Hi Or, I saw below warning when enable CONFIG_DEBUG_MUTEXES
> 1893 May 21 08:56:32 ib2 kernel: [ 44.738725] > ============================================= > 1894 May 21 08:56:32 ib2 kernel: [ 44.738782] [ INFO: possible recursive > locking detected ] > 1895 May 21 08:56:32 ib2 kernel: [ 44.738841] 3.9.0-rc7-pserver #4 > Tainted: G O > 1896 May 21 08:56:32 ib2 kernel: [ 44.738896] > --------------------------------------------- > 1897 May 21 08:56:32 ib2 kernel: [ 44.738953] kworker/u:5/238 is trying to > acquire lock: > 1898 May 21 08:56:32 ib2 kernel: [ 44.739008] > (&priv->vlan_mutex){+.+.+.}, at: [<ffffffffa073f36c>] > __ipoib_ib_dev_flush+0x3c/0x230 [ib_ipoib] > 1899 May 21 08:56:32 ib2 kernel: [ 44.739218] > 1900 May 21 08:56:32 ib2 kernel: [ 44.739218] but task is already holding > lock: > 1901 May 21 08:56:32 ib2 kernel: [ 44.739328] > (&priv->vlan_mutex){+.+.+.}, at: [<ffffffffa073f36c>] > __ipoib_ib_dev_flush+0x3c/0x230 [ib_ipoib] > 1902 May 21 08:56:32 ib2 kernel: [ 44.739537] > 1903 May 21 08:56:32 ib2 kernel: [ 44.739537] other info that might help > us debug this: > 1904 May 21 08:56:32 ib2 kernel: [ 44.739613] Possible unsafe locking > scenario: > 1905 May 21 08:56:32 ib2 kernel: [ 44.739613] > 1906 May 21 08:56:32 ib2 kernel: [ 44.739688] CPU0 > 1907 May 21 08:56:32 ib2 kernel: [ 44.739741] ---- > 1908 May 21 08:56:32 ib2 kernel: [ 44.739791] lock(&priv->vlan_mutex); > 1909 May 21 08:56:32 ib2 kernel: [ 44.739902] lock(&priv->vlan_mutex); > 1910 May 21 08:56:32 ib2 kernel: [ 44.740014] > 1911 May 21 08:56:32 ib2 kernel: [ 44.740014] *** DEADLOCK *** > 1912 May 21 08:56:32 ib2 kernel: [ 44.740014] > 1913 May 21 08:56:32 ib2 kernel: [ 44.740103] May be due to missing lock > nesting notation > 1914 May 21 08:56:32 ib2 kernel: [ 44.740103] > 1915 May 21 08:56:32 ib2 kernel: [ 44.740213] 3 locks held by > kworker/u:5/238: > 1916 May 21 08:56:32 ib2 kernel: [ 44.740266] #0: (ipoib){.+.+.+}, at: > [<ffffffff81067755>] process_one_work+0x165/0x560 > 1917 May 21 08:56:32 ib2 kernel: [ 44.740495] #1: > ((&priv->flush_heavy)){+.+...}, at: [<ffffffff81067755>] > process_one_work+0x165/0x560 > 1918 May 21 08:56:32 ib2 kernel: [ 44.740725] #2: > (&priv->vlan_mutex){+.+.+.}, at: [<ffffffffa073f36c>] > __ipoib_ib_dev_flush+0x3c/0x230 [ib_ipoib] > 1919 May 21 08:56:32 ib2 kernel: [ 44.740961] > 1920 May 21 08:56:32 ib2 kernel: [ 44.740961] stack backtrace: > 1921 May 21 08:56:32 ib2 kernel: [ 44.741035] Pid: 238, comm: kworker/u:5 > Tainted: G O 3.9.0-rc7-pserver #4 > 1922 May 21 08:56:32 ib2 kernel: [ 44.741111] Call Trace: > 1923 May 21 08:56:32 ib2 kernel: [ 44.741170] [<ffffffff81046430>] ? > vprintk_emit+0x280/0x520 > 1924 May 21 08:56:32 ib2 kernel: [ 44.741233] [<ffffffff810ac473>] > __lock_acquire+0x6c3/0x17c0 > 1925 May 21 08:56:32 ib2 