Commit 08da1193 authored Nov 17, 2010 by Markus Trippelsdorf Committed by Theodore Ts'o Nov 17, 2010

ext4: fix setting random pages PageUptodate



ext4_end_bio calls put_page and kmem_cache_free before calling
SetPageUpdate(). This can result in setting the PageUptodate bit on
random pages and causes the following BUG:

 BUG: Bad page state in process rm  pfn:52e54
 page:ffffea0001222260 count:0 mapcount:0 mapping:          (null) index:0x0
 arch kernel: page flags: 0x4000000000000008(uptodate)

Fix the problem by moving put_io_page() after the SetPageUpdate() call.

Thanks to Hugh Dickins for analyzing this problem.

Reported-by: Markus Trippelsdorf <markus@trippelsdorf.de>
Tested-by: Markus Trippelsdorf <markus@trippelsdorf.de>
Signed-off-by: Markus Trippelsdorf <markus@trippelsdorf.de>
Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>

parent e53beacd

fs/ext4/page-io.c

+2 −2

Original line number	Diff line number	Diff line
		@@ -237,8 +237,6 @@ static void ext4_end_bio(struct bio *bio, int error)
		} while (bh != head);
		}

		put_io_page(io_end->pages[i]);

		/*
		* If this is a partial write which happened to make
		* all buffers uptodate then we can optimize away a
		@@ -248,6 +246,8 @@ static void ext4_end_bio(struct bio *bio, int error)
		*/
		if (!partial_write)
		SetPageUptodate(page);

		put_io_page(io_end->pages[i]);
		}
		io_end->num_io_pages = 0;
		inode = io_end->inode;

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