From: Sergey Senozhatsky <sergey.senozhatsky.work@gmail.com>
To: Jia-Ju Bai <baijiaju1990@gmail.com>
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 <akpm@linux-foundation.org>
Subject: Re: [PATCH] block: zram: Replace GFP_ATOMIC with GFP_KERNEL
Date: Tue, 24 Jul 2018 11:52:28 +0900 [thread overview]
Message-ID: <20180724025228.GA558@jagdpanzerIV> (raw)
In-Reply-To: <20180723141304.3300-1-baijiaju1990@gmail.com>
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
prev parent reply other threads:[~2018-07-24 2:52 UTC|newest]
Thread overview: 2+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-07-23 14:13 [PATCH] block: zram: Replace GFP_ATOMIC with GFP_KERNEL Jia-Ju Bai
2018-07-24 2:52 ` Sergey Senozhatsky [this message]
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