[PATCH 1/2] posix-timers: fix RLIMIT_CPU && fork()

From: Oleg Nesterov
Date: Thu Mar 26 2009 - 20:11:41 EST


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.

Reported-by: Peter Lojkin <ia6432@xxxxxxxx>
Signed-off-by: Oleg Nesterov <oleg@xxxxxxxxxx>

--- 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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