Message ID | 20190217181143.14817-1-andrew@lunn.ch |
---|---|
State | Superseded |
Delegated to: | David Miller |
Headers | show |
Series | net: dsa: mv88e6xxx: Add lockdep classes to fix false positive splat | expand |
On Sun, Feb 17, 2019 at 07:11:43PM +0100, Andrew Lunn wrote: > The following false positive lockdep splat has been observed. > > ====================================================== > WARNING: possible circular locking dependency detected > 4.20.0+ #302 Not tainted > ------------------------------------------------------ > systemd-udevd/160 is trying to acquire lock: > edea6080 (&chip->reg_lock){+.+.}, at: __setup_irq+0x640/0x704 > > but task is already holding lock: > edff0340 (&desc->request_mutex){+.+.}, at: __setup_irq+0xa0/0x704 > > which lock already depends on the new lock. > > the existing dependency chain (in reverse order) is: > > -> #1 (&desc->request_mutex){+.+.}: > mutex_lock_nested+0x1c/0x24 > __setup_irq+0xa0/0x704 > request_threaded_irq+0xd0/0x150 > mv88e6xxx_probe+0x41c/0x694 [mv88e6xxx] > mdio_probe+0x2c/0x54 > really_probe+0x200/0x2c4 > driver_probe_device+0x5c/0x174 > __driver_attach+0xd8/0xdc > bus_for_each_dev+0x58/0x7c > bus_add_driver+0xe4/0x1f0 > driver_register+0x7c/0x110 > mdio_driver_register+0x24/0x58 > do_one_initcall+0x74/0x2e8 > do_init_module+0x60/0x1d0 > load_module+0x1968/0x1ff4 > sys_finit_module+0x8c/0x98 > ret_fast_syscall+0x0/0x28 > 0xbedf2ae8 > > -> #0 (&chip->reg_lock){+.+.}: > __mutex_lock+0x50/0x8b8 > mutex_lock_nested+0x1c/0x24 > __setup_irq+0x640/0x704 > request_threaded_irq+0xd0/0x150 > mv88e6xxx_g2_irq_setup+0xcc/0x1b4 [mv88e6xxx] > mv88e6xxx_probe+0x44c/0x694 [mv88e6xxx] > mdio_probe+0x2c/0x54 > really_probe+0x200/0x2c4 > driver_probe_device+0x5c/0x174 > __driver_attach+0xd8/0xdc > bus_for_each_dev+0x58/0x7c > bus_add_driver+0xe4/0x1f0 > driver_register+0x7c/0x110 > mdio_driver_register+0x24/0x58 > do_one_initcall+0x74/0x2e8 > do_init_module+0x60/0x1d0 > load_module+0x1968/0x1ff4 > sys_finit_module+0x8c/0x98 > ret_fast_syscall+0x0/0x28 > 0xbedf2ae8 > > other info that might help us debug this: > > Possible unsafe locking scenario: > > CPU0 CPU1 > ---- ---- > lock(&desc->request_mutex); > lock(&chip->reg_lock); > lock(&desc->request_mutex); > lock(&chip->reg_lock); > > &desc->request_mutex refer to two different mutex. #1 is the GPIO for > the chip interrupt. #2 is the chained interrupt between global 1 and > global 2. > > Add lockdep classes to the GPIO interrupt to avoid this. > > Reported-by: Russell King <rmk+kernel@armlinux.org.uk> > Signed-off-by: Andrew Lunn <andrew@lunn.ch> > --- > > Hi Russell > > Does this fix it for you on Clearfog? Yes, that also fixes the problem, but I do think this is just papering over mv88e6xxx needlessly holding locks when it doesn't need to do so. > > drivers/net/dsa/mv88e6xxx/chip.c | 8 ++++++++ > 1 file changed, 8 insertions(+) > > diff --git a/drivers/net/dsa/mv88e6xxx/chip.c b/drivers/net/dsa/mv88e6xxx/chip.c > index 32e7af5caa69..936d53a92144 100644 > --- a/drivers/net/dsa/mv88e6xxx/chip.c > +++ b/drivers/net/dsa/mv88e6xxx/chip.c > @@ -442,12 +442,20 @@ static int mv88e6xxx_g1_irq_setup_common(struct mv88e6xxx_chip *chip) > > static int mv88e6xxx_g1_irq_setup(struct mv88e6xxx_chip *chip) > { > + static struct lock_class_key lock_key; > + static struct lock_class_key request_key; > int err; > > err = mv88e6xxx_g1_irq_setup_common(chip); > if (err) > return err; > > + /* These lock classes tells lockdep that global 1 irqs are in > + * a different category than their parent GPIO, so it won't > + * report false recursion. > + */ > + irq_set_lockdep_class(chip->irq, &lock_key, &request_key); > + > err = request_threaded_irq(chip->irq, NULL, > mv88e6xxx_g1_irq_thread_fn, > IRQF_ONESHOT | IRQF_SHARED, > -- > 2.20.1 > >
