[RFC PATCH 01/26] block: bdev: blockdev page cache is movable

From: Johannes Weiner <hannes@cmpxchg.org>
To: linux-mm@kvack.org
Cc: Kaiyang Zhao <kaiyang2@cs.cmu.edu>,
	Mel Gorman <mgorman@techsingularity.net>,
	Vlastimil Babka <vbabka@suse.cz>,
	David Rientjes <rientjes@google.com>,
	linux-kernel@vger.kernel.org, kernel-team@fb.com
Subject: [RFC PATCH 01/26] block: bdev: blockdev page cache is movable
Date: Tue, 18 Apr 2023 15:12:48 -0400	[thread overview]
Message-ID: <20230418191313.268131-2-hannes@cmpxchg.org> (raw)
In-Reply-To: <20230418191313.268131-1-hannes@cmpxchg.org>

While inspecting page blocks for the type of pages in them, I noticed
a large number of blockdev cache in unmovable blocks. However, these
pages are actually on the LRU, and their mapping has a .migrate_folio
callback; they can be reclaimed and compacted as necessary.

Put them into movable blocks, so they don't cause pollution, and
subsequent proliferation, of unmovable blocks.

Signed-off-by: Johannes Weiner <hannes@cmpxchg.org>
---
 block/bdev.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/block/bdev.c b/block/bdev.c
index edc110d90df4..6abe4766d073 100644
--- a/block/bdev.c
+++ b/block/bdev.c
@@ -488,7 +488,7 @@ struct block_device *bdev_alloc(struct gendisk *disk, u8 partno)
 	inode->i_mode = S_IFBLK;
 	inode->i_rdev = 0;
 	inode->i_data.a_ops = &def_blk_aops;
-	mapping_set_gfp_mask(&inode->i_data, GFP_USER);
+	mapping_set_gfp_mask(&inode->i_data, GFP_USER|__GFP_MOVABLE);
 
 	bdev = I_BDEV(inode);
 	mutex_init(&bdev->bd_fsfreeze_mutex);
-- 
2.39.2

