Re: [PATCH] show message when exceeded rlimit of pending signals

From: nooiwa
Date: Mon Oct 26 2009 - 06:17:51 EST


Hi Ingo

I remade a patch.

I already tested it. The result was good for me.
Could you please check it.

Thanks you.
Naohiro Ooiwa


Signed-off-by: Naohiro Ooiwa <nooiwa@xxxxxxxxxxxxxxxx>
---
Documentation/kernel-parameters.txt | 14 ++++++++++++++
kernel/signal.c | 24 +++++++++++++++++++++++-
kernel/sysctl.c | 9 +++++++++
3 files changed, 46 insertions(+), 1 deletions(-)

diff --git a/Documentation/kernel-parameters.txt b/Documentation/kernel-parameters.txt
index 9107b38..37104b1 100644
--- a/Documentation/kernel-parameters.txt
+++ b/Documentation/kernel-parameters.txt
@@ -2036,6 +2036,20 @@ and is between 256 and 4096 characters. It is defined in the file
the kernel console.
default: off.

+ print-reach-rlimit-sigpending=
+ [KNL] debug: print caution that reached the limit of
+ pending signals.
+ If your working system may have too many POSIX.1 timers
+ or during the system test, you may as well to enable
+ this parameter.
+ print-reach-rlimit-sigpending=0: disable this print
+ print-reach-rlimit-sigpending=1: print message that
+ reached the limit of pending signals to the kernel
+ console.
+ When this message is printed, maybe you should try to
+ "ulimit -i unlimited".
+ default: off.
+
printk.time= Show timing data prefixed to each printk message line
Format: <bool> (1/Y/y=enable, 0/N/n=disable)

diff --git a/kernel/signal.c b/kernel/signal.c
index 6705320..9943e71 100644
--- a/kernel/signal.c
+++ b/kernel/signal.c
@@ -188,6 +188,24 @@ int next_signal(struct sigpending *pending, sigset_t *mask)
return sig;
}

+int print_reach_rlimit_sigpending;
+
+static void show_reach_rlimit_sigpending(void)
+{
+ if (printk_ratelimit())
+ printk(KERN_WARNING "%s/%d: reached the limit of
+ pending signals.\n", current->comm, current->pid);
+}
+
+static int __init setup_print_reach_rlimit_sigpending(char *str)
+{
+ get_option(&str, &print_reach_rlimit_sigpending);
+
+ return 1;
+}
+
+__setup("print-reach-rlimit-sigpending=", setup_print_reach_rlimit_sigpending);
+
/*
* allocate a new signal queue record
* - this may be called without locks if and only if t == current, otherwise an
@@ -209,8 +227,12 @@ static struct sigqueue *__sigqueue_alloc(struct task_struct *t, gfp_t flags,
atomic_inc(&user->sigpending);
if (override_rlimit ||
atomic_read(&user->sigpending) <=
- t->signal->rlim[RLIMIT_SIGPENDING].rlim_cur)
+ t->signal->rlim[RLIMIT_SIGPENDING].rlim_cur) {
q = kmem_cache_alloc(sigqueue_cachep, flags);
+ } else {
+ if (print_reach_rlimit_sigpending)
+ show_reach_rlimit_sigpending();
+ }
if (unlikely(q == NULL)) {
atomic_dec(&user->sigpending);
free_uid(user);
diff --git a/kernel/sysctl.c b/kernel/sysctl.c
index 0d949c5..93b2760 100644
--- a/kernel/sysctl.c
+++ b/kernel/sysctl.c
@@ -67,6 +67,7 @@ static int deprecated_sysctl_warning(struct __sysctl_args *args);
/* External variables not in a header file. */
extern int C_A_D;
extern int print_fatal_signals;
+extern int print_reach_rlimit_sigpending;
extern int sysctl_overcommit_memory;
extern int sysctl_overcommit_ratio;
extern int sysctl_panic_on_oom;
@@ -467,6 +468,14 @@ static struct ctl_table kern_table[] = {
.mode = 0644,
.proc_handler = &proc_dointvec,
},
+ {
+ .ctl_name = CTL_UNNUMBERED,
+ .procname = "print-reach-rlimit-sigpending",
+ .data = &print_reach_rlimit_sigpending,
+ .maxlen = sizeof(int),
+ .mode = 0644,
+ .proc_handler = &proc_dointvec,
+ },
#ifdef CONFIG_SPARC
{
.ctl_name = KERN_SPARC_REBOOT,
-- 1.5.4.1

Ingo Molnar wrote:
> * Naohiro Ooiwa <nooiwa@xxxxxxxxxxxxxxxx> wrote:
>
>> Hi Ingo, Roland,
>>
>> Now, I received a nice comment from OGAWA-san.
>> How is this impriment like a print_faital_signal().
>>
>> I think it's very nice.
>
> Agreed - i just wanted to suggest that too. print_fatal_signals is
> already a switch that turns on warnings about 'weird looking signal
> behavior'. print-on-overflow seems like a good match.
>
> Ingo



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