Re: [tip:x86/timers] sched/clock: Enable sched clock early
> > - if (cd.actual_read_sched_clock == jiffy_sched_clock_read)
> > + if (cd.actual_read_sched_clock == jiffy_sched_clock_read) {
> > + local_irq_disable();
> > sched_clock_register(jiffy_sched_clock_read, BITS_PER_LONG,
> > HZ);
> > + local_irq_enable();
> > + }
> >
> > update_sched_clock();
>
> I'm thinking maybe disable IRQs for that entire function, instead of
> just the register call.
Sure, I will send a patch.
Thank you,
Pavel
Re: [tip:x86/timers] sched/clock: Enable sched clock early
> > - if (cd.actual_read_sched_clock == jiffy_sched_clock_read)
> > + if (cd.actual_read_sched_clock == jiffy_sched_clock_read) {
> > + local_irq_disable();
> > sched_clock_register(jiffy_sched_clock_read, BITS_PER_LONG,
> > HZ);
> > + local_irq_enable();
> > + }
> >
> > update_sched_clock();
>
> I'm thinking maybe disable IRQs for that entire function, instead of
> just the register call.
Sure, I will send a patch.
Thank you,
Pavel
Re: [tip:x86/timers] sched/clock: Enable sched clock early
On Tue, Jul 24, 2018 at 10:41:19PM -0400, Pavel Tatashin wrote:
> If we need it, we can surround the sched_clock_register() with
> local_irq_disable/local_irq_enable:
>
> diff --git a/kernel/time/sched_clock.c b/kernel/time/sched_clock.c
> index cbc72c2c1fca..5015b165b55b 100644
> --- a/kernel/time/sched_clock.c
> +++ b/kernel/time/sched_clock.c
> @@ -243,8 +243,11 @@ void __init generic_sched_clock_init(void)
> * If no sched_clock() function has been provided at that point,
> * make it the final one one.
> */
> - if (cd.actual_read_sched_clock == jiffy_sched_clock_read)
> + if (cd.actual_read_sched_clock == jiffy_sched_clock_read) {
> + local_irq_disable();
> sched_clock_register(jiffy_sched_clock_read, BITS_PER_LONG,
> HZ);
> + local_irq_enable();
> + }
>
> update_sched_clock();
I'm thinking maybe disable IRQs for that entire function, instead of
just the register call.
Re: [tip:x86/timers] sched/clock: Enable sched clock early
On Tue, Jul 24, 2018 at 10:41:19PM -0400, Pavel Tatashin wrote:
> If we need it, we can surround the sched_clock_register() with
> local_irq_disable/local_irq_enable:
>
> diff --git a/kernel/time/sched_clock.c b/kernel/time/sched_clock.c
> index cbc72c2c1fca..5015b165b55b 100644
> --- a/kernel/time/sched_clock.c
> +++ b/kernel/time/sched_clock.c
> @@ -243,8 +243,11 @@ void __init generic_sched_clock_init(void)
> * If no sched_clock() function has been provided at that point,
> * make it the final one one.
> */
> - if (cd.actual_read_sched_clock == jiffy_sched_clock_read)
> + if (cd.actual_read_sched_clock == jiffy_sched_clock_read) {
> + local_irq_disable();
> sched_clock_register(jiffy_sched_clock_read, BITS_PER_LONG,
> HZ);
> + local_irq_enable();
> + }
>
> update_sched_clock();
I'm thinking maybe disable IRQs for that entire function, instead of
just the register call.
Re: [tip:x86/timers] sched/clock: Enable sched clock early
> integrator_defconfig+CONFIG_DEVTMPFS=y+CONFIG_DEVTMPFS_MOUNT=y > > Qemu command line is > qemu-system-arm -M integratorcp -m 128 \ > -kernel arch/arm/boot/zImage -no-reboot \ > -initrd busybox-armv4.cpio \ > --append "rdinit=/sbin/init console=ttyAMA0,115200" \ > -serial stdio -monitor null -nographic \ > -dtb arch/arm/boot/dts/integratorcp.dtb > > The scripts and files used are available from > g...@github.com:groeck/linux-build-test.git. > qemu is version 2.12. Reproduced. Thank you
Re: [tip:x86/timers] sched/clock: Enable sched clock early
> integrator_defconfig+CONFIG_DEVTMPFS=y+CONFIG_DEVTMPFS_MOUNT=y > > Qemu command line is > qemu-system-arm -M integratorcp -m 128 \ > -kernel arch/arm/boot/zImage -no-reboot \ > -initrd busybox-armv4.cpio \ > --append "rdinit=/sbin/init console=ttyAMA0,115200" \ > -serial stdio -monitor null -nographic \ > -dtb arch/arm/boot/dts/integratorcp.dtb > > The scripts and files used are available from > g...@github.com:groeck/linux-build-test.git. > qemu is version 2.12. Reproduced. Thank you
Re: [tip:x86/timers] sched/clock: Enable sched clock early
Peter,
The problem is in this stack
start_kernel
local_irq_enable
late_time_init
sched_clock_init
generic_sched_clock_init
sched_clock_register
WARN_ON(!irqs_disabled());
Before this work, sched_clock_init() was called prior to enabling
interrupts, but now after. So, we hit this WARN_ON() in
sched_clock_register().
The question is why do we need this warning in sched_clock_register? I
guess because we want to make this section of the code atomic:
195 new_epoch = read(); <- from here
196 cyc = cd.actual_read_sched_clock();
197 ns = rd.epoch_ns + cyc_to_ns((cyc - rd.epoch_cyc) &
rd.sched_clock_mask, rd.mult, rd.shift);
198 cd.actual_read_sched_clock = read;
199
200 rd.read_sched_clock = read;
201 rd.sched_clock_mask = new_mask;
202 rd.mult = new_mult;
203 rd.shift= new_shift;
204 rd.epoch_cyc= new_epoch;
205 rd.epoch_ns = ns;
206
207 update_clock_read_data(); <- to here
If we need it, we can surround the sched_clock_register() with
local_irq_disable/local_irq_enable:
diff --git a/kernel/time/sched_clock.c b/kernel/time/sched_clock.c
index cbc72c2c1fca..5015b165b55b 100644
--- a/kernel/time/sched_clock.c
+++ b/kernel/time/sched_clock.c
@@ -243,8 +243,11 @@ void __init generic_sched_clock_init(void)
* If no sched_clock() function has been provided at that point,
* make it the final one one.
*/
- if (cd.actual_read_sched_clock == jiffy_sched_clock_read)
+ if (cd.actual_read_sched_clock == jiffy_sched_clock_read) {
+ local_irq_disable();
sched_clock_register(jiffy_sched_clock_read, BITS_PER_LONG, HZ);
+ local_irq_enable();
+ }
update_sched_clock();
Thank you,
Pavel
Re: [tip:x86/timers] sched/clock: Enable sched clock early
Peter,
The problem is in this stack
start_kernel
local_irq_enable
late_time_init
sched_clock_init
generic_sched_clock_init
sched_clock_register
WARN_ON(!irqs_disabled());
Before this work, sched_clock_init() was called prior to enabling
interrupts, but now after. So, we hit this WARN_ON() in
sched_clock_register().
The question is why do we need this warning in sched_clock_register? I
guess because we want to make this section of the code atomic:
195 new_epoch = read(); <- from here
196 cyc = cd.actual_read_sched_clock();
197 ns = rd.epoch_ns + cyc_to_ns((cyc - rd.epoch_cyc) &
rd.sched_clock_mask, rd.mult, rd.shift);
198 cd.actual_read_sched_clock = read;
199
200 rd.read_sched_clock = read;
201 rd.sched_clock_mask = new_mask;
202 rd.mult = new_mult;
203 rd.shift= new_shift;
204 rd.epoch_cyc= new_epoch;
205 rd.epoch_ns = ns;
206
207 update_clock_read_data(); <- to here
If we need it, we can surround the sched_clock_register() with
local_irq_disable/local_irq_enable:
diff --git a/kernel/time/sched_clock.c b/kernel/time/sched_clock.c
index cbc72c2c1fca..5015b165b55b 100644
--- a/kernel/time/sched_clock.c
+++ b/kernel/time/sched_clock.c
@@ -243,8 +243,11 @@ void __init generic_sched_clock_init(void)
* If no sched_clock() function has been provided at that point,
* make it the final one one.
