[Devel] [PATCH RH7 v3 1/1] ve/proc: Added separate start time field to task_struct to show in container
Pavel Tikhomirov
ptikhomirov at virtuozzo.com
Fri Jan 17 18:46:12 MSK 2020
Reviewed-by: Pavel Tikhomirov <ptikhomirov at virtuozzo.com>
On 1/14/20 9:54 PM, Valeriy Vdovin wrote:
> https://jira.sw.ru/browse/PSBM-100083
>
> 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.
>
> 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 3aa8a7d..fb611b1 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 07f9954..0832904 100644
> --- a/include/linux/sched.h
> +++ b/include/linux/sched.h
> @@ -1934,6 +1934,11 @@ 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 9d60838..088e274 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 02376de..b185113 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 3d74228..2314eb8 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 c4d633ef..2ce16c7 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 ad3a698..f3970e8 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;
> }
>
>
--
Best regards, Tikhomirov Pavel
Software Developer, Virtuozzo.
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