lkml.org 
[lkml]   [2012]   [Feb]   [12]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
    /
    From
    SubjectRe: Possible circular locking dependency (3.3-rc2)
    Date
    On środa, 8 lutego 2012 o 13:41:48 Felipe Balbi wrote:
    > Hi guys,
    >
    > I have just triggered the folllowing:
    >
    > [ 84.860321] ======================================================
    > [ 84.860321] [ INFO: possible circular locking dependency detected ]
    > [ 84.860321] 3.3.0-rc2-00026-ge4e8a39 #474 Not tainted
    > [ 84.860321] -------------------------------------------------------
    > [ 84.860321] bash/949 is trying to acquire lock:
    > [ 84.860321] (sysfs_lock){+.+.+.}, at: [<c0275358>]
    > gpio_value_store+0x24/0xcc [ 84.860321]
    > [ 84.860321] but task is already holding lock:
    > [ 84.860321] (s_active#22){++++.+}, at: [<c016996c>]
    > sysfs_write_file+0xdc/0x184 [ 84.911468]
    > [ 84.911468] which lock already depends on the new lock.
    > [ 84.911468]
    > [ 84.920043]
    > [ 84.920043] the existing dependency chain (in reverse order) is:
    > [ 84.920043]
    > [ 84.927886] -> #1 (s_active#22){++++.+}:
    > [ 84.927886] [<c008f640>] check_prevs_add+0xdc/0x150
    > [ 84.927886] [<c008fc18>] validate_chain.clone.24+0x564/0x694
    > [ 84.927886] [<c0090cdc>] __lock_acquire+0x49c/0x980
    > [ 84.951660] [<c0091838>] lock_acquire+0x98/0x100
    > [ 84.951660] [<c016a8e8>] sysfs_deactivate+0xb0/0x100
    > [ 84.962982] [<c016b1b4>] sysfs_addrm_finish+0x2c/0x6c
    > [ 84.962982] [<c016b8bc>] sysfs_remove_dir+0x84/0x98
    > [ 84.962982] [<c02590d8>] kobject_del+0x10/0x78
    > [ 84.974670] [<c02c29e8>] device_del+0x140/0x170
    > [ 84.974670] [<c02c2a24>] device_unregister+0xc/0x18
    > [ 84.985382] [<c0276894>] gpio_unexport+0xbc/0xdc
    > [ 84.985382] [<c02768c8>] gpio_free+0x14/0xfc
    > [ 85.001708] [<c0276a28>] unexport_store+0x78/0x8c
    > [ 85.001708] [<c02c5af8>] class_attr_store+0x18/0x24
    > [ 85.007293] [<c0169990>] sysfs_write_file+0x100/0x184
    > [ 85.018981] [<c0109d48>] vfs_write+0xb4/0x148
    > [ 85.018981] [<c0109fd0>] sys_write+0x40/0x70
    > [ 85.018981] [<c0013cc0>] ret_fast_syscall+0x0/0x3c
    > [ 85.035003]
    > [ 85.035003] -> #0 (sysfs_lock){+.+.+.}:
    > [ 85.035003] [<c008f54c>] check_prev_add+0x680/0x698
    > [ 85.035003] [<c008f640>] check_prevs_add+0xdc/0x150
    > [ 85.052093] [<c008fc18>] validate_chain.clone.24+0x564/0x694
    > [ 85.052093] [<c0090cdc>] __lock_acquire+0x49c/0x980
    > [ 85.052093] [<c0091838>] lock_acquire+0x98/0x100
    > [ 85.069885] [<c047e280>] mutex_lock_nested+0x3c/0x2f4
    > [ 85.069885] [<c0275358>] gpio_value_store+0x24/0xcc
    > [ 85.069885] [<c02c18dc>] dev_attr_store+0x18/0x24
    > [ 85.087158] [<c0169990>] sysfs_write_file+0x100/0x184
    > [ 85.087158] [<c0109d48>] vfs_write+0xb4/0x148
    > [ 85.098297] [<c0109fd0>] sys_write+0x40/0x70
    > [ 85.098297] [<c0013cc0>] ret_fast_syscall+0x0/0x3c
    > [ 85.109069]
    > [ 85.109069] other info that might help us debug this:
    > [ 85.109069]
    > [ 85.117462] Possible unsafe locking scenario:
