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linux_dsm_epyc7002/include/linux/init_task.h
Xunlei Pang e96a7705e7 sched/rtmutex/deadline: Fix a PI crash for deadline tasks 
A crash happened while I was playing with deadline PI rtmutex.

    BUG: unable to handle kernel NULL pointer dereference at 0000000000000018
    IP: [<ffffffff810eeb8f>] rt_mutex_get_top_task+0x1f/0x30
    PGD 232a75067 PUD 230947067 PMD 0
    Oops: 0000 [#1] SMP
    CPU: 1 PID: 10994 Comm: a.out Not tainted

    Call Trace:
    [<ffffffff810b658c>] enqueue_task+0x2c/0x80
    [<ffffffff810ba763>] activate_task+0x23/0x30
    [<ffffffff810d0ab5>] pull_dl_task+0x1d5/0x260
    [<ffffffff810d0be6>] pre_schedule_dl+0x16/0x20
    [<ffffffff8164e783>] __schedule+0xd3/0x900
    [<ffffffff8164efd9>] schedule+0x29/0x70
    [<ffffffff8165035b>] __rt_mutex_slowlock+0x4b/0xc0
    [<ffffffff81650501>] rt_mutex_slowlock+0xd1/0x190
    [<ffffffff810eeb33>] rt_mutex_timed_lock+0x53/0x60
    [<ffffffff810ecbfc>] futex_lock_pi.isra.18+0x28c/0x390
    [<ffffffff810ed8b0>] do_futex+0x190/0x5b0
    [<ffffffff810edd50>] SyS_futex+0x80/0x180

This is because rt_mutex_enqueue_pi() and rt_mutex_dequeue_pi()
are only protected by pi_lock when operating pi waiters, while
rt_mutex_get_top_task(), will access them with rq lock held but
not holding pi_lock.

In order to tackle it, we introduce new "pi_top_task" pointer
cached in task_struct, and add new rt_mutex_update_top_task()
to update its value, it can be called by rt_mutex_setprio()
which held both owner's pi_lock and rq lock. Thus "pi_top_task"
can be safely accessed by enqueue_task_dl() under rq lock.

Originally-From: Peter Zijlstra <peterz@infradead.org>
Signed-off-by: Xunlei Pang <xlpang@redhat.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Acked-by: Steven Rostedt <rostedt@goodmis.org>
Reviewed-by: Thomas Gleixner <tglx@linutronix.de>
Cc: juri.lelli@arm.com
Cc: bigeasy@linutronix.de
Cc: mathieu.desnoyers@efficios.com
Cc: jdesfossez@efficios.com
Cc: bristot@redhat.com
Link: http://lkml.kernel.org/r/20170323150216.157682758@infradead.org
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
2017-04-04 11:44:05 +02:00

