* [PATCH 5.15] io-wq: max_worker fixes
@ 2021-10-19 19:31 Pavel Begunkov
2021-10-19 19:41 ` Jens Axboe
2021-10-19 22:54 ` Pavel Begunkov
0 siblings, 2 replies; 4+ messages in thread
From: Pavel Begunkov @ 2021-10-19 19:31 UTC (permalink / raw)
To: io-uring; +Cc: Jens Axboe, asml.silence
First, fix nr_workers checks against max_workers, with max_worker
registration, it may pretty easily happen that nr_workers > max_workers.
Also, synchronise writing to acct->max_worker with wqe->lock. It's not
an actual problem, but as we don't care about io_wqe_create_worker(),
it's better than WRITE_ONCE()/READ_ONCE().
Fixes: 2e480058ddc2 ("io-wq: provide a way to limit max number of workers")
Signed-off-by: Pavel Begunkov <[email protected]>
---
fs/io-wq.c | 7 +++++--
1 file changed, 5 insertions(+), 2 deletions(-)
diff --git a/fs/io-wq.c b/fs/io-wq.c
index 811299ac9684..cdf1719f6be6 100644
--- a/fs/io-wq.c
+++ b/fs/io-wq.c
@@ -253,7 +253,7 @@ static bool io_wqe_create_worker(struct io_wqe *wqe, struct io_wqe_acct *acct)
pr_warn_once("io-wq is not configured for unbound workers");
raw_spin_lock(&wqe->lock);
- if (acct->nr_workers == acct->max_workers) {
+ if (acct->nr_workers >= acct->max_workers) {
raw_spin_unlock(&wqe->lock);
return true;
}
@@ -1290,15 +1290,18 @@ int io_wq_max_workers(struct io_wq *wq, int *new_count)
rcu_read_lock();
for_each_node(node) {
+ struct io_wqe *wqe = wq->wqes[node];
struct io_wqe_acct *acct;
+ raw_spin_lock(&wqe->lock);
for (i = 0; i < IO_WQ_ACCT_NR; i++) {
- acct = &wq->wqes[node]->acct[i];
+ acct = &wqe->acct[i];
prev = max_t(int, acct->max_workers, prev);
if (new_count[i])
acct->max_workers = new_count[i];
new_count[i] = prev;
}
+ raw_spin_unlock(&wqe->lock);
}
rcu_read_unlock();
return 0;
--
2.33.0
^ permalink raw reply related [flat|nested] 4+ messages in thread
* Re: [PATCH 5.15] io-wq: max_worker fixes
2021-10-19 19:31 [PATCH 5.15] io-wq: max_worker fixes Pavel Begunkov
@ 2021-10-19 19:41 ` Jens Axboe
2021-10-19 22:54 ` Pavel Begunkov
1 sibling, 0 replies; 4+ messages in thread
From: Jens Axboe @ 2021-10-19 19:41 UTC (permalink / raw)
To: Pavel Begunkov, io-uring; +Cc: Jens Axboe
On Tue, 19 Oct 2021 20:31:26 +0100, Pavel Begunkov wrote:
> First, fix nr_workers checks against max_workers, with max_worker
> registration, it may pretty easily happen that nr_workers > max_workers.
>
> Also, synchronise writing to acct->max_worker with wqe->lock. It's not
> an actual problem, but as we don't care about io_wqe_create_worker(),
> it's better than WRITE_ONCE()/READ_ONCE().
>
> [...]
Applied, thanks!
[1/1] io-wq: max_worker fixes
commit: 9f7f7ea493a1d5c202760cd6145d6dde744f71a2
Best regards,
--
Jens Axboe
^ permalink raw reply [flat|nested] 4+ messages in thread
* Re: [PATCH 5.15] io-wq: max_worker fixes
2021-10-19 19:31 [PATCH 5.15] io-wq: max_worker fixes Pavel Begunkov
2021-10-19 19:41 ` Jens Axboe
@ 2021-10-19 22:54 ` Pavel Begunkov
2021-10-19 23:09 ` Jens Axboe
1 sibling, 1 reply; 4+ messages in thread
From: Pavel Begunkov @ 2021-10-19 22:54 UTC (permalink / raw)
To: io-uring, Jens Axboe; +Cc: Beld Zhang
On 10/19/21 20:31, Pavel Begunkov wrote:
> First, fix nr_workers checks against max_workers, with max_worker
> registration, it may pretty easily happen that nr_workers > max_workers.
