This issue is found by running liburing/test/io_uring_setup test. When test run, the testcase "attempt to bind to invalid cpu" would not pass with messages like: io_uring_setup(1, 0xbfc2f7c8), \ flags: IORING_SETUP_SQPOLL|IORING_SETUP_SQ_AFF, \ resv: 0x00000000 0x00000000 0x00000000 0x00000000 0x00000000, \ sq_thread_cpu: 2 expected -1, got 3 FAIL On my system, there is: CPU(s) possible : 0-3 CPU(s) online : 0-1 CPU(s) offline : 2-3 CPU(s) present : 0-1 The sq_thread_cpu 2 is offline on my system, so the bind should fail. But cpu_possible() will pass the check. We shouldn't be able to bind to an offline cpu. Use cpu_online() to do the check. After the change, the testcase run as expected: EINVAL will be returned for cpu offlined. Signed-off-by: Shenghui Wang <shhuiw@xxxxxxxxxxx> --- fs/io_uring.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/fs/io_uring.c b/fs/io_uring.c index d91cbd53d3ca..718d7b873f4a 100644 --- a/fs/io_uring.c +++ b/fs/io_uring.c @@ -2472,7 +2472,7 @@ static int io_sq_offload_start(struct io_ring_ctx *ctx, nr_cpu_ids); ret = -EINVAL; - if (!cpu_possible(cpu)) + if (!cpu_online(cpu)) goto err; ctx->sqo_thread = kthread_create_on_cpu(io_sq_thread, -- 2.20.1
