2009-03-27 00:11:41

by Oleg Nesterov

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

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 <[email protected]>
Signed-off-by: Oleg Nesterov <[email protected]>

--- 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);

2009-03-28 00:00:38

by Peter Zijlstra

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

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 <[email protected]>

> Reported-by: Peter Lojkin <[email protected]>
> Signed-off-by: Oleg Nesterov <[email protected]>
>
> --- 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);
>

2009-03-31 03:02:22

by Chris Wright

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

* Oleg Nesterov ([email protected]) 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.

For -stable should this be instead of 37bebc70d7ad4144c571d74500db3bb26ec0c0eb?

thanks,
-chris

2009-03-31 15:03:38

by Oleg Nesterov

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

On 03/31, Chris Wright wrote:
>
> * Oleg Nesterov ([email protected]) 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.
>
> For -stable should this be instead of 37bebc70d7ad4144c571d74500db3bb26ec0c0eb?

Yes, sorry for confusion.

The commit above was targeted for 2.6.29, it is not optimal. When/if
"[PATCH 1/2] posix-timers: fix RLIMIT_CPU && fork()" will be merged, I'll sent
the "revert" patch.

see http://marc.info/?t=123783777600004

Oleg.

2009-04-08 16:10:52

by Oleg Nesterov

Subject: [tip:timers/urgent] posix-timers: fix RLIMIT_CPU && fork()

Commit-ID: 6279a751fe096a21dc7704e918d570d3ff06e769
Gitweb: http://git.kernel.org/tip/6279a751fe096a21dc7704e918d570d3ff06e769
Author: Oleg Nesterov <[email protected]>
AuthorDate: Fri, 27 Mar 2009 01:06:07 +0100
Committer: Ingo Molnar <[email protected]>
CommitDate: Wed, 8 Apr 2009 17:51:38 +0200

posix-timers: fix RLIMIT_CPU && fork()

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 <[email protected]>
Signed-off-by: Oleg Nesterov <[email protected]>
Acked-by: Peter Zijlstra <[email protected]>
Cc: Peter Lojkin <[email protected]>
Cc: Roland McGrath <[email protected]>
Cc: [email protected]
LKML-Reference: <[email protected]>
Signed-off-by: Ingo Molnar <[email protected]>


---
kernel/fork.c | 13 +++++++++----
1 files changed, 9 insertions(+), 4 deletions(-)

diff --git a/kernel/fork.c b/kernel/fork.c
index 4854c2c..9b51a1b 100644
--- a/kernel/fork.c
+++ b/kernel/fork.c
@@ -808,6 +808,12 @@ static void posix_cpu_timers_init_group(struct signal_struct *sig)
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 clone_flags, struct task_struct *tsk)
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 clone_flags, struct task_struct *tsk)
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);