#
f4a80ec8 |
| 26-Jun-2022 |
Masahiro Yamada <masahiroy@kernel.org> |
tick/nohz: unexport __init-annotated tick_nohz_full_setup()
commit 2390095113e98fc52fffe35c5206d30d9efe3f78 upstream.
EXPORT_SYMBOL and __init is a bad combination because the .init.text section is
tick/nohz: unexport __init-annotated tick_nohz_full_setup()
commit 2390095113e98fc52fffe35c5206d30d9efe3f78 upstream.
EXPORT_SYMBOL and __init is a bad combination because the .init.text section is freed up after the initialization. Hence, modules cannot use symbols annotated __init. The access to a freed symbol may end up with kernel panic.
modpost used to detect it, but it had been broken for a decade.
Commit 28438794aba4 ("modpost: fix section mismatch check for exported init/exit sections") fixed it so modpost started to warn it again, then this showed up:
MODPOST vmlinux.symvers WARNING: modpost: vmlinux.o(___ksymtab_gpl+tick_nohz_full_setup+0x0): Section mismatch in reference from the variable __ksymtab_tick_nohz_full_setup to the function .init.text:tick_nohz_full_setup() The symbol tick_nohz_full_setup is exported and annotated __init Fix this by removing the __init annotation of tick_nohz_full_setup or drop the export.
Drop the export because tick_nohz_full_setup() is only called from the built-in code in kernel/sched/isolation.c.
Fixes: ae9e557b5be2 ("time: Export tick start/stop functions for rcutorture") Reported-by: Linus Torvalds <torvalds@linux-foundation.org> Signed-off-by: Masahiro Yamada <masahiroy@kernel.org> Tested-by: Paul E. McKenney <paulmck@kernel.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> Cc: Thomas Backlund <tmb@tmb.nu> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
show more ...
|
#
f4a80ec8 |
| 26-Jun-2022 |
Masahiro Yamada <masahiroy@kernel.org> |
tick/nohz: unexport __init-annotated tick_nohz_full_setup()
commit 2390095113e98fc52fffe35c5206d30d9efe3f78 upstream.
EXPORT_SYMBOL and __init is a bad combination because the .init.text section is
tick/nohz: unexport __init-annotated tick_nohz_full_setup()
commit 2390095113e98fc52fffe35c5206d30d9efe3f78 upstream.
EXPORT_SYMBOL and __init is a bad combination because the .init.text section is freed up after the initialization. Hence, modules cannot use symbols annotated __init. The access to a freed symbol may end up with kernel panic.
modpost used to detect it, but it had been broken for a decade.
Commit 28438794aba4 ("modpost: fix section mismatch check for exported init/exit sections") fixed it so modpost started to warn it again, then this showed up:
MODPOST vmlinux.symvers WARNING: modpost: vmlinux.o(___ksymtab_gpl+tick_nohz_full_setup+0x0): Section mismatch in reference from the variable __ksymtab_tick_nohz_full_setup to the function .init.text:tick_nohz_full_setup() The symbol tick_nohz_full_setup is exported and annotated __init Fix this by removing the __init annotation of tick_nohz_full_setup or drop the export.
Drop the export because tick_nohz_full_setup() is only called from the built-in code in kernel/sched/isolation.c.
Fixes: ae9e557b5be2 ("time: Export tick start/stop functions for rcutorture") Reported-by: Linus Torvalds <torvalds@linux-foundation.org> Signed-off-by: Masahiro Yamada <masahiroy@kernel.org> Tested-by: Paul E. McKenney <paulmck@kernel.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> Cc: Thomas Backlund <tmb@tmb.nu> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
show more ...
|
#
f4a80ec8 |
| 26-Jun-2022 |
Masahiro Yamada <masahiroy@kernel.org> |
tick/nohz: unexport __init-annotated tick_nohz_full_setup()
commit 2390095113e98fc52fffe35c5206d30d9efe3f78 upstream.
EXPORT_SYMBOL and __init is a bad combination because the .init.text section is
tick/nohz: unexport __init-annotated tick_nohz_full_setup()
commit 2390095113e98fc52fffe35c5206d30d9efe3f78 upstream.
EXPORT_SYMBOL and __init is a bad combination because the .init.text section is freed up after the initialization. Hence, modules cannot use symbols annotated __init. The access to a freed symbol may end up with kernel panic.
modpost used to detect it, but it had been broken for a decade.