*/
- if (cd.actual_read_sched_clock == jiffy_sched_clock_read)
+ if (cd.actual_read_sched_clock == jiffy_sched_clock_read) {
+ local_irq_disable();
sched_clock_register(jiffy_sched_clock_read, BITS_PER_LONG, HZ);
+ local_irq_enable();
+ }
update_sched_clock();
Thank you,
Pavel
Re: [tip:x86/timers] sched/clock: Enable sched clock early
On 07/24/2018 05:36 PM, Pavel Tatashin wrote: On Tue, Jul 24, 2018 at 4:22 PM Pavel Tatashin wrote: On Tue, Jul 24, 2018 at 3:54 PM Guenter Roeck wrote: Hi, On Thu, Jul 19, 2018 at 03:33:21PM -0700, tip-bot for Pavel Tatashin wrote: Commit-ID: 857baa87b6422bcfb84ed3631d6839920cb5b09d Gitweb: https://git.kernel.org/tip/857baa87b6422bcfb84ed3631d6839920cb5b09d Author: Pavel Tatashin AuthorDate: Thu, 19 Jul 2018 16:55:42 -0400 Committer: Thomas Gleixner CommitDate: Fri, 20 Jul 2018 00:02:43 +0200 sched/clock: Enable sched clock early Allow sched_clock() to be used before schec_clock_init() is called. This provides a way to get early boot timestamps on machines with unstable clocks. This patch causes a regression when running a qemu emulation with arm:integratorcp. Thank you for the report. I will study it. ... Console: colour dummy device 80x30 [ cut here ] WARNING: CPU: 0 PID: 0 at kernel/time/sched_clock.c:180 sched_clock_register+0x44/0x278 Modules linked in: CPU: 0 PID: 0 Comm: swapper Not tainted 4.18.0-rc6-next-20180724 #1 Hardware name: ARM Integrator/CP (Device Tree) [] (unwind_backtrace) from [] (show_stack+0x10/0x18) [] (show_stack) from [] (dump_stack+0x18/0x24) [] (dump_stack) from [] (__warn+0xc8/0xf0) [] (__warn) from [] (warn_slowpath_null+0x3c/0x4c) [] (warn_slowpath_null) from [] (sched_clock_register+0x44/0x278) [] (sched_clock_register) from [] (generic_sched_clock_init+0x28/0x88) [] (generic_sched_clock_init) from [] (sched_clock_init+0x54/0x74) [] (sched_clock_init) from [] (start_kernel+0x310/0x3e4) [] (start_kernel) from [<>] ( (null)) ---[ end trace 08080eb81afa002c ]--- sched_clock: 32 bits at 100 Hz, resolution 1000ns, wraps every 2147483647500ns ... A complete boot log is available at http://kerneltests.org/builders/qemu-arm-next/builds/979/steps/qemubuildcommand/logs/stdio Unfortunately, reverting the patch results in conflicts, so I am unable to confirm that it is the only culprit. From the context and from looking into the patch, it appears that this can happen in any system if CONFIG_HAVE_UNSTABLE_SCHED_CLOCK is not enabled. Do you have a complete config, and also qemu args that were used? I have tried defconfig arm, and run in qemu, could not reproduce the problem. integrator_defconfig+CONFIG_DEVTMPFS=y+CONFIG_DEVTMPFS_MOUNT=y Qemu command line is qemu-system-arm -M integratorcp -m 128 \ -kernel arch/arm/boot/zImage -no-reboot \ -initrd busybox-armv4.cpio \ --append "rdinit=/sbin/init console=ttyAMA0,115200" \ -serial stdio -monitor null -nographic \ -dtb arch/arm/boot/dts/integratorcp.dtb The scripts and files used are available from g...@github.com:groeck/linux-build-test.git. qemu is version 2.12. Guenter Thank you, Pavel Bisect log is attached. Guenter --- # bad: [3946cd385042069ec57d3f04240def53b4eed7e5] Add linux-next specific files for 20180724 # good: [d72e90f33aa4709ebecc5005562f52335e106a60] Linux 4.18-rc6 git bisect start 'HEAD' 'v4.18-rc6' # good: [f5fa891e325acf096c0f79e1d1b922002e251e5a] Merge remote-tracking branch 'crypto/master' git bisect good f5fa891e325acf096c0f79e1d1b922002e251e5a # good: [cb6471f6bcfdacbeef9c23ba9dac00e67bd3c3a4] Merge remote-tracking branch 'spi/for-next' git bisect good cb6471f6bcfdacbeef9c23ba9dac00e67bd3c3a4 # bad: [6b5bfa57bf4553d051be65d85d021465041406d8] Merge remote-tracking branch 'char-misc/char-misc-next' git bisect bad 6b5bfa57bf4553d051be65d85d021465041406d8 # bad: [675a67e9ef3c041999f412cb75418d2b0def3854] Merge remote-tracking branch 'rcu/rcu/next' git bisect bad 675a67e9ef3c041999f412cb75418d2b0def3854 # good: [e78b01a51131f25fc2d881bc43001575c129069c] Merge branch 'perf/core' git bisect good e78b01a51131f25fc2d881bc43001575c129069c # good: [4e581bce514f4107ce84525f0f75f89c92b4140e] Merge branch 'x86/cpu' git bisect good 4e581bce514f4107ce84525f0f75f89c92b4140e # good: [20fa22e90e54e2d21cace7ba083598531670f7cf] Merge branch 'x86/pti' git bisect good 20fa22e90e54e2d21cace7ba083598531670f7cf # good: [4763f03d3d186ce8a1125844790152d76804ad60] x86/tsc: Use TSC as sched clock early git bisect good 4763f03d3d186ce8a1125844790152d76804ad60 # good: [5f9ef44c7d1c59d0eda1d86e31d981bdffe2a725] tools/memory-model: Rename litmus tests to comply to norm7 git bisect good 5f9ef44c7d1c59d0eda1d86e31d981bdffe2a725 # bad: [fc3d25e1c8f6a9232530db02a1072033e22e0fe3] Merge branch 'x86/timers' git bisect bad fc3d25e1c8f6a9232530db02a1072033e22e0fe3 # bad: [46457ea464f5341d1f9dad8dd213805d45f7f117] sched/clock: Use static key for sched_clock_running git bisect bad 46457ea464f5341d1f9dad8dd213805d45f7f117 # bad: [857baa87b6422bcfb84ed3631d6839920cb5b09d] sched/clock: Enable sched clock early git bisect bad 857baa87b6422bcfb84ed3631d6839920cb5b09d # good: [5d2a4e91a541cb04d20d11602f0f9340291322ac] sched/clock: Move sched clock initialization and merge with generic clock git bisect good
Re: [tip:x86/timers] sched/clock: Enable sched clock early
On 07/24/2018 05:36 PM, Pavel Tatashin wrote: On Tue, Jul 24, 2018 at 4:22 PM Pavel Tatashin wrote: On Tue, Jul 24, 2018 at 3:54 PM Guenter Roeck wrote: Hi, On Thu, Jul 19, 2018 at 03:33:21PM -0700, tip-bot for Pavel Tatashin wrote: Commit-ID: 857baa87b6422bcfb84ed3631d6839920cb5b09d Gitweb: https://git.kernel.org/tip/857baa87b6422bcfb84ed3631d6839920cb5b09d Author: Pavel Tatashin AuthorDate: Thu, 19 Jul 2018 16:55:42 -0400 Committer: Thomas Gleixner CommitDate: Fri, 20 Jul 2018 00:02:43 +0200 sched/clock: Enable sched clock early Allow sched_clock() to be used before schec_clock_init() is called. This provides a way to get early boot timestamps on machines with unstable clocks. This patch causes a regression when running a qemu emulation with arm:integratorcp. Thank you for the report. I will study it. ... Console: colour dummy device 80x30 [ cut here ] WARNING: CPU: 0 PID: 0 at kernel/time/sched_clock.c:180 sched_clock_register+0x44/0x278 Modules linked in: CPU: 0 PID: 0 Comm: swapper Not tainted 4.18.0-rc6-next-20180724 #1 Hardware name: ARM Integrator/CP (Device Tree) [] (unwind_backtrace) from [] (show_stack+0x10/0x18) [] (show_stack) from [] (dump_stack+0x18/0x24) [] (dump_stack) from [] (__warn+0xc8/0xf0) [] (__warn) from [] (warn_slowpath_null+0x3c/0x4c) [] (warn_slowpath_null) from [] (sched_clock_register+0x44/0x278) [] (sched_clock_register) from [] (generic_sched_clock_init+0x28/0x88) [] (generic_sched_clock_init) from [] (sched_clock_init+0x54/0x74) [] (sched_clock_init) from [] (start_kernel+0x310/0x3e4) [] (start_kernel) from [<>] ( (null)) ---[ end trace 08080eb81afa002c ]--- sched_clock: 32 bits at 100 Hz, resolution 1000ns, wraps every 2147483647500ns ... A complete boot log is available at http://kerneltests.org/builders/qemu-arm-next/builds/979/steps/qemubuildcommand/logs/stdio Unfortunately, reverting the patch results in conflicts, so I am unable to confirm that it is the only culprit. From the context and from looking into the patch, it appears that this can happen in any system if CONFIG_HAVE_UNSTABLE_SCHED_CLOCK is not enabled. Do you have a complete config, and also qemu args that were used? I have tried defconfig arm, and run in qemu, could not reproduce the problem. integrator_defconfig+CONFIG_DEVTMPFS=y+CONFIG_DEVTMPFS_MOUNT=y Qemu command line is qemu-system-arm -M integratorcp -m 128 \ -kernel arch/arm/boot/zImage -no-reboot \ -initrd busybox-armv4.cpio \ --append "rdinit=/sbin/init console=ttyAMA0,115200" \ -serial stdio -monitor null -nographic \ -dtb arch/arm/boot/dts/integratorcp.dtb The scripts and files used are available from g...@github.com:groeck/linux-build-test.git. qemu is version 2.12. Guenter Thank you, Pavel Bisect log is attached. Guenter --- # bad: [3946cd385042069ec57d3f04240def53b4eed7e5] Add linux-next specific files for 20180724 # good: [d72e90f33aa4709ebecc5005562f52335e106a60] Linux 4.18-rc6 git bisect start 'HEAD' 'v4.18-rc6' # good: [f5fa891e325acf096c0f79e1d1b922002e251e5a] Merge remote-tracking branch 'crypto/master' git bisect good f5fa891e325acf096c0f79e1d1b922002e251e5a # good: [cb6471f6bcfdacbeef9c23ba9dac00e67bd3c3a4] Merge remote-tracking branch 'spi/for-next' git bisect good cb6471f6bcfdacbeef9c23ba9dac00e67bd3c3a4 # bad: [6b5bfa57bf4553d051be65d85d021465041406d8] Merge remote-tracking branch 'char-misc/char-misc-next' git bisect bad 6b5bfa57bf4553d051be65d85d021465041406d8 # bad: [675a67e9ef3c041999f412cb75418d2b0def3854] Merge remote-tracking branch 'rcu/rcu/next' git bisect bad 675a67e9ef3c041999f412cb75418d2b0def3854 # good: [e78b01a51131f25fc2d881bc43001575c129069c] Merge branch 'perf/core' git bisect good e78b01a51131f25fc2d881bc43001575c129069c # good: [4e581bce514f4107ce84525f0f75f89c92b4140e] Merge branch 'x86/cpu' git bisect good 4e581bce514f4107ce84525f0f75f89c92b4140e # good: [20fa22e90e54e2d21cace7ba083598531670f7cf] Merge branch 'x86/pti' git bisect good 20fa22e90e54e2d21cace7ba083598531670f7cf # good: [4763f03d3d186ce8a1125844790152d76804ad60] x86/tsc: Use TSC as sched clock early git bisect good 4763f03d3d186ce8a1125844790152d76804ad60 # good: [5f9ef44c7d1c59d0eda1d86e31d981bdffe2a725] tools/memory-model: Rename litmus tests to comply to norm7 git bisect good 5f9ef44c7d1c59d0eda1d86e31d981bdffe2a725 # bad: [fc3d25e1c8f6a9232530db02a1072033e22e0fe3] Merge branch 'x86/timers' git bisect bad fc3d25e1c8f6a9232530db02a1072033e22e0fe3 # bad: [46457ea464f5341d1f9dad8dd213805d45f7f117] sched/clock: Use static key for sched_clock_running git bisect bad 46457ea464f5341d1f9dad8dd213805d45f7f117 # bad: [857baa87b6422bcfb84ed3631d6839920cb5b09d] sched/clock: Enable sched clock early git bisect bad 857baa87b6422bcfb84ed3631d6839920cb5b09d # good: [5d2a4e91a541cb04d20d11602f0f9340291322ac] sched/clock: Move sched clock initialization and merge with generic clock git bisect good
Re: [tip:x86/timers] sched/clock: Enable sched clock early
On Tue, Jul 24, 2018 at 4:22 PM Pavel Tatashin wrote: > > On Tue, Jul 24, 2018 at 3:54 PM Guenter Roeck wrote: > > > > Hi, > > > > On Thu, Jul 19, 2018 at 03:33:21PM -0700, tip-bot for Pavel Tatashin wrote: > > > Commit-ID: 857baa87b6422bcfb84ed3631d6839920cb5b09d > > > Gitweb: > > > https://git.kernel.org/tip/857baa87b6422bcfb84ed3631d6839920cb5b09d > > > Author: Pavel Tatashin > > > AuthorDate: Thu, 19 Jul 2018 16:55:42 -0400 > > > Committer: Thomas Gleixner > > > CommitDate: Fri, 20 Jul 2018 00:02:43 +0200 > > > > > > sched/clock: Enable sched clock early > > > > > > Allow sched_clock() to be used before schec_clock_init() is called. This > > > provides a way to get early boot timestamps on machines with unstable > > > clocks. > > > > > > > This patch causes a regression when running a qemu emulation with > > arm:integratorcp. > > Thank you for the report. I will study it. > > > > > ... > > Console: colour dummy device 80x30 > > [ cut here ] > > WARNING: CPU: 0 PID: 0 at kernel/time/sched_clock.c:180 > > sched_clock_register+0x44/0x278 > > Modules linked in: > > CPU: 0 PID: 0 Comm: swapper Not tainted 4.18.0-rc6-next-20180724 #1 > > Hardware name: ARM Integrator/CP (Device Tree) > > [] (unwind_backtrace) from [] (show_stack+0x10/0x18) > > [] (show_stack) from [] (dump_stack+0x18/0x24) > > [] (dump_stack) from [] (__warn+0xc8/0xf0) > > [] (__warn) from [] (warn_slowpath_null+0x3c/0x4c) > > [] (warn_slowpath_null) from [] > > (sched_clock_register+0x44/0x278) > > [] (sched_clock_register) from [] > > (generic_sched_clock_init+0x28/0x88) > > [] (generic_sched_clock_init) from [] > > (sched_clock_init+0x54/0x74) > > [] (sched_clock_init) from [] (start_kernel+0x310/0x3e4) > > [] (start_kernel) from [<>] ( (null)) > > ---[ end trace 08080eb81afa002c ]--- > > sched_clock: 32 bits at 100 Hz, resolution 1000ns, wraps every > > 2147483647500ns > > ... > > > > A complete boot log is available at > > http://kerneltests.org/builders/qemu-arm-next/builds/979/steps/qemubuildcommand/logs/stdio > > > > Unfortunately, reverting the patch results in conflicts, so I am unable > > to confirm that it is the only culprit. > > > > From the context and from looking into the patch, it appears that this > > can happen in any system if CONFIG_HAVE_UNSTABLE_SCHED_CLOCK is not > > enabled. Do you have a complete config, and also qemu args that were used? I have tried defconfig arm, and run in qemu, could not reproduce the problem. Thank you, Pavel > > > > Bisect log is attached. > > > > Guenter > > > > --- > > # bad: [3946cd385042069ec57d3f04240def53b4eed7e5] Add linux-next