It's not safe to call io_cqring_overflow_flush() for IOPOLL mode without hodling uring_lock, because it does synchronisation differently. Make sure we have it.

As for io_ring_exit_work(), we don't even need it there because io_ring_ctx_wait_and_kill() already set force flag making all overflowed requests to be dropped.

Cc: stable@vger.kernel.org # 5.5+ Signed-off-by: Pavel Begunkov asml.silence@gmail.com --- fs/io_uring.c | 10 ++++++---- 1 file changed, 6 insertions(+), 4 deletions(-)

diff --git a/fs/io_uring.c b/fs/io_uring.c index 4fac02ea5f4c..b1ba9a738315 100644 --- a/fs/io_uring.c +++ b/fs/io_uring.c @@ -8393,8 +8393,6 @@ static void io_ring_exit_work(struct work_struct *work) * as nobody else will be looking for them. */ do { - if (ctx->rings) - io_cqring_overflow_flush(ctx, true, NULL, NULL); io_iopoll_try_reap_events(ctx); } while (!wait_for_completion_timeout(&ctx->ref_comp, HZ/20)); io_ring_ctx_free(ctx); @@ -8404,6 +8402,8 @@ static void io_ring_ctx_wait_and_kill(struct io_ring_ctx *ctx) { mutex_lock(&ctx->uring_lock); percpu_ref_kill(&ctx->refs); + if (ctx->rings) + io_cqring_overflow_flush(ctx, true, NULL, NULL); mutex_unlock(&ctx->uring_lock);

io_kill_timeouts(ctx, NULL); @@ -8413,8 +8413,6 @@ static void io_ring_ctx_wait_and_kill(struct io_ring_ctx *ctx) io_wq_cancel_all(ctx->io_wq);

/* if we failed setting up the ctx, we might not have any rings */ - if (ctx->rings) - io_cqring_overflow_flush(ctx, true, NULL, NULL); io_iopoll_try_reap_events(ctx); idr_for_each(&ctx->personality_idr, io_remove_personalities, ctx);

@@ -8691,7 +8689,9 @@ static void io_uring_cancel_task_requests(struct io_ring_ctx *ctx, else io_cancel_defer_files(ctx, task, NULL);

+ io_ring_submit_lock(ctx, (ctx->flags & IORING_SETUP_IOPOLL)); io_cqring_overflow_flush(ctx, true, task, files); + io_ring_submit_unlock(ctx, (ctx->flags & IORING_SETUP_IOPOLL));

while (__io_uring_cancel_task_requests(ctx, task, files)) { io_run_task_work(); @@ -8993,8 +8993,10 @@ SYSCALL_DEFINE6(io_uring_enter, unsigned int, fd, u32, to_submit, */ ret = 0; if (ctx->flags & IORING_SETUP_SQPOLL) { + io_ring_submit_lock(ctx, (ctx->flags & IORING_SETUP_IOPOLL)); if (!list_empty_careful(&ctx->cq_overflow_list)) io_cqring_overflow_flush(ctx, false, NULL, NULL); + io_ring_submit_unlock(ctx, (ctx->flags & IORING_SETUP_IOPOLL)); if (flags & IORING_ENTER_SQ_WAKEUP) wake_up(&ctx->sq_data->wait); if (flags & IORING_ENTER_SQ_WAIT)