kernel: [ 44.741295] [<ffffffff810aca3c>] ? > __lock_acquire+0xc8c/0x17c0 > 1926 May 21 08:56:32 ib2 kernel: [ 44.741357] [<ffffffff810047a7>] ? > dump_trace+0x177/0x2f0 > 1927 May 21 08:56:32 ib2 kernel: [ 44.741418] [<ffffffff810ad612>] > lock_acquire+0xa2/0x180 > 1928 May 21 08:56:32 ib2 kernel: [ 44.741483] [<ffffffffa073f36c>] ? > __ipoib_ib_dev_flush+0x3c/0x230 [ib_ipoib] > 1929 May 21 08:56:32 ib2 kernel: [ 44.741563] [<ffffffff8101090f>] ? > save_stack_trace+0x2f/0x50 > 1930 May 21 08:56:32 ib2 kernel: [ 44.741626] [<ffffffff817bb0cb>] > __mutex_lock_common+0x5b/0x3e0 > 1931 May 21 08:56:32 ib2 kernel: [ 44.741693] [<ffffffffa073f36c>] ? > __ipoib_ib_dev_flush+0x3c/0x230 [ib_ipoib] > 1932 May 21 08:56:32 ib2 kernel: [ 44.741777] [<ffffffffa073f36c>] ? > __ipoib_ib_dev_flush+0x3c/0x230 [ib_ipoib] > 1933 May 21 08:56:32 ib2 kernel: [ 44.741855] [<ffffffff817bb585>] > mutex_lock_nested+0x45/0x50 > 1934 May 21 08:56:32 ib2 kernel: [ 44.741922] [<ffffffffa073f36c>] > __ipoib_ib_dev_flush+0x3c/0x230 [ib_ipoib] > 1935 May 21 08:56:32 ib2 kernel: [ 44.741991] [<ffffffffa073f38a>] > __ipoib_ib_dev_flush+0x5a/0x230 [ib_ipoib] > 1936 May 21 08:56:32 ib2 kernel: [ 44.742060] [<ffffffffa073f57a>] > ipoib_ib_dev_flush_heavy+0x1a/0x20 [ib_ipoib] > 1937 May 21 08:56:32 ib2 kernel: [ 44.742138] [<ffffffff810677c6>] > process_one_work+0x1d6/0x560 > 1938 May 21 08:56:32 ib2 kernel: [ 44.742199] [<ffffffff81067755>] ? > process_one_work+0x165/0x560 > 1939 May 21 08:56:32 ib2 kernel: [ 44.742262] [<ffffffff81068e29>] > worker_thread+0x119/0x370 > 1940 May 21 08:56:32 ib2 kernel: [ 44.742324] [<ffffffff81068d10>] ? > manage_workers+0x340/0x340 > 1941 May 21 08:56:32 ib2 kernel: [ 44.742388] [<ffffffff8106e846>] > kthread+0xe6/0xf0 > 1942 May 21 08:56:32 ib2 kernel: [ 44.742450] [<ffffffff8106e760>] ? > __init_kthread_worker+0x70/0x70 > 1943 May 21 08:56:32 ib2 kernel: [ 44.742513] [<ffffffff817c842c>] > ret_from_fork+0x7c/0xb0 > 1944 May 21 08:56:32 ib2 kernel: [ 44.742575] [<ffffffff8106e760>] ? > __init_kthread_worker+0x70/0x70 > 1945 May 21 08:56:32 ib2 kernel: [ 44.744467] IPv6: > ADDRCONF(NETDEV_CHANGE): ib1: link becomes ready > 1946 May 21 08:56:45 ib2 kernel: [ 57.700823] IPv6: > ADDRCONF(NETDEV_CHANGE): ib0: link becomes ready And I found attached patch you submitted long time ago, I tried that patch, it fixed the warning, I wonder why the patch was not accepted, anything wrong? Regards, Jack
