From: Eric Sandeen <sandeen@redhat.com>
Date: Thu, 3 Feb 2011 19:33:15 +0000 (-0500)
Subject: ext4: fix panic on module unload when stopping lazyinit thread
X-Git-Tag: v2.6.37.1~141
X-Git-Url: http://git.openpandora.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=974bc5d1969424f1a659a8dbe94e4378bf7d2261;p=pandora-kernel.git

ext4: fix panic on module unload when stopping lazyinit thread

commit 8f1f745331c1b560f53c0d60e55a4f4f43f7cce5 upstream.

https://bugzilla.kernel.org/show_bug.cgi?id=27652

If the lazyinit thread is running, the teardown function
ext4_destroy_lazyinit_thread() has problems:

        ext4_clear_request_list();
        while (ext4_li_info->li_task) {
                wake_up(&ext4_li_info->li_wait_daemon);
                wait_event(ext4_li_info->li_wait_task,
                           ext4_li_info->li_task == NULL);
        }

Clearing the request list will cause the thread to exit and free
ext4_li_info, so then we're waiting on something which is getting
freed.

Fix this up by making the thread respond to kthread_stop, and exit,
without the need to wait for that exit in some other homegrown way.

Reported-and-Tested-by: Tao Ma <boyu.mt@taobao.com>
Signed-off-by: Eric Sandeen <sandeen@redhat.com>
Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
---

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