Hi Kamezawa,
I noticed that you are responding to emails right now.
Can you please review the patch below and tell me whether it is
technically correct ?
Or, can you please suggest a suitable change for solving this ?
Thanks.
Kautuk
On Wed, Aug 31, 2011 at 10:41 AM, Rajan Aggarwal
<rajan.aggarwal85@xxxxxxxxx> wrote:
> The bdi_writeback_thread function does not use spin_lock to
> see if the work_list is empty.
>
> If the list is not empty, and if an interrupt happens before we
> set the current->state to TASK_RUNNING then we could be stuck in
> a schedule() due to kernel preemption.
>
> This patch acquires and releases the wb_lock to avoid this scenario.
>
> Signed-off-by: Rajan Aggarwal <rajan.aggarwal85@xxxxxxxxx>
> ---
> fs/fs-writeback.c | 3 +++
> 1 files changed, 3 insertions(+), 0 deletions(-)
>
> diff --git a/fs/fs-writeback.c b/fs/fs-writeback.c
> index 04cf3b9..e333898 100644
> --- a/fs/fs-writeback.c
> +++ b/fs/fs-writeback.c
> @@ -936,11 +936,14 @@ int bdi_writeback_thread(void *data)
> if (pages_written)
> wb->last_active = jiffies;
>
> + spin_lock_bh(&bdi->wb_lock);
> set_current_state(TASK_INTERRUPTIBLE);
> if (!list_empty(&bdi->work_list) || kthread_should_stop()) {
> __set_current_state(TASK_RUNNING);
> + spin_unlock_bh(&bdi->wb_lock);
> continue;
> }
> + spin_unlock_bh(&bdi->wb_lock);
>
> if (wb_has_dirty_io(wb) && dirty_writeback_interval)
> schedule_timeout(msecs_to_jiffies(dirty_writeback_interval * 10));
> --
> 1.7.4.1
>
>
--
To unsubscribe from this list: send the line "unsubscribe linux-fsdevel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
