From f1a0a376ca0c4ef1fc3d24e3e502acbb5b795674 Mon Sep 17 00:00:00 2001 From: Valentin Schneider Date: Wed, 12 May 2021 10:46:36 +0100 Subject: sched/core: Initialize the idle task with preemption disabled As pointed out by commit de9b8f5dcbd9 ("sched: Fix crash trying to dequeue/enqueue the idle thread") init_idle() can and will be invoked more than once on the same idle task. At boot time, it is invoked for the boot CPU thread by sched_init(). Then smp_init() creates the threads for all the secondary CPUs and invokes init_idle() on them. As the hotplug machinery brings the secondaries to life, it will issue calls to idle_thread_get(), which itself invokes init_idle() yet again. In this case it's invoked twice more per secondary: at _cpu_up(), and at bringup_cpu(). Given smp_init() already initializes the idle tasks for all *possible* CPUs, no further initialization should be required. Now, removing init_idle() from idle_thread_get() exposes some interesting expectations with regards to the idle task's preempt_count: the secondary startup always issues a preempt_disable(), requiring some reset of the preempt count to 0 between hot-unplug and hotplug, which is currently served by idle_thread_get() -> idle_init(). Given the idle task is supposed to have preemption disabled once and never see it re-enabled, it seems that what we actually want is to initialize its preempt_count to PREEMPT_DISABLED and leave it there. Do that, and remove init_idle() from idle_thread_get(). Secondary startups were patched via coccinelle: @begone@ @@ -preempt_disable(); ... cpu_startup_entry(CPUHP_AP_ONLINE_IDLE); Signed-off-by: Valentin Schneider Signed-off-by: Ingo Molnar Acked-by: Peter Zijlstra Link: https://lore.kernel.org/r/20210512094636.2958515-1-valentin.schneider@arm.com --- arch/xtensa/kernel/smp.c | 1 - 1 file changed, 1 deletion(-) (limited to 'arch/xtensa') diff --git a/arch/xtensa/kernel/smp.c b/arch/xtensa/kernel/smp.c index cd85a7a2722b..1254da07ead1 100644 --- a/arch/xtensa/kernel/smp.c +++ b/arch/xtensa/kernel/smp.c @@ -145,7 +145,6 @@ void secondary_start_kernel(void) cpumask_set_cpu(cpu, mm_cpumask(mm)); enter_lazy_tlb(mm, current); - preempt_disable(); trace_hardirqs_off(); calibrate_delay(); -- cgit v1.2.3-58-ga151 From b03fbd4ff24c5f075e58eb19261d5f8b3e40d7c6 Mon Sep 17 00:00:00 2001 From: Peter Zijlstra Date: Fri, 11 Jun 2021 10:28:12 +0200 Subject: sched: Introduce task_is_running() Replace a bunch of 'p->state == TASK_RUNNING' with a new helper: task_is_running(p). Signed-off-by: Peter Zijlstra (Intel) Acked-by: Davidlohr Bueso Acked-by: Geert Uytterhoeven Acked-by: Will Deacon Link: https://lore.kernel.org/r/20210611082838.222401495@infradead.org --- arch/alpha/kernel/process.c | 2 +- arch/arc/kernel/stacktrace.c | 2 +- arch/arm/kernel/process.c | 2 +- arch/arm64/kernel/process.c | 2 +- arch/csky/kernel/stacktrace.c | 2 +- arch/h8300/kernel/process.c | 2 +- arch/hexagon/kernel/process.c | 2 +- arch/ia64/kernel/process.c | 4 ++-- arch/m68k/kernel/process.c | 2 +- arch/mips/kernel/process.c | 2 +- arch/nds32/kernel/process.c | 2 +- arch/nios2/kernel/process.c | 2 +- arch/parisc/kernel/process.c | 4 ++-- arch/powerpc/kernel/process.c | 4 ++-- arch/riscv/kernel/stacktrace.c | 2 +- arch/s390/kernel/process.c | 2 +- arch/s390/mm/fault.c | 2 +- arch/sh/kernel/process_32.c | 2 +- arch/sparc/kernel/process_32.c | 3 +-- arch/sparc/kernel/process_64.c | 3 +-- arch/um/kernel/process.c | 2 +- arch/x86/kernel/process.c | 4 ++-- arch/xtensa/kernel/process.c | 2 +- block/blk-mq.c | 2 +- include/linux/sched.h | 2 ++ kernel/kcsan/report.c | 2 +- kernel/locking/lockdep.c | 2 +- kernel/rcu/tree_plugin.h | 2 +- kernel/sched/core.c | 6 +++--- kernel/sched/stats.h | 2 +- kernel/signal.c | 2 +- kernel/softirq.c | 3 +-- mm/compaction.c | 2 +- 33 files changed, 40 insertions(+), 41 deletions(-) (limited to 'arch/xtensa') diff --git a/arch/alpha/kernel/process.c b/arch/alpha/kernel/process.c index 5112ab996394..ef0c08ed0481 100644 --- a/arch/alpha/kernel/process.c +++ b/arch/alpha/kernel/process.c @@ -380,7 +380,7 @@ get_wchan(struct task_struct *p) { unsigned long schedule_frame; unsigned long pc; - if (!p || p == current || p->state == TASK_RUNNING) + if (!p || p == current || task_is_running(p)) return 0; /* * This one depends on the frame size of schedule(). Do a diff --git a/arch/arc/kernel/stacktrace.c b/arch/arc/kernel/stacktrace.c index f73da203b170..1b9576d21e24 100644 --- a/arch/arc/kernel/stacktrace.c +++ b/arch/arc/kernel/stacktrace.c @@ -83,7 +83,7 @@ seed_unwind_frame_info(struct task_struct *tsk, struct pt_regs *regs, * is safe-kept and BLINK at a well known location in there */ - if (tsk->state == TASK_RUNNING) + if (task_is_running(tsk)) return -1; frame_info->task = tsk; diff --git a/arch/arm/kernel/process.c b/arch/arm/kernel/process.c index 6324f4db9b02..fc9e8b37eaa8 100644 --- a/arch/arm/kernel/process.c +++ b/arch/arm/kernel/process.c @@ -288,7 +288,7 @@ unsigned long get_wchan(struct task_struct *p) struct stackframe frame; unsigned long stack_page; int count = 0; - if (!p || p == current || p->state == TASK_RUNNING) + if (!p || p == current || task_is_running(p)) return 0; frame.fp = thread_saved_fp(p); diff --git a/arch/arm64/kernel/process.c b/arch/arm64/kernel/process.c index b4bb67f17a2c..14f3c19c6ad2 100644 --- a/arch/arm64/kernel/process.c +++ b/arch/arm64/kernel/process.c @@ -598,7 +598,7 @@ unsigned long get_wchan(struct task_struct *p) struct stackframe frame; unsigned long stack_page, ret = 0; int count = 0; - if (!p || p == current || p->state == TASK_RUNNING) + if (!p || p == current || task_is_running(p)) return 0; stack_page = (unsigned long)try_get_task_stack(p); diff --git a/arch/csky/kernel/stacktrace.c b/arch/csky/kernel/stacktrace.c index 16ae20a0af34..1b280ef08004 100644 --- a/arch/csky/kernel/stacktrace.c +++ b/arch/csky/kernel/stacktrace.c @@ -115,7 +115,7 @@ unsigned long get_wchan(struct task_struct *task) { unsigned long pc = 0; - if (likely(task && task != current && task->state != TASK_RUNNING)) + if (likely(task && task != current && !task_is_running(task))) walk_stackframe(task, NULL, save_wchan, &pc); return pc; } diff --git a/arch/h8300/kernel/process.c b/arch/h8300/kernel/process.c index 46b1342ce515..2ac27e4248a4 100644 --- a/arch/h8300/kernel/process.c +++ b/arch/h8300/kernel/process.c @@ -134,7 +134,7 @@ unsigned long get_wchan(struct task_struct *p) unsigned long stack_page; int count = 0; - if (!p || p == current || p->state == TASK_RUNNING) + if (!p || p == current || task_is_running(p)) return 0; stack_page = (unsigned long)p; diff --git a/arch/hexagon/kernel/process.c b/arch/hexagon/kernel/process.c index c61165c99ae0..6a6835fb4242 100644 --- a/arch/hexagon/kernel/process.c +++ b/arch/hexagon/kernel/process.c @@ -135,7 +135,7 @@ unsigned long get_wchan(struct task_struct *p) unsigned long fp, pc; unsigned long stack_page; int count = 0; - if (!p || p == current || p->state == TASK_RUNNING) + if (!p || p == current || task_is_running(p)) return 0; stack_page = (unsigned long)task_stack_page(p); diff --git a/arch/ia64/kernel/process.c b/arch/ia64/kernel/process.c index 7e1a1525e202..e56d63f4abf9 100644 --- a/arch/ia64/kernel/process.c +++ b/arch/ia64/kernel/process.c @@ -529,7 +529,7 @@ get_wchan (struct task_struct *p) unsigned long ip; int count = 0; - if (!p || p == current || p->state == TASK_RUNNING) + if (!p || p == current || task_is_running(p)) return 0; /* @@ -542,7 +542,7 @@ get_wchan (struct task_struct *p) */ unw_init_from_blocked_task(&info, p); do { - if (p->state == TASK_RUNNING) + if (task_is_running(p)) return 0; if (unw_unwind(&info) < 0) return 0; diff --git a/arch/m68k/kernel/process.c b/arch/m68k/kernel/process.c index da83cc83e791..db49f9091711 100644 --- a/arch/m68k/kernel/process.c +++ b/arch/m68k/kernel/process.c @@ -268,7 +268,7 @@ unsigned long get_wchan(struct task_struct *p) unsigned long fp, pc; unsigned long stack_page; int count = 0; - if (!p || p == current || p->state == TASK_RUNNING) + if (!p || p == current || task_is_running(p)) return 0; stack_page = (unsigned long)task_stack_page(p); diff --git a/arch/mips/kernel/process.c b/arch/mips/kernel/process.c index bff080db0294..73c8e7990a97 100644 --- a/arch/mips/kernel/process.c +++ b/arch/mips/kernel/process.c @@ -662,7 +662,7 @@ unsigned long get_wchan(struct task_struct *task) unsigned long ra = 0; #endif - if (!task || task == current || task->state == TASK_RUNNING) + if (!task || task == current || task_is_running(task)) goto out; if (!task_stack_page(task)) goto out; diff --git a/arch/nds32/kernel/process.c b/arch/nds32/kernel/process.c index c1327e552ec6..391895b54d13 100644 --- a/arch/nds32/kernel/process.c +++ b/arch/nds32/kernel/process.c @@ -239,7 +239,7 @@ unsigned long get_wchan(struct task_struct *p) unsigned long stack_start, stack_end; int count = 0; - if (!p || p == current || p->state == TASK_RUNNING) + if (!p || p == current || task_is_running(p)) return 0; if (IS_ENABLED(CONFIG_FRAME_POINTER)) { diff --git a/arch/nios2/kernel/process.c b/arch/nios2/kernel/process.c index c5f916ca6845..9ff37ba2bb60 100644 --- a/arch/nios2/kernel/process.c +++ b/arch/nios2/kernel/process.c @@ -223,7 +223,7 @@ unsigned long get_wchan(struct task_struct *p) unsigned long stack_page; int count = 0; - if (!p || p == current || p->state == TASK_RUNNING) + if (!p || p == current || task_is_running(p)) return 0; stack_page = (unsigned long)p; diff --git a/arch/parisc/kernel/process.c b/arch/parisc/kernel/process.c index b144fbe29bc1..184ec3c1eae4 100644 --- a/arch/parisc/kernel/process.c +++ b/arch/parisc/kernel/process.c @@ -249,7 +249,7 @@ get_wchan(struct task_struct *p) unsigned long ip; int count = 0; - if (!p || p == current || p->state == TASK_RUNNING) + if (!p || p == current || task_is_running(p)) return 0; /* @@ -260,7 +260,7 @@ get_wchan(struct task_struct *p) do { if (unwind_once(&info) < 0) return 0; - if (p->state == TASK_RUNNING) + if (task_is_running(p)) return 0; ip = info.ip; if (!in_sched_functions(ip)) diff --git a/arch/powerpc/kernel/process.c