block: avoid infinite loop in get_task_io_context()
Calling get_task_io_context() on a exiting task which isn't %current can
loop forever. This triggers at boot time on my dev machine.
BUG: soft lockup - CPU#3 stuck for 22s ! [mountall.1603]
Fix this by making create_task_io_context() returns -EBUSY in this case
to break the loop.
Signed-off-by: Eric Dumazet <edumazet@google.com>
Cc: Tejun Heo <tj@kernel.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Alan Cox <alan@linux.intel.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
diff --git a/block/blk-ioc.c b/block/blk-ioc.c
index 1e2d53b..893b800 100644
--- a/block/blk-ioc.c
+++ b/block/blk-ioc.c
@@ -235,6 +235,7 @@
int create_task_io_context(struct task_struct *task, gfp_t gfp_flags, int node)
{
struct io_context *ioc;
+ int ret;
ioc = kmem_cache_alloc_node(iocontext_cachep, gfp_flags | __GFP_ZERO,
node);
@@ -262,9 +263,12 @@
task->io_context = ioc;
else
kmem_cache_free(iocontext_cachep, ioc);
+
+ ret = task->io_context ? 0 : -EBUSY;
+
task_unlock(task);
- return 0;
+ return ret;
}
/**