lib/radix-tree.c: swapoff tmpfs radix_tree: remember to rcu_read_unlock
Running fsx on tmpfs with concurrent memhog-swapoff-swapon, lots of
BUG: sleeping function called from invalid context at kernel/fork.c:606
in_atomic(): 0, irqs_disabled(): 0, pid: 1394, name: swapoff
1 lock held by swapoff/1394:
#0: (rcu_read_lock){.+.+.+}, at: [<ffffffff812520a1>] radix_tree_locate_item+0x1f/0x2b6
followed by
================================================
[ BUG: lock held when returning to user space! ]
3.14.0-rc1 #3 Not tainted
------------------------------------------------
swapoff/1394 is leaving the kernel with locks still held!
1 lock held by swapoff/1394:
#0: (rcu_read_lock){.+.+.+}, at: [<ffffffff812520a1>] radix_tree_locate_item+0x1f/0x2b6
after which the system recovered nicely.
Whoops, I long ago forgot the rcu_read_unlock() on one unlikely branch.
Fixes e504f3fdd63d ("tmpfs radix_tree: locate_item to speed up swapoff")
Signed-off-by: Hugh Dickins <hughd@google.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
diff --git a/lib/radix-tree.c b/lib/radix-tree.c
index 7811ed3..bd4a8df 100644
--- a/lib/radix-tree.c
+++ b/lib/radix-tree.c
@@ -1253,8 +1253,10 @@
node = indirect_to_ptr(node);
max_index = radix_tree_maxindex(node->height);
- if (cur_index > max_index)
+ if (cur_index > max_index) {
+ rcu_read_unlock();
break;
+ }
cur_index = __locate(node, item, cur_index, &found_index);
rcu_read_unlock();