b/arch/powerpc/kernel/process.c index 89e34aa273e2..8935c5696bce 100644 --- a/arch/powerpc/kernel/process.c +++ b/arch/powerpc/kernel/process.c @@ -2084,7 +2084,7 @@ static unsigned long __get_wchan(struct task_struct *p) unsigned long ip, sp; int count = 0; - if (!p || p == current || p->state == TASK_RUNNING) + if (!p || p == current || task_is_running(p)) return 0; sp = p->thread.ksp; @@ -2094,7 +2094,7 @@ static unsigned long __get_wchan(struct task_struct *p) do { sp = *(unsigned long *)sp; if (!validate_sp(sp, p, STACK_FRAME_OVERHEAD) || - p->state == TASK_RUNNING) + task_is_running(p)) return 0; if (count > 0) { ip = ((unsigned long *)sp)[STACK_FRAME_LR_SAVE]; diff --git a/arch/riscv/kernel/stacktrace.c b/arch/riscv/kernel/stacktrace.c index bde85fc53357..ff467b98c3e3 100644 --- a/arch/riscv/kernel/stacktrace.c +++ b/arch/riscv/kernel/stacktrace.c @@ -132,7 +132,7 @@ unsigned long get_wchan(struct task_struct *task) { unsigned long pc = 0; - if (likely(task && task != current && task->state != TASK_RUNNING)) + if (likely(task && task != current && !task_is_running(task))) walk_stackframe(task, NULL, save_wchan, &pc); return pc; } diff --git a/arch/s390/kernel/process.c b/arch/s390/kernel/process.c index e20bed1ed34a..7ae5dde9c54d 100644 --- a/arch/s390/kernel/process.c +++ b/arch/s390/kernel/process.c @@ -180,7 +180,7 @@ unsigned long get_wchan(struct task_struct *p) struct unwind_state state; unsigned long ip = 0; - if (!p || p == current || p->state == TASK_RUNNING || !task_stack_page(p)) + if (!p || p == current || task_is_running(p) || !task_stack_page(p)) return 0; if (!try_get_task_stack(p)) diff --git a/arch/s390/mm/fault.c b/arch/s390/mm/fault.c index 826d01777361..8ae3dc5783fd 100644 --- a/arch/s390/mm/fault.c +++ b/arch/s390/mm/fault.c @@ -702,7 +702,7 @@ static void pfault_interrupt(struct ext_code ext_code, * interrupt since it must be a leftover of a PFAULT * CANCEL operation which didn't remove all pending * completion interrupts. */ - if (tsk->state == TASK_RUNNING) + if (task_is_running(tsk)) tsk->thread.pfault_wait = -1; } } else { diff --git a/arch/sh/kernel/process_32.c b/arch/sh/kernel/process_32.c index 1aa508eb0823..717de05c81f4 100644 --- a/arch/sh/kernel/process_32.c +++ b/arch/sh/kernel/process_32.c @@ -186,7 +186,7 @@ unsigned long get_wchan(struct task_struct *p) { unsigned long pc; - if (!p || p == current || p->state == TASK_RUNNING) + if (!p || p == current || task_is_running(p)) return 0; /* diff --git a/arch/sparc/kernel/process_32.c b/arch/sparc/kernel/process_32.c index 3b9794978e5b..93983d6d431d 100644 --- a/arch/sparc/kernel/process_32.c +++ b/arch/sparc/kernel/process_32.c @@ -376,8 +376,7 @@ unsigned long get_wchan(struct task_struct *task) struct reg_window32 *rw; int count = 0; - if (!task || task == current || - task->state == TASK_RUNNING) + if (!task || task == current || task_is_running(task)) goto out; fp = task_thread_info(task)->ksp + bias; diff --git a/arch/sparc/kernel/process_64.c b/arch/sparc/kernel/process_64.c index 7afd0a859a78..d33c58a58d4f 100644 --- a/arch/sparc/kernel/process_64.c +++ b/arch/sparc/kernel/process_64.c @@ -674,8 +674,7 @@ unsigned long get_wchan(struct task_struct *task) unsigned long ret = 0; int count = 0; - if (!task || task == current || - task->state == TASK_RUNNING) + if (!task || task == current || task_is_running(task)) goto out; tp = task_thread_info(task); diff --git a/arch/um/kernel/process.c b/arch/um/kernel/process.c index c5011064b5dd..457a38db368b 100644 --- a/arch/um/kernel/process.c +++ b/arch/um/kernel/process.c @@ -369,7 +369,7 @@ unsigned long get_wchan(struct task_struct *p) unsigned long stack_page, sp, ip; bool seen_sched = 0; - if ((p == NULL) || (p == current) || (p->state == TASK_RUNNING)) + if ((p == NULL) || (p == current) || task_is_running(p)) return 0; stack_page = (unsigned long) task_stack_page(p); diff --git a/arch/x86/kernel/process.c b/arch/x86/kernel/process.c index 5e1f38179f49..e52b208b4641 100644 --- a/arch/x86/kernel/process.c +++ b/arch/x86/kernel/process.c @@ -931,7 +931,7 @@ unsigned long get_wchan(struct task_struct *p) unsigned long start, bottom, top, sp, fp, ip, ret = 0; int count = 0; - if (p == current || p->state == TASK_RUNNING) + if (p == current || task_is_running(p)) return 0; if (!try_get_task_stack(p)) @@ -975,7 +975,7 @@ unsigned long get_wchan(struct task_struct *p) goto out; } fp = READ_ONCE_NOCHECK(*(unsigned long *)fp); - } while (count++ < 16 && p->state != TASK_RUNNING); + } while (count++ < 16 && !task_is_running(p)); out: put_task_stack(p); diff --git a/arch/xtensa/kernel/process.c b/arch/xtensa/kernel/process.c index 9534ef515d74..060165340612 100644 --- a/arch/xtensa/kernel/process.c +++ b/arch/xtensa/kernel/process.c @@ -304,7 +304,7 @@ unsigned long get_wchan(struct task_struct *p) unsigned long stack_page = (unsigned long) task_stack_page(p); int count = 0; - if (!p || p == current || p->state == TASK_RUNNING) + if (!p || p == current || task_is_running(p)) return 0; sp = p->thread.sp; diff --git a/block/blk-mq.c b/block/blk-mq.c index c86c01bfecdb..655db5fb46d0 100644 --- a/block/blk-mq.c +++ b/block/blk-mq.c @@ -3926,7 +3926,7 @@ int blk_poll(struct request_queue *q, blk_qc_t cookie, bool spin) if (signal_pending_state(state, current)) __set_current_state(TASK_RUNNING); - if (current->state == TASK_RUNNING) + if (task_is_running(current)) return 1; if (ret < 0 || !spin) break; diff --git a/include/linux/sched.h b/include/linux/sched.h index ac5a7d29fd4f..2cd56352dae1 100644 --- a/include/linux/sched.h +++ b/include/linux/sched.h @@ -113,6 +113,8 @@ struct task_group; __TASK_TRACED | EXIT_DEAD | EXIT_ZOMBIE | \ TASK_PARKED) +#define task_is_running(task) (READ_ONCE((task)->state) == TASK_RUNNING) + #define task_is_traced(task) ((task->state & __TASK_TRACED) != 0) #define task_is_stopped(task) ((task->state & __TASK_STOPPED) != 0) diff --git a/kernel/kcsan/report.c b/kernel/kcsan/report.c index 13dce3c664d6..56016e8e7461 100644 --- a/kernel/kcsan/report.c +++ b/kernel/kcsan/report.c @@ -460,7 +460,7 @@ static void set_other_info_task_blocking(unsigned long *flags, * We may be instrumenting a code-path where current->state is already * something other than TASK_RUNNING. */ - const bool is_running = current->state == TASK_RUNNING; + const bool is_running = task_is_running(current); /* * To avoid deadlock in case we are in an interrupt here and this is a * race with a task on the same CPU (KCSAN_INTERRUPT_WATCHER), provide a diff --git a/kernel/locking/lockdep.c b/kernel/locking/lockdep.c index 7641bd407239..4931a93c5162 100644 --- a/kernel/locking/lockdep.c +++ b/kernel/locking/lockdep.c @@ -760,7 +760,7 @@ static void