Commit 28438794aba4 ("modpost: fix section mismatch check for exported init/exit sections") fixed it so modpost started to warn it again, then this showed up:
MODPOST vmlinux.symvers WARNING: modpost: vmlinux.o(___ksymtab_gpl+tick_nohz_full_setup+0x0): Section mismatch in reference from the variable __ksymtab_tick_nohz_full_setup to the function .init.text:tick_nohz_full_setup() The symbol tick_nohz_full_setup is exported and annotated __init Fix this by removing the __init annotation of tick_nohz_full_setup or drop the export.
Drop the export because tick_nohz_full_setup() is only called from the built-in code in kernel/sched/isolation.c.
Fixes: ae9e557b5be2 ("time: Export tick start/stop functions for rcutorture") Reported-by: Linus Torvalds <torvalds@linux-foundation.org> Signed-off-by: Masahiro Yamada <masahiroy@kernel.org> Tested-by: Paul E. McKenney <paulmck@kernel.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> Cc: Thomas Backlund <tmb@tmb.nu> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
show more ...
|
#
f4a80ec8 |
| 26-Jun-2022 |
Masahiro Yamada <masahiroy@kernel.org> |
tick/nohz: unexport __init-annotated tick_nohz_full_setup()
commit 2390095113e98fc52fffe35c5206d30d9efe3f78 upstream.
EXPORT_SYMBOL and __init is a bad combination because the .init.text section is
tick/nohz: unexport __init-annotated tick_nohz_full_setup()
commit 2390095113e98fc52fffe35c5206d30d9efe3f78 upstream.
EXPORT_SYMBOL and __init is a bad combination because the .init.text section is freed up after the initialization. Hence, modules cannot use symbols annotated __init. The access to a freed symbol may end up with kernel panic.
modpost used to detect it, but it had been broken for a decade.
Commit 28438794aba4 ("modpost: fix section mismatch check for exported init/exit sections") fixed it so modpost started to warn it again, then this showed up:
MODPOST vmlinux.symvers WARNING: modpost: vmlinux.o(___ksymtab_gpl+tick_nohz_full_setup+0x0): Section mismatch in reference from the variable __ksymtab_tick_nohz_full_setup to the function .init.text:tick_nohz_full_setup() The symbol tick_nohz_full_setup is exported and annotated __init Fix this by removing the __init annotation of tick_nohz_full_setup or drop the export.
Drop the export because tick_nohz_full_setup() is only called from the built-in code in kernel/sched/isolation.c.
Fixes: ae9e557b5be2 ("time: Export tick start/stop functions for rcutorture") Reported-by: Linus Torvalds <torvalds@linux-foundation.org> Signed-off-by: Masahiro Yamada <masahiroy@kernel.org> Tested-by: Paul E. McKenney <paulmck@kernel.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> Cc: Thomas Backlund <tmb@tmb.nu> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
show more ...
|
#
f4a80ec8 |
| 26-Jun-2022 |
Masahiro Yamada <masahiroy@kernel.org> |
tick/nohz: unexport __init-annotated tick_nohz_full_setup()
commit 2390095113e98fc52fffe35c5206d30d9efe3f78 upstream.
EXPORT_SYMBOL and __init is a bad combination because the .init.text section is
tick/nohz: unexport __init-annotated tick_nohz_full_setup()
commit 2390095113e98fc52fffe35c5206d30d9efe3f78 upstream.
EXPORT_SYMBOL and __init is a bad combination because the .init.text section is freed up after the initialization. Hence, modules cannot use symbols annotated __init. The access to a freed symbol may end up with kernel panic.
modpost used to detect it, but it had been broken for a decade.
Commit 28438794aba4 ("modpost: fix section mismatch check for exported init/exit sections") fixed it so modpost started to warn it again, then this showed up:
MODPOST vmlinux.symvers WARNING: modpost: vmlinux.o(___ksymtab_gpl+tick_nohz_full_setup+0x0): Section mismatch in reference from the variable __ksymtab_tick_nohz_full_setup to the function .init.text:tick_nohz_full_setup() The symbol tick_nohz_full_setup is exported and annotated __init Fix this by removing the __init annotation of tick_nohz_full_setup or drop the export.
Drop the export because tick_nohz_full_setup() is only called from the built-in code in kernel/sched/isolation.c.
Fixes: ae9e557b5be2 ("time: Export tick start/stop functions for rcutorture") Reported-by: Linus Torvalds <torvalds@linux-foundation.org> Signed-off-by: Masahiro Yamada <masahiroy@kernel.org> Tested-by: Paul E. McKenney <paulmck@kernel.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> Cc: Thomas Backlund <tmb@tmb.nu> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
show more ...
