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io-wq: ensure all pending work is canceled on exit 

If we race on shutting down the io-wq, then we should ensure that any
work that was queued after workers shutdown is canceled. Harden the
add work check a bit too, checking for IO_WQ_BIT_EXIT and cancel if
it's set.

Add a WARN_ON() for having any work before we kill the io-wq context.

Reported-by: syzbot+91b4b56ead187d35c9d3@syzkaller.appspotmail.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
This commit is contained in:
Jens Axboe 2021-03-03 15:47:04 -07:00
parent e4b4a13f49
commit f01272541d
1 changed files with 33 additions and 9 deletions
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42
fs/io-wq.c
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@ -129,6 +129,17 @@ struct io_wq {
static enum cpuhp_state io_wq_online;
struct io_cb_cancel_data {
work_cancel_fn *fn;
void *data;
int nr_running;
int nr_pending;
bool cancel_all;
};
static void io_wqe_cancel_pending_work(struct io_wqe *wqe,
struct io_cb_cancel_data *match);
static bool io_worker_get(struct io_worker *worker)
{
return refcount_inc_not_zero(&worker->ref);
@ -713,6 +724,23 @@ static void io_wq_check_workers(struct io_wq *wq)
}
}
static bool io_wq_work_match_all(struct io_wq_work *work, void *data)
{
return true;
}
static void io_wq_cancel_pending(struct io_wq *wq)
{
struct io_cb_cancel_data match = {
.fn = io_wq_work_match_all,
.cancel_all = true,
};
int node;
for_each_node(node)
io_wqe_cancel_pending_work(wq->wqes[node], &match);
}
/*
* Manager thread. Tasked with creating new workers, if we need them.
*/
@ -748,6 +776,8 @@ static int io_wq_manager(void *data)
/* we might not ever have created any workers */
if (atomic_read(&wq->worker_refs))
wait_for_completion(&wq->worker_done);
io_wq_cancel_pending(wq);
complete(&wq->exited);
do_exit(0);
}
@ -809,7 +839,8 @@ static void io_wqe_enqueue(struct io_wqe *wqe, struct io_wq_work *work)
unsigned long flags;
/* Can only happen if manager creation fails after exec */
if (unlikely(io_wq_fork_manager(wqe->wq))) {
if (io_wq_fork_manager(wqe->wq) ||
test_bit(IO_WQ_BIT_EXIT, &wqe->wq->state)) {
work->flags |= IO_WQ_WORK_CANCEL;
wqe->wq->do_work(work);
return;
@ -845,14 +876,6 @@ void io_wq_hash_work(struct io_wq_work *work, void *val)
work->flags |= (IO_WQ_WORK_HASHED | (bit << IO_WQ_HASH_SHIFT));
}
struct io_cb_cancel_data {
work_cancel_fn *fn;
void *data;
int nr_running;
int nr_pending;
bool cancel_all;
};
static bool io_wq_worker_cancel(struct io_worker *worker, void *data)
{
struct io_cb_cancel_data *match = data;
@ -1086,6 +1109,7 @@ static void io_wq_destroy(struct io_wq *wq)
struct io_wqe *wqe = wq->wqes[node];
list_del_init(&wqe->wait.entry);
WARN_ON_ONCE(!wq_list_empty(&wqe->work_list));
kfree(wqe);
}
spin_unlock_irq(&wq->hash->wait.lock);