On Tue, Oct 10, 2023 at 06:04:48PM -0400, Alexander Aring wrote:
> If there is a burst of message the receive worker will filling up the
> processing queue but where are too slow to process dlm messages. This
> patch will slow down the receiver worker to keep the buffer on the
> socket layer to tell the sender to backoff. This is done by a threshold
> to get the next buffers from the socket after all messages were
> processed done by a flush_workqueue(). This however only occurs when we
> have a message burst when we e.g. create 1 million locks. If we put more
> and more new messages to process in the processqueue we will soon run out
> of memory.
>
> Signed-off-by: Alexander Aring <aahri...@redhat.com>
> ---
> fs/dlm/lowcomms.c | 12 ++++++++++++
> 1 file changed, 12 insertions(+)
>
> diff --git a/fs/dlm/lowcomms.c b/fs/dlm/lowcomms.c
> index f7bc22e74db2..67f8dd8a05ef 100644
> --- a/fs/dlm/lowcomms.c
> +++ b/fs/dlm/lowcomms.c
> @@ -63,6 +63,7 @@
> #include "config.h"
>
> #define DLM_SHUTDOWN_WAIT_TIMEOUT msecs_to_jiffies(5000)
> +#define DLM_MAX_PROCESS_BUFFERS 24
> #define NEEDED_RMEM (4*1024*1024)
>
> struct connection {
> @@ -194,6 +195,7 @@ static const struct dlm_proto_ops *dlm_proto_ops;
> #define DLM_IO_END 1
> #define DLM_IO_EOF 2
> #define DLM_IO_RESCHED 3
> +#define DLM_IO_FLUSH 4
>
> static void process_recv_sockets(struct work_struct *work);
> static void process_send_sockets(struct work_struct *work);
> @@ -202,6 +204,7 @@ static void process_dlm_messages(struct work_struct
> *work);
> static DECLARE_WORK(process_work, process_dlm_messages);
> static DEFINE_SPINLOCK(processqueue_lock);
> static bool process_dlm_messages_pending;
> +static atomic_t processqueue_count;
> static LIST_HEAD(processqueue);
>
> bool dlm_lowcomms_is_running(void)
> @@ -874,6 +877,7 @@ static void process_dlm_messages(struct work_struct *work)
> }
>
> list_del(&pentry->list);
> + atomic_dec(&processqueue_count);
> spin_unlock(&processqueue_lock);
>
> for (;;) {
> @@ -891,6 +895,7 @@ static void process_dlm_messages(struct work_struct *work)
> }
>
> list_del(&pentry->list);
> + atomic_dec(&processqueue_count);
> spin_unlock(&processqueue_lock);
> }
> }
> @@ -962,6 +967,7 @@ static int receive_from_sock(struct connection *con, int
> buflen)
> con->rx_leftover);
>
> spin_lock(&processqueue_lock);
> + ret = atomic_inc_return(&processqueue_count);
> list_add_tail(&pentry->list, &processqueue);
> if (!process_dlm_messages_pending) {
> process_dlm_messages_pending = true;
> @@ -969,6 +975,9 @@ static int receive_from_sock(struct connection *con, int
> buflen)
> }
> spin_unlock(&processqueue_lock);
>
> + if (ret > DLM_MAX_PROCESS_BUFFERS)
> + return DLM_IO_FLUSH;
> +
> return DLM_IO_SUCCESS;
> }
>
> @@ -1503,6 +1512,9 @@ static void process_recv_sockets(struct work_struct
> *work)
> wake_up(&con->shutdown_wait);
> /* CF_RECV_PENDING cleared */
> break;
> + case DLM_IO_FLUSH:
> + flush_workqueue(process_workqueue);
> + fallthrough;
> case DLM_IO_RESCHED:
> cond_resched();
> queue_work(io_workqueue, &con->rwork);
> --
> 2.39.3
>
<formletter>
This is not the correct way to submit patches for inclusion in the
stable kernel tree. Please read:
https://www.kernel.org/doc/html/latest/process/stable-kernel-rules.html
for how to do this properly.
</formletter>
