On 2021/02/17 4:42, Dan Carpenter wrote:
> Hello Johannes Thumshirn,
>
> The patch 5795eb443060: "scsi: sd_zbc: emulate ZONE_APPEND commands"
> from May 12, 2020, leads to the following static checker warning:
>
> drivers/scsi/sd_zbc.c:741 sd_zbc_revalidate_zones()
> error: kvmalloc() only makes sense with GFP_KERNEL
>
> drivers/scsi/sd_zbc.c
> 721 /*
> 722 * There is nothing to do for regular disks, including host-aware disks
> 723 * that have partitions.
> 724 */
> 725 if (!blk_queue_is_zoned(q))
> 726 return 0;
> 727
> 728 /*
> 729 * Make sure revalidate zones are serialized to ensure exclusive
> 730 * updates of the scsi disk data.
> 731 */
> 732 mutex_lock(&sdkp->rev_mutex);
> 733
> 734 if (sdkp->zone_blocks == zone_blocks &&
> 735 sdkp->nr_zones == nr_zones &&
> 736 disk->queue->nr_zones == nr_zones)
> 737 goto unlock;
> 738
> 739 sdkp->zone_blocks = zone_blocks;
> 740 sdkp->nr_zones = nr_zones;
> 741 sdkp->rev_wp_offset = kvcalloc(nr_zones, sizeof(u32), GFP_NOIO);
> ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
> We're passing GFP_NOIO here so it just defaults to kcalloc() and will
> not vmalloc() the memory.
Indeed... And the allocation can get a little too big for kmalloc().
Johannes, I think we need to move that allocation before the rev_mutex locking,
using a local var for the allocated address, and then using GFP_KERNEL should be
safe... But not entirely sure. Using kmalloc would be simpler but on large SMR
drives, that allocation will soon need to be 400K or so (i.e. 100,000 zones or
even more), too large for kmalloc to succeed reliably.
>
> 742 if (!sdkp->rev_wp_offset) {
> 743 ret = -ENOMEM;
> 744 goto unlock;
> 745 }
> 746
> 747 ret = blk_revalidate_disk_zones(disk, sd_zbc_revalidate_zones_cb);
> 748
>
> regards,
> dan carpenter
>
--
Damien Le Moal
Western Digital Research
