The patch titled
Subject: mm/gup: mark lock taken only after a successful retake
has been added to the -mm tree. Its filename is
mm-gup-mark-lock-taken-only-after-a-successful-retake.patch
This patch should soon appear at
http://ozlabs.org/~akpm/mmots/broken-out/mm-gup-mark-lock-taken-only-after-a-successful-retake.patch
and later at
http://ozlabs.org/~akpm/mmotm/broken-out/mm-gup-mark-lock-taken-only-after-a-successful-retake.patch
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------------------------------------------------------
From: Peter Xu <peterx@xxxxxxxxxx>
Subject: mm/gup: mark lock taken only after a successful retake
It's definitely incorrect to mark the lock as taken even if
down_read_killable() failed. It's overlooked when we switched from
down_read() to down_read_killable() because down_read() won't fail while
down_read_killable() could.
Link: http://lkml.kernel.org/r/20200407204754.GA66033@xz-x1
Fixes: 71335f37c5e8 ("mm/gup: allow to react to fatal signals")
Signed-off-by: Peter Xu <peterx@xxxxxxxxxx>
Reported-by: syzbot+a8c70b7f3579fc0587dc@xxxxxxxxxxxxxxxxxxxxxxxxx
Tested-by: syzbot+a8c70b7f3579fc0587dc@xxxxxxxxxxxxxxxxxxxxxxxxx
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
mm/gup.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
--- a/mm/gup.c~mm-gup-mark-lock-taken-only-after-a-successful-retake
+++ a/mm/gup.c
@@ -1329,7 +1329,6 @@ retry:
if (fatal_signal_pending(current))
break;
- *locked = 1;
ret = down_read_killable(&mm->mmap_sem);
if (ret) {
BUG_ON(ret > 0);
@@ -1338,6 +1337,7 @@ retry:
break;
}
+ *locked = 1;
ret = __get_user_pages(tsk, mm, start, 1, flags | FOLL_TRIED,
pages, NULL, locked);
if (!*locked) {
_
Patches currently in -mm which might be from peterx@xxxxxxxxxx are
mm-merge-parameters-for-change_protection.patch
userfaultfd-wp-apply-_page_uffd_wp-bit.patch
userfaultfd-wp-drop-_page_uffd_wp-properly-when-fork.patch
userfaultfd-wp-add-pmd_swp_uffd_wp-helpers.patch
userfaultfd-wp-support-swap-and-page-migration.patch
khugepaged-skip-collapse-if-uffd-wp-detected.patch
userfaultfd-wp-dont-wake-up-when-doing-write-protect.patch
userfaultfd-wp-declare-_uffdio_writeprotect-conditionally.patch
userfaultfd-selftests-refactor-statistics.patch
userfaultfd-selftests-add-write-protect-test.patch
mm-mempolicy-allow-lookup_node-to-handle-fatal-signal.patch
mm-gup-mark-lock-taken-only-after-a-successful-retake.patch
