linux-kernel - Re: (2) [PATCH] zram_drv: allow reclaim on bio

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Date:   Tue, 7 Sep 2021 10:00:35 -0700
From:   Minchan Kim <minchan@...nel.org>
To:     Jaewon Kim <jaewon31.kim@...sung.com>
Cc:     Christoph Hellwig <hch@...radead.org>,
        "akpm@...ux-foundation.org" <akpm@...ux-foundation.org>,
        "linux-mm@...ck.org" <linux-mm@...ck.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        YongTaek Lee <ytk.lee@...sung.com>,
        "jaewon31.kim@...il.com" <jaewon31.kim@...il.com>
Subject: Re: (2) [PATCH] zram_drv: allow reclaim on bio_alloc

Hi Jaewon,

On Mon, Sep 06, 2021 at 06:14:48PM +0900, Jaewon Kim wrote:
> > 
> > 
> >--------- Original Message ---------
> >Sender : Christoph Hellwig <hch@...radead.org>
> >Date : 2021-09-06 17:39 (GMT+9)
> >Title : Re: [PATCH] zram_drv: allow reclaim on bio_alloc
> > 
> >On Mon, Sep 06, 2021 at 02:29:26PM +0900, Jaewon Kim wrote:
> >> The read_from_bdev_async is not called on atomic context. So GFP_NOIO is
> >> available rather than GFP_ATOMIC. If there were reclaimable pages with
> >> GFP_NOIO, we can avoid allocation failure and page fault failure.
> >> 
> >> Reported-by: Yong-Taek Lee <ytk.lee@...sung.com>
> >> Signed-off-by: Jaewon Kim <jaewon31.kim@...sung.com>

Looks reasonable to me.
Feel free to add after dealing with Christoph's comment.

Acked-by: Minchan Kim <minchan@...nel.org>

Thank you.

> >> ---
> >>  drivers/block/zram/zram_drv.c | 2 +-
> >>  1 file changed, 1 insertion(+), 1 deletion(-)
> >> 
> >> diff --git a/drivers/block/zram/zram_drv.c b/drivers/block/zram/zram_drv.c
> >> index fcaf2750f68f..53be528a39a2 100644
> >> --- a/drivers/block/zram/zram_drv.c
> >> +++ b/drivers/block/zram/zram_drv.c
> >> @@ -587,7 +587,7 @@ static int read_from_bdev_async(struct zram *zram, struct bio_vec *bvec,
> >>  {
> >>          struct bio *bio;
> >>  
> >> -        bio = bio_alloc(GFP_ATOMIC, 1);
> >> +        bio = bio_alloc(GFP_NOIO|__GFP_HIGHMEM, 1);
> > 
> >Passing __GFP_HIGHMEM to bio_alloc does not make any sense whatsoever.
> > 
> Correct, let me remove __GFP_HIGHMEM if I send v2 patch.
> Thank you