfaults to be handled under per-vma lock
Date: Mon, 27 Feb 2023 09:36:26 -0800
Due to the possibility of handle_userfault dropping mmap_lock, avoid fault
handling under VMA lock and retry holding mmap_lock. This can be handled
more gracefully in the future.
Link: https://lkml.kernel.org/r/20230227173632.3292573-28-surenb@xxxxxxxxxx
Signed-off-by: Suren Baghdasaryan <surenb@xxxxxxxxxx>
Suggested-by: Peter Xu <peterx@xxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
mm/memory.c | 9 +++++++++
1 file changed, 9 insertions(+)
--- a/mm/memory.c~mm-prevent-userfaults-to-be-handled-under-per-vma-lock
+++ a/mm/memory.c
@@ -5266,6 +5266,15 @@ retry:
if (!vma_start_read(vma))
goto inval;
+ /*
+ * Due to the possibility of userfault handler dropping mmap_lock, avoid
+ * it for now and fall back to page fault handling under mmap_lock.
+ */
+ if (userfaultfd_armed(vma)) {
+ vma_end_read(vma);
+ goto inval;
+ }
+
/* Check since vm_start/vm_end might change before we lock the VMA */
if (unlikely(address < vma->vm_start || address >= vma->vm_end)) {
vma_end_read(vma);
_
Patches currently in -mm which might be from surenb@xxxxxxxxxx are
