6.12-stable review patch. If anyone has any objections, please let me know. ------------------ From: Josef Bacik Commit 3774e4d4c8533da2caae95556c4d635c7c4f45b8 upstream. IORING_REGISTER_SYNC_CANCEL waits without a limit if both fields of io_uring_sync_cancel_reg::timeout are -1. io_sync_cancel() compares them with -1UL. They are of type long long. With a long of 32 bits -1UL is 4294967295, which is what it stays when it is converted for the comparison, and the fields are never equal to it. So { -1, -1 } is taken for a timeout. ktime_set() takes the nanoseconds as an unsigned long, so what becomes of it is -1s + 4294967295ns = 3.29s. If the request is being run by io-wq and can't be interrupted, the call returns -ETIME after that time, rather than waiting for the request to be gone. On i386, with a buffered read from a null_blk device that takes 4s to complete a request, IOSQE_ASYNC, that is what each call does. Fixes: 78a861b94959 ("io_uring: add sync cancelation API through io_uring_register()") Assisted-by: LLM Signed-off-by: Josef Bacik Link: https://patch.msgid.link/20261015-b4-io-uring-fixes-v1-17-c1556f5d7bf5@toxicpanda.com Signed-off-by: Jens Axboe Signed-off-by: Greg Kroah-Hartman --- io_uring/cancel.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) --- a/io_uring/cancel.c +++ b/io_uring/cancel.c @@ -315,7 +315,7 @@ int io_sync_cancel(struct io_ring_ctx *c if (ret != -EALREADY) goto out; - if (sc.timeout.tv_sec != -1UL || sc.timeout.tv_nsec != -1UL) { + if (sc.timeout.tv_sec != -1 || sc.timeout.tv_nsec != -1) { struct timespec64 ts = { .tv_sec = sc.timeout.tv_sec, .tv_nsec = sc.timeout.tv_nsec