do nested flushing only if the device isn't a child Signed-off-by: Or Gerlitz <ogerl...@mellanox.com> ---- setting CONFIG_DEBUG_MUTEXES I see the below warning, however, for some reason, I didn't manage to trigger it without my other patch that adds the clones, I don't see how that patch could be the reason for the warning, as the code always goes nested, I've instrumented the flush code to dump its caller/stack and indeed, you can see that the flushing code is called recursively and should have that warning, but it doesn't... ib0.8001: downing ib_dev ib0: downing ib_dev ib0: ipoib_ib_dev_flush_light called ib0: __ipoib_ib_dev_flush pid 29251 Pid: 29251, comm: kworker/u:1 Not tainted 3.2.0-06106-g75f0703-dirty #16 Call Trace: [<ffffffffa02b5e1e>] __ipoib_ib_dev_flush+0x57/0x204 [ib_ipoib] [<ffffffffa02b6057>] ? ipoib_ib_dev_flush_normal+0x46/0x46 [ib_ipoib] [<ffffffffa02b6096>] ipoib_ib_dev_flush_light+0x3f/0x43 [ib_ipoib] [<ffffffff81041ee6>] process_one_work+0x2bd/0x4a6 [<ffffffff81041e39>] ? process_one_work+0x210/0x4a6 [<ffffffff810424e6>] worker_thread+0x1d6/0x350 [<ffffffff81042310>] ? rescuer_thread+0x241/0x241 [<ffffffff81045d5a>] kthread+0x84/0x8c [<ffffffff81366ee4>] kernel_thread_helper+0x4/0x10 [<ffffffff810514d1>] ? finish_task_switch+0x154/0x156 [<ffffffff8135f243>] ? _raw_spin_unlock_irq+0x2b/0x40 [<ffffffff8135f59d>] ? retint_restore_args+0xe/0xe [<ffffffff81045cd6>] ? __init_kthread_worker+0x56/0x56 [<ffffffff81366ee0>] ? gs_change+0xb/0xb ib0.8001: __ipoib_ib_dev_flush pid 29251 Pid: 29251, comm: kworker/u:1 Not tainted 3.2.0-06106-g75f0703-dirty #16 Call Trace: [<ffffffffa02b5e1e>] __ipoib_ib_dev_flush+0x57/0x204 [ib_ipoib] [<ffffffffa02b5e4e>] __ipoib_ib_dev_flush+0x87/0x204 [ib_ipoib] [<ffffffffa02b6057>] ? ipoib_ib_dev_flush_normal+0x46/0x46 [ib_ipoib] [<ffffffffa02b6096>] ipoib_ib_dev_flush_light+0x3f/0x43 [ib_ipoib] [<ffffffff81041ee6>] process_one_work+0x2bd/0x4a6 [<ffffffff81041e39>] ? process_one_work+0x210/0x4a6 [<ffffffff810424e6>] worker_thread+0x1d6/0x350 [<ffffffff81042310>] ? rescuer_thread+0x241/0x241 [<ffffffff81045d5a>] kthread+0x84/0x8c [<ffffffff81366ee4>] kernel_thread_helper+0x4/0x10 [<ffffffff810514d1>] ? finish_task_switch+0x154/0x156 [<ffffffff8135f243>] ? _raw_spin_unlock_irq+0x2b/0x40 [<ffffffff8135f59d>] ? retint_restore_args+0xe/0xe [<ffffffff81045cd6>] ? __init_kthread_worker+0x56/0x56 [<ffffffff81366ee0>] ? gs_change+0xb/0xb --- ============================================= [ INFO: possible recursive locking detected ] 3.2.0-06106-g75f0703-dirty #16 Not tainted --------------------------------------------- kworker/u:2/1578 is trying to acquire lock: (&priv->vlan_mutex){+.+.+.}, at: [<ffffffffa021ae9f>] __ipoib_ib_dev_flush+0x2c/0x1cf [ib_ipoib] but task is already holding lock: (&priv->vlan_mutex){+.+.+.}, at: [<ffffffffa021ae9f>] __ipoib_ib_dev_flush+0x2c/0x1cf [ib_ipoib] other info that might help us debug this: Possible unsafe locking scenario: CPU0 ---- lock(&priv->vlan_mutex); lock(&priv->vlan_mutex); *** DEADLOCK *** May be due to missing lock nesting notation 3 locks held by kworker/u:2/1578: #0: (ipoib){.+.+.