On Sun, Feb 17, 2019 at 07:55:24PM +0000, Russell King - ARM Linux admin wrote: > On Sun, Feb 17, 2019 at 07:11:43PM +0100, Andrew Lunn wrote: > > The following false positive lockdep splat has been observed. > > > > ====================================================== > > WARNING: possible circular locking dependency detected > > 4.20.0+ #302 Not tainted > > ------------------------------------------------------ > > systemd-udevd/160 is trying to acquire lock: > > edea6080 (&chip->reg_lock){+.+.}, at: __setup_irq+0x640/0x704 > > > > but task is already holding lock: > > edff0340 (&desc->request_mutex){+.+.}, at: __setup_irq+0xa0/0x704 > > > > which lock already depends on the new lock. > > > > the existing dependency chain (in reverse order) is: > > > > -> #1 (&desc->request_mutex){+.+.}: > > mutex_lock_nested+0x1c/0x24 > > __setup_irq+0xa0/0x704 > > request_threaded_irq+0xd0/0x150 > > mv88e6xxx_probe+0x41c/0x694 [mv88e6xxx] > > mdio_probe+0x2c/0x54 > > really_probe+0x200/0x2c4 > > driver_probe_device+0x5c/0x174 > > __driver_attach+0xd8/0xdc > > bus_for_each_dev+0x58/0x7c > > bus_add_driver+0xe4/0x1f0 > > driver_register+0x7c/0x110 > > mdio_driver_register+0x24/0x58 > > do_one_initcall+0x74/0x2e8 > > do_init_module+0x60/0x1d0 > > load_module+0x1968/0x1ff4 > > sys_finit_module+0x8c/0x98 > > ret_fast_syscall+0x0/0x28 > > 0xbedf2ae8 > > > > -> #0 (&chip->reg_lock){+.+.}: > > __mutex_lock+0x50/0x8b8 > > mutex_lock_nested+0x1c/0x24 > > __setup_irq+0x640/0x704 > > request_threaded_irq+0xd0/0x150 > > mv88e6xxx_g2_irq_setup+0xcc/0x1b4 [mv88e6xxx] > > mv88e6xxx_probe+0x44c/0x694 [mv88e6xxx] > > mdio_probe+0x2c/0x54 > > really_probe+0x200/0x2c4 > > driver_probe_device+0x5c/0x174 > > __driver_attach+0xd8/0xdc > > bus_for_each_dev+0x58/0x7c > > bus_add_driver+0xe4/0x1f0 > > driver_register+0x7c/0x110 > > mdio_driver_register+0x24/0x58 > > do_one_initcall+0x74/0x2e8 > > do_init_module+0x60/0x1d0 > > load_module+0x1968/0x1ff4 > > sys_finit_module+0x8c/0x98 > > ret_fast_syscall+0x0/0x28 > > 0xbedf2ae8 > > > > other info that might help us debug this: > > > > Possible unsafe locking scenario: > > > > CPU0 CPU1 > > ---- ---- > > lock(&desc->request_mutex); > > lock(&chip->reg_lock); > > lock(&desc->request_mutex); > > lock(&chip->reg_lock); > > > > &desc->request_mutex refer to two different mutex. #1 is the GPIO for > > the chip interrupt. #2 is the chained interrupt between global 1 and > > global 2. > > > > Add lockdep classes to the GPIO interrupt to avoid this. > > > > Reported-by: Russell King <rmk+kernel@armlinux.org.uk> > > Signed-off-by: Andrew Lunn <andrew@lunn.ch> > > --- > > > > Hi Russell > > > > Does this fix it for you on Clearfog? > > Yes, that also fixes the problem, but I do think this is just papering > over mv88e6xxx needlessly holding locks when it doesn't need to do so. Hi Andrew, Do we have a way forward for this issue? Thanks. > > > > > drivers/net/dsa/mv88e6xxx/chip.c | 8 ++++++++ > > 1 file changed, 8 insertions(+) > > > > diff --git a/drivers/net/dsa/mv88e6xxx/chip.c b/drivers/net/dsa/mv88e6xxx/chip.c > > index 32e7af5caa69..936d53a92144 100644 > > --- a/drivers/net/dsa/mv88e6xxx/chip.c > > +++ b/drivers/net/dsa/mv88e6xxx/chip.c > > @@ -442,12 +442,20 @@ static int mv88e6xxx_g1_irq_setup_common(struct mv88e6xxx_chip *chip) > > > > static int mv88e6xxx_g1_irq_setup(struct mv88e6xxx_chip *chip) > > { > > + static struct lock_class_key lock_key; > > + static struct lock_class_key request_key; > > int err; > > > > err = mv88e6xxx_g1_irq_setup_common(chip); > > if (err) > > return err; > > > > + /* These lock classes tells lockdep that global 1 irqs are in > > + * a different category than their parent GPIO, so it won't > > + * report false recursion. > > + */ > > + irq_set_lockdep_class(chip->irq, &lock_key, &request_key); > > + > > err = request_threaded_irq(chip->irq, NULL, > > mv88e6xxx_g1_irq_thread_fn, > > IRQF_ONESHOT | IRQF_SHARED, > > -- > > 2.20.1 > > > > > > -- > RMK's Patch system: https://www.armlinux.org.uk/developer/patches/ > FTTC broadband for 0.8mile line in suburbia: sync at 12.1Mbps down 622kbps up > According to speedtest.net: 11.9Mbps down 500kbps up
> Hi Andrew, > > Do we have a way forward for this issue? Hi Russell Yes. I tested releasing the mutex around the request for the interrupt. That works. So i will submit a patchset adding both the lockdep class, and the unlock/lock pair. Andrew
From: Andrew Lunn <andrew@lunn.ch> Date: Fri, 22 Feb 2019 18:59:16 +0100 >> Hi Andrew, >> >> Do we have a way forward for this issue? > > Hi Russell > > Yes. I tested releasing the mutex around the request for the > interrupt. That works. So i will submit a patchset adding both the > lockdep class, and the unlock/lock pair. So I'll drop this patch from patchwork.
