On 3/11/25 17:59, Uladzislau Rezki (Sony) wrote:
The first line of the changelog needs to say:
commit dfd3df31c9db752234d7d2e09bef2aeabb643ce4 upstream.
I think Greg prefers if you resend with that fixed rather than fixing up
locally.
If the same backport applies to both 6.12 and 6.13 (it seems to me it does?)
I guess a single mail with [PATCH 6.12.y 6.13.y] could be enough.
> Apart of that, since kvfree_rcu() does reclaim memory it is worth
> to go with WQ_MEM_RECLAIM type of wq because it is designed for
> this purpose.
>
> Fixes: 6c6c47b063b5 ("mm, slab: call kvfree_rcu_barrier() from kmem_cache_destroy()"),
> Reported-by: Keith Busch <kbusch@xxxxxxxxxx>
> Closes: https://lore.kernel.org/all/Z7iqJtCjHKfo8Kho@kbusch-mbp/
> Cc: stable@xxxxxxxxxxxxxxx
> Signed-off-by: Uladzislau Rezki (Sony) <urezki@xxxxxxxxx>
> Reviewed-by: Joel Fernandes <joelagnelf@xxxxxxxxxx>
> Signed-off-by: Vlastimil Babka <vbabka@xxxxxxx>
I don't know if you need to add another
Signed-off-by: Uladzislau Rezki (Sony) <urezki@xxxxxxxxx>
opinions on that differ and not sure where stable stands...
(does "git commit -s" add it or detects your previous one?)
Thanks!
> ---
> kernel/rcu/tree.c | 14 ++++++++++----
> 1 file changed, 10 insertions(+), 4 deletions(-)
>
> diff --git a/kernel/rcu/tree.c b/kernel/rcu/tree.c
> index ff98233d4aa5..4703b08fb882 100644
> --- a/kernel/rcu/tree.c
> +++ b/kernel/rcu/tree.c
> @@ -3191,6 +3191,8 @@ void call_rcu(struct rcu_head *head, rcu_callback_t func)
> }
> EXPORT_SYMBOL_GPL(call_rcu);
>
> +static struct workqueue_struct *rcu_reclaim_wq;
> +
> /* Maximum number of jiffies to wait before draining a batch. */
> #define KFREE_DRAIN_JIFFIES (5 * HZ)
> #define KFREE_N_BATCHES 2
> @@ -3519,10 +3521,10 @@ __schedule_delayed_monitor_work(struct kfree_rcu_cpu *krcp)
> if (delayed_work_pending(&krcp->monitor_work)) {
> delay_left = krcp->monitor_work.timer.expires - jiffies;
> if (delay < delay_left)
> - mod_delayed_work(system_unbound_wq, &krcp->monitor_work, delay);
> + mod_delayed_work(rcu_reclaim_wq, &krcp->monitor_work, delay);
> return;
> }
> - queue_delayed_work(system_unbound_wq, &krcp->monitor_work, delay);
> + queue_delayed_work(rcu_reclaim_wq, &krcp->monitor_work, delay);
> }
>
> static void
> @@ -3620,7 +3622,7 @@ kvfree_rcu_queue_batch(struct kfree_rcu_cpu *krcp)
> // "free channels", the batch can handle. Break
> // the loop since it is done with this CPU thus
> // queuing an RCU work is _always_ success here.
> - queued = queue_rcu_work(system_unbound_wq, &krwp->rcu_work);
> + queued = queue_rcu_work(rcu_reclaim_wq, &krwp->rcu_work);
> WARN_ON_ONCE(!queued);
> break;
> }
> @@ -3708,7 +3710,7 @@ run_page_cache_worker(struct kfree_rcu_cpu *krcp)
> if (rcu_scheduler_active == RCU_SCHEDULER_RUNNING &&
> !atomic_xchg(&krcp->work_in_progress, 1)) {
> if (atomic_read(&krcp->backoff_page_cache_fill)) {
> - queue_delayed_work(system_unbound_wq,
> + queue_delayed_work(rcu_reclaim_wq,
> &krcp->page_cache_work,
> msecs_to_jiffies(rcu_delay_page_cache_fill_msec));
> } else {
> @@ -5654,6 +5656,10 @@ static void __init kfree_rcu_batch_init(void)
> int i, j;
> struct shrinker *kfree_rcu_shrinker;
>
> + rcu_reclaim_wq = alloc_workqueue("kvfree_rcu_reclaim",
> + WQ_UNBOUND | WQ_MEM_RECLAIM, 0);
> + WARN_ON(!rcu_reclaim_wq);
> +
> /* Clamp it to [0:100] seconds interval. */
> if (rcu_delay_page_cache_fill_msec < 0 ||
> rcu_delay_page_cache_fill_msec > 100 * MSEC_PER_SEC) {
