From de2d741edaeabd4e8fb56e83750f045088f6eb6d Mon Sep 17 00:00:00 2001
From: Jens Axboe <axboe@kernel.dk>
Date: Wed, 27 Sep 2017 06:08:57 -0600
Subject: [PATCH] buffer: eliminate the need to call free_more_memory() in
 __getblk_slow()

References: bnc#971975 VM performance -- memory usage during reclaim
Patch-mainline: v4.15-rc1
Git-commit: bc48f001de12225b6430a243504aa60b5ae8a91a

Since the previous commit removed any case where grow_buffers()
would return failure due to memory allocations, we can safely
remove the case where we have to call free_more_memory() in
this function.

Since this is also the last user of free_more_memory(), kill
it off completely.

Reviewed-by: Nikolay Borisov <nborisov@suse.com>
Reviewed-by: Jan Kara <jack@suse.cz>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Mel Gorman <mgorman@suse.de>
---
 fs/buffer.c | 23 -----------------------
 1 file changed, 23 deletions(-)

diff --git a/fs/buffer.c b/fs/buffer.c
index c4d9d65ebe77..4a79554e4668 100644
--- a/fs/buffer.c
+++ b/fs/buffer.c
@@ -252,27 +252,6 @@ __find_get_block_slow(struct block_device *bdev, sector_t block)
 	return ret;
 }
 
-/*
- * Kick the writeback threads then try to free up some ZONE_NORMAL memory.
- */
-static void free_more_memory(void)
-{
-	struct zoneref *z;
-	int nid;
-
-	wakeup_flusher_threads(1024, WB_REASON_FREE_MORE_MEM);
-	yield();
-
-	for_each_online_node(nid) {
-
-		z = first_zones_zonelist(node_zonelist(nid, GFP_NOFS),
-						gfp_zone(GFP_NOFS), NULL);
-		if (z->zone)
-			try_to_free_pages(node_zonelist(nid, GFP_NOFS), 0,
-						GFP_NOFS, NULL);
-	}
-}
-
 /*
  * I/O completion handler for block_read_full_page() - pages
  * which come unlocked at the end of I/O.
@@ -1089,8 +1068,6 @@ __getblk_slow(struct block_device *bdev, sector_t block,
 		ret = grow_buffers(bdev, block, size, gfp);
 		if (ret < 0)
 			return NULL;
-		if (ret == 0)
-			free_more_memory();
 	}
 }