From 917257daa0fea7a007102691c0e27d9216a96768 Mon Sep 17 00:00:00 2001 From: Jens Axboe Date: Sat, 13 Apr 2019 09:28:55 -0600 Subject: [PATCH] io_uring: only test SQPOLL cpu after we've verified it We currently call cpu_possible() even if we don't use the CPU. Move the test under the SQ_AFF branch, which is the only place where we'll use the value. Do the cpu_possible() test AFTER we've limited it to a max of NR_CPUS. This avoids triggering the following warning: WARNING: CPU: 1 PID: 7600 at include/linux/cpumask.h:121 cpu_max_bits_warn if CONFIG_DEBUG_PER_CPU_MAPS is enabled. While in there, also move the SQ thread idle period assignment inside SETUP_SQPOLL, as we don't use it otherwise either. Reported-by: syzbot+cd714a07c6de2bc34293@syzkaller.appspotmail.com Fixes: 6c271ce2f1d5 ("io_uring: add submission polling") Signed-off-by: Jens Axboe --- fs/io_uring.c | 12 ++++++++---- 1 file changed, 8 insertions(+), 4 deletions(-) diff --git a/fs/io_uring.c b/fs/io_uring.c index e5008c1b82be..24355e0c47f0 100644 --- a/fs/io_uring.c +++ b/fs/io_uring.c @@ -2241,10 +2241,6 @@ static int io_sq_offload_start(struct io_ring_ctx *ctx, mmgrab(current->mm); ctx->sqo_mm = current->mm; - ctx->sq_thread_idle = msecs_to_jiffies(p->sq_thread_idle); - if (!ctx->sq_thread_idle) - ctx->sq_thread_idle = HZ; - ret = -EINVAL; if (!cpu_possible(p->sq_thread_cpu)) goto err; @@ -2254,10 +2250,18 @@ static int io_sq_offload_start(struct io_ring_ctx *ctx, if (!capable(CAP_SYS_ADMIN)) goto err; + ctx->sq_thread_idle = msecs_to_jiffies(p->sq_thread_idle); + if (!ctx->sq_thread_idle) + ctx->sq_thread_idle = HZ; + if (p->flags & IORING_SETUP_SQ_AFF) { int cpu; cpu = array_index_nospec(p->sq_thread_cpu, NR_CPUS); + ret = -EINVAL; + if (!cpu_possible(p->sq_thread_cpu)) + goto err; + ctx->sqo_thread = kthread_create_on_cpu(io_sq_thread, ctx, cpu, "io_uring-sq"); -- 2.30.2