Peter Zijlstra f5d39b0208 freezer,sched: Rewrite core freezer logic ... Rewrite the core freezer to behave better wrt thawing and be simpler in general. By replacing PF_FROZEN with TASK_FROZEN, a special block state, it is ensured frozen tasks stay frozen until thawed and don't randomly wake up early, as is currently possible. As such, it does away with PF_FROZEN and PF_FREEZER_SKIP, freeing up two PF_flags (yay!). Specifically; the current scheme works a little like: freezer_do_not_count(); schedule(); freezer_count(); And either the task is blocked, or it lands in try_to_freezer() through freezer_count(). Now, when it is blocked, the freezer considers it frozen and continues. However, on thawing, once pm_freezing is cleared, freezer_count() stops working, and any random/spurious wakeup will let a task run before its time. That is, thawing tries to thaw things in explicit order; kernel threads and workqueues before doing bringing SMP back before userspace etc.. However due to the above mentioned races it is entirely possible for userspace tasks to thaw (by accident) before SMP is back. This can be a fatal problem in asymmetric ISA architectures (eg ARMv9) where the userspace task requires a special CPU to run. As said; replace this with a special task state TASK_FROZEN and add the following state transitions: TASK_FREEZABLE -> TASK_FROZEN __TASK_STOPPED -> TASK_FROZEN __TASK_TRACED -> TASK_FROZEN The new TASK_FREEZABLE can be set on any state part of TASK_NORMAL (IOW. TASK_INTERRUPTIBLE and TASK_UNINTERRUPTIBLE) -- any such state is already required to deal with spurious wakeups and the freezer causes one such when thawing the task (since the original state is lost). The special __TASK_{STOPPED,TRACED} states *can* be restored since their canonical state is in ->jobctl. With this, frozen tasks need an explicit TASK_FROZEN wakeup and are free of undue (early / spurious) wakeups. Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Reviewed-by: Ingo Molnar <mingo@kernel.org> Acked-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com> Link: https://lore.kernel.org/r/20220822114649.055452969@infradead.org		2022-09-07 21:53:50 +02:00
..
bpf	Networking changes for 6.0.	2022-08-03 16:29:08 -07:00
cgroup	freezer,sched: Rewrite core freezer logic	2022-09-07 21:53:50 +02:00
configs	Char / Misc driver changes for 6.0-rc1	2022-08-04 11:05:48 -07:00
debug	Modules updates for v5.19-rc1	2022-05-26 17:13:43 -07:00
dma	remoteproc updates for v5.20	2022-08-08 15:16:29 -07:00
entry	context_tracking: Take NMI eqs entrypoints over RCU	2022-07-05 13:32:59 -07:00
events	Misc fixes to kprobes and the faddr2line script, plus a cleanup.	2022-08-06 17:28:12 -07:00
futex	freezer,sched: Rewrite core freezer logic	2022-09-07 21:53:50 +02:00
gcov	gcov: Remove compiler version check	2021-12-02 17:25:21 +09:00
irq	irqchip/genirq updates for 5.20:	2022-07-28 12:36:35 +02:00
kcsan	kcsan: test: Add a .kunitconfig to run KCSAN tests	2022-07-22 09:22:59 -06:00
livepatch	Livepatching changes for 5.19	2022-06-02 08:55:01 -07:00
locking	RCU pull request for v5.20 (or whatever)	2022-08-02 19:12:45 -07:00
module	Modules updates for 6.0	2022-08-08 14:12:19 -07:00
power	freezer,sched: Rewrite core freezer logic	2022-09-07 21:53:50 +02:00
printk	printk: do not wait for consoles when suspended	2022-07-15 10:52:11 +02:00
rcu	- The usual batches of cleanups from Baoquan He, Muchun Song, Miaohe	2022-08-05 16:32:45 -07:00
sched	freezer,sched: Rewrite core freezer logic	2022-09-07 21:53:50 +02:00
time	freezer,sched: Rewrite core freezer logic	2022-09-07 21:53:50 +02:00
trace	Tracing updates for 5.20 / 6.0	2022-08-05 09:41:12 -07:00
