diff options
| author | Jens Axboe <axboe@kernel.dk> | 2026-01-21 10:40:33 -0700 |
|---|---|---|
| committer | Jens Axboe <axboe@kernel.dk> | 2026-01-22 07:25:35 -0700 |
| commit | 1f293098a31368a5d5cfab215a56f4cbed3f657a (patch) | |
| tree | 7745b0269ab9e7d67c17e8b6efbee2ec24f1cb6b | |
| parent | dd120bddc43af583e3bc9afe75f58bb9280947b0 (diff) | |
io_uring/io-wq: don't trigger hung task for syzbot craziness
Use the same trick that blk_io_schedule() does to avoid triggering the
hung task warning (and potential reboot/panic, depending on system
settings), and only wait for half the hung task timeout at the time.
If we exceed the default IO_URING_EXIT_WAIT_MAX period where we expect
things to certainly have finished unless there's a bug, then throw a
WARN_ON_ONCE() for that case.
Reported-by: syzbot+4eb282331cab6d5b6588@syzkaller.appspotmail.com
Tested-by: syzbot+4eb282331cab6d5b6588@syzkaller.appspotmail.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
| -rw-r--r-- | io_uring/io-wq.c | 22 |
1 files changed, 21 insertions, 1 deletions
diff --git a/io_uring/io-wq.c b/io_uring/io-wq.c index cd13d8aac3d2..aaf1dfc21763 100644 --- a/io_uring/io-wq.c +++ b/io_uring/io-wq.c @@ -17,6 +17,7 @@ #include <linux/task_work.h> #include <linux/audit.h> #include <linux/mmu_context.h> +#include <linux/sched/sysctl.h> #include <uapi/linux/io_uring.h> #include "io-wq.h" @@ -1316,6 +1317,8 @@ static void io_wq_cancel_tw_create(struct io_wq *wq) static void io_wq_exit_workers(struct io_wq *wq) { + unsigned long timeout, warn_timeout; + if (!wq->task) return; @@ -1325,7 +1328,24 @@ static void io_wq_exit_workers(struct io_wq *wq) io_wq_for_each_worker(wq, io_wq_worker_wake, NULL); rcu_read_unlock(); io_worker_ref_put(wq); - wait_for_completion(&wq->worker_done); + + /* + * Shut up hung task complaint, see for example + * + * https://lore.kernel.org/all/696fc9e7.a70a0220.111c58.0006.GAE@google.com/ + * + * where completely overloading the system with tons of long running + * io-wq items can easily trigger the hung task timeout. Only sleep + * uninterruptibly for half that time, and warn if we exceeded end + * up waiting more than IO_URING_EXIT_WAIT_MAX. + */ + timeout = sysctl_hung_task_timeout_secs * HZ / 2; + warn_timeout = jiffies + IO_URING_EXIT_WAIT_MAX; + do { + if (wait_for_completion_timeout(&wq->worker_done, timeout)) + break; + WARN_ON_ONCE(time_after(jiffies, warn_timeout)); + } while (1); spin_lock_irq(&wq->hash->wait.lock); list_del_init(&wq->wait.entry); |