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    Subject[PATCH 4/4] reiserfs: Relax reiserfs lock while freeing the journal
    Date
    Keeping the reiserfs lock while freeing the journal on
    umount path triggers a lock inversion between bdev->bd_mutex
    and the reiserfs lock.

    We don't need the reiserfs lock at this stage. The filesystem
    is not usable anymore, and there are no more pending commits,
    everything got flushed (even this operation was done in parallel
    and didn't required the reiserfs lock from the current process).

    This fixes the following lockdep report:

    =======================================================
    [ INFO: possible circular locking dependency detected ]
    2.6.32-atom #172
    -------------------------------------------------------
    umount/3904 is trying to acquire lock:
    (&bdev->bd_mutex){+.+.+.}, at: [<c10de2c2>] __blkdev_put+0x22/0x160

    but task is already holding lock:
    (&REISERFS_SB(s)->lock){+.+.+.}, at: [<c1143279>] reiserfs_write_lock+0x29/0x40

    which lock already depends on the new lock.

    the existing dependency chain (in reverse order) is:

    -> #3 (&REISERFS_SB(s)->lock){+.+.+.}:
    [<c105ea7f>] __lock_acquire+0x11ff/0x19e0
    [<c105f2c8>] lock_acquire+0x68/0x90
    [<c140199b>] mutex_lock_nested+0x5b/0x340
    [<c1143229>] reiserfs_write_lock_once+0x29/0x50
    [<c111c485>] reiserfs_get_block+0x85/0x1620
    [<c10e1040>] do_mpage_readpage+0x1f0/0x6d0
    [<c10e1640>] mpage_readpages+0xc0/0x100
    [<c1119b89>] reiserfs_readpages+0x19/0x20
    [<c108f1ec>] __do_page_cache_readahead+0x1bc/0x260
    [<c108f2b8>] ra_submit+0x28/0x40
    [<c1087e3e>] filemap_fault+0x40e/0x420
    [<c109b5fd>] __do_fault+0x3d/0x430
    [<c109d47e>] handle_mm_fault+0x12e/0x790
    [<c1022a65>] do_page_fault+0x135/0x330
    [<c1403663>] error_code+0x6b/0x70
    [<c10ef9ca>] load_elf_binary+0x82a/0x1a10
    [<c10ba130>] search_binary_handler+0x90/0x1d0
    [<c10bb70f>] do_execve+0x1df/0x250
    [<c1001746>] sys_execve+0x46/0x70
    [<c1002fa5>] syscall_call+0x7/0xb

    -> #2 (&mm->mmap_sem){++++++}:
    [<c105ea7f>] __lock_acquire+0x11ff/0x19e0
    [<c105f2c8>] lock_acquire+0x68/0x90
    [<c109b1ab>] might_fault+0x8b/0xb0
    [<c11b8f52>] copy_to_user+0x32/0x70
    [<c10c3b94>] filldir64+0xa4/0xf0
    [<c1109116>] sysfs_readdir+0x116/0x210
    [<c10c3e1d>] vfs_readdir+0x8d/0xb0
    [<c10c3ea9>] sys_getdents64+0x69/0xb0
    [<c1002ec4>] sysenter_do_call+0x12/0x32

    -> #1 (sysfs_mutex){+.+.+.}:
    [<c105ea7f>] __lock_acquire+0x11ff/0x19e0
    [<c105f2c8>] lock_acquire+0x68/0x90
    [<c140199b>] mutex_lock_nested+0x5b/0x340
    [<c110951c>] sysfs_addrm_start+0x2c/0xb0
    [<c1109aa0>] create_dir+0x40/0x90
    [<c1109b1b>] sysfs_create_dir+0x2b/0x50
    [<c11b2352>] kobject_add_internal+0xc2/0x1b0
    [<c11b2531>] kobject_add_varg+0x31/0x50
    [<c11b25ac>] kobject_add+0x2c/0x60
    [<c1258294>] device_add+0x94/0x560
    [<c11036ea>] add_partition+0x18a/0x2a0
    [<c110418a>] rescan_partitions+0x33a/0x450
    [<c10de5bf>] __blkdev_get+0x12f/0x2d0
    [<c10de76a>] blkdev_get+0xa/0x10
    [<c11034b8>] register_disk+0x108/0x130
    [<c11a87a9>] add_disk+0xd9/0x130
    [<c12998e5>] sd_probe_async+0x105/0x1d0
    [<c10528af>] async_thread+0xcf/0x230
    [<c104bfd4>] kthread+0x74/0x80
    [<c1003aab>] kernel_thread_helper+0x7/0x3c