.gitignore
acct.c	kernel/acct: move acct sysctls to its own file	2022-04-06 13:43:44 -07:00
async.c	Revert "module, async: async_synchronize_full() on module init iff async is used"	2022-02-03 11:20:34 -08:00
audit_fsnotify.c	fsnotify: make allow_dups a property of the group	2022-04-25 14:37:18 +02:00
audit_tree.c	audit: use fsnotify group lock helpers	2022-04-25 14:37:28 +02:00
audit_watch.c	fsnotify: pass flags argument to fsnotify_alloc_group()	2022-04-25 14:37:12 +02:00
audit.c	audit: make is_audit_feature_set() static	2022-06-13 14:08:57 -04:00
audit.h	audit: log AUDIT_TIME_* records only from rules	2022-02-22 13:51:40 -05:00
auditfilter.c	audit/stable-5.17 PR 20220110	2022-01-11 13:08:21 -08:00
auditsc.c	audit: free module name	2022-06-15 19:28:44 -04:00
backtracetest.c
bounds.c
capability.c	xfs: don't generate selinux audit messages for capability testing	2022-03-09 10:32:06 -08:00
cfi.c	context_tracking: Take IRQ eqs entrypoints over RCU	2022-07-05 13:32:59 -07:00
compat.c
configs.c
context_tracking.c	MAINTAINERS: Add Paul as context tracking maintainer	2022-07-05 13:33:00 -07:00
cpu_pm.c	context_tracking: Take IRQ eqs entrypoints over RCU	2022-07-05 13:32:59 -07:00
cpu.c	Intel Trust Domain Extensions	2022-05-23 17:51:12 -07:00
crash_core.c	kdump: round up the total memory size to 128M for crashkernel reservation	2022-07-17 17:31:40 -07:00
crash_dump.c
cred.c	x86: Mark __invalid_creds() __noreturn	2022-03-15 10:32:44 +01:00
delayacct.c	delayacct: track delays from write-protect copy	2022-06-01 15:55:25 -07:00
dma.c
exec_domain.c
exit.c	freezer,sched: Rewrite core freezer logic	2022-09-07 21:53:50 +02:00
extable.c	context_tracking: Take NMI eqs entrypoints over RCU	2022-07-05 13:32:59 -07:00
fail_function.c
fork.c	freezer,sched: Rewrite core freezer logic	2022-09-07 21:53:50 +02:00
freezer.c	freezer,sched: Rewrite core freezer logic	2022-09-07 21:53:50 +02:00
gen_kheaders.sh	kheaders: Have cpio unconditionally replace files	2022-05-08 03:16:59 +09:00
groups.c	security: Add LSM hook to setgroups() syscall	2022-07-15 18:21:49 +00:00
hung_task.c	freezer,sched: Rewrite core freezer logic	2022-09-07 21:53:50 +02:00
iomem.c
irq_work.c	irq_work: use kasan_record_aux_stack_noalloc() record callstack	2022-04-15 14:49:55 -07:00
jump_label.c	jump_label: make initial NOP patching the special case	2022-06-24 09:48:55 +02:00
kallsyms_internal.h	kallsyms: move declarations to internal header	2022-07-17 17:31:39 -07:00
kallsyms.c	Updates to various subsystems which I help look after. lib, ocfs2,	2022-08-07 10:03:24 -07:00
kcmp.c
Kconfig.freezer
Kconfig.hz
Kconfig.locks
Kconfig.preempt	Revert "signal, x86: Delay calling signals in atomic on RT enabled kernels"	2022-03-31 10:36:55 +02:00
kcov.c	kcov: update pos before writing pc in trace function	2022-05-25 13:05:42 -07:00
kexec_core.c	kexec: drop weak attribute from functions	2022-07-15 12:21:16 -04:00
kexec_elf.c
kexec_file.c	Updates to various subsystems which I help look after. lib, ocfs2,	2022-08-07 10:03:24 -07:00
kexec_internal.h
kexec.c
kheaders.c
kmod.c
kprobes.c	kprobes: Forbid probing on trampoline and BPF code areas	2022-08-02 11:47:29 +02:00
ksysfs.c	kernel/ksysfs.c: use helper macro __ATTR_RW	2022-03-23 19:00:33 -07:00
kthread.c	kthread: make it clear that kthread_create_on_node() might be terminated by any fatal signal	2022-06-16 19:11:30 -07:00
latencytop.c	latencytop: move sysctl to its own file	2022-04-21 11:40:59 -07:00
Makefile	kernel: remove platform_has() infrastructure	2022-08-01 07:42:56 +02:00
module_signature.c
notifier.c	notifier: Add blocking/atomic_notifier_chain_register_unique_prio()	2022-05-19 19:30:30 +02:00