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#ifndef _LINUX__INIT_TASK_H
#define _LINUX__INIT_TASK_H
#include <linux/rcupdate.h>
#include <linux/irqflags.h>
#include <linux/utsname.h>
#include <linux/lockdep.h>
#include <linux/ftrace.h>
#include <linux/ipc.h>
#include <linux/pid_namespace.h>
#include <linux/user_namespace.h>
#include <linux/securebits.h>
#include <linux/seqlock.h>
#include <linux/rbtree.h>
#include <linux/sched/autogroup.h>
#include <net/net_namespace.h>
#include <linux/sched/rt.h>
#include <linux/mm_types.h>
#include <asm/thread_info.h>
#ifdef CONFIG_SMP
# define INIT_PUSHABLE_TASKS(tsk) \
.pushable_tasks = PLIST_NODE_INIT(tsk.pushable_tasks, MAX_PRIO),
#else
# define INIT_PUSHABLE_TASKS(tsk)
#endif
extern struct files_struct init_files;
extern struct fs_struct init_fs;
#ifdef CONFIG_CPUSETS
#define INIT_CPUSET_SEQ(tsk) \
.mems_allowed_seq = SEQCNT_ZERO(tsk.mems_allowed_seq),
#else
#define INIT_CPUSET_SEQ(tsk)
#endif
#ifndef CONFIG_VIRT_CPU_ACCOUNTING_NATIVE
#define INIT_PREV_CPUTIME(x) .prev_cputime = { \
.lock = __RAW_SPIN_LOCK_UNLOCKED(x.prev_cputime.lock), \
},
#else
#define INIT_PREV_CPUTIME(x)
#endif
#ifdef CONFIG_POSIX_TIMERS
#define INIT_POSIX_TIMERS(s) \
.posix_timers = LIST_HEAD_INIT(s.posix_timers),
#define INIT_CPU_TIMERS(s) \
.cpu_timers = { \
LIST_HEAD_INIT(s.cpu_timers[0]), \
LIST_HEAD_INIT(s.cpu_timers[1]), \
LIST_HEAD_INIT(s.cpu_timers[2]), \
},
#define INIT_CPUTIMER(s) \
.cputimer = { \
.cputime_atomic = INIT_CPUTIME_ATOMIC, \
.running = false, \
.checking_timer = false, \
},
#else
#define INIT_POSIX_TIMERS(s)
#define INIT_CPU_TIMERS(s)
#define INIT_CPUTIMER(s)
#endif
#define INIT_SIGNALS(sig) { \
.nr_threads = 1, \
.thread_head = LIST_HEAD_INIT(init_task.thread_node), \
.wait_chldexit = __WAIT_QUEUE_HEAD_INITIALIZER(sig.wait_chldexit),\
.shared_pending = { \
.list = LIST_HEAD_INIT(sig.shared_pending.list), \
.signal = {{0}}}, \
INIT_POSIX_TIMERS(sig) \
INIT_CPU_TIMERS(sig) \
.rlim = INIT_RLIMITS, \
INIT_CPUTIMER(sig) \
INIT_PREV_CPUTIME(sig) \
.cred_guard_mutex = \
__MUTEX_INITIALIZER(sig.cred_guard_mutex), \
}
extern struct nsproxy init_nsproxy;
#define INIT_SIGHAND(sighand) { \
.count = ATOMIC_INIT(1), \
.action = { { { .sa_handler = SIG_DFL, } }, }, \
.siglock = __SPIN_LOCK_UNLOCKED(sighand.siglock), \
.signalfd_wqh = __WAIT_QUEUE_HEAD_INITIALIZER(sighand.signalfd_wqh), \
}
extern struct group_info init_groups;
#define INIT_STRUCT_PID { \
.count = ATOMIC_INIT(1), \
.tasks = { \
{ .first = NULL }, \
{ .first = NULL }, \
{ .first = NULL }, \
}, \
.level = 0, \
.numbers = { { \
.nr = 0, \
.ns = &init_pid_ns, \
.pid_chain = { .next = NULL, .pprev = NULL }, \
}, } \
}
#define INIT_PID_LINK(type) \
{ \
.node = { \
.next = NULL, \
.pprev = NULL, \
}, \
.pid = &init_struct_pid, \
}
#ifdef CONFIG_AUDITSYSCALL
#define INIT_IDS \
.loginuid = INVALID_UID, \
.sessionid = (unsigned int)-1,
#else
#define INIT_IDS
#endif
#ifdef CONFIG_PREEMPT_RCU
#define INIT_TASK_RCU_TREE_PREEMPT() \
.rcu_blocked_node = NULL,
#else
#define INIT_TASK_RCU_TREE_PREEMPT(tsk)
#endif
#ifdef CONFIG_PREEMPT_RCU
#define INIT_TASK_RCU_PREEMPT(tsk) \
.rcu_read_lock_nesting = 0, \
.rcu_read_unlock_special.s = 0, \
.rcu_node_entry = LIST_HEAD_INIT(tsk.rcu_node_entry), \
INIT_TASK_RCU_TREE_PREEMPT()
#else
#define INIT_TASK_RCU_PREEMPT(tsk)
#endif
#ifdef CONFIG_TASKS_RCU
#define INIT_TASK_RCU_TASKS(tsk) \
.rcu_tasks_holdout = false, \
.rcu_tasks_holdout_list = \
LIST_HEAD_INIT(tsk.rcu_tasks_holdout_list), \
.rcu_tasks_idle_cpu = -1,
#else
#define INIT_TASK_RCU_TASKS(tsk)
#endif
extern struct cred init_cred;
#ifdef CONFIG_CGROUP_SCHED