    > [ 85.117462]
    > [ 85.117462] CPU0 CPU1
    > [ 85.128417] ---- ----
    > [ 85.128417] lock(s_active#22);
    > [ 85.128417] lock(sysfs_lock);
    > [ 85.128417] lock(s_active#22);
    > [ 85.142486] lock(sysfs_lock);
    > [ 85.151794]
    > [ 85.151794] *** DEADLOCK ***
    > [ 85.151794]
    > [ 85.151794] 2 locks held by bash/949:
    > [ 85.158020] #0: (&buffer->mutex){+.+.+.}, at: [<c01698b8>]
    > sysfs_write_file+0x28/0x184 [ 85.170349] #1: (s_active#22){++++.+},
    > at: [<c016996c>] sysfs_write_file+0xdc/0x184 [ 85.170349]
    > [ 85.178588] stack backtrace:
    > [ 85.178588] [<c001b824>] (unwind_backtrace+0x0/0xf0) from [<c008de64>]
    > (print_circular_bug+0x100/0x114) [ 85.193023] [<c008de64>]
    > (print_circular_bug+0x100/0x114) from [<c008f54c>]
    > (check_prev_add+0x680/0x698) [ 85.193023] [<c008f54c>]
    > (check_prev_add+0x680/0x698) from [<c008f640>]
    > (check_prevs_add+0xdc/0x150) [ 85.212524] [<c008f640>]
    > (check_prevs_add+0xdc/0x150) from [<c008fc18>]
    > (validate_chain.clone.24+0x564/0x694) [ 85.212524] [<c008fc18>]
    > (validate_chain.clone.24+0x564/0x694) from [<c0090cdc>]
    > (__lock_acquire+0x49c/0x980) [ 85.233306] [<c0090cdc>]
    > (__lock_acquire+0x49c/0x980) from [<c0091838>] (lock_acquire+0x98/0x100) [
    > 85.233306] [<c0091838>] (lock_acquire+0x98/0x100) from [<c047e280>]
    > (mutex_lock_nested+0x3c/0x2f4) [ 85.242614] [<c047e280>]
    > (mutex_lock_nested+0x3c/0x2f4) from [<c0275358>]
    > (gpio_value_store+0x24/0xcc) [ 85.261840] [<c0275358>]
    > (gpio_value_store+0x24/0xcc) from [<c02c18dc>] (dev_attr_store+0x18/0x24)
    > [ 85.261840] [<c02c18dc>] (dev_attr_store+0x18/0x24) from [<c0169990>]
    > (sysfs_write_file+0x100/0x184) [ 85.271240] [<c0169990>]
    > (sysfs_write_file+0x100/0x184) from [<c0109d48>] (vfs_write+0xb4/0x148) [
    > 85.290008] [<c0109d48>] (vfs_write+0xb4/0x148) from [<c0109fd0>]
    > (sys_write+0x40/0x70) [ 85.298400] [<c0109fd0>] (sys_write+0x40/0x70)
    > from [<c0013cc0>] (ret_fast_syscall+0x0/0x3c) -bash: echo: write error:
    > Operation not permitted
    >
    > the way to trigger is:
    >
    >
    > root@legolas:~# cd /sys/class/gpio/
    > root@legolas:/sys/class/gpio# echo 2 > export
    > root@legolas:/sys/class/gpio# echo 2 > unexport
    > root@legolas:/sys/class/gpio# echo 2 > export
    > root@legolas:/sys/class/gpio# cd gpio2/
    > root@legolas:/sys/class/gpio/gpio2# echo 1 > value

    I created a Bugzilla entry at
    https://bugzilla.kernel.org/show_bug.cgi?id=42761
    for your bug/regression report, please add your address to the CC list in
    there, thanks!

    --
    Maciej Rutecki
    http://www.mrutecki.pl
    --
    To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
    the body of a message to majordomo@vger.kernel.org
    More majordomo info at http://vger.kernel.org/majordomo-info.html
    Please read the FAQ at http://www.tux.org/lkml/

    \
     
     \ /
      Last update: 2012-02-12 14:35    [W:0.040 / U:0.308 seconds]
    ©2003-2016 Jasper Spaans. hosted at Digital OceanAdvertise on this site