specific > > files for 20180724 > > # good: [d72e90f33aa4709ebecc5005562f52335e106a60] Linux 4.18-rc6 > > git bisect start 'HEAD' 'v4.18-rc6' > > # good: [f5fa891e325acf096c0f79e1d1b922002e251e5a] Merge remote-tracking > > branch 'crypto/master' > > git bisect good f5fa891e325acf096c0f79e1d1b922002e251e5a > > # good: [cb6471f6bcfdacbeef9c23ba9dac00e67bd3c3a4] Merge remote-tracking > > branch 'spi/for-next' > > git bisect good cb6471f6bcfdacbeef9c23ba9dac00e67bd3c3a4 > > # bad: [6b5bfa57bf4553d051be65d85d021465041406d8] Merge remote-tracking > > branch 'char-misc/char-misc-next' > > git bisect bad 6b5bfa57bf4553d051be65d85d021465041406d8 > > # bad: [675a67e9ef3c041999f412cb75418d2b0def3854] Merge remote-tracking > > branch 'rcu/rcu/next' > > git bisect bad 675a67e9ef3c041999f412cb75418d2b0def3854 > > # good: [e78b01a51131f25fc2d881bc43001575c129069c] Merge branch 'perf/core' > > git bisect good e78b01a51131f25fc2d881bc43001575c129069c > > # good: [4e581bce514f4107ce84525f0f75f89c92b4140e] Merge branch 'x86/cpu' > > git bisect good 4e581bce514f4107ce84525f0f75f89c92b4140e > > # good: [20fa22e90e54e2d21cace7ba083598531670f7cf] Merge branch 'x86/pti' > > git bisect good 20fa22e90e54e2d21cace7ba083598531670f7cf > > # good: [4763f03d3d186ce8a1125844790152d76804ad60] x86/tsc: Use TSC as > > sched clock early > > git bisect good 4763f03d3d186ce8a1125844790152d76804ad60 > > # good: [5f9ef44c7d1c59d0eda1d86e31d981bdffe2a725] tools/memory-model: > > Rename litmus tests to comply to norm7 > > git bisect good 5f9ef44c7d1c59d0eda1d86e31d981bdffe2a725 > > # bad: [fc3d25e1c8f6a9232530db02a1072033e22e0fe3] Merge branch 'x86/timers' > > git bisect bad fc3d25e1c8f6a9232530db02a1072033e22e0fe3 > > # bad: [46457ea464f5341d1f9dad8dd213805d45f7f117] sched/clock: Use static > > key for sched_clock_running > > git bisect bad 46457ea464f5341d1f9dad8dd213805d45f7f117 > > # bad: [857baa87b6422bcfb84ed3631d6839920cb5b09d] sched/clock: Enable sched > > clock early > > git bisect bad 857baa87b6422bcfb84ed3631d6839920cb5b09d > > # good: [5d2a4e91a541cb04d20d11602f0f9340291322ac] sched/clock: Move sched > > clock initialization and merge with generic clock > > git bisect good 5d2a4e91a541cb04d20d11602f0f9340291322ac > > # first bad commit: [857baa87b6422bcfb84ed3631d6839920cb5b09d] sched/clock: > > Enable sched clock
Re: [tip:x86/timers] sched/clock: Enable sched clock early
On Tue, Jul 24, 2018 at 4:22 PM Pavel Tatashin wrote: > > On Tue, Jul 24, 2018 at 3:54 PM Guenter Roeck wrote: > > > > Hi, > > > > On Thu, Jul 19, 2018 at 03:33:21PM -0700, tip-bot for Pavel Tatashin wrote: > > > Commit-ID: 857baa87b6422bcfb84ed3631d6839920cb5b09d > > > Gitweb: > > > https://git.kernel.org/tip/857baa87b6422bcfb84ed3631d6839920cb5b09d > > > Author: Pavel Tatashin > > > AuthorDate: Thu, 19 Jul 2018 16:55:42 -0400 > > > Committer: Thomas Gleixner > > > CommitDate: Fri, 20 Jul 2018 00:02:43 +0200 > > > > > > sched/clock: Enable sched clock early > > > > > > Allow sched_clock() to be used before schec_clock_init() is called. This > > > provides a way to get early boot timestamps on machines with unstable > > > clocks. > > > > > > > This patch causes a regression when running a qemu emulation with > > arm:integratorcp. > > Thank you for the report. I will study it. > > > > > ... > > Console: colour dummy device 80x30 > > [ cut here ] > > WARNING: CPU: 0 PID: 0 at kernel/time/sched_clock.c:180 > > sched_clock_register+0x44/0x278 > > Modules linked in: > > CPU: 0 PID: 0 Comm: swapper Not tainted 4.18.0-rc6-next-20180724 #1 > > Hardware name: ARM Integrator/CP (Device Tree) > > [] (unwind_backtrace) from [] (show_stack+0x10/0x18) > > [] (show_stack) from [] (dump_stack+0x18/0x24) > > [] (dump_stack) from [] (__warn+0xc8/0xf0) > > [] (__warn) from [] (warn_slowpath_null+0x3c/0x4c) > > [] (warn_slowpath_null) from [] > > (sched_clock_register+0x44/0x278) > > [] (sched_clock_register) from [] > > (generic_sched_clock_init+0x28/0x88) > > [] (generic_sched_clock_init) from [] > > (sched_clock_init+0x54/0x74) > > [] (sched_clock_init) from [] (start_kernel+0x310/0x3e4) > > [] (start_kernel) from [<>] ( (null)) > > ---[ end trace 08080eb81afa002c ]--- > > sched_clock: 32 bits at 100 Hz, resolution 1000ns, wraps every > > 2147483647500ns > > ... > > > > A complete boot log is available at > > http://kerneltests.org/builders/qemu-arm-next/builds/979/steps/qemubuildcommand/logs/stdio > > > > Unfortunately, reverting the patch results in conflicts, so I am unable > > to confirm that it is the only culprit. > > > > From the context and from looking into the patch, it appears that this > > can happen in any system if CONFIG_HAVE_UNSTABLE_SCHED_CLOCK is not > > enabled. Do you have a complete config, and also qemu args that were used? I have tried defconfig arm, and run in qemu, could not reproduce the problem. Thank you, Pavel > > > > Bisect log is attached. > > > > Guenter > > > > --- > > # bad: [3946cd385042069ec57d3f04240def53b4eed7e5] Add linux-next specific > > files for 20180724 > > # good: [d72e90f33aa4709ebecc5005562f52335e106a60] Linux 4.18-rc6 > > git bisect start 'HEAD' 'v4.18-rc6' > > # good: [f5fa891e325acf096c0f79e1d1b922002e251e5a] Merge remote-tracking > > branch 'crypto/master' > > git bisect good f5fa891e325acf096c0f79e1d1b922002e251e5a > > # good: [cb6471f6bcfdacbeef9c23ba9dac00e67bd3c3a4] Merge remote-tracking > > branch 'spi/for-next' > > git bisect good cb6471f6bcfdacbeef9c23ba9dac00e67bd3c3a4 > > # bad: [6b5bfa57bf4553d051be65d85d021465041406d8] Merge remote-tracking > > branch 'char-misc/char-misc-next' > > git bisect bad 6b5bfa57bf4553d051be65d85d021465041406d8 > > # bad: [675a67e9ef3c041999f412cb75418d2b0def3854] Merge remote-tracking > > branch 'rcu/rcu/next' > > git bisect bad 675a67e9ef3c041999f412cb75418d2b0def3854 > > # good: [e78b01a51131f25fc2d881bc43001575c129069c] Merge branch 'perf/core' > > git bisect good e78b01a51131f25fc2d881bc43001575c129069c > > # good: [4e581bce514f4107ce84525f0f75f89c92b4140e] Merge branch 'x86/cpu' > > git bisect good 4e581bce514f4107ce84525f0f75f89c92b4140e > > # good: [20fa22e90e54e2d21cace7ba083598531670f7cf] Merge branch 'x86/pti' > > git bisect good 20fa22e90e54e2d21cace7ba083598531670f7cf > > # good: [4763f03d3d186ce8a1125844790152d76804ad60] x86/tsc: Use TSC as > > sched clock early > > git bisect good 4763f03d3d186ce8a1125844790152d76804ad60 > > # good: [5f9ef44c7d1c59d0eda1d86e31d981bdffe2a725] tools/memory-model: > > Rename litmus tests to comply to norm7 > > git bisect good 5f9ef44c7d1c59d0eda1d86e31d981bdffe2a725 > > # bad: [fc3d25e1c8f6a9232530db02a1072033e22e0fe3] Merge branch 'x86/timers' > > git bisect bad fc3d25e1c8f6a9232530db02a1072033e22e0fe3 > > # bad: [46457ea464f5341d1f9dad8dd213805d45f7f117] sched/clock: Use static > > key for sched_clock_running > > git bisect bad 46457ea464f5341d1f9dad8dd213805d45f7f117 > > # bad: [857baa87b6422bcfb84ed3631d6839920cb5b09d] sched/clock: Enable sched > > clock early > > git bisect bad 857baa87b6422bcfb84ed3631d6839920cb5b09d > > # good: [5d2a4e91a541cb04d20d11602f0f9340291322ac] sched/clock: Move sched > > clock initialization and merge with generic clock > > git bisect good 5d2a4e91a541cb04d20d11602f0f9340291322ac > > # first bad commit: [857baa87b6422bcfb84ed3631d6839920cb5b09d] sched/clock: > > Enable sched clock
