[RHEL8,COMMIT] ve/proc: Added separate start time field to task_struct to show in container

Submitted by Konstantin Khorenko on Dec. 22, 2020, 10:55 a.m.

Details

Message ID 202012221055.0BMAtHNX227678@finist-co8.sw.ru
State New
Series "Series without cover letter"
Headers show

Commit Message

Konstantin Khorenko Dec. 22, 2020, 10:55 a.m.
The commit is pushed to "branch-rh8-4.18.0-240.1.1.vz8.5.x-ovz" and will appear at https://src.openvz.org/scm/ovz/vzkernel.git
after rh8-4.18.0-240.1.1.vz8.5.3
------>
commit bd69a02332b3f8f9e286370399b1e5e1babd9dd1
Author: Valeriy Vdovin <valeriy.vdovin@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@virtuozzo.com>
    
    (cherry picked from vz7 commit eca790eaed527bae7029b4ae1cd557ce847ac6c0)
    Signed-off-by: Konstantin Khorenko <khorenko@virtuozzo.com>
    Reviewed-by: Valeriy Vdovin <valeriy.vdovin@virtuozzo.com>
---
 fs/proc/array.c            | 12 +++---------
 include/linux/sched.h      |  7 ++++++-
 include/linux/ve.h         | 16 ++++++++++++++++
 include/uapi/linux/prctl.h |  6 ++++++
 kernel/fork.c              | 12 ++++++++++++
 kernel/sys.c               | 23 +++++++++++++++++++++++
 kernel/ve/ve.c             |  2 ++
 7 files changed, 68 insertions(+), 10 deletions(-)

Patch hide | download patch | download mbox

diff --git a/fs/proc/array.c b/fs/proc/array.c
index ba712f18e5ff..735876a51a18 100644
--- a/fs/proc/array.c
+++ b/fs/proc/array.c
@@ -555,16 +555,10 @@  static int do_task_stat(struct seq_file *m, struct pid_namespace *ns,
 	start_time = task->real_start_time;
 
 #ifdef CONFIG_VE
-	if (!is_super) {
-		u64 offset = get_exec_env()->real_start_time;
-		start_time -= (unsigned long long)offset;
-	}
-	/* 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 = 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 19ca9cc0f3b9..9846553f7039 100644
--- a/include/linux/sched.h
+++ b/include/linux/sched.h
@@ -839,7 +839,6 @@  struct task_struct {
 #ifdef CONFIG_VIRT_CPU_ACCOUNTING_GEN
 	struct vtime			vtime;
 #endif
-
 #ifdef CONFIG_NO_HZ_FULL
 	atomic_t			tick_dep_mask;
 #endif
@@ -853,6 +852,12 @@  struct task_struct {
 	/* Boot based time in nsecs: */
 	u64				real_start_time;
 
+	/*
+	 * This is a Container-side copy of 'real_start_time' field
+	 * shown from inside of a Container and modified by host.
+	 */
+	u64				real_start_time_ct;
+
 	/* MM fault and swap info: this can arguably be seen as either mm-specific or thread-specific: */
 	unsigned long			min_flt;
 	unsigned long			maj_flt;
diff --git a/include/linux/ve.h b/include/linux/ve.h
index 3aa0ea0b1bab..ab8da4dceec1 100644
--- a/include/linux/ve.h
+++ b/include/linux/ve.h
@@ -148,6 +148,22 @@  static u64 ve_get_uptime(struct ve_struct *ve)
 	return ktime_get_boot_ns() - ve->real_start_time;
 }
 
+static inline void ve_set_task_start_time(struct ve_struct *ve,
+					  struct task_struct *t)
+{
+	/*
+	 * Mitigate memory access reordering risks by doing double check,
+	 * 'is_running' could be read as 1 before we see
+	 * 'real_start_time' 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 || !ve->real_start_time)
+		t->real_start_time_ct = 0;
+	else
+		t->real_start_time_ct = ve_get_uptime(ve);
+}
+
 extern void monotonic_abs_to_ve(clockid_t which_clock, struct timespec64 *tp);
 extern void monotonic_ve_to_abs(clockid_t which_clock, struct timespec64 *tp);
 
diff --git a/include/uapi/linux/prctl.h b/include/uapi/linux/prctl.h
index 947191def935..0d7697ead271 100644
--- a/include/uapi/linux/prctl.h
+++ b/include/uapi/linux/prctl.h
@@ -232,5 +232,11 @@  struct prctl_mm_map {
 /* Control reclaim behavior when allocating memory */
 #define PR_SET_IO_FLUSHER		57
 #define PR_GET_IO_FLUSHER		58
+/* Set task container related fields */
+#define PR_SET_TASK_CT_FIELDS		1000
+#define PR_TASK_CT_FIELDS_START_TIME	(1UL << 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 da7bda595d44..c996de548127 100644
--- a/kernel/fork.c
+++ b/kernel/fork.c
@@ -91,6 +91,7 @@ 
 #include <linux/kcov.h>
 #include <linux/livepatch.h>
 #include <linux/thread_info.h>
+#include <linux/ve.h>
 
 #include <asm/pgtable.h>
 #include <asm/pgalloc.h>
@@ -1711,6 +1712,9 @@  static __latent_entropy struct task_struct *copy_process(
 	int retval;
 	struct task_struct *p;
 	struct multiprocess_signals delayed;
+#ifdef CONFIG_VE
+	struct ve_struct *ve = get_exec_env();
+#endif
 
 	/*
 	 * Don't allow sharing the root directory with processes in a different
@@ -1863,6 +1867,14 @@  static __latent_entropy struct task_struct *copy_process(
 
 	p->start_time = ktime_get_ns();
 	p->real_start_time = ktime_get_boot_ns();
+
+	p->real_start_time_ct = 0;
+
+#ifdef CONFIG_VE
+	if (!ve_is_super(ve))
+		ve_set_task_start_time(ve, p);
+#endif
+
 	p->io_context = NULL;
 	audit_set_context(p, NULL);
 	cgroup_fork(p);
diff --git a/kernel/sys.c b/kernel/sys.c
index b0914885cd68..7ca6e68eafa9 100644
--- a/kernel/sys.c
+++ b/kernel/sys.c
@@ -2261,6 +2261,26 @@  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(&params, (const void __user *)arg, sizeof(params)))
+		return -EFAULT;
+
+	if (flags & PR_TASK_CT_FIELDS_START_TIME)
+		t->real_start_time_ct = (u64)params.real_start_time;
+
+	return 0;
+}
+
 static int propagate_has_child_subreaper(struct task_struct *p, void *data)
 {
 	/*
@@ -2538,6 +2558,9 @@  SYSCALL_DEFINE5(prctl, int, option, unsigned long, arg2, unsigned long, arg3,
 
 		error = (current->flags & PR_IO_FLUSHER) == PR_IO_FLUSHER;
 		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 0c6630c6616a..3f53641455ad 100644
--- a/kernel/ve/ve.c
+++ b/kernel/ve/ve.c
@@ -820,6 +820,8 @@  static void ve_attach(struct cgroup_taskset *tset)
 
 		if (cpuid_override_on())
 			set_tsk_thread_flag(task, TIF_CPUID_OVERRIDE);
+
+		ve_set_task_start_time(ve, task);
 		task->task_ve = ve;
 	}
 }