[PATCH 6.15.y] mm/madvise: handle madvise_lock() failure during race unwinding

[SeongJae Park <sj@kernel.org>]

When unwinding race on -ERESTARTNOINTR handling of process_madvise(),
madvise_lock() failure is ignored.  Check the failure and abort remaining
works in the case.

Link: https://lkml.kernel.org/r/20250602174926.1074-1-sj@kernel.org
Fixes: 4000e3d0a367 ("mm/madvise: remove redundant mmap_lock operations from process_madvise()")
Signed-off-by: SeongJae Park <sj@kernel.org>
Reported-by: Barry Song <21cnbao@gmail.com>
Closes: https://lore.kernel.org/CAGsJ_4xJXXO0G+4BizhohSZ4yDteziPw43_uF8nPXPWxUVChzw@mail.gmail.com
Reviewed-by: Jann Horn <jannh@google.com>
Reviewed-by: Lorenzo Stoakes <lorenzo.stoakes@oracle.com>
Acked-by: David Hildenbrand <david@redhat.com>
Reviewed-by: Shakeel Butt <shakeel.butt@linux.dev>
Reviewed-by: Barry Song <baohua@kernel.org>
Cc: Liam Howlett <liam.howlett@oracle.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
(cherry picked from commit 9c49e5d09f076001e05537734d7df002162eb2b5)
---
 mm/madvise.c | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/mm/madvise.c b/mm/madvise.c
index b17f684322ad..69510e737783 100644
--- a/mm/madvise.c
+++ b/mm/madvise.c
@@ -1830,7 +1830,9 @@ static ssize_t vector_madvise(struct mm_struct *mm, struct iov_iter *iter,
 
 			/* Drop and reacquire lock to unwind race. */
 			madvise_unlock(mm, behavior);
-			madvise_lock(mm, behavior);
+			ret = madvise_lock(mm, behavior);
+			if (ret)
+				goto out;
 			continue;
 		}
 		if (ret < 0)
@@ -1839,6 +1841,7 @@ static ssize_t vector_madvise(struct mm_struct *mm, struct iov_iter *iter,
 	}
 	madvise_unlock(mm, behavior);
 
+out:
 	ret = (total_len - iov_iter_count(iter)) ? : ret;
 
 	return ret;
-- 
2.39.5