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#
f4a80ec8 |
| 26-Jun-2022 |
Masahiro Yamada <masahiroy@kernel.org> |
tick/nohz: unexport __init-annotated tick_nohz_full_setup()
commit 2390095113e98fc52fffe35c5206d30d9efe3f78 upstream.
EXPORT_SYMBOL and __init is a bad combination because the .init.text section is
tick/nohz: unexport __init-annotated tick_nohz_full_setup()
commit 2390095113e98fc52fffe35c5206d30d9efe3f78 upstream.
EXPORT_SYMBOL and __init is a bad combination because the .init.text section is freed up after the initialization. Hence, modules cannot use symbols annotated __init. The access to a freed symbol may end up with kernel panic.
modpost used to detect it, but it had been broken for a decade.
Commit 28438794aba4 ("modpost: fix section mismatch check for exported init/exit sections") fixed it so modpost started to warn it again, then this showed up:
MODPOST vmlinux.symvers WARNING: modpost: vmlinux.o(___ksymtab_gpl+tick_nohz_full_setup+0x0): Section mismatch in reference from the variable __ksymtab_tick_nohz_full_setup to the function .init.text:tick_nohz_full_setup() The symbol tick_nohz_full_setup is exported and annotated __init Fix this by removing the __init annotation of tick_nohz_full_setup or drop the export.
Drop the export because tick_nohz_full_setup() is only called from the built-in code in kernel/sched/isolation.c.
Fixes: ae9e557b5be2 ("time: Export tick start/stop functions for rcutorture") Reported-by: Linus Torvalds <torvalds@linux-foundation.org> Signed-off-by: Masahiro Yamada <masahiroy@kernel.org> Tested-by: Paul E. McKenney <paulmck@kernel.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> Cc: Thomas Backlund <tmb@tmb.nu> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
show more ...
|
#
f4a80ec8 |
| 26-Jun-2022 |
Masahiro Yamada <masahiroy@kernel.org> |
tick/nohz: unexport __init-annotated tick_nohz_full_setup()
commit 2390095113e98fc52fffe35c5206d30d9efe3f78 upstream.
EXPORT_SYMBOL and __init is a bad combination because the .init.text section is
tick/nohz: unexport __init-annotated tick_nohz_full_setup()
commit 2390095113e98fc52fffe35c5206d30d9efe3f78 upstream.
EXPORT_SYMBOL and __init is a bad combination because the .init.text section is freed up after the initialization. Hence, modules cannot use symbols annotated __init. The access to a freed symbol may end up with kernel panic.
modpost used to detect it, but it had been broken for a decade.
Commit 28438794aba4 ("modpost: fix section mismatch check for exported init/exit sections") fixed it so modpost started to warn it again, then this showed up:
MODPOST vmlinux.symvers WARNING: modpost: vmlinux.o(___ksymtab_gpl+tick_nohz_full_setup+0x0): Section mismatch in reference from the variable __ksymtab_tick_nohz_full_setup to the function .init.text:tick_nohz_full_setup() The symbol tick_nohz_full_setup is exported and annotated __init Fix this by removing the __init annotation of tick_nohz_full_setup or drop the export.
Drop the export because tick_nohz_full_setup() is only called from the built-in code in kernel/sched/isolation.c.
Fixes: ae9e557b5be2 ("time: Export tick start/stop functions for rcutorture") Reported-by: Linus Torvalds <torvalds@linux-foundation.org> Signed-off-by: Masahiro Yamada <masahiroy@kernel.org> Tested-by: Paul E. McKenney <paulmck@kernel.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> Cc: Thomas Backlund <tmb@tmb.nu> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
show more ...
|
#
f4a80ec8 |
| 26-Jun-2022 |
Masahiro Yamada <masahiroy@kernel.org> |
tick/nohz: unexport __init-annotated tick_nohz_full_setup()
commit 2390095113e98fc52fffe35c5206d30d9efe3f78 upstream.
EXPORT_SYMBOL and __init is a bad combination because the .init.text section is
tick/nohz: unexport __init-annotated tick_nohz_full_setup()
commit 2390095113e98fc52fffe35c5206d30d9efe3f78 upstream.
EXPORT_SYMBOL and __init is a bad combination because the .init.text section is freed up after the initialization. Hence, modules cannot use symbols annotated __init. The access to a freed symbol may end up with kernel panic.
modpost used to detect it, but it had been broken for a decade.
