[Devel] [PATCH rh8 v3 2/2] ve/proc: Added separate start time field to task_struct to show in container
Valeriy Vdovin
valeriy.vdovin at virtuozzo.com
Tue Dec 22 12:42:19 MSK 2020
On Mon, Dec 21, 2020 at 06:09:56PM +0300, Konstantin Khorenko wrote:
> From: Valeriy Vdovin <valeriy.vdovin at virtuozzo.com>
>
> 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>
>
> (cherry picked from vz7 commit eca790eaed527bae7029b4ae1cd557ce847ac6c0)
> Signed-off-by: Konstantin Khorenko <khorenko at virtuozzo.com>
Reviewed-by: Valeriy Vdovin <valeriy.vdovin at virtuozzo.com>
>
> v2: rebased to branch-rh8-4.18.0-240.1.1.vz8.5.x-ovz branch
> v3: added missing ve.h include
> ---
> 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(-)
>
> 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(¶ms, (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;
> }
> }
> --
> 2.28.0
>
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