[Devel] [PATCH RHEL7 COMMIT] ve/proc: Added separate start time field to task_struct to show in container
Konstantin Khorenko
khorenko at virtuozzo.com
Thu Jan 30 22:15:37 MSK 2020
The commit is pushed to "branch-rh7-3.10.0-1062.7.1.vz7.130.x-ovz" and will appear at https://src.openvz.org/scm/ovz/vzkernel.git
after rh7-3.10.0-1062.7.1.vz7.130.13
------>
commit a6d2403bcdf4a6a8c415743f3f802942cb91b3fb
Author: Valeriy Vdovin <valeriy.vdovin at virtuozzo.com>
Date: Thu Jan 30 22:15:34 2020 +0300
ve/proc: Added separate start time field to task_struct to show in container
Introduced 'real_start_time_ct' field in task_struct.
The value is READ:
1. When the process lives inside of a ve group and any process
inside of the same ve group wants to know it's start time by reading
it's /proc/[pid]/stat file.
2. At container suspend operation to store this value to a dump image.
The value is WRITTEN:
1. At creation time (copy_process function)
1.1. If a process is being created outside of ve group / on host, then
this value is initialized to 0
1.2. If a process is being created by process already living in ve
group, this value is calculated as host_uptime - ve_uptime.
2. During attach to ve. (ve_attach function). The process can be created on
a host and later attached to ve. It's container's start_time value has been
already initialized to 0 at creation time. After the process enters the
domain of a ve, the value should be initialized.
Note that the process can be attached to a non-running container, in which
case it's start_time value should not be calculated and left initialized to
0.
3. At container restore via prctl (prctl_set_task_ct_fields function).
In this case the value is only settable outside of a container.
During restore the processes would be created from the dump image.
At restore step each process will execute prctl to set it's start_time
value, read from the dump. This would only be permitted during
pseudosuper ve mode. The value is set as is (read from the dump), without
any calculations.
https://jira.sw.ru/browse/PSBM-64123
Signed-off-by: Valeriy Vdovin <valeriy.vdovin at virtuozzo.com>
---
fs/proc/array.c | 16 ++++------------
include/linux/sched.h | 5 +++++
include/linux/ve.h | 23 +++++++++++++++++++++++
include/uapi/linux/prctl.h | 7 +++++++
kernel/fork.c | 13 +++++++++++++
kernel/sys.c | 23 +++++++++++++++++++++++
kernel/ve/ve.c | 2 ++
7 files changed, 77 insertions(+), 12 deletions(-)
diff --git a/fs/proc/array.c b/fs/proc/array.c
index 3aa8a7dad5e35..fb611b1723f26 100644
--- a/fs/proc/array.c
+++ b/fs/proc/array.c
@@ -611,19 +611,11 @@ static int do_task_stat(struct seq_file *m, struct pid_namespace *ns,
(unsigned long long)task->real_start_time.tv_sec * NSEC_PER_SEC
+ task->real_start_time.tv_nsec;
#ifdef CONFIG_VE
- if (!is_super) {
- struct timespec *ve_start_ts =
- &get_exec_env()->real_start_timespec;
- start_time -=
- (unsigned long long)ve_start_ts->tv_sec * NSEC_PER_SEC
- + ve_start_ts->tv_nsec;
- }
- /* tasks inside a CT can have negative start time e.g. if the CT was
- * migrated from another hw node, in which case we will report 0 in
- * order not to confuse userspace */
- if ((s64)start_time < 0)
- start_time = 0;
+ if (!is_super)
+ start_time = (unsigned long long)
+ timespec_to_ns(&task->real_start_time_ct);
#endif
+
/* convert nsec -> ticks */
start_time = nsec_to_clock_t(start_time);
diff --git a/include/linux/sched.h b/include/linux/sched.h
index f0d976c3800a1..89982455835e5 100644
--- a/include/linux/sched.h
+++ b/include/linux/sched.h
@@ -1928,6 +1928,11 @@ struct task_struct {
struct wake_q_node wake_q;
struct prev_cputime prev_cputime;
struct vtime vtime;
+ /*
+ * this is a container-side copy of 'real_start_time' field
+ * shown from inside of a container and modified by host.