====================================================== WARNING: possible circular locking dependency detected 4.20.0+ #302 Not tainted ------------------------------------------------------ systemd-udevd/160 is trying to acquire lock: edea6080 (&chip->reg_lock){+.+.}, at: __setup_irq+0x640/0x704 but task is already holding lock: edff0340 (&desc->request_mutex){+.+.}, at: __setup_irq+0xa0/0x704 which lock already depends on the new lock. the existing dependency chain (in reverse order) is: -> #1 (&desc->request_mutex){+.+.}: mutex_lock_nested+0x1c/0x24 __setup_irq+0xa0/0x704 request_threaded_irq+0xd0/0x150 mv88e6xxx_probe+0x41c/0x694 [mv88e6xxx] mdio_probe+0x2c/0x54 really_probe+0x200/0x2c4 driver_probe_device+0x5c/0x174 __driver_attach+0xd8/0xdc bus_for_each_dev+0x58/0x7c bus_add_driver+0xe4/0x1f0 driver_register+0x7c/0x110 mdio_driver_register+0x24/0x58 do_one_initcall+0x74/0x2e8 do_init_module+0x60/0x1d0 load_module+0x1968/0x1ff4 sys_finit_module+0x8c/0x98 ret_fast_syscall+0x0/0x28 0xbedf2ae8 -> #0 (&chip->reg_lock){+.+.}: __mutex_lock+0x50/0x8b8 mutex_lock_nested+0x1c/0x24 __setup_irq+0x640/0x704 request_threaded_irq+0xd0/0x150 mv88e6xxx_g2_irq_setup+0xcc/0x1b4 [mv88e6xxx] mv88e6xxx_probe+0x44c/0x694 [mv88e6xxx] mdio_probe+0x2c/0x54 really_probe+0x200/0x2c4 driver_probe_device+0x5c/0x174 __driver_attach+0xd8/0xdc bus_for_each_dev+0x58/0x7c bus_add_driver+0xe4/0x1f0 driver_register+0x7c/0x110 mdio_driver_register+0x24/0x58 do_one_initcall+0x74/0x2e8 do_init_module+0x60/0x1d0 load_module+0x1968/0x1ff4 sys_finit_module+0x8c/0x98 ret_fast_syscall+0x0/0x28 0xbedf2ae8 other info that might help us debug this: Possible unsafe locking scenario: CPU0 CPU1 ---- ---- lock(&desc->request_mutex); lock(&chip->reg_lock); lock(&desc->request_mutex); lock(&chip->reg_lock); &desc->request_mutex refer to two different mutex. #1 is the GPIO for the chip interrupt. #2 is the chained interrupt between global 1 and global 2. Add lockdep classes to the GPIO interrupt to avoid this. Reported-by: Russell King <rmk+kernel@armlinux.org.uk> Signed-off-by: Andrew Lunn <andrew@lunn.ch> --- Hi Russell Does this fix it for you on Clearfog? drivers/net/dsa/mv88e6xxx/chip.c | 8 ++++++++ 1 file changed, 8 insertions(+) diff --git a/drivers/net/dsa/mv88e6xxx/chip.c b/drivers/net/dsa/mv88e6xxx/chip.c index 32e7af5caa69..936d53a92144 100644 --- a/drivers/net/dsa/mv88e6xxx/chip.c +++ b/drivers/net/dsa/mv88e6xxx/chip.c @@ -442,12 +442,20 @@ static int mv88e6xxx_g1_irq_setup_common(struct mv88e6xxx_chip *chip) static int mv88e6xxx_g1_irq_setup(struct mv88e6xxx_chip *chip) { + static struct lock_class_key lock_key; + static struct lock_class_key request_key; int err; err = mv88e6xxx_g1_irq_setup_common(chip); if (err) return err; + /* These lock classes tells lockdep that global 1 irqs are in + * a different category than their parent GPIO, so it won't + * report false recursion. + */ + irq_set_lockdep_class(chip->irq, &lock_key, &request_key); + err = request_threaded_irq(chip->irq, NULL, mv88e6xxx_g1_irq_thread_fn, IRQF_ONESHOT | IRQF_SHARED,