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Peter Zijlstra says: 

The most anticipated fix in this pull request is probably the horrible build
 fix for the RANDSTRUCT fail that didn't make -rc2. Also included is the cleanup
 that removes those BUILD_BUG_ON()s and replaces it with ugly unions.
 
 Also included is the try_to_wake_up() race fix that was first triggered by
 Paul's RCU-torture runs, but was independently hit by Dave Chinner's fstest
 runs as well.
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Merge tag 'sched_urgent_for_5.8_rc3' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip

Pull scheduler fixes from Borislav Petkov:
 "The most anticipated fix in this pull request is probably the horrible
  build fix for the RANDSTRUCT fail that didn't make -rc2. Also included
  is the cleanup that removes those BUILD_BUG_ON()s and replaces it with
  ugly unions.

  Also included is the try_to_wake_up() race fix that was first
  triggered by Paul's RCU-torture runs, but was independently hit by
  Dave Chinner's fstest runs as well"

* tag 'sched_urgent_for_5.8_rc3' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  sched/cfs: change initial value of runnable_avg
  smp, irq_work: Continue smp_call_function*() and irq_work*() integration
  sched/core: s/WF_ON_RQ/WQ_ON_CPU/
  sched/core: Fix ttwu() race
  sched/core: Fix PI boosting between RT and DEADLINE tasks
  sched/deadline: Initialize ->dl_boosted
  sched/core: Check cpus_mask, not cpus_ptr in __set_cpus_allowed_ptr(), to fix mask corruption
  sched/core: Fix CONFIG_GCC_PLUGIN_RANDSTRUCT build fail
This commit is contained in:
Linus Torvalds 2020-06-28 10:37:39 -07:00
parent 098c793821 e21cf43406
commit 91a9a90d04
9 changed files with 120 additions and 65 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

26
include/linux/irq_work.h
View File

@ -2,7 +2,7 @@
#ifndef _LINUX_IRQ_WORK_H
#define _LINUX_IRQ_WORK_H
#include <linux/llist.h>
#include <linux/smp_types.h>
/*
* An entry can be in one of four states:
@ -13,24 +13,14 @@
* busy NULL, 2 -> {free, claimed} : callback in progress, can be claimed
*/
/* flags share CSD_FLAG_ space */
#define IRQ_WORK_PENDING BIT(0)
#define IRQ_WORK_BUSY BIT(1)
/* Doesn't want IPI, wait for tick: */
#define IRQ_WORK_LAZY BIT(2)
/* Run hard IRQ context, even on RT */
#define IRQ_WORK_HARD_IRQ BIT(3)
#define IRQ_WORK_CLAIMED (IRQ_WORK_PENDING | IRQ_WORK_BUSY)
/*
* structure shares layout with single_call_data_t.
*/
struct irq_work {
struct llist_node llnode;
atomic_t flags;
union {
struct __call_single_node node;
struct {
struct llist_node llnode;
atomic_t flags;
};
};
void (*func)(struct irq_work *);
};

3
include/linux/sched.h
View File

@ -654,9 +654,8 @@ struct task_struct {
unsigned int ptrace;
#ifdef CONFIG_SMP
struct llist_node wake_entry;
unsigned int wake_entry_type;
int on_cpu;
struct __call_single_node wake_entry;
#ifdef CONFIG_THREAD_INFO_IN_TASK
/* Current CPU: */
unsigned int cpu;

23
include/linux/smp.h
View File

@ -12,29 +12,22 @@
#include <linux/list.h>
#include <linux/cpumask.h>
#include <linux/init.h>
#include <linux/llist.h>
#include <linux/smp_types.h>
typedef void (*smp_call_func_t)(void *info);
typedef bool (*smp_cond_func_t)(int cpu, void *info);
enum {
CSD_FLAG_LOCK = 0x01,
/* IRQ_WORK_flags */
CSD_TYPE_ASYNC = 0x00,
CSD_TYPE_SYNC = 0x10,
CSD_TYPE_IRQ_WORK = 0x20,
CSD_TYPE_TTWU = 0x30,
CSD_FLAG_TYPE_MASK = 0xF0,
};
/*
* structure shares (partial) layout with struct irq_work
*/
struct __call_single_data {
struct llist_node llist;
unsigned int flags;
union {
struct __call_single_node node;
struct {
struct llist_node llist;
unsigned int flags;
};
};
smp_call_func_t func;
void *info;
};

