From:   Huangzhaoyang <huangzhaoyang@gmail.com>
To:     Andrew Morton <akpm@linux-foundation.org>,
        Zhaoyang Huang <zhaoyang.huang@unisoc.com>, linux-mm@kvack.org,
        linux-kernel@vger.kernel.org
Subject: [PATCH] mm: mask DIRECT_RECLAIM in kswapd
Date:   Mon,  6 Dec 2021 11:19:22 +0800
Message-Id: <1638760762-27239-1-git-send-email-huangzhaoyang@gmail.com>
Precedence: bulk

From: Zhaoyang Huang <zhaoyang.huang@unisoc.com>

As the eg bellowing, using GFP_KERNEL could confuse the registered .releasepage
or .shrinker functions when called in kswapd and have them acting wrongly.Mask
__GFP_DIRECT_RECLAIM in kswapd.

eg,
kswapd
  shrink_page_list
    try_to_release_page
      __fscache_maybe_release_page
	...
         if (!(gfp & __GFP_DIRECT_RECLAIM) || !(gfp & __GFP_FS)) {
                 fscache_stat(&fscache_n_store_vmscan_busy);
                 return false;
         }

Signed-off-by: Zhaoyang Huang <zhaoyang.huang@unisoc.com>
---
 mm/vmscan.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/mm/vmscan.c b/mm/vmscan.c
index ef4a6dc..3b5c5e6 100644
--- a/mm/vmscan.c
+++ b/mm/vmscan.c
@@ -4083,7 +4083,7 @@ static int balance_pgdat(pg_data_t *pgdat, int order, int highest_zoneidx)
 	bool boosted;
 	struct zone *zone;
 	struct scan_control sc = {
-		.gfp_mask = GFP_KERNEL,
+		.gfp_mask = GFP_KERNEL & ~__GFP_DIRECT_RECLAIM,
 		.order = order,
 		.may_unmap = 1,
 	};
-- 
1.9.1