Commit 28438794aba4 ("modpost: fix section mismatch check for exported init/exit sections") fixed it so modpost started to warn it again, then this showed up:
MODPOST vmlinux.symvers WARNING: modpost: vmlinux.o(___ksymtab_gpl+tick_nohz_full_setup+0x0): Section mismatch in reference from the variable __ksymtab_tick_nohz_full_setup to the function .init.text:tick_nohz_full_setup() The symbol tick_nohz_full_setup is exported and annotated __init Fix this by removing the __init annotation of tick_nohz_full_setup or drop the export.
Drop the export because tick_nohz_full_setup() is only called from the built-in code in kernel/sched/isolation.c.
Fixes: ae9e557b5be2 ("time: Export tick start/stop functions for rcutorture") Reported-by: Linus Torvalds <torvalds@linux-foundation.org> Signed-off-by: Masahiro Yamada <masahiroy@kernel.org> Tested-by: Paul E. McKenney <paulmck@kernel.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> Cc: Thomas Backlund <tmb@tmb.nu> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
show more ...
|
#
f4a80ec8 |
| 26-Jun-2022 |
Masahiro Yamada <masahiroy@kernel.org> |
tick/nohz: unexport __init-annotated tick_nohz_full_setup()
commit 2390095113e98fc52fffe35c5206d30d9efe3f78 upstream.
EXPORT_SYMBOL and __init is a bad combination because the .init.text section is
tick/nohz: unexport __init-annotated tick_nohz_full_setup()
commit 2390095113e98fc52fffe35c5206d30d9efe3f78 upstream.
EXPORT_SYMBOL and __init is a bad combination because the .init.text section is freed up after the initialization. Hence, modules cannot use symbols annotated __init. The access to a freed symbol may end up with kernel panic.
modpost used to detect it, but it had been broken for a decade.
Commit 28438794aba4 ("modpost: fix section mismatch check for exported init/exit sections") fixed it so modpost started to warn it again, then this showed up:
MODPOST vmlinux.symvers WARNING: modpost: vmlinux.o(___ksymtab_gpl+tick_nohz_full_setup+0x0): Section mismatch in reference from the variable __ksymtab_tick_nohz_full_setup to the function .init.text:tick_nohz_full_setup() The symbol tick_nohz_full_setup is exported and annotated __init Fix this by removing the __init annotation of tick_nohz_full_setup or drop the export.
Drop the export because tick_nohz_full_setup() is only called from the built-in code in kernel/sched/isolation.c.
Fixes: ae9e557b5be2 ("time: Export tick start/stop functions for rcutorture") Reported-by: Linus Torvalds <torvalds@linux-foundation.org> Signed-off-by: Masahiro Yamada <masahiroy@kernel.org> Tested-by: Paul E. McKenney <paulmck@kernel.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> Cc: Thomas Backlund <tmb@tmb.nu> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
show more ...
|
#
f4a80ec8 |
| 26-Jun-2022 |
Masahiro Yamada <masahiroy@kernel.org> |
tick/nohz: unexport __init-annotated tick_nohz_full_setup()
commit 2390095113e98fc52fffe35c5206d30d9efe3f78 upstream.
EXPORT_SYMBOL and __init is a bad combination because the .init.text section is
tick/nohz: unexport __init-annotated tick_nohz_full_setup()
commit 2390095113e98fc52fffe35c5206d30d9efe3f78 upstream.
EXPORT_SYMBOL and __init is a bad combination because the .init.text section is freed up after the initialization. Hence, modules cannot use symbols annotated __init. The access to a freed symbol may end up with kernel panic.
modpost used to detect it, but it had been broken for a decade.
Commit 28438794aba4 ("modpost: fix section mismatch check for exported init/exit sections") fixed it so modpost started to warn it again, then this showed up:
MODPOST vmlinux.symvers WARNING: modpost: vmlinux.o(___ksymtab_gpl+tick_nohz_full_setup+0x0): Section mismatch in reference from the variable __ksymtab_tick_nohz_full_setup to the function .init.text:tick_nohz_full_setup() The symbol tick_nohz_full_setup is exported and annotated __init Fix this by removing the __init annotation of tick_nohz_full_setup or drop the export.
Drop the export because tick_nohz_full_setup() is only called from the built-in code in kernel/sched/isolation.c.
Fixes: ae9e557b5be2 ("time: Export tick start/stop functions for rcutorture") Reported-by: Linus Torvalds <torvalds@linux-foundation.org> Signed-off-by: Masahiro Yamada <masahiroy@kernel.org> Tested-by: Paul E. McKenney <paulmck@kernel.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> Cc: Thomas Backlund <tmb@tmb.nu> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
show more ...