66
include/linux/smp_types.h Normal file
View File

@ -0,0 +1,66 @@
/* SPDX-License-Identifier: GPL-2.0 */
#ifndef __LINUX_SMP_TYPES_H
#define __LINUX_SMP_TYPES_H
#include <linux/llist.h>
enum {
CSD_FLAG_LOCK = 0x01,
IRQ_WORK_PENDING = 0x01,
IRQ_WORK_BUSY = 0x02,
IRQ_WORK_LAZY = 0x04, /* No IPI, wait for tick */
IRQ_WORK_HARD_IRQ = 0x08, /* IRQ context on PREEMPT_RT */
IRQ_WORK_CLAIMED = (IRQ_WORK_PENDING | IRQ_WORK_BUSY),
CSD_TYPE_ASYNC = 0x00,
CSD_TYPE_SYNC = 0x10,
CSD_TYPE_IRQ_WORK = 0x20,
CSD_TYPE_TTWU = 0x30,
CSD_FLAG_TYPE_MASK = 0xF0,
};
/*
* struct __call_single_node is the primary type on
* smp.c:call_single_queue.
*
* flush_smp_call_function_queue() only reads the type from
* __call_single_node::u_flags as a regular load, the above
* (anonymous) enum defines all the bits of this word.
*
* Other bits are not modified until the type is known.
*
* CSD_TYPE_SYNC/ASYNC:
* struct {
* struct llist_node node;
* unsigned int flags;
* smp_call_func_t func;
* void *info;
* };
*
* CSD_TYPE_IRQ_WORK:
* struct {
* struct llist_node node;
* atomic_t flags;
* void (*func)(struct irq_work *);
* };
*
* CSD_TYPE_TTWU:
* struct {
* struct llist_node node;
* unsigned int flags;
* };
*
*/
struct __call_single_node {
struct llist_node llist;
union {
unsigned int u_flags;
atomic_t a_flags;
};
};
#endif /* __LINUX_SMP_TYPES_H */

44
kernel/sched/core.c
View File

@ -1637,7 +1637,7 @@ static int __set_cpus_allowed_ptr(struct task_struct *p,
goto out;
}
if (cpumask_equal(p->cpus_ptr, new_mask))
if (cpumask_equal(&p->cpus_mask, new_mask))
goto out;
/*
@ -2293,8 +2293,15 @@ void sched_ttwu_pending(void *arg)
rq_lock_irqsave(rq, &rf);
update_rq_clock(rq);
llist_for_each_entry_safe(p, t, llist, wake_entry)
llist_for_each_entry_safe(p, t, llist, wake_entry.llist) {
if (WARN_ON_ONCE(p->on_cpu))
smp_cond_load_acquire(&p->on_cpu, !VAL);
if (WARN_ON_ONCE(task_cpu(p) != cpu_of(rq)))
set_task_cpu(p, cpu_of(rq));
ttwu_do_activate(rq, p, p->sched_remote_wakeup ? WF_MIGRATED : 0, &rf);
}
rq_unlock_irqrestore(rq, &rf);
}
@ -2322,7 +2329,7 @@ static void __ttwu_queue_wakelist(struct task_struct *p, int cpu, int wake_flags
p->sched_remote_wakeup = !!(wake_flags & WF_MIGRATED);
WRITE_ONCE(rq->ttwu_pending, 1);
__smp_call_single_queue(cpu, &p->wake_entry);
__smp_call_single_queue(cpu, &p->wake_entry.llist);
}
void wake_up_if_idle(int cpu)
@ -2369,7 +2376,7 @@ static inline bool ttwu_queue_cond(int cpu, int wake_flags)
* the soon-to-be-idle CPU as the current CPU is likely busy.
* nr_running is checked to avoid unnecessary task stacking.
*/
if ((wake_flags & WF_ON_RQ) && cpu_rq(cpu)->nr_running <= 1)
if ((wake_flags & WF_ON_CPU) && cpu_rq(cpu)->nr_running <= 1)
return true;
return false;
@ -2378,6 +2385,9 @@ static inline bool ttwu_queue_cond(int cpu, int wake_flags)
static bool ttwu_queue_wakelist(struct task_struct *p, int cpu, int wake_flags)
{
if (sched_feat(TTWU_QUEUE) && ttwu_queue_cond(cpu, wake_flags)) {
if (WARN_ON_ONCE(cpu == smp_processor_id()))
return false;
sched_clock_cpu(cpu); /* Sync clocks across CPUs */
__ttwu_queue_wakelist(p, cpu, wake_flags);
return true;
@ -2528,7 +2538,6 @@ try_to_wake_up(struct task_struct *p, unsigned int state, int wake_flags)
goto out;
success = 1;
cpu = task_cpu(p);
trace_sched_waking(p);
p->state = TASK_RUNNING;
trace_sched_wakeup(p);
@ -2550,7 +2559,6 @@ try_to_wake_up(struct task_struct *p, unsigned int state, int wake_flags)
/* We're going to change ->state: */
success = 1;
cpu = task_cpu(p);
/*
* Ensure we load p->on_rq _after_ p->state, otherwise it would
@ -2614,8 +2622,21 @@ try_to_wake_up(struct task_struct *p, unsigned int state, int wake_flags)
* which potentially sends an IPI instead of spinning on p->on_cpu to
* let the waker make forward progress. This is safe because IRQs are
* disabled and the IPI will deliver after on_cpu is cleared.
*
* Ensure we load task_cpu(p) after p->on_cpu:
*
* set_task_cpu(p, cpu);
* STORE p->cpu = @cpu
* __schedule() (switch to task 'p')
* LOCK rq->lock
* smp_mb__after_spin_lock() smp_cond_load_acquire(&p->on_cpu)
* STORE p->on_cpu = 1 LOAD p->cpu
*
* to ensure we observe the correct CPU on which the task is currently
* scheduling.
*/
if (READ_ONCE(p->on_cpu) && ttwu_queue_wakelist(p, cpu, wake_flags | WF_ON_RQ))
if (smp_load_acquire(&p->on_cpu) &&
ttwu_queue_wakelist(p, task_cpu(p), wake_flags | WF_ON_CPU))
goto unlock;
/*
@ -2635,6 +2656,8 @@ try_to_wake_up(struct task_struct *p, unsigned int state, int wake_flags)
psi_ttwu_dequeue(p);
set_task_cpu(p, cpu);
}
#else
cpu = task_cpu(p);
#endif /* CONFIG_SMP */
ttwu_queue(p, cpu, wake_flags);
@ -2642,7 +2665,7 @@ unlock:
raw_spin_unlock_irqrestore(&p->pi_lock, flags);
out:
if (success)
ttwu_stat(p, cpu, wake_flags);
ttwu_stat(p, task_cpu(p), wake_flags);
preempt_enable();
return success;
@ -2763,7 +2786,7 @@ static void __sched_fork(unsigned long clone_flags, struct task_struct *p)
#endif
init_numa_balancing(clone_flags, p);
#ifdef CONFIG_SMP
p->wake_entry_type = CSD_TYPE_TTWU;
p->wake_entry.u_flags = CSD_TYPE_TTWU;
#endif
}
@ -4533,7 +4556,8 @@ void rt_mutex_setprio(struct task_struct *p, struct task_struct *pi_task)
*/
if (dl_prio(prio)) {
if (!dl_prio(p->normal_prio) ||
(pi_task && dl_entity_preempt(&pi_task->dl, &p->dl))) {
(pi_task && dl_prio(pi_task->prio) &&
dl_entity_preempt(&pi_task->dl, &p->dl))) {
p->dl.dl_boosted = 1;
queue_flag |= ENQUEUE_REPLENISH;
} else

