Re: [PATCH] writeback: account BDI's min_ratio for unregistered device

[Tejun Heo]

On Mon, Aug 17, 2015 at 11:45:53PM +0900, Akinobu Mita wrote:
> From mm/page-writeback.c:
> 
> 	/*
> 	 * bdi_min_ratio keeps the sum of the minimum dirty shares of all
> 	 * registered backing devices, which, for obvious reasons, can not
> 	 * exceed 100%.
> 	 */
> 	static unsigned int bdi_min_ratio;
> 
> But when a backing device is unregistered, the BDI's min_ratio is not
> subtracted from bdi_min_ratio.  So the second attempt to set min_ratio
> in the following commands will fail.
> 
> 	# modprobe null_blk
> 	# echo 50 > /sys/block/nullb0/bdi/min_ratio
> 	# modprobe -r null_blk
> 	# modprobe null_blk
> 	# echo 50 > /sys/block/nullb0/bdi/min_ratio
> 
> Signed-off-by: Akinobu Mita <akinobu.mita@xxxxxxxxx>
> Cc: Tejun Heo <tj@xxxxxxxxxx>
> Cc: Jens Axboe <axboe@xxxxxxxxx>

Acked-by: Tejun Heo <tj@xxxxxxxxxx>

We probably want to cc stable too.

Thanks.

-- 
tejun
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/