linux-kernel - Re: [PATCH v5 1/2] erofs: avoid memory allocation failure during rolling decompression

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Date:   Tue, 16 Mar 2021 09:11:02 +0800
From:   Chao Yu <yuchao0@...wei.com>
To:     Huang Jianan <huangjianan@...o.com>
CC:     <zhangshiming@...o.com>, <guoweichao@...o.com>,
        <linux-erofs@...ts.ozlabs.org>, <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v5 1/2] erofs: avoid memory allocation failure during
 rolling decompression

On 2021/3/5 17:58, Huang Jianan via Linux-erofs wrote:
> Currently, err would be treated as io error. Therefore, it'd be
> better to ensure memory allocation during rolling decompression
> to avoid such io error.
> 
> In the long term, we might consider adding another !Uptodate case
> for such case.
> 
> Signed-off-by: Huang Jianan <huangjianan@...o.com>
> Signed-off-by: Guo Weichao <guoweichao@...o.com>
> ---
>   fs/erofs/decompressor.c | 3 ++-
>   1 file changed, 2 insertions(+), 1 deletion(-)
> 
> diff --git a/fs/erofs/decompressor.c b/fs/erofs/decompressor.c
> index 1cb1ffd10569..3d276a8aad86 100644
> --- a/fs/erofs/decompressor.c
> +++ b/fs/erofs/decompressor.c
> @@ -73,7 +73,8 @@ static int z_erofs_lz4_prepare_destpages(struct z_erofs_decompress_req *rq,
>   			victim = availables[--top];
>   			get_page(victim);
>   		} else {
> -			victim = erofs_allocpage(pagepool, GFP_KERNEL);
> +			victim = erofs_allocpage(pagepool,
> +						 GFP_KERNEL | __GFP_NOFAIL);
>   			if (!victim)
>   				return -ENOMEM;

A little bit weird that we still need to check return value of erofs_allocpage()
after we pass __GFP_NOFAIL parameter.

Thanks,

>   			set_page_private(victim, Z_EROFS_SHORTLIVED_PAGE);
>