1
kernel/sched/deadline.c
View File

@ -2692,6 +2692,7 @@ void __dl_clear_params(struct task_struct *p)
dl_se->dl_bw = 0;
dl_se->dl_density = 0;
dl_se->dl_boosted = 0;
dl_se->dl_throttled = 0;
dl_se->dl_yielded = 0;
dl_se->dl_non_contending = 0;

2
kernel/sched/fair.c
View File

@ -806,7 +806,7 @@ void post_init_entity_util_avg(struct task_struct *p)
}
}
sa->runnable_avg = cpu_scale;
sa->runnable_avg = sa->util_avg;
if (p->sched_class != &fair_sched_class) {
/*

2
kernel/sched/sched.h
View File

@ -1682,7 +1682,7 @@ static inline int task_on_rq_migrating(struct task_struct *p)
#define WF_SYNC 0x01 /* Waker goes to sleep after wakeup */
#define WF_FORK 0x02 /* Child wakeup after fork */
#define WF_MIGRATED 0x04 /* Internal use, task got migrated */
#define WF_ON_RQ 0x08 /* Wakee is on_rq */
#define WF_ON_CPU 0x08 /* Wakee is on_cpu */
/*
* To aid in avoiding the subversion of "niceness" due to uneven distribution

18
kernel/smp.c
View File

@ -669,24 +669,6 @@ void __init smp_init(void)
{
int num_nodes, num_cpus;
/*
* Ensure struct irq_work layout matches so that
* flush_smp_call_function_queue() can do horrible things.
*/
BUILD_BUG_ON(offsetof(struct irq_work, llnode) !=
offsetof(struct __call_single_data, llist));
BUILD_BUG_ON(offsetof(struct irq_work, func) !=
offsetof(struct __call_single_data, func));
BUILD_BUG_ON(offsetof(struct irq_work, flags) !=
offsetof(struct __call_single_data, flags));
/*
* Assert the CSD_TYPE_TTWU layout is similar enough
* for task_struct to be on the @call_single_queue.
*/
BUILD_BUG_ON(offsetof(struct task_struct, wake_entry_type) - offsetof(struct task_struct, wake_entry) !=
offsetof(struct __call_single_data, flags) - offsetof(struct __call_single_data, llist));
idle_threads_init();
cpuhp_threads_init();