On 2020/11/05 16:17, Damien Le Moal wrote:
> Commit aa1c09cb65e2 ("null_blk: Fix locking in zoned mode") changed zone
> locking to using the potentially sleeping wait_on_bit_io() function. A
> zoned null_blk device must thus be marked as blocking to avoid calls to
> queue_rq() from invalid contexts triggering might_sleep() warnings.
>
> Reported-by: kernel test robot <lkp@xxxxxxxxx>
> Fixes: aa1c09cb65e2 ("null_blk: Fix locking in zoned mode")
> Cc: stable@xxxxxxxxxxxxxxx
> Signed-off-by: Damien Le Moal <damien.lemoal@xxxxxxx>
Jens,
Please ignore this patch. Sending shortly another one that removes the need for
BLK_MQ_F_BLOCKING when memory backing is disabled.
> ---
> Changes from v1:
> * Add "|| g_zoned" to condition for setting blocking to correctly handle
> creation through modprobe.
>
> drivers/block/null_blk_main.c | 9 +++++----
> 1 file changed, 5 insertions(+), 4 deletions(-)
>
> diff --git a/drivers/block/null_blk_main.c b/drivers/block/null_blk_main.c
> index 4685ea401d5b..6bcf95d611a3 100644
> --- a/drivers/block/null_blk_main.c
> +++ b/drivers/block/null_blk_main.c
> @@ -1714,7 +1714,7 @@ static int null_init_tag_set(struct nullb *nullb, struct blk_mq_tag_set *set)
> set->flags |= BLK_MQ_F_TAG_HCTX_SHARED;
> set->driver_data = NULL;
>
> - if ((nullb && nullb->dev->blocking) || g_blocking)
> + if ((nullb && nullb->dev->blocking) || g_blocking || g_zoned)
> set->flags |= BLK_MQ_F_BLOCKING;
>
> return blk_mq_alloc_tag_set(set);
> @@ -1736,10 +1736,11 @@ static int null_validate_conf(struct nullb_device *dev)
> dev->queue_mode = min_t(unsigned int, dev->queue_mode, NULL_Q_MQ);
> dev->irqmode = min_t(unsigned int, dev->irqmode, NULL_IRQ_TIMER);
>
> - /* Do memory allocation, so set blocking */
> - if (dev->memory_backed)
> + /* Memory allocation and zone handling may sleep, so set blocking */
> + if (dev->memory_backed || dev->zoned)
> dev->blocking = true;
> - else /* cache is meaningless */
> + /* Cache is meaningless without memory backing */
> + if (!dev->memory_backed)
> dev->cache_size = 0;
> dev->cache_size = min_t(unsigned long, ULONG_MAX / 1024 / 1024,
> dev->cache_size);
>
--
Damien Le Moal
Western Digital Research
