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From: Jan Kara <jack@suse.cz>
To: Andrew Morton <akpm@linux-foundation.org>
Cc: Ross Zwisler <ross.zwisler@linux.intel.com>,
	Dan Williams <dan.j.williams@intel.com>,
	linux-nvdimm@lists.01.org, linux-mm@kvack.org,
	Jan Kara <jack@suse.cz>,
	stable@vger.kernel.org
Subject: [PATCH] dax: Fix inefficiency in dax_writeback_mapping_range()
Date: Mon, 19 Jun 2017 14:45:31 +0200
Message-ID: <20170619124531.21491-1-jack@suse.cz> (raw)

dax_writeback_mapping_range() fails to update iteration index when
searching radix tree for entries needing cache flushing. Thus each
pagevec worth of entries is searched starting from the start which is
inefficient and prone to livelocks. Update index properly.

CC: stable@vger.kernel.org
Fixes: 9973c98ecfda3a1dfcab981665b5f1e39bcde64a
Signed-off-by: Jan Kara <jack@suse.cz>
---
 fs/dax.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/fs/dax.c b/fs/dax.c
index 2a6889b3585f..9187f3b07f3e 100644
--- a/fs/dax.c
+++ b/fs/dax.c
@@ -859,6 +859,7 @@ int dax_writeback_mapping_range(struct address_space *mapping,
 			if (ret < 0)
 				goto out;
 		}
+		start_index = indices[pvec.nr - 1] + 1;
 	}
 out:
 	put_dax(dax_dev);
-- 
2.12.3

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Thread overview: 2+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2017-06-19 12:45 Jan Kara [this message]
2017-06-19 16:34 ` Ross Zwisler

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