Received-SPF: pass (google.com: domain of linux-kernel+bounces-47836-linux.lists.archive=gmail.com@vger.kernel.org designates 2604:1380:45d1:ec00::1 as permitted sender) client-ip=2604:1380:45d1:ec00::1;
From: Liu Shixin <liushixin2@huawei.com>
To: Alexander Viro <viro@zeniv.linux.org.uk>, Christian Brauner
	<brauner@kernel.org>, Jan Kara <jack@suse.cz>, Matthew Wilcox
	<willy@infradead.org>, Andrew Morton <akpm@linux-foundation.org>
CC: <linux-fsdevel@vger.kernel.org>, <linux-kernel@vger.kernel.org>,
	<linux-mm@kvack.org>, Liu Shixin <liushixin2@huawei.com>
Subject: [PATCH 1/2] mm/readahead: stop readahead loop if memcg charge fails
Date: Thu, 1 Feb 2024 18:08:34 +0800
Message-ID: <20240201100835.1626685-2-liushixin2@huawei.com>
In-Reply-To: <20240201100835.1626685-1-liushixin2@huawei.com>
References: <20240201100835.1626685-1-liushixin2@huawei.com>
Precedence: bulk
MIME-Version: 1.0
Content-Transfer-Encoding: 8bit
Content-Type: text/plain

When a task in memcg readaheads file pages, page_cache_ra_unbounded()
will try to readahead nr_to_read pages. Even if the new allocated page
fails to charge, page_cache_ra_unbounded() still tries to readahead
next page. This leads to too much memory reclaim.

Stop readahead if mem_cgroup_charge() fails, i.e. add_to_page_cache_lru()
returns -ENOMEM.

Signed-off-by: Liu Shixin <liushixin2@huawei.com>
Signed-off-by: Jinjiang Tu <tujinjiang@huawei.com>
---
 mm/readahead.c | 8 ++++++--
 1 file changed, 6 insertions(+), 2 deletions(-)

diff --git a/mm/readahead.c b/mm/readahead.c
index 23620c57c1225..cc4abb67eb223 100644
--- a/mm/readahead.c
+++ b/mm/readahead.c
@@ -228,6 +228,7 @@ void page_cache_ra_unbounded(struct readahead_control *ractl,
 	 */
 	for (i = 0; i < nr_to_read; i++) {
 		struct folio *folio = xa_load(&mapping->i_pages, index + i);
+		int ret;
 
 		if (folio && !xa_is_value(folio)) {
 			/*
@@ -247,9 +248,12 @@ void page_cache_ra_unbounded(struct readahead_control *ractl,
 		folio = filemap_alloc_folio(gfp_mask, 0);
 		if (!folio)
 			break;
-		if (filemap_add_folio(mapping, folio, index + i,
-					gfp_mask) < 0) {
+
+		ret = filemap_add_folio(mapping, folio, index + i, gfp_mask);
+		if (ret < 0) {
 			folio_put(folio);
+			if (ret == -ENOMEM)
+				break;
 			read_pages(ractl);
 			ractl->_index++;
 			i = ractl->_index + ractl->_nr_pages - index - 1;
-- 
2.25.1