nsproxy.c	fs/exec: allow to unshare a time namespace on vfork+exec	2022-06-15 07:58:04 -07:00
padata.c	padata: replace cpumask_weight with cpumask_empty in padata.c	2022-01-31 11:21:46 +11:00
panic.c	linux-kselftest-kunit-5.20-rc1	2022-08-02 19:34:45 -07:00
params.c	kobject: remove kset from struct kset_uevent_ops callbacks	2021-12-28 11:26:18 +01:00
pid_namespace.c	kernel: pid_namespace: use NULL instead of using plain integer as pointer	2022-04-29 14:38:00 -07:00
pid.c	pid: add pidfd_get_task() helper	2021-10-14 13:29:18 +02:00
profile.c	profile: setup_profiling_timer() is moslty not implemented	2022-07-29 18:12:36 -07:00
ptrace.c	freezer,sched: Rewrite core freezer logic	2022-09-07 21:53:50 +02:00
range.c
reboot.c	Merge branch 'rework/kthreads' into for-linus	2022-06-23 19:11:28 +02:00
regset.c
relay.c	relay: remove redundant assignment to pointer buf	2022-05-12 20:38:37 -07:00
resource_kunit.c
resource.c	resource: Introduce alloc_free_mem_region()	2022-07-21 17:19:25 -07:00
rseq.c	rseq: Kill process when unknown flags are encountered in ABI structures	2022-08-01 15:21:42 +02:00
scftorture.c	scftorture: Fix distribution of short handler delays	2022-04-11 17:07:29 -07:00
scs.c	kasan, vmalloc: only tag normal vmalloc allocations	2022-03-24 19:06:48 -07:00
seccomp.c	seccomp: Add wait_killable semantic to seccomp user notifier	2022-05-03 14:11:58 -07:00
signal.c	freezer,sched: Rewrite core freezer logic	2022-09-07 21:53:50 +02:00
smp.c	locking/csd_lock: Change csdlock_debug from early_param to __setup	2022-07-19 11:40:00 -07:00
smpboot.c	cpu/hotplug: Allow the CPU in CPU_UP_PREPARE state to be brought up again.	2022-04-12 14:13:01 +02:00
smpboot.h
softirq.c	context_tracking: Take IRQ eqs entrypoints over RCU	2022-07-05 13:32:59 -07:00
stackleak.c	stackleak: add on/off stack variants	2022-05-08 01:33:09 -07:00
stacktrace.c	uaccess: remove CONFIG_SET_FS	2022-02-25 09:36:06 +01:00
static_call_inline.c	static_call: Don't make __static_call_return0 static	2022-04-05 09:59:38 +02:00
static_call.c	static_call: Don't make __static_call_return0 static	2022-04-05 09:59:38 +02:00
stop_machine.c	Scheduler changes in this cycle were:	2022-05-24 11:11:13 -07:00
sys_ni.c	mm/mempolicy: wire up syscall set_mempolicy_home_node	2022-01-15 16:30:30 +02:00
sys.c	arm64/sme: Implement vector length configuration prctl()s	2022-04-22 18:50:54 +01:00
sysctl-test.c
sysctl.c	kernel/sysctl.c: Remove trailing white space	2022-08-08 09:01:36 -07:00
task_work.c	task_work: allow TWA_SIGNAL without a rescheduling IPI	2022-04-30 08:39:32 -06:00
taskstats.c	kernel: make taskstats available from all net namespaces	2022-04-29 14:38:03 -07:00
torture.c	torture: Wake up kthreads after storing task_struct pointer	2022-02-01 17:24:39 -08:00
tracepoint.c
tsacct.c	taskstats: version 12 with thread group and exe info	2022-04-29 14:38:03 -07:00
ucount.c	ucounts: Handle wrapping in is_ucounts_overlimit	2022-02-17 09:11:57 -06:00
uid16.c
uid16.h
umh.c	freezer,sched: Rewrite core freezer logic	2022-09-07 21:53:50 +02:00
up.c
user_namespace.c	ucounts: Fix systemd LimitNPROC with private users regression	2022-02-25 10:40:14 -06:00
user-return-notifier.c
user.c
usermode_driver.c	blob_to_mnt(): kern_unmount() is needed to undo kern_mount()	2022-05-19 23:25:47 -04:00
utsname_sysctl.c
utsname.c
watch_queue.c	This was a moderately busy cycle for documentation, but nothing all that	2022-08-02 19:24:24 -07:00
watchdog_hld.c	Revert "printk: add functions to prefer direct printing"	2022-06-23 18:41:40 +02:00
watchdog.c	powerpc updates for 6.0	2022-08-06 16:38:17 -07:00
workqueue_internal.h
workqueue.c	drm for 5.20/6.0	2022-08-03 19:52:08 -07:00