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#
68a38b07 |
| 06-Dec-2021 |
Paul Gortmaker <paul.gortmaker@windriver.com> |
tick/nohz: Use WARN_ON_ONCE() to prevent console saturation
commit 40e97e42961f8c6cc7bd5fe67cc18417e02d78f1 upstream.
While running some testing on code that happened to allow the variable tick_noh
tick/nohz: Use WARN_ON_ONCE() to prevent console saturation
commit 40e97e42961f8c6cc7bd5fe67cc18417e02d78f1 upstream.
While running some testing on code that happened to allow the variable tick_nohz_full_running to get set but with no "possible" NOHZ cores to back up that setting, this warning triggered:
if (unlikely(tick_do_timer_cpu == TICK_DO_TIMER_NONE)) WARN_ON(tick_nohz_full_running);
The console was overwhemled with an endless stream of one WARN per tick per core and there was no way to even see what was going on w/o using a serial console to capture it and then trace it back to this.
Change it to WARN_ON_ONCE().
Fixes: 08ae95f4fd3b ("nohz_full: Allow the boot CPU to be nohz_full") Signed-off-by: Paul Gortmaker <paul.gortmaker@windriver.com> Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Cc: stable@vger.kernel.org Link: https://lore.kernel.org/r/20211206145950.10927-3-paul.gortmaker@windriver.com Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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Revision tags: v5.14.14, v5.14.13, v5.14.12, v5.14.11, v5.14.10, v5.14.9, v5.14.8, v5.14.7, v5.14.6, v5.10.67, v5.10.66, v5.14.5, v5.14.4, v5.10.65, v5.14.3, v5.10.64, v5.14.2, v5.10.63, v5.14.1, v5.10.62, v5.14, v5.10.61, v5.10.60, v5.10.53, v5.10.52, v5.10.51, v5.10.50, v5.10.49, v5.13, v5.10.46, v5.10.43, v5.10.42, v5.10.41 |
|
#
f268c373 |
| 27-May-2021 |
Frederic Weisbecker <frederic@kernel.org> |
tick/nohz: Only check for RCU deferred wakeup on user/guest entry when needed
Checking for and processing RCU-nocb deferred wakeup upon user/guest entry is only relevant when nohz_full runs on the l
tick/nohz: Only check for RCU deferred wakeup on user/guest entry when needed
Checking for and processing RCU-nocb deferred wakeup upon user/guest entry is only relevant when nohz_full runs on the local CPU, otherwise the periodic tick should take care of it.
Make sure we don't needlessly pollute these fast-paths as a -3% performance regression on a will-it-scale.per_process_ops has been reported so far.
Fixes: 47b8ff194c1f (entry: Explicitly flush pending rcuog wakeup before last rescheduling point) Fixes: 4ae7dc97f726 (entry/kvm: Explicitly flush pending rcuog wakeup before last rescheduling point) Reported-by: kernel test robot <oliver.sang@intel.com> Signed-off-by: Frederic Weisbecker <frederic@kernel.org> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Reviewed-by: Paul E. McKenney <paulmck@kernel.org> Cc: stable@vger.kernel.org Link: https://lkml.kernel.org/r/20210527113441.465489-1-frederic@kernel.org
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Revision tags: v5.10.40, v5.10.39, v5.4.119 |
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#
0fdcccfa |
| 12-May-2021 |
Peter Zijlstra <peterz@infradead.org> |
tick/nohz: Call tick_nohz_task_switch() with interrupts disabled
Call tick_nohz_task_switch() slightly earlier after the context switch to benefit from disabled IRQs. This way the function doesn't n
tick/nohz: Call tick_nohz_task_switch() with interrupts disabled
Call tick_nohz_task_switch() slightly earlier after the context switch to benefit from disabled IRQs. This way the function doesn't need to disable them once more.
Signed-off-by: Peter Zijlstra <peterz@infradead.org> Signed-off-by: Frederic Weisbecker <frederic@kernel.org> Signed-off-by: Ingo Molnar <mingo@kernel.org> Link: https://lore.kernel.org/r/20210512232924.150322-10-frederic@kernel.org
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#
a1dfb631 |
| 12-May-2021 |
Marcelo Tosatti <mtosatti@redhat.com> |
tick/nohz: Kick only _queued_ task whose tick dependency is updated
When the tick dependency of a task is updated, we want it to aknowledge the new state and restart the tick if needed. If the task
tick/nohz: Kick only _queued_ task whose tick dependency is updated
When the tick dependency of a task is updated, we want it to aknowledge the new state and restart the tick if needed. If the task is not running, we don't need to kick it because it will observe the new dependency upon scheduling in. But if the task is running, we may need to send an IPI to it so that it gets notified.
