Re: [PATCH] raid5: fix incorrectly counter of conf->empty_inactive_list_nr

[Shaohua Li <shli@kernel.org>]

On Wed, Jul 20, 2016 at 05:22:00PM +0800, Zhengyuan Liu wrote:
> The counter conf->empty_inactive_list_nr is only used for determine if
> the raid5 is congested which is deal with in function
> raid5_congested(). It was increased in get_free_stripe() when
> conf->inactive_list got emptied and decreased in
> release_inactive_stripe_list() when  splice temp_inactive_list to
> conf->inactive_list. However, this could cause to problem when
> raid5_get_active_stripe was called, this function may call
> list_del_init(&sh->lru) to delete sh from  "conf->inactive_list +
> hash" which may cause  "conf->inactive_list + hash" to be empty when
> atomic_inc_not_zero(&sh->count) got false.
>  I have found conf->empty_inactive_list_nr to be negative number
> during my random test.
> Is there anything out of my thinking?

Good catch! I think you are right, we get a stripe from inactive list and
should decrement the count. Also we should do the same thing for
stripe_add_to_batch_list. Please resend the patch with proper format, see
Documentation/email-clients.txt

Thanks,
Shaohua