IOPOLL allows buffer remove/provide requests, but they doesn't synchronise by rules of IOPOLL, namely it have to hold uring_lock.

Cc: stable@vger.kernel.org # 5.7+ Signed-off-by: Pavel Begunkov asml.silence@gmail.com --- fs/io_uring.c | 23 ++++++++++++++++++----- 1 file changed, 18 insertions(+), 5 deletions(-)

diff --git a/fs/io_uring.c b/fs/io_uring.c index c895a306f919..4fac02ea5f4c 100644 --- a/fs/io_uring.c +++ b/fs/io_uring.c @@ -3948,11 +3948,17 @@ static int io_remove_buffers(struct io_kiocb *req, bool force_nonblock, head = idr_find(&ctx->io_buffer_idr, p->bgid); if (head) ret = __io_remove_buffers(ctx, head, p->bgid, p->nbufs); - - io_ring_submit_lock(ctx, !force_nonblock); if (ret < 0) req_set_fail_links(req); - __io_req_complete(req, ret, 0, cs); + + /* need to hold the lock to complete IOPOLL requests */ + if (ctx->flags & IORING_SETUP_IOPOLL) { + __io_req_complete(req, ret, 0, cs); + io_ring_submit_unlock(ctx, !force_nonblock); + } else { + io_ring_submit_unlock(ctx, !force_nonblock); + __io_req_complete(req, ret, 0, cs); + } return 0; }

@@ -4037,10 +4043,17 @@ static int io_provide_buffers(struct io_kiocb *req, bool force_nonblock, } } out: - io_ring_submit_unlock(ctx, !force_nonblock); if (ret < 0) req_set_fail_links(req); - __io_req_complete(req, ret, 0, cs); + + /* need to hold the lock to complete IOPOLL requests */ + if (ctx->flags & IORING_SETUP_IOPOLL) { + __io_req_complete(req, ret, 0, cs); + io_ring_submit_unlock(ctx, !force_nonblock); + } else { + io_ring_submit_unlock(ctx, !force_nonblock); + __io_req_complete(req, ret, 0, cs); + } return 0; }