Re: [PATCH] zram: set physical queue limits to avoid array out of bounds accesses

[Minchan Kim]

On Wed, Mar 08, 2017 at 08:58:02AM +0100, Johannes Thumshirn wrote:
> On 03/08/2017 06:11 AM, Minchan Kim wrote:
> > And could you test this patch? It avoids split bio so no need new bio
> > allocations and makes zram code simple.
> > 
> > From f778d7564d5cd772f25bb181329362c29548a257 Mon Sep 17 00:00:00 2001
> > From: Minchan Kim <minchan@xxxxxxxxxx>
> > Date: Wed, 8 Mar 2017 13:35:29 +0900
> > Subject: [PATCH] fix
> > 
> > Not-yet-Signed-off-by: Minchan Kim <minchan@xxxxxxxxxx>
> > ---
> 
> [...]
> 
> Yup, this works here.
> 
> I did a mkfs.xfs /dev/nvme0n1
> dd if=/dev/urandom of=/test.bin bs=1M count=128
> sha256sum test.bin
> mount /dev/nvme0n1 /dir
> mv test.bin /dir/
> sha256sum /dir/test.bin
> 
> No panics and sha256sum of the 128MB test file still matches
> 
> Tested-by: Johannes Thumshirn <jthumshirn@xxxxxxx>
> Reviewed-by: Johannes Thumshirn <jthumshirn@xxxxxxx>

Thanks a lot, Johannes and Hannes!!

> 
> Now that you removed the one page limit in zram_bvec_rw() you can also
> add this hunk to remove the queue splitting:

Right. I added what you suggested with detailed description.

> 
> diff --git a/drivers/block/zram/zram_drv.c b/drivers/block/zram/zram_drv.c
> index 85f4df8..27b168f6 100644
> --- a/drivers/block/zram/zram_drv.c
> +++ b/drivers/block/zram/zram_drv.c
> @@ -868,8 +868,6 @@ static blk_qc_t zram_make_request(struct
> request_queue *queue, struct bio *bio)
>  {
>         struct zram *zram = queue->queuedata;
> 
> -       blk_queue_split(queue, &bio, queue->bio_split);
> -
>         if (!valid_io_request(zram, bio->bi_iter.bi_sector,
>                                         bio->bi_iter.bi_size)) {
>                 atomic64_inc(&zram->stats.invalid_io);
> 
> Byte,
> 	Johannes
> 

Jens, Could you replace the one merged with this? And I don't want
to add stable mark in this patch because I feel it need enough
testing in 64K page system I don't have. ;(