On 18/04/2013 11:33, Michael S. Tsirkin wrote:
On Sun, Apr 14, 2013 at 06:43:39AM -0700, Tejun Heo wrote:
On Sun, Apr 14, 2013 at 03:58:55PM +0300, Or Gerlitz wrote:
So the patch eliminated the lockdep warning for mlx4 nested probing
sequence, but introduced lockdep warning for
00:13.0 PIC: Intel Corporation 7500/5520/5500/X58 I/O Hub I/OxAPIC
Interrupt Controller (rev 22)
Oops, the patch in itself doesn't really change anything. The caller
should use a different subclass for the nested invocation, just like
spin_lock_nested() and friends. Sorry about not being clear.
Michael, can you please help?
Thanks.
--
tejun
So like this on top. Tejun, you didn't add your S.O.B and patch
description, if this helps as we expect they will be needed.
---->
pci: use work_on_cpu_nested for nested SRIOV
Snce 3.9-rc1 mlx driver started triggering a lockdep warning.
The issue is that a driver, in it's probe function, calls
pci_sriov_enable so a PF device probe causes VF probe (AKA nested
probe). Each probe in pci_device_probe which is (normally) run through
work_on_cpu (this is to get the right numa node for memory allocated by
the driver). In turn work_on_cpu does this internally:
schedule_work_on(cpu, &wfc.work);
flush_work(&wfc.work);
So if you are running probe on CPU1, and cause another
probe on the same CPU, this will try to flush
workqueue from inside same workqueue which triggers
a lockdep warning.
Nested probing might be tricky to get right generally.
But for pci_sriov_enable, the situation is actually very simple:
VFs almost never use the same driver as the PF so the warning
is bogus there.
This is hardly elegant as it might shut up some real warnings if a buggy
driver actually probes itself in a nested way, but looks to me like an
appropriate quick fix for 3.9.
Signed-off-by: Michael S. Tsirkin <mst@xxxxxxxxxx>
---
diff --git a/drivers/pci/pci-driver.c b/drivers/pci/pci-driver.c
index 1fa1e48..9c836ef 100644
--- a/drivers/pci/pci-driver.c
+++ b/drivers/pci/pci-driver.c
@@ -286,9 +286,9 @@ static int pci_call_probe(struct pci_driver *drv, struct pci_dev *dev,
int cpu;
get_online_cpus();
- cpu = cpumask_any_and(cpumask_of_node(node), cpu_online_mask);
- if (cpu < nr_cpu_ids)
- error = work_on_cpu(cpu, local_pci_probe, &ddi);
+ cpu = cpumask_first_and(cpumask_of_node(node), cpu_online_mask);
+ if (cpu != raw_smp_processor_id() && cpu < nr_cpu_ids)
+ error = work_on_cpu_nested(cpu, local_pci_probe, &ddi);
as you wrote to me later, missing here is SINGLE_DEPTH_NESTING as the
last param to work_on_cpu_nested
else
error = local_pci_probe(&ddi);
put_online_cpus();
So now I used Tejun's patch and Michael patch on top of the net.git as
of commit 2e0cbf2cc2c9371f0aa198857d799175ffe231a6
"net: mvmdio: add select PHYLIB" from April 13 -- and I still see
this... so we're not there yet
=====================================
[ BUG: bad unlock balance detected! ]
3.9.0-rc6+ #56 Not tainted
-------------------------------------
swapper/0/1 is trying to release lock ((&wfc.work)) at:
[<ffffffff81220167>] pci_device_probe+0x117/0x120
but there are no more locks to release!
other info that might help us debug this:
2 locks held by swapper/0/1:
#0: (&__lockdep_no_validate__){......}, at: [<ffffffff812da443>]
__driver_attach+0x53/0xb0
#1: (&__lockdep_no_validate__){......}, at: [<ffffffff812da451>]
__driver_attach+0x61/0xb0
stack backtrace:
Pid: 1, comm: swapper/0 Not tainted 3.9.0-rc6+ #56
Call Trace:
[<ffffffff81220167>] ? pci_device_probe+0x117/0x120
[<ffffffff81093529>] print_unlock_imbalance_bug+0xf9/0x100
[<ffffffff8109616f>] lock_set_class+0x27f/0x7c0
[<ffffffff81091d9e>] ? mark_held_locks+0x9e/0x130
[<ffffffff81220167>] ? pci_device_probe+0x117/0x120
[<ffffffff81066aeb>] work_on_cpu_nested+0x8b/0xc0
[<ffffffff810633c0>] ? keventd_up+0x20/0x20
[<ffffffff8121f420>] ? pci_pm_prepare+0x60/0x60
[<ffffffff81220167>] pci_device_probe+0x117/0x120
[<ffffffff812da0fa>] ? driver_sysfs_add+0x7a/0xb0
[<ffffffff812da24f>] driver_probe_device+0x8f/0x230
[<ffffffff812da493>] __driver_attach+0xa3/0xb0
[<ffffffff812da3f0>] ? driver_probe_device+0x230/0x230
[<ffffffff812da3f0>] ? driver_probe_device+0x230/0x230
[<ffffffff812d86fc>] bus_for_each_dev+0x8c/0xb0
[<ffffffff812da079>] driver_attach+0x19/0x20
[<ffffffff812d91a0>] bus_add_driver+0x1f0/0x250
[<ffffffff818bd596>] ? dmi_pcie_pme_disable_msi+0x21/0x21
[<ffffffff812daadf>] driver_register+0x6f/0x150
[<ffffffff818bd596>] ? dmi_pcie_pme_disable_msi+0x21/0x21
[<ffffffff8122026f>] __pci_register_driver+0x5f/0x70
[<ffffffff818bd5ff>] pcie_portdrv_init+0x69/0x7a
[<ffffffff810001fd>] do_one_initcall+0x3d/0x170
[<ffffffff81895943>] kernel_init_freeable+0x10d/0x19c
[<ffffffff818959d2>] ? kernel_init_freeable+0x19c/0x19c
[<ffffffff8145a040>] ? rest_init+0x160/0x160
[<ffffffff8145a049>] kernel_init+0x9/0xf0
[<ffffffff8146ca6c>] ret_from_fork+0x7c/0xb0
[<ffffffff8145a040>] ? rest_init+0x160/0x160
ioapic: probe of 0000:00:13.0 failed with error -22
pci_hotplug: PCI Hot Plug PCI Core version: 0.5
--
To unsubscribe from this list: send the line "unsubscribe linux-pci" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
