From: Eric Dumazet <eduma...@google.com> rcu_dereference() should be used in sections protected by rcu_read_lock.
For writers, holding some kind of mutex or lock, rcu_dereference_protected() is the way to go, adding explicit lockdep bits. In __unbind(), although there is no mutex or lock held, we are about to free the mapped device, so can use the constant '1' instead of a lockdep_is_held() Reported-by: Kirill A. Shutemov <kir...@shutemov.name> Signed-off-by: Eric Dumazet <eduma...@google.com> Fixes: 33423974bfc1 ("dm: Use rcu_dereference() for accessing rcu pointer") Cc: Pranith Kumar <bobby.pr...@gmail.com> --- drivers/md/dm.c | 8 +++++--- 1 file changed, 5 insertions(+), 3 deletions(-) diff --git a/drivers/md/dm.c b/drivers/md/dm.c index a0ece87ad426..2e0aa2273382 100644 --- a/drivers/md/dm.c +++ b/drivers/md/dm.c @@ -2335,7 +2335,8 @@ static struct dm_table *__bind(struct mapped_device *md, struct dm_table *t, merge_is_optional = dm_table_merge_is_optional(t); - old_map = rcu_dereference(md->map); + old_map = rcu_dereference_protected(md->map, + lockdep_is_held(&md->suspend_lock)); rcu_assign_pointer(md->map, t); md->immutable_target_type = dm_table_get_immutable_target_type(t); @@ -2355,7 +2356,7 @@ static struct dm_table *__bind(struct mapped_device *md, struct dm_table *t, */ static struct dm_table *__unbind(struct mapped_device *md) { - struct dm_table *map = rcu_dereference(md->map); + struct dm_table *map = rcu_dereference_protected(md->map, 1); if (!map) return NULL; @@ -2850,7 +2851,8 @@ retry: goto retry; } - map = rcu_dereference(md->map); + map = rcu_dereference_protected(md->map, + lockdep_is_held(&md->suspend_lock)); r = __dm_suspend(md, map, suspend_flags, TASK_INTERRUPTIBLE); if (r) -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/