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SubjectRe: [PATCH 1/2] posix-timers: fix RLIMIT_CPU && fork()
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On Fri, 2009-03-27 at 01:06 +0100, Oleg Nesterov wrote:
> See http://bugzilla.kernel.org/show_bug.cgi?id=12911
>
> copy_signal() copies signal->rlim, but RLIMIT_CPU is "lost". Because
> posix_cpu_timers_init_group() sets cputime_expires.prof_exp = 0 and thus
> fastpath_timer_check() returns false unless we have other expired cpu timers.
>
> Change copy_signal() to set cputime_expires.prof_exp if we have RLIMIT_CPU.
> Also, set cputimer.running = 1 in that case. This is not strictly necessary,
> but imho makes sense.

The other site that enables is also syncs the timer with the clock, but
since we're doing clone_signal, I presume there isn't much of a thread
group to sync to anyway.

Looks good, thanks for looking into this.

Acked-by: Peter Zijlstra <a.p.zijlstra@chello.nl>

> Reported-by: Peter Lojkin <ia6432@inbox.ru>
> Signed-off-by: Oleg Nesterov <oleg@redhat.com>
>
> --- 6.29/kernel/fork.c~1_FORK 2009-03-23 18:14:34.000000000 +0100
> +++ 6.29/kernel/fork.c 2009-03-27 00:25:52.000000000 +0100
> @@ -808,6 +808,12 @@ static void posix_cpu_timers_init_group(
> sig->cputime_expires.virt_exp = cputime_zero;
> sig->cputime_expires.sched_exp = 0;
>
> + if (sig->rlim[RLIMIT_CPU].rlim_cur != RLIM_INFINITY) {
> + sig->cputime_expires.prof_exp =
> + secs_to_cputime(sig->rlim[RLIMIT_CPU].rlim_cur);
> + sig->cputimer.running = 1;
> + }
> +
> /* The timer lists. */
> INIT_LIST_HEAD(&sig->cpu_timers[0]);
> INIT_LIST_HEAD(&sig->cpu_timers[1]);
> @@ -823,11 +829,8 @@ static int copy_signal(unsigned long clo
> atomic_inc(&current->signal->live);
> return 0;
> }
> - sig = kmem_cache_alloc(signal_cachep, GFP_KERNEL);
> -
> - if (sig)
> - posix_cpu_timers_init_group(sig);
>
> + sig = kmem_cache_alloc(signal_cachep, GFP_KERNEL);
> tsk->signal = sig;
> if (!sig)
> return -ENOMEM;
> @@ -865,6 +868,8 @@ static int copy_signal(unsigned long clo
> memcpy(sig->rlim, current->signal->rlim, sizeof sig->rlim);
> task_unlock(current->group_leader);
>
> + posix_cpu_timers_init_group(sig);
> +
> acct_init_pacct(&sig->pacct);
>
> tty_audit_fork(sig);
>



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