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

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Date:   Mon, 06 Sep 2021 18:14:48 +0900
From:   Jaewon Kim <jaewon31.kim@...sung.com>
To:     Christoph Hellwig <hch@...radead.org>,
        Jaewon Kim <jaewon31.kim@...sung.com>
CC:     "minchan@...nel.org" <minchan@...nel.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

> 
> 
>--------- 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>
>> ---
>>  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