Unfortunately we don't have the means to check if a task is running in a race free way. Checking p->on_cpu in a synchronized way against p->tick_dep_mask would imply adding a full barrier between prepare_task_switch() and tick_nohz_task_switch(), which we want to avoid in this fast-path.
Therefore we blindly fire an IPI to the task's CPU.
Meanwhile we can check if the task is queued on the CPU rq because p->on_rq is always set to TASK_ON_RQ_QUEUED _before_ schedule() and its full barrier that precedes tick_nohz_task_switch(). And if the task is queued on a nohz_full CPU, it also has fair chances to be running as the isolation constraints prescribe running single tasks on full dynticks CPUs.
So use this as a trick to check if we can spare an IPI toward a non-running task.
NOTE: For the ordering to be correct, it is assumed that we never deactivate a task while it is running, the only exception being the task deactivating itself while scheduling out.
Suggested-by: Peter Zijlstra <peterz@infradead.org> Signed-off-by: Marcelo Tosatti <mtosatti@redhat.com> Signed-off-by: Frederic Weisbecker <frederic@kernel.org> Signed-off-by: Ingo Molnar <mingo@kernel.org> Acked-by: Peter Zijlstra <peterz@infradead.org> Link: https://lore.kernel.org/r/20210512232924.150322-9-frederic@kernel.org
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#
1e4ca26d |
| 12-May-2021 |
Marcelo Tosatti <mtosatti@redhat.com> |
tick/nohz: Change signal tick dependency to wake up CPUs of member tasks
Rather than waking up all nohz_full CPUs on the system, only wake up the target CPUs of member threads of the signal.
Reduce
tick/nohz: Change signal tick dependency to wake up CPUs of member tasks
Rather than waking up all nohz_full CPUs on the system, only wake up the target CPUs of member threads of the signal.
Reduces interruptions to nohz_full CPUs.
Signed-off-by: Marcelo Tosatti <mtosatti@redhat.com> Signed-off-by: Frederic Weisbecker <frederic@kernel.org> Signed-off-by: Ingo Molnar <mingo@kernel.org> Acked-by: Peter Zijlstra <peterz@infradead.org> Link: https://lore.kernel.org/r/20210512232924.150322-8-frederic@kernel.org
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29721b85 |
| 12-May-2021 |
Frederic Weisbecker <frederic@kernel.org> |
tick/nohz: Only wake up a single target cpu when kicking a task
When adding a tick dependency to a task, its necessary to wake up the CPU where the task resides to reevaluate tick dependencies on th
tick/nohz: Only wake up a single target cpu when kicking a task
When adding a tick dependency to a task, its necessary to wake up the CPU where the task resides to reevaluate tick dependencies on that CPU.
However the current code wakes up all nohz_full CPUs, which is unnecessary.
Switch to waking up a single CPU, by using ordering of writes to task->cpu and task->tick_dep_mask.
[ mingo: Minor readability edit. ]
Suggested-by: Peter Zijlstra <peterz@infradead.org> Signed-off-by: Frederic Weisbecker <frederic@kernel.org> Signed-off-by: Marcelo Tosatti <mtosatti@redhat.com> Signed-off-by: Ingo Molnar <mingo@kernel.org> Acked-by: Peter Zijlstra <peterz@infradead.org> Link: https://lore.kernel.org/r/20210512232924.150322-7-frederic@kernel.org
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96c9b903 |
| 12-May-2021 |
Yunfeng Ye <yeyunfeng@huawei.com> |
tick/nohz: Update idle_exittime on actual idle exit
The idle_exittime field of tick_sched is used to record the time when the idle state was left. but currently the idle_exittime is updated in the f
tick/nohz: Update idle_exittime on actual idle exit
The idle_exittime field of tick_sched is used to record the time when the idle state was left. but currently the idle_exittime is updated in the function tick_nohz_restart_sched_tick(), which is not always in idle state when nohz_full is configured:
tick_irq_exit tick_nohz_irq_exit tick_nohz_full_update_tick tick_nohz_restart_sched_tick ts->idle_exittime = now;
It's thus overwritten by mistake on nohz_full tick restart. Move the update to the appropriate idle exit path instead.
