On Tue, 23 Jan 2024, Johannes Thumshirn wrote:
> The call to blkdev_zone_mgmt() in dm-zoned is only used to perform a
> ZONE_RESET operation when freeing a zone.
>
> This is not done in the IO path, so we can use GFP_KERNEL here, as it will
> never recurse back into the driver on reclaim.
Hi
This doesn't seem safe to me. There's a possible call chain dmz_handle_bio
-> dmz_put_chunk_mapping -> dmz_free_zone -> dmz_reset_zone ->
blkdev_zone_mgmt -> recursion (via GFP_KERNEL) back into the dm-zoned
target.
Mikulas
> Signed-off-by: Johannes Thumshirn <johannes.thumshirn@xxxxxxx>
> ---
> drivers/md/dm-zoned-metadata.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/drivers/md/dm-zoned-metadata.c b/drivers/md/dm-zoned-metadata.c
> index fdfe30f7b697..a39734f0cb7d 100644
> --- a/drivers/md/dm-zoned-metadata.c
> +++ b/drivers/md/dm-zoned-metadata.c
> @@ -1658,7 +1658,7 @@ static int dmz_reset_zone(struct dmz_metadata *zmd, struct dm_zone *zone)
>
> ret = blkdev_zone_mgmt(dev->bdev, REQ_OP_ZONE_RESET,
> dmz_start_sect(zmd, zone),
> - zmd->zone_nr_sectors, GFP_NOIO);
> + zmd->zone_nr_sectors, GFP_KERNEL);
> if (ret) {
> dmz_dev_err(dev, "Reset zone %u failed %d",
> zone->id, ret);
>
> --
> 2.43.0
>
>
