On Thu, Mar 05, 2020 at 11:50:37AM +0100, Marek Szyprowski wrote: > Dear All, > > On 28.02.2020 10:24, madhuparnabhowmik10@xxxxxxxxx wrote: > > From: Madhuparna Bhowmik <madhuparnabhowmik10@xxxxxxxxx> > > > > This patch default enables CONFIG_PROVE_RCU_LIST option with > > CONFIG_PROVE_RCU for RCU list lockdep debugging. > > > > With this change, RCU list lockdep debugging will be default > > enabled in CONFIG_PROVE_RCU=y kernels. > > > > Most of the RCU users (in core kernel/, drivers/, and net/ > > subsystem) have already been modified to include lockdep > > expressions hence RCU list debugging can be enabled by > > default. > > > > However, there are still chances of enountering > > false-positive lockdep splats because not everything is converted, > > in case RCU list primitives are used in non-RCU read-side critical > > section but under the protection of a lock. It would be okay to > > have a few false-positives, as long as bugs are identified, since this > > patch only affects debugging kernels. > > > > Co-developed-by: Amol Grover <frextrite@xxxxxxxxx> > > Signed-off-by: Amol Grover <frextrite@xxxxxxxxx> > > Signed-off-by: Madhuparna Bhowmik <madhuparnabhowmik10@xxxxxxxxx> > > This patch landed in today's linux-next (20200305) as commit > c9af03c14bfdfd21515e556c3a90ffe2aadc964d. It causes the following kernel > warning during system suspend/resume cycle on all ARM 32bit Samsung > Exynos-based boards (kernel compiled from exynos_defconfig): > > # rtcwake -s 10 -m mem > rtcwake: wakeup from "mem" using /dev/rtc0 at Sat Jan 1 00:01:13 2000 > PM: suspend entry (deep) > Filesystems sync: 0.008 seconds > Freezing user space processes ... (elapsed 0.003 seconds) done. > OOM killer disabled. > Freezing remaining freezable tasks ... (elapsed 0.013 seconds) done. > printk: Suspending console(s) (use no_console_suspend to debug) > Hi, These warnings in power/main.c and power/wakeup.c are already addressed. Check this https://lore.kernel.org/patchwork/patch/1204515/ Thank you, Madhuparna > ============================= > WARNING: suspicious RCU usage > 5.6.0-rc1-00177-gc9af03c14bfd #7728 Not tainted > ----------------------------- > drivers/base/power/main.c:326 RCU-list traversed in non-reader section!! > > other info that might help us debug this: > > > rcu_scheduler_active = 2, debug_locks = 1 > 5 locks held by rtcwake/1452: > #0: edba7270 (sb_writers#7){.+.+}, at: vfs_write+0x16c/0x180 > #1: ece71f44 (&of->mutex){+.+.}, at: kernfs_fop_write+0xd0/0x228 > #2: eda72008 (kn->count#98){.+.+}, at: kernfs_fop_write+0xd8/0x228 > #3: c121223c (system_transition_mutex){+.+.}, at: pm_suspend+0xc0/0x480 > #4: c1285d98 (device_links_srcu){....}, at: > device_links_read_lock+0x0/0x50 > > stack backtrace: > CPU: 7 PID: 1452 Comm: rtcwake Not tainted 5.6.0-rc1-00177-gc9af03c14bfd > #7728 > Hardware name: Samsung Exynos (Flattened Device Tree) > [<c0112710>] (unwind_backtrace) from [<c010e1f4>] (show_stack+0x10/0x14) > [<c010e1f4>] (show_stack) from [<c0b5c50c>] (dump_stack+0xb4/0xe0) > [<c0b5c50c>] (dump_stack) from [<c061ea2c>] > (dpm_wait_for_subordinate+0xf4/0xfc) > [<c061ea2c>] (dpm_wait_for_subordinate) from [<c061f578>] > (__device_suspend+0x20/0x838) > [<c061f578>] (__device_suspend) from [<c0622e1c>] (dpm_suspend+0x188/0x57c) > [<c0622e1c>] (dpm_suspend) from [<c0623bfc>] (dpm_suspend_start+0x98/0xa0) > [<c0623bfc>] (dpm_suspend_start) from [<c0197e20>] > (suspend_devices_and_enter+0xec/0xc74) > [<c0197e20>] (suspend_devices_and_enter) from [<c0198da0>] > (pm_suspend+0x3f8/0x480) > [<c0198da0>] (pm_suspend) from [<c019696c>] (state_store+0x6c/0xc8) > [<c019696c>] (state_store) from [<c0356c78>] (kernfs_fop_write+0x10c/0x228) > [<c0356c78>] (kernfs_fop_write) from [<c02b52c8>] (__vfs_write+0x30/0x1d0) > [<c02b52c8>] (__vfs_write) from [<c02b8264>] (vfs_write+0xa4/0x180) > [<c02b8264>] (vfs_write) from [<c02b84c0>] (ksys_write+0x60/0xd8) > [<c02b84c0>] (ksys_write) from [<c0101000>] (ret_fast_syscall+0x0/0x28) > Exception stack(0xeac89fa8 to 0xeac89ff0) > 9fa0: 00000004 0002b440 00000004 0002b440 00000004 > 00000000 > 9fc0: 00000004 0002b440 000291b0 00000004 0002b440 00000004 be980bfc > 00028160 > 9fe0: 0000006c be980ac8 b6eae000 b6f0b634 > > ============================= > WARNING: suspicious RCU usage > 5.6.0-rc1-00177-gc9af03c14bfd #7728 Not tainted > ----------------------------- > drivers/base/power/main.c:1698 RCU-list traversed in non-reader section!! > > other info that might help us debug this: > > > rcu_scheduler_active = 2, debug_locks = 1 > 6 locks held by rtcwake/1452: > #0: edba7270 (sb_writers#7){.+.+}, at: vfs_write+0x16c/0x180 > #1: ece71f44 (&of->mutex){+.+.}, at: kernfs_fop_write+0xd0/0x228 > #2: eda72008 (kn->count#98){.+.+}, at: kernfs_fop_write+0xd8/0x228 > #3: c121223c (system_transition_mutex){+.+.}, at: pm_suspend+0xc0/0x480 > #4: ebecd984 (&dev->mutex){....}, at: __device_suspend+0xf8/0x838 > #5: c1285d98 (device_links_srcu){....}, at: > device_links_read_lock+0x0/0x50 > > stack backtrace: > CPU: 7 PID: 1452 Comm: rtcwake Not tainted 5.6.0-rc1-00177-gc9af03c14bfd > #7728 > Hardware name: Samsung Exynos (Flattened Device Tree) > [<c0112710>] (unwind_backtrace) from [<c010e1f4>] (show_stack+0x10/0x14) > [<c010e1f4>] (show_stack) from [<c0b5c50c>] (dump_stack+0xb4/0xe0) > [<c0b5c50c>] (dump_stack) from [<c061f8bc>] (__device_suspend+0x364/0x838) > [<c061f8bc>] (__device_suspend) from [<c0622e1c>] (dpm_suspend+0x188/0x57c) > [<c0622e1c>] (dpm_suspend) from [<c0623bfc>] (dpm_suspend_start+0x98/0xa0) > [<c0623bfc>] (dpm_suspend_start) from [<c0197e20>] > (suspend_devices_and_enter+0xec/0xc74) > [<c0197e20>] (suspend_devices_and_enter) from [<c0198da0>] > (pm_suspend+0x3f8/0x480) > [<c0198da0>] (pm_suspend) from [<c019696c>] (state_store+0x6c/0xc8) > [<c019696c>] (state_store) from [<c0356c78>] (kernfs_fop_write+0x10c/0x228) > [<c0356c78>] (kernfs_fop_write) from [<c02b52c8>] (__vfs_write+0x30/0x1d0) > [<c02b52c8>] (__vfs_write) from [<c02b8264>] (vfs_write+0xa4/0x180) > [<c02b8264>] (vfs_write) from [<c02b84c0>] (ksys_write+0x60/0xd8) > [<c02b84c0>] (ksys_write) from [<c0101000>] (ret_fast_syscall+0x0/0x28) > Exception stack(0xeac89fa8 to 0xeac89ff0) > 9fa0: 00000004 0002b440 00000004 0002b440 00000004 > 00000000 > 9fc0: 00000004 0002b440 000291b0 00000004 0002b440 00000004 be980bfc > 00028160 > 9fe0: 0000006c be980ac8 b6eae000 b6f0b634 > wake enabled for irq 160 > wake enabled for irq 164 > samsung-pinctrl 13400000.pinctrl: Setting external wakeup interrupt > mask: 0xffffffe7 > > ============================= > WARNING: suspicious RCU usage > 5.6.0-rc1-00177-gc9af03c14bfd #7728 Not tainted > ----------------------------- > drivers/base/power/wakeup.c:408 RCU-list traversed in non-reader section!! > > other info that might help us debug this: > > > rcu_scheduler_active = 2, debug_locks = 1 > 5 locks held by rtcwake/1452: > #0: edba7270 (sb_writers#7){.