Re: [tip:x86/timers] sched/clock: Enable sched clock early
On Tue, Jul 24, 2018 at 3:54 PM Guenter Roeck wrote: > > Hi, > > On Thu, Jul 19, 2018 at 03:33:21PM -0700, tip-bot for Pavel Tatashin wrote: > > Commit-ID: 857baa87b6422bcfb84ed3631d6839920cb5b09d > > Gitweb: > > https://git.kernel.org/tip/857baa87b6422bcfb84ed3631d6839920cb5b09d > > Author: Pavel Tatashin > > AuthorDate: Thu, 19 Jul 2018 16:55:42 -0400 > > Committer: Thomas Gleixner > > CommitDate: Fri, 20 Jul 2018 00:02:43 +0200 > > > > sched/clock: Enable sched clock early > > > > Allow sched_clock() to be used before schec_clock_init() is called. This > > provides a way to get early boot timestamps on machines with unstable > > clocks. > > > > This patch causes a regression when running a qemu emulation with > arm:integratorcp. Thank you for the report. I will study it. > > ... > Console: colour dummy device 80x30 > [ cut here ] > WARNING: CPU: 0 PID: 0 at kernel/time/sched_clock.c:180 > sched_clock_register+0x44/0x278 > Modules linked in: > CPU: 0 PID: 0 Comm: swapper Not tainted 4.18.0-rc6-next-20180724 #1 > Hardware name: ARM Integrator/CP (Device Tree) > [] (unwind_backtrace) from [] (show_stack+0x10/0x18) > [] (show_stack) from [] (dump_stack+0x18/0x24) > [] (dump_stack) from [] (__warn+0xc8/0xf0) > [] (__warn) from [] (warn_slowpath_null+0x3c/0x4c) > [] (warn_slowpath_null) from [] > (sched_clock_register+0x44/0x278) > [] (sched_clock_register) from [] > (generic_sched_clock_init+0x28/0x88) > [] (generic_sched_clock_init) from [] > (sched_clock_init+0x54/0x74) > [] (sched_clock_init) from [] (start_kernel+0x310/0x3e4) > [] (start_kernel) from [<>] ( (null)) > ---[ end trace 08080eb81afa002c ]--- > sched_clock: 32 bits at 100 Hz, resolution 1000ns, wraps every > 2147483647500ns > ... > > A complete boot log is available at > http://kerneltests.org/builders/qemu-arm-next/builds/979/steps/qemubuildcommand/logs/stdio > > Unfortunately, reverting the patch results in conflicts, so I am unable > to confirm that it is the only culprit. > > From the context and from looking into the patch, it appears that this > can happen in any system if CONFIG_HAVE_UNSTABLE_SCHED_CLOCK is not > enabled. > > Bisect log is attached. > > Guenter > > --- > # bad: [3946cd385042069ec57d3f04240def53b4eed7e5] Add linux-next specific > files for 20180724 > # good: [d72e90f33aa4709ebecc5005562f52335e106a60] Linux 4.18-rc6 > git bisect start 'HEAD' 'v4.18-rc6' > # good: [f5fa891e325acf096c0f79e1d1b922002e251e5a] Merge remote-tracking > branch 'crypto/master' > git bisect good f5fa891e325acf096c0f79e1d1b922002e251e5a > # good: [cb6471f6bcfdacbeef9c23ba9dac00e67bd3c3a4] Merge remote-tracking > branch 'spi/for-next' > git bisect good cb6471f6bcfdacbeef9c23ba9dac00e67bd3c3a4 > # bad: [6b5bfa57bf4553d051be65d85d021465041406d8] Merge remote-tracking > branch 'char-misc/char-misc-next' > git bisect bad 6b5bfa57bf4553d051be65d85d021465041406d8 > # bad: [675a67e9ef3c041999f412cb75418d2b0def3854] Merge remote-tracking > branch 'rcu/rcu/next' > git bisect bad 675a67e9ef3c041999f412cb75418d2b0def3854 > # good: [e78b01a51131f25fc2d881bc43001575c129069c] Merge branch 'perf/core' > git bisect good e78b01a51131f25fc2d881bc43001575c129069c > # good: [4e581bce514f4107ce84525f0f75f89c92b4140e] Merge branch 'x86/cpu' > git bisect good 4e581bce514f4107ce84525f0f75f89c92b4140e > # good: [20fa22e90e54e2d21cace7ba083598531670f7cf] Merge branch 'x86/pti' > git bisect good 20fa22e90e54e2d21cace7ba083598531670f7cf > # good: [4763f03d3d186ce8a1125844790152d76804ad60] x86/tsc: Use TSC as sched > clock early > git bisect good 4763f03d3d186ce8a1125844790152d76804ad60 > # good: [5f9ef44c7d1c59d0eda1d86e31d981bdffe2a725] tools/memory-model: Rename > litmus tests to comply to norm7 > git bisect good 5f9ef44c7d1c59d0eda1d86e31d981bdffe2a725 > # bad: [fc3d25e1c8f6a9232530db02a1072033e22e0fe3] Merge branch 'x86/timers' > git bisect bad fc3d25e1c8f6a9232530db02a1072033e22e0fe3 > # bad: [46457ea464f5341d1f9dad8dd213805d45f7f117] sched/clock: Use static key > for sched_clock_running > git bisect bad 46457ea464f5341d1f9dad8dd213805d45f7f117 > # bad: [857baa87b6422bcfb84ed3631d6839920cb5b09d] sched/clock: Enable sched > clock early > git bisect bad 857baa87b6422bcfb84ed3631d6839920cb5b09d > # good: [5d2a4e91a541cb04d20d11602f0f9340291322ac] sched/clock: Move sched > clock initialization and merge with generic clock > git bisect good 5d2a4e91a541cb04d20d11602f0f9340291322ac > # first bad commit: [857baa87b6422bcfb84ed3631d6839920cb5b09d] sched/clock: > Enable sched clock early
Re: [tip:x86/timers] sched/clock: Enable sched clock early