>
> Also, synchronise writing to acct->max_worker with wqe->lock. It's not
> an actual problem, but as we don't care about io_wqe_create_worker(),
> it's better than WRITE_ONCE()/READ_ONCE().
Jens, can you add
Reported-by: Beld Zhang <[email protected]>
>
> Fixes: 2e480058ddc2 ("io-wq: provide a way to limit max number of workers")
> Signed-off-by: Pavel Begunkov <[email protected]>
> ---
> fs/io-wq.c | 7 +++++--
> 1 file changed, 5 insertions(+), 2 deletions(-)
>
> diff --git a/fs/io-wq.c b/fs/io-wq.c
> index 811299ac9684..cdf1719f6be6 100644
> --- a/fs/io-wq.c
> +++ b/fs/io-wq.c
> @@ -253,7 +253,7 @@ static bool io_wqe_create_worker(struct io_wqe *wqe, struct io_wqe_acct *acct)
> pr_warn_once("io-wq is not configured for unbound workers");
>
> raw_spin_lock(&wqe->lock);
> - if (acct->nr_workers == acct->max_workers) {
> + if (acct->nr_workers >= acct->max_workers) {
> raw_spin_unlock(&wqe->lock);
> return true;
> }
> @@ -1290,15 +1290,18 @@ int io_wq_max_workers(struct io_wq *wq, int *new_count)
>
> rcu_read_lock();
> for_each_node(node) {
> + struct io_wqe *wqe = wq->wqes[node];
> struct io_wqe_acct *acct;
>
> + raw_spin_lock(&wqe->lock);
> for (i = 0; i < IO_WQ_ACCT_NR; i++) {
> - acct = &wq->wqes[node]->acct[i];
> + acct = &wqe->acct[i];
> prev = max_t(int, acct->max_workers, prev);
> if (new_count[i])
> acct->max_workers = new_count[i];
> new_count[i] = prev;
> }
> + raw_spin_unlock(&wqe->lock);
> }
> rcu_read_unlock();
> return 0;
>
--
Pavel Begunkov
^ permalink raw reply [flat|nested] 4+ messages in thread
* Re: [PATCH 5.15] io-wq: max_worker fixes
2021-10-19 22:54 ` Pavel Begunkov
@ 2021-10-19 23:09 ` Jens Axboe
0 siblings, 0 replies; 4+ messages in thread
From: Jens Axboe @ 2021-10-19 23:09 UTC (permalink / raw)
To: Pavel Begunkov, io-uring; +Cc: Beld Zhang
On 10/19/21 4:54 PM, Pavel Begunkov wrote:
> On 10/19/21 20:31, Pavel Begunkov wrote:
>> First, fix nr_workers checks against max_workers, with max_worker
>> registration, it may pretty easily happen that nr_workers > max_workers.
>>
>> Also, synchronise writing to acct->max_worker with wqe->lock. It's not
>> an actual problem, but as we don't care about io_wqe_create_worker(),
>> it's better than WRITE_ONCE()/READ_ONCE().
>
> Jens, can you add
>
> Reported-by: Beld Zhang <[email protected]>
Yep, done.
--
Jens Axboe
^ permalink raw reply [flat|nested] 4+ messages in thread
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2021-10-19 19:31 [PATCH 5.15] io-wq: max_worker fixes Pavel Begunkov
2021-10-19 19:41 ` Jens Axboe
2021-10-19 22:54 ` Pavel Begunkov
2021-10-19 23:09 ` Jens Axboe
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