lockdep_print_held_locks(struct task_struct *p) * It's not reliable to print a task's held locks if it's not sleeping * and it's not the current task. */ - if (p->state == TASK_RUNNING && p != current) + if (p != current && task_is_running(p)) return; for (i = 0; i < depth; i++) { printk(" #%d: ", i); diff --git a/kernel/rcu/tree_plugin.h b/kernel/rcu/tree_plugin.h index ad0156b86937..4d6962048c30 100644 --- a/kernel/rcu/tree_plugin.h +++ b/kernel/rcu/tree_plugin.h @@ -2768,7 +2768,7 @@ EXPORT_SYMBOL_GPL(rcu_bind_current_to_nocb); #ifdef CONFIG_SMP static char *show_rcu_should_be_on_cpu(struct task_struct *tsp) { - return tsp && tsp->state == TASK_RUNNING && !tsp->on_cpu ? "!" : ""; + return tsp && task_is_running(tsp) && !tsp->on_cpu ? "!" : ""; } #else // #ifdef CONFIG_SMP static char *show_rcu_should_be_on_cpu(struct task_struct *tsp) diff --git a/kernel/sched/core.c b/kernel/sched/core.c index 75655cdee3bb..618c2b5a5758 100644 --- a/kernel/sched/core.c +++ b/kernel/sched/core.c @@ -5974,7 +5974,7 @@ static inline void sched_submit_work(struct task_struct *tsk) { unsigned int task_flags; - if (!tsk->state) + if (task_is_running(tsk)) return; task_flags = tsk->flags; @@ -7949,7 +7949,7 @@ again: if (curr->sched_class != p->sched_class) goto out_unlock; - if (task_running(p_rq, p) || p->state) + if (task_running(p_rq, p) || !task_is_running(p)) goto out_unlock; yielded = curr->sched_class->yield_to_task(rq, p); @@ -8152,7 +8152,7 @@ void sched_show_task(struct task_struct *p) pr_info("task:%-15.15s state:%c", p->comm, task_state_to_char(p)); - if (p->state == TASK_RUNNING) + if (task_is_running(p)) pr_cont(" running task "); #ifdef CONFIG_DEBUG_STACK_USAGE free = stack_not_used(p); diff --git a/kernel/sched/stats.h b/kernel/sched/stats.h index 111072ee9663..d8f8eb0c655b 100644 --- a/kernel/sched/stats.h +++ b/kernel/sched/stats.h @@ -217,7 +217,7 @@ static inline void sched_info_depart(struct rq *rq, struct task_struct *t) rq_sched_info_depart(rq, delta); - if (t->state == TASK_RUNNING) + if (task_is_running(t)) sched_info_enqueue(rq, t); } diff --git a/kernel/signal.c b/kernel/signal.c index f7c6ffcbd044..5fc8fcf70c24 100644 --- a/kernel/signal.c +++ b/kernel/signal.c @@ -4719,7 +4719,7 @@ void kdb_send_sig(struct task_struct *t, int sig) } new_t = kdb_prev_t != t; kdb_prev_t = t; - if (t->state != TASK_RUNNING && new_t) { + if (!task_is_running(t) && new_t) { spin_unlock(&t->sighand->siglock); kdb_printf("Process is not RUNNING, sending a signal from " "kdb risks deadlock\n" diff --git a/kernel/softirq.c b/kernel/softirq.c index 5ddc3b15a4db..f3a012179f47 100644 --- a/kernel/softirq.c +++ b/kernel/softirq.c @@ -92,8 +92,7 @@ static bool ksoftirqd_running(unsigned long pending) if (pending & SOFTIRQ_NOW_MASK) return false; - return tsk && (tsk->state == TASK_RUNNING) && - !__kthread_should_park(tsk); + return tsk && task_is_running(tsk) && !__kthread_should_park(tsk); } #ifdef CONFIG_TRACE_IRQFLAGS diff --git a/mm/compaction.c b/mm/compaction.c index 84fde270ae74..725f564a5664 100644 --- a/mm/compaction.c +++ b/mm/compaction.c @@ -1955,7 +1955,7 @@ static inline bool is_via_compact_memory(int order) static bool kswapd_is_running(pg_data_t *pgdat) { - return pgdat->kswapd && (pgdat->kswapd->state == TASK_RUNNING); + return pgdat->kswapd && task_is_running(pgdat->kswapd); } /* -- cgit v1.2.3-58-ga151