+.+}, at: vfs_write+0x16c/0x180 > #1: ece71f44 (&of->mutex){+.+.}, at: kernfs_fop_write+0xd0/0x228 > #2: eda72008 (kn->count#98){.+.+}, at: kernfs_fop_write+0xd8/0x228 > #3: c121223c (system_transition_mutex){+.+.}, at: pm_suspend+0xc0/0x480 > #4: c128722c (wakeup_srcu){....}, at: > device_wakeup_arm_wake_irqs+0x0/0x124 > > stack backtrace: > CPU: 5 PID: 1452 Comm: rtcwake Not tainted 5.6.0-rc1-00177-gc9af03c14bfd > #7728 > Hardware name: Samsung Exynos (Flattened Device Tree) > [<c0112710>] (unwind_backtrace) from [<c010e1f4>] (show_stack+0x10/0x14) > [<c010e1f4>] (show_stack) from [<c0b5c50c>] (dump_stack+0xb4/0xe0) > [<c0b5c50c>] (dump_stack) from [<c0625740>] > (device_wakeup_arm_wake_irqs+0xdc/0x124) > [<c0625740>] (device_wakeup_arm_wake_irqs) from [<c0622120>] > (dpm_suspend_noirq+0x1c/0x5a0) > [<c0622120>] (dpm_suspend_noirq) from [<c019805c>] > (suspend_devices_and_enter+0x328/0xc74) > [<c019805c>] (suspend_devices_and_enter) from [<c0198da0>] > (pm_suspend+0x3f8/0x480) > [<c0198da0>] (pm_suspend) from [<c019696c>] (state_store+0x6c/0xc8) > [<c019696c>] (state_store) from [<c0356c78>] (kernfs_fop_write+0x10c/0x228) > [<c0356c78>] (kernfs_fop_write) from [<c02b52c8>] (__vfs_write+0x30/0x1d0) > [<c02b52c8>] (__vfs_write) from [<c02b8264>] (vfs_write+0xa4/0x180) > [<c02b8264>] (vfs_write) from [<c02b84c0>] (ksys_write+0x60/0xd8) > [<c02b84c0>] (ksys_write) from [<c0101000>] (ret_fast_syscall+0x0/0x28) > Exception stack(0xeac89fa8 to 0xeac89ff0) > 9fa0: 00000004 0002b440 00000004 0002b440 00000004 > 00000000 > 9fc0: 00000004 0002b440 000291b0 00000004 0002b440 00000004 be980bfc > 00028160 > 9fe0: 0000006c be980ac8 b6eae000 b6f0b634 > > ============================= > WARNING: suspicious RCU usage > 5.6.0-rc1-00177-gc9af03c14bfd #7728 Not tainted > ----------------------------- > drivers/base/power/main.c:1238 RCU-list traversed in non-reader section!! > > other info that might help us debug this: > > > rcu_scheduler_active = 2, debug_locks = 1 > 5 locks held by rtcwake/1452: > #0: edba7270 (sb_writers#7){.+.+}, at: vfs_write+0x16c/0x180 > #1: ece71f44 (&of->mutex){+.+.}, at: kernfs_fop_write+0xd0/0x228 > #2: eda72008 (kn->count#98){.+.+}, at: kernfs_fop_write+0xd8/0x228 > #3: c121223c (system_transition_mutex){+.+.}, at: pm_suspend+0xc0/0x480 > #4: c1285d98 (device_links_srcu){....}, at: > device_links_read_lock+0x0/0x50 > > stack backtrace: > CPU: 5 PID: 1452 Comm: rtcwake Not tainted 5.6.0-rc1-00177-gc9af03c14bfd > #7728 > Hardware name: Samsung Exynos (Flattened Device Tree) > [<c0112710>] (unwind_backtrace) from [<c010e1f4>] (show_stack+0x10/0x14) > [<c010e1f4>] (show_stack) from [<c0b5c50c>] (dump_stack+0xb4/0xe0) > [<c0b5c50c>] (dump_stack) from [<c06202d4>] > (__device_suspend_noirq+0x234/0x304) > [<c06202d4>] (__device_suspend_noirq) from [<c0622284>] > (dpm_suspend_noirq+0x180/0x5a0) > [<c0622284>] (dpm_suspend_noirq) from [<c019805c>] > (suspend_devices_and_enter+0x328/0xc74) > [<c019805c>] (suspend_devices_and_enter) from [<c0198da0>] > (pm_suspend+0x3f8/0x480) > [<c0198da0>] (pm_suspend) from [<c019696c>] (state_store+0x6c/0xc8) > [<c019696c>] (state_store) from [<c0356c78>] (kernfs_fop_write+0x10c/0x228) > [<c0356c78>] (kernfs_fop_write) from [<c02b52c8>] (__vfs_write+0x30/0x1d0) > [<c02b52c8>] (__vfs_write) from [<c02b8264>] (vfs_write+0xa4/0x180) > [<c02b8264>] (vfs_write) from [<c02b84c0>] (ksys_write+0x60/0xd8) > [<c02b84c0>] (ksys_write) from [<c0101000>] (ret_fast_syscall+0x0/0x28) > Exception stack(0xeac89fa8 to 0xeac89ff0) > 9fa0: 00000004 0002b440 00000004 0002b440 00000004 > 00000000 > 9fc0: 00000004 0002b440 000291b0 00000004 0002b440 00000004 be980bfc > 00028160 > 9fe0: 0000006c be980ac8 b6eae000 b6f0b634 > Disabling non-boot CPUs ... > IRQ 51: no longer affine to CPU1 > IRQ 52: no longer affine to CPU2 > IRQ 53: no longer affine to CPU3 > IRQ 54: no longer affine to CPU4 > IRQ 55: no longer affine to CPU5 > IRQ 56: no longer affine to CPU6 > IRQ 57: no longer affine to CPU7 > Enabling non-boot CPUs ... > CPU1 is up > CPU2 is up > CPU3 is up > CPU4: detected I-Cache line size mismatch, workaround enabled > CPU4 is up > CPU5: detected I-Cache line size mismatch, workaround enabled > CPU5 is up > CPU6: detected I-Cache line size mismatch, workaround enabled > CPU6 is up > CPU7: detected I-Cache line size mismatch, workaround enabled > CPU7 is up > > ============================= > WARNING: suspicious RCU usage > 5.6.0-rc1-00177-gc9af03c14bfd #7728 Not tainted > ----------------------------- > drivers/base/power/main.c:269 RCU-list traversed in non-reader section!! > > other info that might help us debug this: > > > rcu_scheduler_active = 2, debug_locks = 1 > 5 locks held by rtcwake/1452: > #0: edba7270 (sb_writers#7){.+.+}, at: vfs_write+0x16c/0x180 > #1: ece71f44 (&of->mutex){+.+.}, at: kernfs_fop_write+0xd0/0x228 > #2: eda72008 (kn->count#98){.+.+}, at: kernfs_fop_write+0xd8/0x228 > #3: c121223c (system_transition_mutex){+.+.}, at: pm_suspend+0xc0/0x480 > #4: c1285d98 (device_links_srcu){....}, at: > device_links_read_lock+0x0/0x50 > > stack backtrace: > CPU: 0 PID: 1452 Comm: rtcwake Not tainted 5.6.0-rc1-00177-gc9af03c14bfd > #7728 > Hardware name: Samsung Exynos (Flattened Device Tree) > [<c0112710>] (unwind_backtrace) from [<c010e1f4>] (show_stack+0x10/0x14) > [<c010e1f4>] (show_stack) from [<c0b5c50c>] (dump_stack+0xb4/0xe0) > [<c0b5c50c>] (dump_stack) from [<c061ebf0>] > (dpm_wait_for_superior+0x114/0x12c) > [<c061ebf0>] (dpm_wait_for_superior) from [<c061fe98>] > (device_resume_noirq+0x74/0x238) > [<c061fe98>] (device_resume_noirq) from [<c0620a34>] > (dpm_resume_noirq+0x160/0x53c) > [<c0620a34>] (dpm_resume_noirq) from [<c01983c8>] > (suspend_devices_and_enter+0x694/0xc74) > [<c01983c8>] (suspend_devices_and_enter) from [<c0198da0>] > (pm_suspend+0x3f8/0x480) > [<c0198da0>] (pm_suspend) from [<c019696c>] (state_store+0x6c/0xc8) > [<c019696c>] (state_store) from [<c0356c78>] (kernfs_fop_write+0x10c/0x228) > [<c0356c78>] (kernfs_fop_write) from [<c02b52c8>] (__vfs_write+0x30/0x1d0) > [<c02b52c8>] (__vfs_write) from [<c02b8264>] (vfs_write+0xa4/0x180) > [<c02b8264>] (vfs_write) from [<c02b84c0>] (ksys_write+0x60/0xd8) > [<c02b84c0>] (ksys_write) from [<c0101000>] (ret_fast_syscall+0x0/0x28) > Exception stack(0xeac89fa8 to 0xeac89ff0) > 9fa0: 00000004 0002b440 00000004 0002b440 00000004 > 00000000 > 9fc0: 00000004 0002b440 000291b0 00000004 0002b440 00000004 