Signed-off-by: Yunfeng Ye <yeyunfeng@huawei.com> Signed-off-by: Frederic Weisbecker <frederic@kernel.org> Signed-off-by: Ingo Molnar <mingo@kernel.org> Acked-by: Peter Zijlstra <peterz@infradead.org> Link: https://lore.kernel.org/r/20210512232924.150322-5-frederic@kernel.org
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3f624314 |
| 12-May-2021 |
Frederic Weisbecker <frederic@kernel.org> |
tick/nohz: Remove superflous check for CONFIG_VIRT_CPU_ACCOUNTING_NATIVE
The vtime_accounting_enabled_this_cpu() early check already makes what follows as dead code in the case of CONFIG_VIRT_CPU_AC
tick/nohz: Remove superflous check for CONFIG_VIRT_CPU_ACCOUNTING_NATIVE
The vtime_accounting_enabled_this_cpu() early check already makes what follows as dead code in the case of CONFIG_VIRT_CPU_ACCOUNTING_NATIVE. No need to keep the ifdeferry around.
Signed-off-by: Frederic Weisbecker <frederic@kernel.org> Signed-off-by: Ingo Molnar <mingo@kernel.org> Acked-by: Peter Zijlstra <peterz@infradead.org> Link: https://lore.kernel.org/r/20210512232924.150322-4-frederic@kernel.org
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a5183862 |
| 12-May-2021 |
Yunfeng Ye <yeyunfeng@huawei.com> |
tick/nohz: Conditionally restart tick on idle exit
In nohz_full mode, switching from idle to a task will unconditionally issue a tick restart. If the task is alone in the runqueue or is the highest
tick/nohz: Conditionally restart tick on idle exit
In nohz_full mode, switching from idle to a task will unconditionally issue a tick restart. If the task is alone in the runqueue or is the highest priority, the tick will fire once then eventually stop. But that alone is still undesired noise.
Therefore, only restart the tick on idle exit when it's strictly necessary.
Signed-off-by: Yunfeng Ye <yeyunfeng@huawei.com> Signed-off-by: Frederic Weisbecker <frederic@kernel.org> Signed-off-by: Ingo Molnar <mingo@kernel.org> Acked-by: Peter Zijlstra <peterz@infradead.org> Link: https://lore.kernel.org/r/20210512232924.150322-3-frederic@kernel.org
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Revision tags: v5.10.36, v5.10.35, v5.10.34, v5.4.116, v5.10.33, v5.12, v5.10.32, v5.10.31, v5.10.30, v5.10.27 |
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4c81cb7e |
| 29-Mar-2021 |
Rafael J. Wysocki <rafael.j.wysocki@intel.com> |
tick/nohz: Improve tick_nohz_get_next_hrtimer() kerneldoc
Make the tick_nohz_get_next_hrtimer() kerneldoc comment state clearly that the function may return negative numbers.
Signed-off-by: Rafael
tick/nohz: Improve tick_nohz_get_next_hrtimer() kerneldoc
Make the tick_nohz_get_next_hrtimer() kerneldoc comment state clearly that the function may return negative numbers.
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
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Revision tags: v5.10.26 |
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4bf07f65 |
| 22-Mar-2021 |
Ingo Molnar <mingo@kernel.org> |
timekeeping, clocksource: Fix various typos in comments
Fix ~56 single-word typos in timekeeping & clocksource code comments.
Signed-off-by: Ingo Molnar <mingo@kernel.org> Cc: Thomas Gleixner <tglx
timekeeping, clocksource: Fix various typos in comments
Fix ~56 single-word typos in timekeeping & clocksource code comments.
Signed-off-by: Ingo Molnar <mingo@kernel.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: John Stultz <john.stultz@linaro.org> Cc: Stephen Boyd <sboyd@kernel.org> Cc: Daniel Lezcano <daniel.lezcano@linaro.org> Cc: linux-kernel@vger.kernel.org
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Revision tags: v5.10.25, v5.10.24, v5.10.23, v5.10.22 |
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47c218dc |
| 09-Mar-2021 |
Thomas Gleixner <tglx@linutronix.de> |
tick/sched: Prevent false positive softirq pending warnings on RT
On RT a task which has soft interrupts disabled can block on a lock and schedule out to idle while soft interrupts are pending. This
tick/sched: Prevent false positive softirq pending warnings on RT
On RT a task which has soft interrupts disabled can block on a lock and schedule out to idle while soft interrupts are pending. This triggers the warning in the NOHZ idle code which complains about going idle with pending soft interrupts. But as the task is blocked soft interrupt processing is temporarily blocked as well which means that such a warning is a false positive.
