From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Return-Path: Date: Tue, 24 Jul 2018 11:52:28 +0900 From: Sergey Senozhatsky To: Jia-Ju Bai Cc: minchan@kernel.org, ngupta@vflare.org, sergey.senozhatsky.work@gmail.com, axboe@kernel.dk, linux-kernel@vger.kernel.org, linux-block@vger.kernel.org, Andrew Morton Subject: Re: [PATCH] block: zram: Replace GFP_ATOMIC with GFP_KERNEL Message-ID: <20180724025228.GA558@jagdpanzerIV> References: <20180723141304.3300-1-baijiaju1990@gmail.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii In-Reply-To: <20180723141304.3300-1-baijiaju1990@gmail.com> List-ID: On (07/23/18 22:13), Jia-Ju Bai wrote: > read_from_bdev_async() and write_to_bdev() are never called in atomic > context. They call bio_alloc() with GFP_ATOMIC, which is not necessary. > GFP_ATOMIC can be replaced with GFP_KERNEL. [..] > diff --git a/drivers/block/zram/zram_drv.c b/drivers/block/zram/zram_drv.c > index 0f3fadd71230..b958ed0b8c35 100644 > --- a/drivers/block/zram/zram_drv.c > +++ b/drivers/block/zram/zram_drv.c > @@ -450,7 +450,7 @@ 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_KERNEL, 1); > if (!bio) > return -ENOMEM; > > @@ -538,7 +538,7 @@ static int write_to_bdev(struct zram *zram, struct bio_vec *bvec, > struct bio *bio; > unsigned long entry; > > - bio = bio_alloc(GFP_ATOMIC, 1); > + bio = bio_alloc(GFP_KERNEL, 1); > if (!bio) > return -ENOMEM; I think the intent here is different and is not related to atomic contexts. Consider the following OMM -> swapout -> __zram_bvec_write() -> write_to_bdev() -> bio_alloc(GFP_KERNEL) -> [OOM?] So maybe we can do a bit better than GFP_ATOMIC (NOIO, etc.), but in general, I believe, we can't use GFP_KERNEL [at least in write_to_bdev()]. -ss