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

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Message-ID: <20210316012911.GA931077@xiangao.remote.csb>
Date:   Tue, 16 Mar 2021 09:29:11 +0800
From:   Gao Xiang <hsiangkao@...hat.com>
To:     Chao Yu <yuchao0@...wei.com>, Huang Jianan <huangjianan@...o.com>
Cc:     zhangshiming@...o.com, linux-erofs@...ts.ozlabs.org,
        guoweichao@...o.com, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v5 1/2] erofs: avoid memory allocation failure during
 rolling decompression

On Tue, Mar 16, 2021 at 09:11:02AM +0800, Chao Yu wrote:
> 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.

Yeah, good point! sorry I forgot that.

Jianan,
Could you take some time resending the next version with all new things
updated?... thus Chao could review easily, Thanks!

Thanks,
Gao Xiang

> 
> Thanks,
> 
> >   			set_page_private(victim, Z_EROFS_SHORTLIVED_PAGE);
> > 
>