To prevent that check the per CPU state which indicates that a scheduled out task has soft interrupts disabled.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Tested-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de> Tested-by: Paul E. McKenney <paulmck@kernel.org> Reviewed-by: Frederic Weisbecker <frederic@kernel.org> Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org> Link: https://lore.kernel.org/r/20210309085727.527563866@linutronix.de
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Revision tags: v5.10.21, v5.10.20, v5.10.19, v5.4.101, v5.10.18, v5.10.17, v5.11, v5.10.16, v5.10.15, v5.10.14, v5.10 |
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ba8ea8e7 |
| 06-Dec-2020 |
Thomas Gleixner <tglx@linutronix.de> |
tick/sched: Remove bogus boot "safety" check
can_stop_idle_tick() checks whether the do_timer() duty has been taken over by a CPU on boot. That's silly because the boot CPU always takes over with th
tick/sched: Remove bogus boot "safety" check
can_stop_idle_tick() checks whether the do_timer() duty has been taken over by a CPU on boot. That's silly because the boot CPU always takes over with the initial clockevent device.
But even if no CPU would have installed a clockevent and taken over the duty then the question whether the tick on the current CPU can be stopped or not is moot. In that case the current CPU would have no clockevent either, so there would be nothing to keep ticking.
Remove it.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Acked-by: Frederic Weisbecker <frederic@kernel.org> Link: https://lore.kernel.org/r/20201206212002.725238293@linutronix.de
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aa3b66f4 |
| 04-Dec-2020 |
Thomas Gleixner <tglx@linutronix.de> |
tick/sched: Make jiffies update quick check more robust
The quick check in tick_do_update_jiffies64() whether jiffies need to be updated is not really correct under all circumstances and on all arch
tick/sched: Make jiffies update quick check more robust
The quick check in tick_do_update_jiffies64() whether jiffies need to be updated is not really correct under all circumstances and on all architectures, especially not on 32bit systems.
The quick check does:
if (now < READ_ONCE(tick_next_period)) return;
and the counterpart in the update is:
WRITE_ONCE(tick_next_period, next_update_time);
This has two problems:
1) On weakly ordered architectures there is no guarantee that the stores before the WRITE_ONCE() are visible which means that other CPUs can operate on a stale jiffies value.
2) On 32bit the store of tick_next_period which is an u64 is split into two 32bit stores. If the first 32bit store advances tick_next_period far out and the second 32bit store is delayed (virt, NMI ...) then jiffies will become stale until the second 32bit store happens.
Address this by seperating the handling for 32bit and 64bit.
On 64bit problem #1 is addressed by replacing READ_ONCE() / WRITE_ONCE() with smp_load_acquire() / smp_store_release().
On 32bit problem #2 is addressed by protecting the quick check with the jiffies sequence counter. The load and stores can be plain because the sequence count mechanics provides the required barriers already.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Reviewed-by: Frederic Weisbecker <frederic@kernel.org> Link: https://lore.kernel.org/r/87czzpc02w.fsf@nanos.tec.linutronix.de
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Revision tags: v5.8.17, v5.8.16, v5.8.15, v5.9, v5.8.14, v5.8.13, v5.8.12, v5.8.11, v5.8.10, v5.8.9, v5.8.8, v5.8.7, v5.8.6, v5.4.62, v5.8.5, v5.8.4, v5.4.61, v5.8.3, v5.4.60, v5.8.2, v5.4.59, v5.8.1, v5.4.58, v5.4.57, v5.4.56, v5.8, v5.7.12, v5.4.55, v5.7.11, v5.4.54, v5.7.10, v5.4.53, v5.4.52, v5.7.9, v5.7.8, v5.4.51, v5.4.50, v5.7.7, v5.4.49, v5.7.6, v5.7.5, v5.4.48, v5.7.4, v5.7.3, v5.4.47 |
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7a9f50a0 |
| 15-Jun-2020 |
Peter Zijlstra <peterz@infradead.org> |
irq_work: Cleanup
Get rid of the __call_single_node union and clean up the API a little to avoid external code relying on the structure layout as much.
Signed-off-by: Peter Zijlstra (Intel) <peterz
irq_work: Cleanup
Get rid of the __call_single_node union and clean up the API a little to avoid external code relying on the structure layout as much.
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Reviewed-by: Frederic Weisbecker <frederic@kernel.org>
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