mm: mmap_lock: fix disabling preemption directly

Commit 832b50725373 ("mm: mmap_lock: use local locks instead of
disabling preemption") fixed a bug by using local locks.

But commit d01079f3d0c0 ("mm/mmap_lock: remove dead code for
!CONFIG_TRACING configurations") changed those lines back to the
original version.

I guess it was introduced by fixing conflicts.

Link: https://lkml.kernel.org/r/20210720074228.76342-1-songmuchun@bytedance.com
Fixes: d01079f3d0c0 ("mm/mmap_lock: remove dead code for !CONFIG_TRACING configurations")
Signed-off-by: Muchun Song <songmuchun@bytedance.com>
Acked-by: Mel Gorman <mgorman@techsingularity.net>
Reviewed-by: Yang Shi <shy828301@gmail.com>
Reviewed-by: Pankaj Gupta <pankaj.gupta@ionos.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

diff --git a/mm/mmap_lock.c b/mm/mmap_lock.c
index f5852a0..1854850 100644 (file)
--- a/mm/mmap_lock.c
+++ b/mm/mmap_lock.c
@@ -156,14 +156,14 @@ static inline void put_memcg_path_buf(void)
 #define TRACE_MMAP_LOCK_EVENT(type, mm, ...)                                   \
        do {                                                                   \
                const char *memcg_path;                                        \
-               preempt_disable();                                             \
+               local_lock(&memcg_paths.lock);                                 \
                memcg_path = get_mm_memcg_path(mm);                            \
                trace_mmap_lock_##type(mm,                                     \
                                       memcg_path != NULL ? memcg_path : "",   \
                                       ##__VA_ARGS__);                         \
                if (likely(memcg_path != NULL))                                \
                        put_memcg_path_buf();                                  \
-               preempt_enable();                                              \
+               local_unlock(&memcg_paths.lock);                               \
        } while (0)
 
 #else /* !CONFIG_MEMCG */