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Commit 917257da authored by Jens Axboe's avatar Jens Axboe
Browse files

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: default avatar <syzbot+cd714a07c6de2bc34293@syzkaller.appspotmail.com>
Fixes: 6c271ce2 ("io_uring: add submission polling")
Signed-off-by: default avatarJens Axboe <axboe@kernel.dk>
parent 06058632

fs/io_uring.c

+8 −4
Original line number Diff line number Diff line
@@ -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");