From: Johannes Weiner <hannes@cmpxchg.org>
To: Andrew Morton <akpm@linux-foundation.org>
Cc: Hugh Dickins <hughd@google.com>, Michal Hocko <mhocko@suse.com>,
Shakeel Butt <shakeelb@google.com>, Roman Gushchin <guro@fb.com>,
linux-mm@kvack.org, cgroups@vger.kernel.org,
linux-kernel@vger.kernel.org, kernel-team@fb.com
Subject: [PATCH] mm: page-writeback: simplify memcg handling in test_clear_page_writeback()
Date: Tue, 9 Feb 2021 16:45:43 -0500 [thread overview]
Message-ID: <20210209214543.112655-1-hannes@cmpxchg.org> (raw)
Page writeback doesn't hold a page reference, which allows truncate to
free a page the second PageWriteback is cleared. This used to require
special attention in test_clear_page_writeback(), where we had to be
careful not to rely on the unstable page->memcg binding and look up
all the necessary information before clearing the writeback flag.
Since commit 073861ed77b6 ("mm: fix VM_BUG_ON(PageTail) and
BUG_ON(PageWriteback)") test_clear_page_writeback() is called with an
explicit reference on the page, and this dance is no longer needed.
Use unlock_page_memcg() and dec_lruvec_page_stat() directly.
Signed-off-by: Johannes Weiner <hannes@cmpxchg.org>
---
mm/page-writeback.c | 9 +++------
1 file changed, 3 insertions(+), 6 deletions(-)
diff --git a/mm/page-writeback.c b/mm/page-writeback.c
index eb34d204d4ee..f6c2c3165d4d 100644
--- a/mm/page-writeback.c
+++ b/mm/page-writeback.c
@@ -2722,12 +2722,9 @@ EXPORT_SYMBOL(clear_page_dirty_for_io);
int test_clear_page_writeback(struct page *page)
{
struct address_space *mapping = page_mapping(page);
- struct mem_cgroup *memcg;
- struct lruvec *lruvec;
int ret;
- memcg = lock_page_memcg(page);
- lruvec = mem_cgroup_page_lruvec(page, page_pgdat(page));
+ lock_page_memcg(page);
if (mapping && mapping_use_writeback_tags(mapping)) {
struct inode *inode = mapping->host;
struct backing_dev_info *bdi = inode_to_bdi(inode);
@@ -2755,11 +2752,11 @@ int test_clear_page_writeback(struct page *page)
ret = TestClearPageWriteback(page);
}
if (ret) {
- dec_lruvec_state(lruvec, NR_WRITEBACK);
+ dec_lruvec_page_state(page, NR_WRITEBACK);
dec_zone_page_state(page, NR_ZONE_WRITE_PENDING);
inc_node_page_state(page, NR_WRITTEN);
}
- __unlock_page_memcg(memcg);
+ unlock_page_memcg(page);
return ret;
}
--
2.30.0
next reply other threads:[~2021-02-09 21:45 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-02-09 21:45 Johannes Weiner [this message]
2021-02-10 5:16 ` [PATCH] mm: page-writeback: simplify memcg handling in test_clear_page_writeback() Hugh Dickins
2021-02-10 16:22 ` Hugh Dickins
2021-02-10 17:44 ` [PATCH v2] " Johannes Weiner
2021-02-10 20:14 ` Hugh Dickins
2021-02-10 22:59 ` Shakeel Butt
2021-02-11 0:33 ` Johannes Weiner
2021-02-12 10:05 ` Michal Hocko
2021-02-10 13:46 ` [PATCH] " Shakeel Butt
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