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

[Christoph Hellwig <hch@lst.de>]

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))