# define INIT_CGROUP_SCHED(tsk) \
.sched_task_group = &root_task_group,
#else
# define INIT_CGROUP_SCHED(tsk)
#endif
#ifdef CONFIG_PERF_EVENTS
# define INIT_PERF_EVENTS(tsk) \
.perf_event_mutex = \
__MUTEX_INITIALIZER(tsk.perf_event_mutex), \
.perf_event_list = LIST_HEAD_INIT(tsk.perf_event_list),
#else
# define INIT_PERF_EVENTS(tsk)
#endif
#ifdef CONFIG_VIRT_CPU_ACCOUNTING_GEN
# define INIT_VTIME(tsk) \
.vtime_seqcount = SEQCNT_ZERO(tsk.vtime_seqcount), \
.vtime_snap = 0, \
.vtime_snap_whence = VTIME_SYS,
#else
# define INIT_VTIME(tsk)
#endif
#define INIT_TASK_COMM "swapper"
#ifdef CONFIG_RT_MUTEXES
# define INIT_RT_MUTEXES(tsk) \
.pi_waiters = RB_ROOT, \
.pi_top_task = NULL, \
.pi_waiters_leftmost = NULL,
#else
# define INIT_RT_MUTEXES(tsk)
#endif
#ifdef CONFIG_NUMA_BALANCING
# define INIT_NUMA_BALANCING(tsk) \
.numa_preferred_nid = -1, \
.numa_group = NULL, \
.numa_faults = NULL,
#else
# define INIT_NUMA_BALANCING(tsk)
#endif
#ifdef CONFIG_KASAN
# define INIT_KASAN(tsk) \
.kasan_depth = 1,
#else
# define INIT_KASAN(tsk)
#endif
#ifdef CONFIG_THREAD_INFO_IN_TASK
# define INIT_TASK_TI(tsk) \
.thread_info = INIT_THREAD_INFO(tsk), \
.stack_refcount = ATOMIC_INIT(1),
#else
# define INIT_TASK_TI(tsk)
#endif
/*
* INIT_TASK is used to set up the first task table, touch at
* your own risk!. Base=0, limit=0x1fffff (=2MB)
*/
#define INIT_TASK(tsk) \
{ \
INIT_TASK_TI(tsk) \
.state = 0, \
.stack = init_stack, \
.usage = ATOMIC_INIT(2), \
.flags = PF_KTHREAD, \
.prio = MAX_PRIO-20, \
.static_prio = MAX_PRIO-20, \
.normal_prio = MAX_PRIO-20, \
.policy = SCHED_NORMAL, \
.cpus_allowed = CPU_MASK_ALL, \
.nr_cpus_allowed= NR_CPUS, \
.mm = NULL, \
.active_mm = &init_mm, \
.restart_block = { \
.fn = do_no_restart_syscall, \
}, \
.se = { \
.group_node = LIST_HEAD_INIT(tsk.se.group_node), \
}, \
.rt = { \
.run_list = LIST_HEAD_INIT(tsk.rt.run_list), \
.time_slice = RR_TIMESLICE, \
}, \
.tasks = LIST_HEAD_INIT(tsk.tasks), \
INIT_PUSHABLE_TASKS(tsk) \
INIT_CGROUP_SCHED(tsk) \
.ptraced = LIST_HEAD_INIT(tsk.ptraced), \
.ptrace_entry = LIST_HEAD_INIT(tsk.ptrace_entry), \
.real_parent = &tsk, \
.parent = &tsk, \
.children = LIST_HEAD_INIT(tsk.children), \
.sibling = LIST_HEAD_INIT(tsk.sibling), \
.group_leader = &tsk, \
RCU_POINTER_INITIALIZER(real_cred, &init_cred), \
RCU_POINTER_INITIALIZER(cred, &init_cred), \
.comm = INIT_TASK_COMM, \
.thread = INIT_THREAD, \
.fs = &init_fs, \
.files = &init_files, \
.signal = &init_signals, \
.sighand = &init_sighand, \
.nsproxy = &init_nsproxy, \
.pending = { \
.list = LIST_HEAD_INIT(tsk.pending.list), \
.signal = {{0}}}, \
.blocked = {{0}}, \
.alloc_lock = __SPIN_LOCK_UNLOCKED(tsk.alloc_lock), \
.journal_info = NULL, \
INIT_CPU_TIMERS(tsk) \
.pi_lock = __RAW_SPIN_LOCK_UNLOCKED(tsk.pi_lock), \
.timer_slack_ns = 50000, /* 50 usec default slack */ \
.pids = { \
[PIDTYPE_PID] = INIT_PID_LINK(PIDTYPE_PID), \
[PIDTYPE_PGID] = INIT_PID_LINK(PIDTYPE_PGID), \
[PIDTYPE_SID] = INIT_PID_LINK(PIDTYPE_SID), \
}, \
.thread_group = LIST_HEAD_INIT(tsk.thread_group), \
.thread_node = LIST_HEAD_INIT(init_signals.thread_head), \
INIT_IDS \
INIT_PERF_EVENTS(tsk) \
INIT_TRACE_IRQFLAGS \
INIT_LOCKDEP \
INIT_FTRACE_GRAPH \
INIT_TRACE_RECURSION \
INIT_TASK_RCU_PREEMPT(tsk) \
INIT_TASK_RCU_TASKS(tsk) \
INIT_CPUSET_SEQ(tsk) \
INIT_RT_MUTEXES(tsk) \
INIT_PREV_CPUTIME(tsk) \
INIT_VTIME(tsk) \
INIT_NUMA_BALANCING(tsk) \
INIT_KASAN(tsk) \
}
/* Attach to the init_task data structure for proper alignment */
#define __init_task_data __attribute__((__section__(".data..init_task")))
#endif
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