Re: [dm-devel] [PATCH 01/19] fs: remove mpage_alloc

[Guenter Roeck <linux@roeck-us.net>]

On Wed, Mar 23, 2022 at 07:42:48AM +0100, Christoph Hellwig wrote:
> On Wed, Mar 23, 2022 at 06:38:22AM +0900, Ryusuke Konishi wrote:
> > This looks because the mask of GFP_KERNEL is removed along with
> > the removal of mpage_alloc().
> > 
> 
> > The default value of the gfp flag is set to GFP_HIGHUSER_MOVABLE by
> > inode_init_always().
> > So, __GFP_HIGHMEM hits the gfp warning at bio_alloc() that
> > do_mpage_readpage() calls.
> 
> Yeah.  Let's try this to match the iomap code:
> 
> diff --git a/fs/mpage.c b/fs/mpage.c
> index 9ed1e58e8d70b..d465883edf719 100644
> --- a/fs/mpage.c
> +++ b/fs/mpage.c
> @@ -148,13 +148,11 @@ static struct bio *do_mpage_readpage(struct mpage_readpage_args *args)
>  	int op = REQ_OP_READ;
>  	unsigned nblocks;
>  	unsigned relative_block;
> -	gfp_t gfp;
> +	gfp_t gfp = mapping_gfp_constraint(page->mapping, GFP_KERNEL);
>  
>  	if (args->is_readahead) {
>  		op |= REQ_RAHEAD;
> -		gfp = readahead_gfp_mask(page->mapping);
> -	} else {
> -		gfp = mapping_gfp_constraint(page->mapping, GFP_KERNEL);
> +		gfp |= __GFP_NORETRY | __GFP_NOWARN;
>  	}
>  
>  	if (page_has_buffers(page))

That fixes the problem for me.

Tested-by: Guenter Roeck <linux@roeck-us.net>

Guenter