be980bfc > 00028160 > 9fe0: 0000006c be980ac8 b6eae000 b6f0b634 > s3c-i2c 12c80000.i2c: slave address 0x00 > s3c-i2c 12c80000.i2c: bus frequency set to 65 KHz > > ============================= > WARNING: suspicious RCU usage > 5.6.0-rc1-00177-gc9af03c14bfd #7728 Not tainted > ----------------------------- > drivers/base/power/wakeup.c:424 RCU-list traversed in non-reader section!! > > other info that might help us debug this: > > > rcu_scheduler_active = 2, debug_locks = 1 > 5 locks held by rtcwake/1452: > #0: edba7270 (sb_writers#7){.+.+}, at: vfs_write+0x16c/0x180 > #1: ece71f44 (&of->mutex){+.+.}, at: kernfs_fop_write+0xd0/0x228 > #2: eda72008 (kn->count#98){.+.+}, at: kernfs_fop_write+0xd8/0x228 > #3: c121223c (system_transition_mutex){+.+.}, at: pm_suspend+0xc0/0x480 > #4: c128722c (wakeup_srcu){....}, at: > device_wakeup_disarm_wake_irqs+0x0/0x124 > > stack backtrace: > CPU: 0 PID: 1452 Comm: rtcwake Not tainted 5.6.0-rc1-00177-gc9af03c14bfd > #7728 > Hardware name: Samsung Exynos (Flattened Device Tree) > [<c0112710>] (unwind_backtrace) from [<c010e1f4>] (show_stack+0x10/0x14) > [<c010e1f4>] (show_stack) from [<c0b5c50c>] (dump_stack+0xb4/0xe0) > [<c0b5c50c>] (dump_stack) from [<c0625864>] > (device_wakeup_disarm_wake_irqs+0xdc/0x124) > [<c0625864>] (device_wakeup_disarm_wake_irqs) from [<c0620b84>] > (dpm_resume_noirq+0x2b0/0x53c) > [<c0620b84>] (dpm_resume_noirq) from [<c01983c8>] > (suspend_devices_and_enter+0x694/0xc74) > [<c01983c8>] (suspend_devices_and_enter) from [<c0198da0>] > (pm_suspend+0x3f8/0x480) > [<c0198da0>] (pm_suspend) from [<c019696c>] (state_store+0x6c/0xc8) > [<c019696c>] (state_store) from [<c0356c78>] (kernfs_fop_write+0x10c/0x228) > [<c0356c78>] (kernfs_fop_write) from [<c02b52c8>] (__vfs_write+0x30/0x1d0) > [<c02b52c8>] (__vfs_write) from [<c02b8264>] (vfs_write+0xa4/0x180) > [<c02b8264>] (vfs_write) from [<c02b84c0>] (ksys_write+0x60/0xd8) > [<c02b84c0>] (ksys_write) from [<c0101000>] (ret_fast_syscall+0x0/0x28) > Exception stack(0xeac89fa8 to 0xeac89ff0) > 9fa0: 00000004 0002b440 00000004 0002b440 00000004 > 00000000 > 9fc0: 00000004 0002b440 000291b0 00000004 0002b440 00000004 be980bfc > 00028160 > 9fe0: 0000006c be980ac8 b6eae000 b6f0b634 > > I can help debugging this issue. > > > --- > > kernel/rcu/Kconfig.debug | 11 +++-------- > > 1 file changed, 3 insertions(+), 8 deletions(-) > > > > diff --git a/kernel/rcu/Kconfig.debug b/kernel/rcu/Kconfig.debug > > index 4aa02eee8f6c..ec4bb6c09048 100644 > > --- a/kernel/rcu/Kconfig.debug > > +++ b/kernel/rcu/Kconfig.debug > > @@ -9,15 +9,10 @@ config PROVE_RCU > > def_bool PROVE_LOCKING > > > > config PROVE_RCU_LIST > > - bool "RCU list lockdep debugging" > > - depends on PROVE_RCU && RCU_EXPERT > > - default n > > + def_bool PROVE_RCU > > help > > - Enable RCU lockdep checking for list usages. By default it is > > - turned off since there are several list RCU users that still > > - need to be converted to pass a lockdep expression. To prevent > > - false-positive splats, we keep it default disabled but once all > > - users are converted, we can remove this config option. > > + Enable RCU lockdep checking for list usages. It is default > > + enabled with CONFIG_PROVE_RCU. > > > > config TORTURE_TEST > > tristate > > Best regards > -- > Marek Szyprowski, PhD > Samsung R&D Institute Poland >