On Tue, Jul 24, 2018 at 3:54 PM Guenter Roeck wrote: > > Hi, > > On Thu, Jul 19, 2018 at 03:33:21PM -0700, tip-bot for Pavel Tatashin wrote: > > Commit-ID: 857baa87b6422bcfb84ed3631d6839920cb5b09d > > Gitweb: > > https://git.kernel.org/tip/857baa87b6422bcfb84ed3631d6839920cb5b09d > > Author: Pavel Tatashin > > AuthorDate: Thu, 19 Jul 2018 16:55:42 -0400 > > Committer: Thomas Gleixner > > CommitDate: Fri, 20 Jul 2018 00:02:43 +0200 > > > > sched/clock: Enable sched clock early > > > > Allow sched_clock() to be used before schec_clock_init() is called. This > > provides a way to get early boot timestamps on machines with unstable > > clocks. > > > > This patch causes a regression when running a qemu emulation with > arm:integratorcp. Thank you for the report. I will study it. > > ... > Console: colour dummy device 80x30 > [ cut here ] > WARNING: CPU: 0 PID: 0 at kernel/time/sched_clock.c:180 > sched_clock_register+0x44/0x278 > Modules linked in: > CPU: 0 PID: 0 Comm: swapper Not tainted 4.18.0-rc6-next-20180724 #1 > Hardware name: ARM Integrator/CP (Device Tree) > [] (unwind_backtrace) from [] (show_stack+0x10/0x18) > [] (show_stack) from [] (dump_stack+0x18/0x24) > [] (dump_stack) from [] (__warn+0xc8/0xf0) > [] (__warn) from [] (warn_slowpath_null+0x3c/0x4c) > [] (warn_slowpath_null) from [] > (sched_clock_register+0x44/0x278) > [] (sched_clock_register) from [] > (generic_sched_clock_init+0x28/0x88) > [] (generic_sched_clock_init) from [] > (sched_clock_init+0x54/0x74) > [] (sched_clock_init) from [] (start_kernel+0x310/0x3e4) > [] (start_kernel) from [<>] ( (null)) > ---[ end trace 08080eb81afa002c ]--- > sched_clock: 32 bits at 100 Hz, resolution 1000ns, wraps every > 2147483647500ns > ... > > A complete boot log is available at > http://kerneltests.org/builders/qemu-arm-next/builds/979/steps/qemubuildcommand/logs/stdio > > Unfortunately, reverting the patch results in conflicts, so I am unable > to confirm that it is the only culprit. > > From the context and from looking into the patch, it appears that this > can happen in any system if CONFIG_HAVE_UNSTABLE_SCHED_CLOCK is not > enabled. > > Bisect log is attached. > > Guenter > > --- > # bad: [3946cd385042069ec57d3f04240def53b4eed7e5] Add linux-next specific > files for 20180724 > # good: [d72e90f33aa4709ebecc5005562f52335e106a60] Linux 4.18-rc6 > git bisect start 'HEAD' 'v4.18-rc6' > # good: [f5fa891e325acf096c0f79e1d1b922002e251e5a] Merge remote-tracking > branch 'crypto/master' > git bisect good f5fa891e325acf096c0f79e1d1b922002e251e5a > # good: [cb6471f6bcfdacbeef9c23ba9dac00e67bd3c3a4] Merge remote-tracking > branch 'spi/for-next' > git bisect good cb6471f6bcfdacbeef9c23ba9dac00e67bd3c3a4 > # bad: [6b5bfa57bf4553d051be65d85d021465041406d8] Merge remote-tracking > branch 'char-misc/char-misc-next' > git bisect bad 6b5bfa57bf4553d051be65d85d021465041406d8 > # bad: [675a67e9ef3c041999f412cb75418d2b0def3854] Merge remote-tracking > branch 'rcu/rcu/next' > git bisect bad 675a67e9ef3c041999f412cb75418d2b0def3854 > # good: [e78b01a51131f25fc2d881bc43001575c129069c] Merge branch 'perf/core' > git bisect good e78b01a51131f25fc2d881bc43001575c129069c > # good: [4e581bce514f4107ce84525f0f75f89c92b4140e] Merge branch 'x86/cpu' > git bisect good 4e581bce514f4107ce84525f0f75f89c92b4140e > # good: [20fa22e90e54e2d21cace7ba083598531670f7cf] Merge branch 'x86/pti' > git bisect good 20fa22e90e54e2d21cace7ba083598531670f7cf > # good: [4763f03d3d186ce8a1125844790152d76804ad60] x86/tsc: Use TSC as sched > clock early > git bisect good 4763f03d3d186ce8a1125844790152d76804ad60 > # good: [5f9ef44c7d1c59d0eda1d86e31d981bdffe2a725] tools/memory-model: Rename > litmus tests to comply to norm7 > git bisect good 5f9ef44c7d1c59d0eda1d86e31d981bdffe2a725 > # bad: [fc3d25e1c8f6a9232530db02a1072033e22e0fe3] Merge branch 'x86/timers' > git bisect bad fc3d25e1c8f6a9232530db02a1072033e22e0fe3 > # bad: [46457ea464f5341d1f9dad8dd213805d45f7f117] sched/clock: Use static key > for sched_clock_running > git bisect bad 46457ea464f5341d1f9dad8dd213805d45f7f117 > # bad: [857baa87b6422bcfb84ed3631d6839920cb5b09d] sched/clock: Enable sched > clock early > git bisect bad 857baa87b6422bcfb84ed3631d6839920cb5b09d > # good: [5d2a4e91a541cb04d20d11602f0f9340291322ac] sched/clock: Move sched > clock initialization and merge with generic clock > git bisect good 5d2a4e91a541cb04d20d11602f0f9340291322ac > # first bad commit: [857baa87b6422bcfb84ed3631d6839920cb5b09d] sched/clock: > Enable sched clock early
Re: [tip:x86/timers] sched/clock: Enable sched clock early
Hi, On Thu, Jul 19, 2018 at 03:33:21PM -0700, tip-bot for Pavel Tatashin wrote: > Commit-ID: 857baa87b6422bcfb84ed3631d6839920cb5b09d > Gitweb: > https://git.kernel.org/tip/857baa87b6422bcfb84ed3631d6839920cb5b09d > Author: Pavel Tatashin > AuthorDate: Thu, 19 Jul 2018 16:55:42 -0400 > Committer: Thomas Gleixner > CommitDate: Fri, 20 Jul 2018 00:02:43 +0200 > > sched/clock: Enable sched clock early > > Allow sched_clock() to be used before schec_clock_init() is called. This > provides a way to get early boot timestamps on machines with unstable > clocks. > This patch causes a regression when running a qemu emulation with arm:integratorcp. ... Console: colour dummy device 80x30 [ cut here ] WARNING: CPU: 0 PID: 0 at kernel/time/sched_clock.c:180 sched_clock_register+0x44/0x278 Modules linked in: CPU: 0 PID: 0 Comm: swapper Not tainted 4.18.0-rc6-next-20180724 #1 Hardware name: ARM Integrator/CP (Device Tree) [] (unwind_backtrace) from [] (show_stack+0x10/0x18) [] (show_stack) from [] (dump_stack+0x18/0x24) [] (dump_stack) from [] (__warn+0xc8/0xf0) [] (__warn) from [] (warn_slowpath_null+0x3c/0x4c) [] (warn_slowpath_null) from [] (sched_clock_register+0x44/0x278) [] (sched_clock_register) from [] (generic_sched_clock_init+0x28/0x88) [] (generic_sched_clock_init) from [] (sched_clock_init+0x54/0x74) [] (sched_clock_init) from [] (start_kernel+0x310/0x3e4) [] (start_kernel) from [<>] ( (null)) ---[ end trace 08080eb81afa002c ]--- sched_clock: 32 bits at 100 Hz, resolution 1000ns, wraps every 2147483647500ns ... A complete boot log is available at http://kerneltests.org/builders/qemu-arm-next/builds/979/steps/qemubuildcommand/logs/stdio Unfortunately, reverting the patch results in conflicts, so I am unable to confirm that it is the only culprit. >From the context and from looking into the patch, it appears that this can happen in any system if CONFIG_HAVE_UNSTABLE_SCHED_CLOCK is not enabled. Bisect log is attached. Guenter --- # bad: [3946cd385042069ec57d3f04240def53b4eed7e5] Add linux-next specific files for 20180724 # good: [d72e90f33aa4709ebecc5005562f52335e106a60] Linux 4.18-rc6 git bisect start 'HEAD' 'v4.18-rc6' # good: [f5fa891e325acf096c0f79e1d1b922002e251e5a] Merge remote-tracking branch 'crypto/master' git bisect good f5fa891e325acf096c0f79e1d1b922002e251e5a # good: [cb6471f6bcfdacbeef9c23ba9dac00e67bd3c3a4] Merge remote-tracking branch 'spi/for-next' git bisect good cb6471f6bcfdacbeef9c23ba9dac00e67bd3c3a4 # bad: [6b5bfa57bf4553d051be65d85d021465041406d8] Merge remote-tracking branch 'char-misc/char-misc-next' git bisect bad 6b5bfa57bf4553d051be65d85d021465041406d8 # bad: [675a67e9ef3c041999f412cb75418d2b0def3854] Merge remote-tracking branch 'rcu/rcu/next' git bisect bad 675a67e9ef3c041999f412cb75418d2b0def3854 # good: [e78b01a51131f25fc2d881bc43001575c129069c] Merge branch 'perf/core' git bisect good e78b01a51131f25fc2d881bc43001575c129069c # good: [4e581bce514f4107ce84525f0f75f89c92b4140e] Merge branch 'x86/cpu' git bisect good 4e581bce514f4107ce84525f0f75f89c92b4140e # good: [20fa22e90e54e2d21cace7ba083598531670f7cf] Merge branch 'x86/pti' git bisect good 20fa22e90e54e2d21cace7ba083598531670f7cf # good: [4763f03d3d186ce8a1125844790152d76804ad60] x86/tsc: Use TSC as sched clock early git bisect good 4763f03d3d186ce8a1125844790152d76804ad60 # good: [5f9ef44c7d1c59d0eda1d86e31d981bdffe2a725] tools/memory-model: Rename litmus tests to comply to norm7 git bisect good 5f9ef44c7d1c59d0eda1d86e31d981bdffe2a725 # bad: [fc3d25e1c8f6a9232530db02a1072033e22e0fe3] Merge branch 'x86/timers' git bisect bad fc3d25e1c8f6a9232530db02a1072033e22e0fe3 # bad: [46457ea464f5341d1f9dad8dd213805d45f7f117] sched/clock: Use static key for sched_clock_running git bisect bad 46457ea464f5341d1f9dad8dd213805d45f7f117 # bad: [857baa87b6422bcfb84ed3631d6839920cb5b09d] sched/clock: Enable sched clock early git bisect bad 857baa87b6422bcfb84ed3631d6839920cb5b09d # good: [5d2a4e91a541cb04d20d11602f0f9340291322ac] sched/clock: Move sched clock initialization and merge with generic clock git bisect good 5d2a4e91a541cb04d20d11602f0f9340291322ac # first bad commit: [857baa87b6422bcfb84ed3631d6839920cb5b09d] sched/clock: Enable sched clock early
Re: [tip:x86/timers] sched/clock: Enable sched clock early
Hi, On Thu, Jul 19, 2018 at 03:33:21PM -0700, tip-bot for Pavel Tatashin wrote: > Commit-ID: 857baa87b6422bcfb84ed3631d6839920cb5b09d > Gitweb: > https://git.kernel.org/tip/857baa87b6422bcfb84ed3631d6839920cb5b09d > Author: Pavel Tatashin > AuthorDate: Thu, 19 Jul 2018 16:55:42 -0400 > Committer: Thomas Gleixner > CommitDate: Fri, 20 Jul 2018 00:02:43 +0200 > > sched/clock: Enable sched clock early > > Allow sched_clock() to be used before schec_clock_init() is called. This > provides a way to get early boot timestamps on machines with unstable > clocks. > This patch causes a regression when running a qemu emulation with arm:integratorcp. ... Console: colour dummy device 80x30 [ cut here ] WARNING: CPU: 0 PID: 0 at kernel/time/sched_clock.c:180 sched_clock_register+0x44/0x278 Modules linked in: CPU: 0 PID: 0 Comm: swapper Not tainted 4.18.0-rc6-next-20180724 #1 Hardware name: ARM Integrator/CP (Device Tree) [] (unwind_backtrace) from [] (show_stack+0x10/0x18) [] (show_stack) from [] (dump_stack+0x18/0x24) [] (dump_stack) from [] (__warn+0xc8/0xf0) [] (__warn) from [] (warn_slowpath_null+0x3c/0x4c) [] (warn_slowpath_null) from [] (sched_clock_register+0x44/0x278) [] (sched_clock_register) from [] (generic_sched_clock_init+0x28/0x88) [] (generic_sched_clock_init) from [] (sched_clock_init+0x54/0x74) [] (sched_clock_init) from [] (start_kernel+0x310/0x3e4) [] (start_kernel) from [<>] ( (null)) ---[ end trace 08080eb81afa002c ]--- sched_clock: 32 bits at 100 Hz, resolution 1000ns, wraps every 2147483647500ns ... A complete boot log is available at http://kerneltests.org/builders/qemu-arm-next/builds/979/steps/qemubuildcommand/logs/stdio Unfortunately, reverting the patch results in conflicts, so I am unable to confirm that it is the only culprit. >From the context and from looking into the patch, it appears that this can happen in any system if CONFIG_HAVE_UNSTABLE_SCHED_CLOCK is not enabled. Bisect log is attached. Guenter --- # bad: [3946cd385042069ec57d3f04240def53b4eed7e5] Add linux-next specific files for 20180724 # good: [d72e90f33aa4709ebecc5005562f52335e106a60] Linux 4.18-rc6 git bisect start 'HEAD' 'v4.18-rc6' # good: [f5fa891e325acf096c0f79e1d1b922002e251e5a] Merge remote-tracking branch 'crypto/master' git bisect good f5fa891e325acf096c0f79e1d1b922002e251e5a # good: [cb6471f6bcfdacbeef9c23ba9dac00e67bd3c3a4] Merge remote-tracking branch 'spi/for-next' git bisect good cb6471f6bcfdacbeef9c23ba9dac00e67bd3c3a4 # bad: [6b5bfa57bf4553d051be65d85d021465041406d8] Merge remote-tracking branch 'char-misc/char-misc-next' git bisect bad 6b5bfa57bf4553d051be65d85d021465041406d8 # bad: [675a67e9ef3c041999f412cb75418d2b0def3854] Merge remote-tracking branch 'rcu/rcu/next' git bisect bad 675a67e9ef3c041999f412cb75418d2b0def3854 # good: [e78b01a51131f25fc2d881bc43001575c129069c] Merge branch 'perf/core' git bisect good e78b01a51131f25fc2d881bc43001575c129069c # good: [4e581bce514f4107ce84525f0f75f89c92b4140e] Merge branch 'x86/cpu' git bisect good 4e581bce514f4107ce84525f0f75f89c92b4140e # good: [20fa22e90e54e2d21cace7ba083598531670f7cf] Merge branch 'x86/pti' git bisect good 20fa22e90e54e2d21cace7ba083598531670f7cf # good: [4763f03d3d186ce8a1125844790152d76804ad60] x86/tsc: Use TSC as sched clock early git bisect good 4763f03d3d186ce8a1125844790152d76804ad60 # good: [5f9ef44c7d1c59d0eda1d86e31d981bdffe2a725] tools/memory-model: Rename litmus tests to comply to norm7 git bisect good 5f9ef44c7d1c59d0eda1d86e31d981bdffe2a725 # bad: [fc3d25e1c8f6a9232530db02a1072033e22e0fe3] Merge branch 'x86/timers' git bisect bad fc3d25e1c8f6a9232530db02a1072033e22e0fe3 # bad: [46457ea464f5341d1f9dad8dd213805d45f7f117] sched/clock: Use static key for sched_clock_running git bisect bad 46457ea464f5341d1f9dad8dd213805d45f7f117 # bad: [857baa87b6422bcfb84ed3631d6839920cb5b09d] sched/clock: Enable sched clock early git bisect bad 857baa87b6422bcfb84ed3631d6839920cb5b09d # good: [5d2a4e91a541cb04d20d11602f0f9340291322ac] sched/clock: Move sched clock initialization and merge with generic clock git bisect good 5d2a4e91a541cb04d20d11602f0f9340291322ac # first bad commit: [857baa87b6422bcfb84ed3631d6839920cb5b09d] sched/clock: Enable sched clock early
[tip:x86/timers] sched/clock: Enable sched clock early
Commit-ID: 857baa87b6422bcfb84ed3631d6839920cb5b09d
Gitweb: https://git.kernel.org/tip/857baa87b6422bcfb84ed3631d6839920cb5b09d
Author: Pavel Tatashin
AuthorDate: Thu, 19 Jul 2018 16:55:42 -0400
Committer: Thomas Gleixner
CommitDate: Fri, 20 Jul 2018 00:02:43 +0200
sched/clock: Enable sched clock early
Allow sched_clock() to be used before schec_clock_init() is called. This
provides a way to get early boot timestamps on machines with unstable
clocks.