+ */
+ struct timespec real_start_time_ct;
#endif /* __GENKSYMS__ */
};
diff --git a/include/linux/ve.h b/include/linux/ve.h
index 9d60838677133..088e27455fea1 100644
--- a/include/linux/ve.h
+++ b/include/linux/ve.h
@@ -199,6 +199,29 @@ static inline struct ve_struct *cgroup_ve(struct cgroup *cgroup)
struct ve_struct, css);
}
+static inline void ve_try_set_task_start_time(struct ve_struct *ve,
+ struct task_struct *t)
+{
+ struct timespec host_uptime;
+
+ /*
+ * mitigate memory access reordering risks by doing double check,
+ * 'is_running' could be read as 1 before we see
+ * 'real_start_timespec' updated here. If it's still 0,
+ * we know 'is_running' is being modified right NOW in
+ * parallel so it's safe to say that start time is also 0
+ */
+ if (!ve->is_running || !timespec_to_ns(&ve->real_start_timespec)) {
+ t->real_start_time_ct.tv_sec = 0;
+ t->real_start_time_ct.tv_nsec = 0;
+ } else {
+ do_posix_clock_monotonic_gettime(&host_uptime);
+ monotonic_to_bootbased(&host_uptime);
+ t->real_start_time_ct = timespec_sub(host_uptime,
+ ve->real_start_timespec);
+ }
+}
+
extern unsigned long long ve_relative_clock(struct timespec * ts);
extern void monotonic_abs_to_ve(clockid_t which_clock, struct timespec *tp);
extern void monotonic_ve_to_abs(clockid_t which_clock, struct timespec *tp);
diff --git a/include/uapi/linux/prctl.h b/include/uapi/linux/prctl.h
index 02376de8e771d..b1851139b545d 100644
--- a/include/uapi/linux/prctl.h
+++ b/include/uapi/linux/prctl.h
@@ -204,5 +204,12 @@ struct prctl_mm_map {
# define PR_SPEC_DISABLE (1UL << 2)
# define PR_SPEC_FORCE_DISABLE (1UL << 3)
# define PR_SPEC_DISABLE_NOEXEC (1UL << 4)
+/* Set task container related fields */
+#define PR_SET_TASK_CT_FIELDS 1000
+#define PR_TASK_CT_FIELDS_START_TIME (1ULL << 0)
+
+struct prctl_task_ct_fields {
+ __s64 real_start_time;
+};
#endif /* _LINUX_PRCTL_H */
diff --git a/kernel/fork.c b/kernel/fork.c
index 3d74228c9ab29..2314eb886f417 100644
--- a/kernel/fork.c
+++ b/kernel/fork.c
@@ -1350,6 +1350,10 @@ static struct task_struct *copy_process(unsigned long clone_flags,
struct task_struct *p;
void *cgrp_ss_priv[CGROUP_CANFORK_COUNT] = {};
+#ifdef CONFIG_VE
+ struct ve_struct *ve = get_exec_env();
+#endif
+
if ((clone_flags & (CLONE_NEWNS|CLONE_FS)) == (CLONE_NEWNS|CLONE_FS))
return ERR_PTR(-EINVAL);
@@ -1472,6 +1476,15 @@ static struct task_struct *copy_process(unsigned long clone_flags,
do_posix_clock_monotonic_gettime(&p->start_time);
p->real_start_time = p->start_time;
monotonic_to_bootbased(&p->real_start_time);
+
+ p->real_start_time_ct.tv_sec = 0;
+ p->real_start_time_ct.tv_nsec = 0;
+
+#ifdef CONFIG_VE
+ if (!ve_is_super(ve))
+ ve_try_set_task_start_time(ve, p);
+#endif
+
p->io_context = NULL;
p->audit_context = NULL;
if (clone_flags & CLONE_THREAD)
diff --git a/kernel/sys.c b/kernel/sys.c
index c4d633efe44cc..2ce16c7d15cdc 100644
--- a/kernel/sys.c
+++ b/kernel/sys.c
@@ -2457,6 +2457,26 @@ static int prctl_get_tid_address(struct task_struct *me, int __user **tid_addr)
}
#endif
+static int prctl_set_task_ct_fields(struct task_struct *t, unsigned long arg,
+ unsigned long flags)
+{
+ struct prctl_task_ct_fields params;
+#ifdef CONFIG_VE
+ struct ve_struct *ve = t->task_ve;
+
+ if (!ve_is_super(ve) && !ve->is_pseudosuper)
+ return -EPERM;
+#endif
+
+ if (copy_from_user(¶ms, (const void __user *)arg, sizeof(params)))
+ return -EFAULT;
+
+ if (flags & PR_TASK_CT_FIELDS_START_TIME)
+ t->real_start_time_ct = ns_to_timespec(params.real_start_time);
+
+ return 0;
+}
+
int __weak arch_prctl_spec_ctrl_get(struct task_struct *t, unsigned long which)
{
return -EINVAL;
@@ -2684,6 +2704,9 @@ SYSCALL_DEFINE5(prctl, int, option, unsigned long, arg2, unsigned long, arg3,
return -EINVAL;
error = arch_prctl_spec_ctrl_set(me, arg2, arg3);
break;
+ case PR_SET_TASK_CT_FIELDS:
+ error = prctl_set_task_ct_fields(me, arg2, arg3);
+ break;
default:
error = -EINVAL;
break;
diff --git a/kernel/ve/ve.c b/kernel/ve/ve.c
index ad3a698ba9dee..f3970e8ef0f6a 100644
--- a/kernel/ve/ve.c
+++ b/kernel/ve/ve.c
@@ -850,6 +850,8 @@ static void ve_attach(struct cgroup *cg, struct cgroup_taskset *tset)
/* Leave parent exec domain */
task->parent_exec_id--;
+ ve_try_set_task_start_time(ve, task);
+
task->task_ve = ve;
}
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