io_uring: Fix double list add in io_queue_async_work()

BugLink: https://bugs.launchpad.net/bugs/1902110
If we queue work in io_poll_wake(), it will leads to list double
add. So we should add the list when the callback func is the
io_sq_wq_submit_work.

The following oops was seen:

    list_add double add: new=ffff9ca6a8f1b0e0, prev=ffff9ca62001cee8,
    next=ffff9ca6a8f1b0e0.
    ------------[ cut here ]------------
    kernel BUG at lib/list_debug.c:31!
    Call Trace:
     <IRQ>
     io_poll_wake+0xf3/0x230
     __wake_up_common+0x91/0x170
     __wake_up_common_lock+0x7a/0xc0
     io_commit_cqring+0xea/0x280
     ? blkcg_iolatency_done_bio+0x2b/0x610
     io_cqring_add_event+0x3e/0x60
     io_complete_rw+0x58/0x80
     dio_complete+0x106/0x250
     blk_update_request+0xa0/0x3b0
     blk_mq_end_request+0x1a/0x110
     blk_mq_complete_request+0xd0/0xe0
     nvme_irq+0x129/0x270 [nvme]
     __handle_irq_event_percpu+0x7b/0x190
     handle_irq_event_percpu+0x30/0x80
     handle_irq_event+0x3c/0x60
     handle_edge_irq+0x91/0x1e0
     do_IRQ+0x4d/0xd0
     common_interrupt+0xf/0xf

Fixes: 1c4404efcf2c ("io_uring: make sure async workqueue is canceled on exit")
Reported-by: Jiachen Zhang <zhangjiachen.jaycee@bytedance.com>
Signed-off-by: Muchun Song <songmuchun@bytedance.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Kamal Mostafa <kamal@canonical.com>
Signed-off-by: Ian May <ian.may@canonical.com>

diff --git a/fs/io_uring.c b/fs/io_uring.c
index 242612fe9b4844b460277d9c20795f4e8ffd3da2..4127ea027a14dcf62fa103be75b76a314b79d13a 100644 (file)
--- a/fs/io_uring.c
+++ b/fs/io_uring.c
@@ -514,12 +514,14 @@ static inline void io_queue_async_work(struct io_ring_ctx *ctx,
                }
        }
 
-       req->files = current->files;
+       if (req->work.func == io_sq_wq_submit_work) {
+               req->files = current->files;
 
-       spin_lock_irqsave(&ctx->task_lock, flags);
-       list_add(&req->task_list, &ctx->task_list);
-       req->work_task = NULL;
-       spin_unlock_irqrestore(&ctx->task_lock, flags);
+               spin_lock_irqsave(&ctx->task_lock, flags);
+               list_add(&req->task_list, &ctx->task_list);
+               req->work_task = NULL;
+               spin_unlock_irqrestore(&ctx->task_lock, flags);
+       }
 
        queue_work(ctx->sqo_wq[rw], &req->work);
 }
@@ -668,6 +670,7 @@ static struct io_kiocb *io_get_req(struct io_ring_ctx *ctx,
                state->cur_req++;
        }
 
+       INIT_LIST_HEAD(&req->task_list);
        req->file = NULL;
        req->ctx = ctx;
        req->flags = 0;