From mboxrd@z Thu Jan 1 00:00:00 1970 From: Michal Hocko Subject: Re: [PATCH] Adding support of RLIMIT_CPUNS Date: Fri, 18 Aug 2017 13:46:17 +0200 Message-ID: <20170818114617.GC18513@dhcp22.suse.cz> References: <1502999145.913410989@f459.i.mail.ru> Mime-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 8bit Return-path: Content-Disposition: inline In-Reply-To: <1502999145.913410989@f459.i.mail.ru> Sender: linux-kernel-owner@vger.kernel.org To: =?utf-8?B?0JPRgNC40LPQvtGA0LjQuSDQoNC10LfQvdC40LrQvtCy?= Cc: akpm@linux-foundation.org, linux-kernel@vger.kernel.org, linux-api@vger.kernel.org List-Id: linux-api@vger.kernel.org Appart from Andrew said about the usecase make sure to CC linux-api for any user visible interface change. On Thu 17-08-17 22:45:45, Григорий Резников wrote: > To set time limit for process now we can use RLIMIT_CPU. > However, it has precision up to one second and it can be > too big for some purposes. > > This patch adds support of RLIMIT_CPUNS, which works > almost as RLIMIT_CPU, but has nanosecond precision. > > At the moment, RLIMIT_CPU and RLIMIT_CPUNS are two > independent values, because I don't see any nice way > for them to be together. > > Signed-off-by: Grigory Reznikov > --- > fs/proc/base.c | 1 + > include/asm-generic/resource.h | 1 + > include/linux/posix-timers.h | 1 + > include/uapi/asm-generic/resource.h | 4 +++- > kernel/fork.c | 20 +++++++++++++---- > kernel/sys.c | 11 ++++++++- > kernel/time/posix-cpu-timers.c | 45 +++++++++++++++++++++++++++++++++---- > 7 files changed, 73 insertions(+), 10 deletions(-) > > diff --git a/fs/proc/base.c b/fs/proc/base.c > index 719c2e9..1e3049e 100644 > --- a/fs/proc/base.c > +++ b/fs/proc/base.c > @@ -567,6 +567,7 @@ static const struct limit_names lnames[RLIM_NLIMITS] = { > [RLIMIT_NICE] = {"Max nice priority", NULL}, > [RLIMIT_RTPRIO] = {"Max realtime priority", NULL}, > [RLIMIT_RTTIME] = {"Max realtime timeout", "us"}, > + [RLIMIT_CPUNS] = {"Max cpu time", "ns"}, > }; > > /* Display limits for a process */ > diff --git a/include/asm-generic/resource.h b/include/asm-generic/resource.h > index 5e752b9..ec7b0c5 100644 > --- a/include/asm-generic/resource.h > +++ b/include/asm-generic/resource.h > @@ -25,6 +25,7 @@ > [RLIMIT_NICE] = { 0, 0 }, \ > [RLIMIT_RTPRIO] = { 0, 0 }, \ > [RLIMIT_RTTIME] = { RLIM_INFINITY, RLIM_INFINITY }, \ > + [RLIMIT_CPUNS] = { RLIM_INFINITY, RLIM_INFINITY }, \ > } > > #endif > diff --git a/include/linux/posix-timers.h b/include/linux/posix-timers.h > index 62839fd..0e22bde 100644 > --- a/include/linux/posix-timers.h > +++ b/include/linux/posix-timers.h > @@ -110,6 +110,7 @@ void posix_cpu_timers_exit_group(struct task_struct *task); > void set_process_cpu_timer(struct task_struct *task, unsigned int clock_idx, > u64 *newval, u64 *oldval); > > +void update_rlimit_cpu_ns(struct task_struct *task, unsigned long rlim_new); > void update_rlimit_cpu(struct task_struct *task, unsigned long rlim_new); > > void posixtimer_rearm(struct siginfo *info); > diff --git a/include/uapi/asm-generic/resource.h b/include/uapi/asm-generic/resource.h > index c6d10af..a86b2f4 100644 > --- a/include/uapi/asm-generic/resource.h > +++ b/include/uapi/asm-generic/resource.h > @@ -45,7 +45,9 @@ > 0-39 for nice level 19 .. -20 */ > #define RLIMIT_RTPRIO 14 /* maximum realtime priority */ > #define RLIMIT_RTTIME 15 /* timeout for RT tasks in us */ > -#define RLIM_NLIMITS 16 > +#define RLIMIT_CPUNS 16 /* CPU time in ns, > + doesn't depend on RLIMIT_CPU */ > +#define RLIM_NLIMITS 17 > > /* > * SuS says limits have to be unsigned. > diff --git a/kernel/fork.c b/kernel/fork.c > index e075b77..33f9bbf 100644 > --- a/kernel/fork.c > +++ b/kernel/fork.c > @@ -1348,11 +1348,23 @@ void __cleanup_sighand(struct sighand_struct *sighand) > */ > static void posix_cpu_timers_init_group(struct signal_struct *sig) > { > - unsigned long cpu_limit; > - > + unsigned long cpu_limit, cpuns_limit, total_limit; > + /* RLIMIT_CPU timeout, RLIMIT_CPUNS timeout and time > + * to closest timeout > + */ > + > cpu_limit = READ_ONCE(sig->rlim[RLIMIT_CPU].rlim_cur); > - if (cpu_limit != RLIM_INFINITY) { > - sig->cputime_expires.prof_exp = cpu_limit * NSEC_PER_SEC; > + cpuns_limit = READ_ONCE(sig->rlim[RLIMIT_CPUNS].rlim_cur); > + > + total_limit = RLIM_INFINITY; > + > + if (cpu_limit != RLIM_INFINITY) > + total_limit = cpu_limit * NSEC_PER_SEC; > + if (cpuns_limit != RLIM_INFINITY && cpuns_limit < total_limit) > + total_limit = cpuns_limit; > + > + if (total_limit != RLIM_INFINITY) { > + sig->cputime_expires.prof_exp = total_limit; > sig->cputimer.running = true; > } > > diff --git a/kernel/sys.c b/kernel/sys.c > index 2855ee7..539b110 100644 > --- a/kernel/sys.c > +++ b/kernel/sys.c > @@ -1504,6 +1504,8 @@ int do_prlimit(struct task_struct *tsk, unsigned int resource, > */ > new_rlim->rlim_cur = 1; > } > + if (resource == RLIMIT_CPUNS && new_rlim->rlim_cur == 0) > + new_rlim->rlim_cur = NSEC_PER_SEC; > } > if (!retval) { > if (old_rlim) > @@ -1519,10 +1521,17 @@ int do_prlimit(struct task_struct *tsk, unsigned int resource, > * very long-standing error, and fixing it now risks breakage of > * applications, so we live with it > */ > - if (!retval && new_rlim && resource == RLIMIT_CPU && > + if (!retval && new_rlim && resource == RIMIT_CPU && > new_rlim->rlim_cur != RLIM_INFINITY && > IS_ENABLED(CONFIG_POSIX_TIMERS)) > update_rlimit_cpu(tsk, new_rlim->rlim_cur); > + > + if (!retval && new_rlim && resource == RLIMIT_CPUNS && > + new_rlim->rlim_cur != RLIM_INFINITY && > + IS_ENABLED(CONFIG_POSIX_TIMERS)) > + update_rlimit_cpu_ns(tsk, new_rlim->rlim_cur); > + > + > out: > read_unlock(&tasklist_lock); > return retval; > diff --git a/kernel/time/posix-cpu-timers.c b/kernel/time/posix-cpu-timers.c > index a3bd5db..e4830f6 100644 > --- a/kernel/time/posix-cpu-timers.c > +++ b/kernel/time/posix-cpu-timers.c > @@ -19,20 +19,26 @@ > static void posix_cpu_timer_rearm(struct k_itimer *timer); > > /* > - * Called after updating RLIMIT_CPU to run cpu timer and update > + * Called after updating RLIMIT_CPUNS to run cpu timer and update > * tsk->signal->cputime_expires expiration cache if necessary. Needs > * siglock protection since other code may update expiration cache as > * well. > */ > -void update_rlimit_cpu(struct task_struct *task, unsigned long rlim_new) > +void update_rlimit_cpu_ns(struct task_struct *task, unsigned long rlim_new) > { > - u64 nsecs = rlim_new * NSEC_PER_SEC; > + u64 nsecs = rlim_new; > > spin_lock_irq(&task->sighand->siglock); > set_process_cpu_timer(task, CPUCLOCK_PROF, &nsecs, NULL); > spin_unlock_irq(&task->sighand->siglock); > } > > +/* Same function for RLIMIT_CPU */ > +void update_rlimit_cpu(struct task_struct *task, unsigned long rlim_new) > +{ > + update_rlimit_cpu(task, rlim_new * NSEC_PER_SEC); > +} > + > static int check_clock(const clockid_t which_clock) > { > int error = 0; > @@ -938,6 +944,9 @@ static void check_process_timers(struct task_struct *tsk, > SIGPROF); > check_cpu_itimer(tsk, &sig->it[CPUCLOCK_VIRT], &virt_expires, utime, > SIGVTALRM); > + /* > + * RLIMIT_CPU check > + */ > soft = READ_ONCE(sig->rlim[RLIMIT_CPU].rlim_cur); > if (soft != RLIM_INFINITY) { > unsigned long psecs = div_u64(ptime, NSEC_PER_SEC); > @@ -974,7 +983,35 @@ static void check_process_timers(struct task_struct *tsk, > if (!prof_expires || x < prof_expires) > prof_expires = x; > } > - > + /* > + * RLIMIT_CPUNS check > + */ > + soft = READ_ONCE(sig->rlim[RLIMIT_CPUNS].rlim_cur); > + if (soft != RLIM_INFINITY) { > + unsigned long hard = > + READ_ONCE(sig->rlim[RLIMIT_CPUNS].rlim_max); > + if (ptime >= hard) { > + if (print_fatal_signals) { > + pr_info("RT Watchdog Timeout (hard): %s[%d]\n", > + tsk->comm, task_pid_nr(tsk)); > + } > + __group_send_sig_info(SIGKILL, SEND_SIG_PRIV, tsk); > + return; > + } > + if (ptime >= soft) { > + if (print_fatal_signals) { > + pr_info("CPU Watchdog Timeout (soft): %s[%d]\n", > + tsk->comm, task_pid_nr(tsk)); > + } > + __group_send_sig_info(SIGXCPU, SEND_SIG_PRIV, tsk); > + if (soft < hard) { > + soft += NSEC_PER_SEC; > + sig->rlim[RLIMIT_CPUNS].rlim_cur = soft; > + } > + } > + if (!prof_expires || soft < prof_expires) > + prof_expires = soft; > + } > sig->cputime_expires.prof_exp = prof_expires; > sig->cputime_expires.virt_exp = virt_expires; > sig->cputime_expires.sched_exp = sched_expires; > -- > 2.7.4 -- Michal Hocko SUSE Labs