    -> #0 (&bdev->bd_mutex){+.+.+.}:
    [<c105f176>] __lock_acquire+0x18f6/0x19e0
    [<c105f2c8>] lock_acquire+0x68/0x90
    [<c140199b>] mutex_lock_nested+0x5b/0x340
    [<c10de2c2>] __blkdev_put+0x22/0x160
    [<c10de40a>] blkdev_put+0xa/0x10
    [<c113ce22>] free_journal_ram+0xd2/0x130
    [<c113ea18>] do_journal_release+0x98/0x190
    [<c113eb2a>] journal_release+0xa/0x10
    [<c1128eb6>] reiserfs_put_super+0x36/0x130
    [<c10b776f>] generic_shutdown_super+0x4f/0xe0
    [<c10b7825>] kill_block_super+0x25/0x40
    [<c11255df>] reiserfs_kill_sb+0x7f/0x90
    [<c10b7f4a>] deactivate_super+0x7a/0x90
    [<c10cccd8>] mntput_no_expire+0x98/0xd0
    [<c10ccfcc>] sys_umount+0x4c/0x310
    [<c10cd2a9>] sys_oldumount+0x19/0x20
    [<c1002ec4>] sysenter_do_call+0x12/0x32

    other info that might help us debug this:

    2 locks held by umount/3904:
    #0: (&type->s_umount_key#30){+++++.}, at: [<c10b7f45>] deactivate_super+0x75/0x90
    #1: (&REISERFS_SB(s)->lock){+.+.+.}, at: [<c1143279>] reiserfs_write_lock+0x29/0x40

    stack backtrace:
    Pid: 3904, comm: umount Not tainted 2.6.32-atom #172
    Call Trace:
    [<c13ff903>] ? printk+0x18/0x1a
    [<c105d33a>] print_circular_bug+0xca/0xd0
    [<c105f176>] __lock_acquire+0x18f6/0x19e0
    [<c108b66f>] ? free_pcppages_bulk+0x1f/0x250
    [<c105f2c8>] lock_acquire+0x68/0x90
    [<c10de2c2>] ? __blkdev_put+0x22/0x160
    [<c10de2c2>] ? __blkdev_put+0x22/0x160
    [<c140199b>] mutex_lock_nested+0x5b/0x340
    [<c10de2c2>] ? __blkdev_put+0x22/0x160
    [<c105c932>] ? mark_held_locks+0x62/0x80
    [<c10afe12>] ? kfree+0x92/0xd0
    [<c10de2c2>] __blkdev_put+0x22/0x160
    [<c105cc3b>] ? trace_hardirqs_on+0xb/0x10
    [<c10de40a>] blkdev_put+0xa/0x10
    [<c113ce22>] free_journal_ram+0xd2/0x130
    [<c113ea18>] do_journal_release+0x98/0x190
    [<c113eb2a>] journal_release+0xa/0x10
    [<c1128eb6>] reiserfs_put_super+0x36/0x130
    [<c1050596>] ? up_write+0x16/0x30
    [<c10b776f>] generic_shutdown_super+0x4f/0xe0
    [<c10b7825>] kill_block_super+0x25/0x40
    [<c10f41e0>] ? vfs_quota_off+0x0/0x20
    [<c11255df>] reiserfs_kill_sb+0x7f/0x90
    [<c10b7f4a>] deactivate_super+0x7a/0x90
    [<c10cccd8>] mntput_no_expire+0x98/0xd0
    [<c10ccfcc>] sys_umount+0x4c/0x310
    [<c10cd2a9>] sys_oldumount+0x19/0x20
    [<c1002ec4>] sysenter_do_call+0x12/0x32

    Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
    Cc: Alexander Beregalov <a.beregalov@gmail.com>
    Cc: Chris Mason <chris.mason@oracle.com>
    Cc: Ingo Molnar <mingo@elte.hu>
    ---
    fs/reiserfs/journal.c | 3 ++-
    1 files changed, 2 insertions(+), 1 deletions(-)

    diff --git a/fs/reiserfs/journal.c b/fs/reiserfs/journal.c
    index a059879..83ac4d3 100644
    --- a/fs/reiserfs/journal.c
    +++ b/fs/reiserfs/journal.c
    @@ -2009,10 +2009,11 @@ static int do_journal_release(struct reiserfs_transaction_handle *th,
    destroy_workqueue(commit_wq);
    commit_wq = NULL;
    }
    - reiserfs_write_lock(sb);

    free_journal_ram(sb);

    + reiserfs_write_lock(sb);
    +
    return 0;
    }

    --
    1.6.2.3


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