Messages in this thread Patch in this message | | | Date | Tue, 1 May 2012 09:17:29 -0700 | From | Tejun Heo <> | Subject | [PATCH v3.4-rc5] block: iocontext->nr_tasks should be initialized to one |
| |
create_task_io_context() left ioc->nr_tasks at zero; however, a newly created ioc should have its nr_tasks initialized to one as it begins attached to the task creating it.
This affects only CLONE_IO which currently doesn't seem to have any actual user. Sasha triggered WARN_ON_ONCE() in ioc_task_link() using syscall fuzzer. Even when it happens, the failure mode isn't critical (blk-cgroup may allow attaching a CLONE_IO'd task to a cgroup when it shouldn't and blkcg limits may behave weirdly).
Fix it by initializing it to one in create_task_io_context().
Signed-off-by: Tejun Heo <tj@kernel.org> Reported-by: Sasha Levin <levinsasha928@gmail.com> LKML-Reference: <1335873936.16988.148.camel@lappy> Cc: stable@vger.kernel.org --- block/blk-ioc.c | 1 + 1 file changed, 1 insertion(+)
diff --git a/block/blk-ioc.c b/block/blk-ioc.c index 1e2d53b..c942409 100644 --- a/block/blk-ioc.c +++ b/block/blk-ioc.c @@ -244,6 +244,7 @@ int create_task_io_context(struct task_struct *task, gfp_t gfp_flags, int node) /* initialize */ atomic_long_set(&ioc->refcount, 1); atomic_set(&ioc->active_ref, 1); + atomic_set(&ioc->nr_tasks, 1); spin_lock_init(&ioc->lock); INIT_RADIX_TREE(&ioc->icq_tree, GFP_ATOMIC | __GFP_HIGH); INIT_HLIST_HEAD(&ioc->icq_list);
| |