From 5f30fc94ca985974fd54de454c7a6070388443db Mon Sep 17 00:00:00 2001 From: Hugh Dickins Date: Mon, 3 Mar 2014 15:38:23 -0800 Subject: 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: [] 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: [] 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 Cc: Johannes Weiner Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- lib/radix-tree.c | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-) diff --git a/lib/radix-tree.c b/lib/radix-tree.c index 7811ed3b4e70..bd4a8dfdf0b8 100644 --- a/lib/radix-tree.c +++ b/lib/radix-tree.c @@ -1253,8 +1253,10 @@ unsigned long radix_tree_locate_item(struct radix_tree_root *root, void *item) 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(); -- cgit v1.2.3