Signed-off-by: Pavel Tatashin
Signed-off-by: Thomas Gleixner
Cc: steven.sist...@oracle.com
Cc: daniel.m.jor...@oracle.com
Cc: li...@armlinux.org.uk
Cc: schwidef...@de.ibm.com
Cc: heiko.carst...@de.ibm.com
Cc: john.stu...@linaro.org
Cc: sb...@codeaurora.org
Cc: h...@zytor.com
Cc: douly.f...@cn.fujitsu.com
Cc: pet...@infradead.org
Cc: pra...@redhat.com
Cc: feng.t...@intel.com
Cc: pmla...@suse.com
Cc: gno...@lxorguk.ukuu.org.uk
Cc: linux-s...@vger.kernel.org
Cc: boris.ostrov...@oracle.com
Cc: jgr...@suse.com
Cc: pbonz...@redhat.com
Link:
https://lkml.kernel.org/r/20180719205545.16512-24-pasha.tatas...@oracle.com
---
init/main.c | 2 +-
kernel/sched/clock.c | 20 +++-
2 files changed, 20 insertions(+), 2 deletions(-)
diff --git a/init/main.c b/init/main.c
index 162d931c9511..ff0a24170b95 100644
--- a/init/main.c
+++ b/init/main.c
@@ -642,7 +642,6 @@ asmlinkage __visible void __init start_kernel(void)
softirq_init();
timekeeping_init();
time_init();
- sched_clock_init();
printk_safe_init();
perf_event_init();
profile_init();
@@ -697,6 +696,7 @@ asmlinkage __visible void __init start_kernel(void)
acpi_early_init();
if (late_time_init)
late_time_init();
+ sched_clock_init();
calibrate_delay();
pid_idr_init();
anon_vma_init();
diff --git a/kernel/sched/clock.c b/kernel/sched/clock.c
index 0e9dbb2d9aea..422cd63f8f17 100644
--- a/kernel/sched/clock.c
+++ b/kernel/sched/clock.c
@@ -202,7 +202,25 @@ static void __sched_clock_gtod_offset(void)
void __init sched_clock_init(void)
{
+ unsigned long flags;
+
+ /*
+* Set __gtod_offset such that once we mark sched_clock_running,
+* sched_clock_tick() continues where sched_clock() left off.
+*
+* Even if TSC is buggered, we're still UP at this point so it
+* can't really be out of sync.
+*/
+ local_irq_save(flags);
+ __sched_clock_gtod_offset();
+ local_irq_restore(flags);
+
sched_clock_running = 1;
+
+ /* Now that sched_clock_running is set adjust scd */
+ local_irq_save(flags);
+ sched_clock_tick();
+ local_irq_restore(flags);
}
/*
* We run this as late_initcall() such that it runs after all built-in drivers,
@@ -356,7 +374,7 @@ u64 sched_clock_cpu(int cpu)
return sched_clock() + __sched_clock_offset;
if (unlikely(!sched_clock_running))
- return 0ull;
+ return sched_clock();
preempt_disable_notrace();
scd = cpu_sdc(cpu);
[tip:x86/timers] sched/clock: Enable sched clock early
Commit-ID: 857baa87b6422bcfb84ed3631d6839920cb5b09d
Gitweb: https://git.kernel.org/tip/857baa87b6422bcfb84ed3631d6839920cb5b09d
Author: Pavel Tatashin
AuthorDate: Thu, 19 Jul 2018 16:55:42 -0400
Committer: Thomas Gleixner
CommitDate: Fri, 20 Jul 2018 00:02:43 +0200
sched/clock: Enable sched clock early
Allow sched_clock() to be used before schec_clock_init() is called. This
provides a way to get early boot timestamps on machines with unstable
clocks.
Signed-off-by: Pavel Tatashin
Signed-off-by: Thomas Gleixner
Cc: steven.sist...@oracle.com
Cc: daniel.m.jor...@oracle.com
Cc: li...@armlinux.org.uk
Cc: schwidef...@de.ibm.com
Cc: heiko.carst...@de.ibm.com
Cc: john.stu...@linaro.org
Cc: sb...@codeaurora.org
Cc: h...@zytor.com
Cc: douly.f...@cn.fujitsu.com
Cc: pet...@infradead.org
Cc: pra...@redhat.com
Cc: feng.t...@intel.com
Cc: pmla...@suse.com
Cc: gno...@lxorguk.ukuu.org.uk
Cc: linux-s...@vger.kernel.org
Cc: boris.ostrov...@oracle.com
Cc: jgr...@suse.com
Cc: pbonz...@redhat.com
Link:
https://lkml.kernel.org/r/20180719205545.16512-24-pasha.tatas...@oracle.com
---
init/main.c | 2 +-
kernel/sched/clock.c | 20 +++-
2 files changed, 20 insertions(+), 2 deletions(-)
diff --git a/init/main.c b/init/main.c
index 162d931c9511..ff0a24170b95 100644
--- a/init/main.c
+++ b/init/main.c
@@ -642,7 +642,6 @@ asmlinkage __visible void __init start_kernel(void)
softirq_init();
timekeeping_init();
time_init();
- sched_clock_init();
printk_safe_init();
perf_event_init();
profile_init();
@@ -697,6 +696,7 @@ asmlinkage __visible void __init start_kernel(void)
acpi_early_init();
if (late_time_init)
late_time_init();
+ sched_clock_init();
calibrate_delay();
pid_idr_init();
anon_vma_init();
diff --git a/kernel/sched/clock.c b/kernel/sched/clock.c
index 0e9dbb2d9aea..422cd63f8f17 100644
--- a/kernel/sched/clock.c
+++ b/kernel/sched/clock.c
@@ -202,7 +202,25 @@ static void __sched_clock_gtod_offset(void)
void __init sched_clock_init(void)
{
+ unsigned long flags;
+
+ /*
+* Set __gtod_offset such that once we mark sched_clock_running,
+* sched_clock_tick() continues where sched_clock() left off.
+*
+* Even if TSC is buggered, we're still UP at this point so it
+* can't really be out of sync.
+*/
+ local_irq_save(flags);
+ __sched_clock_gtod_offset();
+ local_irq_restore(flags);
+
sched_clock_running = 1;
+
+ /* Now that sched_clock_running is set adjust scd */
+ local_irq_save(flags);
+ sched_clock_tick();
+ local_irq_restore(flags);
}
/*
* We run this as late_initcall() such that it runs after all built-in drivers,
@@ -356,7 +374,7 @@ u64 sched_clock_cpu(int cpu)
return sched_clock() + __sched_clock_offset;
if (unlikely(!sched_clock_running))
- return 0ull;
+ return sched_clock();
preempt_disable_notrace();
scd = cpu_sdc(cpu);