+}, at: [<ffffffff81041e39>] process_one_work+0x210/0x4a6 #1: ((&priv->flush_heavy)){+.+...}, at: [<ffffffff81041e39>] process_one_work+0x210/0x4a6 #2: (&priv->vlan_mutex){+.+.+.}, at: [<ffffffffa021ae9f>] __ipoib_ib_dev_flush+0x2c/0x1cf [ib_ipoib] stack backtrace: Pid: 1578, comm: kworker/u:2 Not tainted 3.2.0-06106-g75f0703-dirty #16 Call Trace: [<ffffffff81029a02>] ? console_unlock+0x10c/0x207 [<ffffffff810668a6>] __lock_acquire+0x16b5/0x174e [<ffffffff8100ca22>] ? save_stack_trace+0x2a/0x47 [<ffffffff81066a2f>] lock_acquire+0xf0/0x116 [<ffffffffa021ae9f>] ? __ipoib_ib_dev_flush+0x2c/0x1cf [ib_ipoib] [<ffffffff8135cbb9>] mutex_lock_nested+0x64/0x2e6 [<ffffffffa021ae9f>] ? __ipoib_ib_dev_flush+0x2c/0x1cf [ib_ipoib] [<ffffffff81063bad>] ? trace_hardirqs_on_caller+0x11e/0x155 [<ffffffffa021ae9f>] __ipoib_ib_dev_flush+0x2c/0x1cf [ib_ipoib] [<ffffffffa021aec5>] __ipoib_ib_dev_flush+0x52/0x1cf [ib_ipoib] [<ffffffff81063bad>] ? trace_hardirqs_on_caller+0x11e/0x155 [<ffffffffa021b042>] ? __ipoib_ib_dev_flush+0x1cf/0x1cf [ib_ipoib] [<ffffffffa021b057>] ipoib_ib_dev_flush_heavy+0x15/0x17 [ib_ipoib] [<ffffffff81041ee6>] process_one_work+0x2bd/0x4a6 [<ffffffff81041e39>] ? process_one_work+0x210/0x4a6 [<ffffffff8135f243>] ? _raw_spin_unlock_irq+0x2b/0x40 [<ffffffff810424e6>] worker_thread+0x1d6/0x350 [<ffffffff81042310>] ? rescuer_thread+0x241/0x241 [<ffffffff81045d5a>] kthread+0x84/0x8c [<ffffffff81366ee4>] kernel_thread_helper+0x4/0x10 [<ffffffff8135f59d>] ? retint_restore_args+0xe/0xe [<ffffffff81045cd6>] ? __init_kthread_worker+0x56/0x56 [<ffffffff81366ee0>] ? gs_change+0xb/0xb ADDRCONF(NETDEV_CHANGE): ib0.8001: link becomes ready ADDRCONF(NETDEV_CHANGE): ib0: link becomes ready drivers/infiniband/ulp/ipoib/ipoib_ib.c | 18 ++++++++++-------- 1 file changed, 10 insertions(+), 8 deletions(-) diff --git a/drivers/infiniband/ulp/ipoib/ipoib_ib.c b/drivers/infiniband/ulp/ipoib/ipoib_ib.c index 5c1bc99..cac2b71 100644 --- a/drivers/infiniband/ulp/ipoib/ipoib_ib.c +++ b/drivers/infiniband/ulp/ipoib/ipoib_ib.c @@ -934,16 +934,18 @@ static void __ipoib_ib_dev_flush(struct ipoib_dev_priv *priv, struct net_device *dev = priv->dev; u16 new_index; - mutex_lock(&priv->vlan_mutex); + if (!priv->parent) { + mutex_lock(&priv->vlan_mutex); - /* - * Flush any child interfaces too -- they might be up even if - * the parent is down. - */ - list_for_each_entry(cpriv, &priv->child_intfs, list) - __ipoib_ib_dev_flush(cpriv, level); + /* + * Flush any child interfaces too -- they might be up even if + * the parent is down. + */ + list_for_each_entry(cpriv, &priv->child_intfs, list) + __ipoib_ib_dev_flush(cpriv, level); - mutex_unlock(&priv->vlan_mutex); + mutex_unlock(&priv->vlan_mutex); + } if (!test_bit(IPOIB_FLAG_INITIALIZED, &priv->flags)) { ipoib_dbg(priv, "Not flushing - IPOIB_FLAG_INITIALIZED not set.\n");