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From: Waiman Long <longman@redhat.com>
To: Alexander Viro <viro@zeniv.linux.org.uk>,
	Jonathan Corbet <corbet@lwn.net>
Cc: linux-kernel@vger.kernel.org, linux-fsdevel@vger.kernel.org,
	linux-mm@kvack.org, linux-doc@vger.kernel.org,
	"Luis R. Rodriguez" <mcgrof@kernel.org>,
	Kees Cook <keescook@chromium.org>,
	Linus Torvalds <torvalds@linux-foundation.org>,
	Jan Kara <jack@suse.cz>,
	"Paul E. McKenney" <paulmck@linux.vnet.ibm.com>,
	Andrew Morton <akpm@linux-foundation.org>,
	Ingo Molnar <mingo@kernel.org>,
	Miklos Szeredi <mszeredi@redhat.com>,
	Matthew Wilcox <willy@infradead.org>,
	Larry Woodman <lwoodman@redhat.com>,
	James Bottomley <James.Bottomley@HansenPartnership.com>,
	"Wangkai (Kevin C)" <wangkai86@huawei.com>,
	Michal Hocko <mhocko@kernel.org>,
	Waiman Long <longman@redhat.com>
Subject: [PATCH v2 1/4] fs/dcache: Fix incorrect nr_dentry_unused accounting in shrink_dcache_sb()
Date: Thu, 30 Aug 2018 17:55:04 -0400	[thread overview]
Message-ID: <1535666107-25699-2-git-send-email-longman@redhat.com> (raw)
In-Reply-To: <1535666107-25699-1-git-send-email-longman@redhat.com>

The nr_dentry_unused per-cpu counter tracks dentries in both the
LRU lists and the shrink lists where the DCACHE_LRU_LIST bit is set.
The shrink_dcache_sb() function moves dentries from the LRU list to a
shrink list and subtracts the dentry count from nr_dentry_unused. This
is incorrect as the nr_dentry_unused count Will also be decremented in
shrink_dentry_list() via d_shrink_del(). To fix this double decrement,
the decrement in the shrink_dcache_sb() function is taken out.

Fixes: 4e717f5c1083 ("list_lru: remove special case function list_lru_dispose_all."

Signed-off-by: Waiman Long <longman@redhat.com>
---
 fs/dcache.c | 6 +-----
 1 file changed, 1 insertion(+), 5 deletions(-)

diff --git a/fs/dcache.c b/fs/dcache.c
index 2e7e8d8..cb515f1 100644
--- a/fs/dcache.c
+++ b/fs/dcache.c
@@ -1202,15 +1202,11 @@ static enum lru_status dentry_lru_isolate_shrink(struct list_head *item,
  */
 void shrink_dcache_sb(struct super_block *sb)
 {
-	long freed;
-
 	do {
 		LIST_HEAD(dispose);
 
-		freed = list_lru_walk(&sb->s_dentry_lru,
+		list_lru_walk(&sb->s_dentry_lru,
 			dentry_lru_isolate_shrink, &dispose, 1024);
-
-		this_cpu_sub(nr_dentry_unused, freed);
 		shrink_dentry_list(&dispose);
 	} while (list_lru_count(&sb->s_dentry_lru) > 0);
 }
-- 
1.8.3.1

  reply	other threads:[~2018-08-30 21:55 UTC|newest]

Thread overview: 5+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-08-30 21:55 [PATCH v2 0/4] fs/dcache: Track # of negative dentries Waiman Long
2018-08-30 21:55 ` Waiman Long [this message]
2018-08-30 21:55 ` [PATCH v2 2/4] fs: Don't need to put list_lru into its own cacheline Waiman Long
2018-08-30 21:55 ` [PATCH v2 3/4] fs/dcache: Track & report number of negative dentries Waiman Long
2018-08-30 21:55 ` [PATCH v2 4/4] fs/dcache: Eliminate branches in nr_dentry_negative accounting Waiman Long

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