Messages in this thread | | | Date | Sat, 31 Oct 2009 01:57:08 -0700 | From | Andrew Morton <> | Subject | Re: [PATCH] show message when exceeded rlimit of pending signals |
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On Sat, 31 Oct 2009 17:50:14 +0900 Naohiro Ooiwa <nooiwa@miraclelinux.com> wrote:
> Naohiro Ooiwa wrote: > > Andrew Morton wrote: > >> On Fri, 30 Oct 2009 20:36:31 +0900 > >> Naohiro Ooiwa <nooiwa@miraclelinux.com> wrote: > >>> > >>> +static void show_reach_rlimit_sigpending(void) > >>> +{ > >>> + if (!printk_ratelimit()) > >>> + return; > >> printk_ratelimit() is a bad thing and we should be working toward > >> removing it altogether, not adding new callers. > >> > >> Because it uses global state. So if subsystem A is trying to generate > >> lots of printk's, subsystem B's important message might get > >> accidentally suppressed. > >> > >> It's better to use DEFINE_RATELIMIT_STATE() and __ratelimit() directly. > > > > > > Thank you for your advices. > > And I was glad to talk to you in Japan Linux Symposium. > > > > I got it, now that you mention it. > > I will fix my patch. > > > >>> + printk(KERN_INFO "%s/%d: reached the limit of pending signals.\n", > >>> + current->comm, current->pid); > >> I suggest that this be > >> > >> "reached RLIMIT_SIGPENDING" > >> > >> because RLIMIT_SIGPENDING is a well-understood term and concept. > >> > > > > OK, I see. > > I fixed my patch. > Could you please check it. >
Please always include the full changelog and signoff with each iteration of a patch. That changelog might of course need updating as the patch changes.
> --- > Documentation/kernel-parameters.txt | 11 +++++++++-- > kernel/signal.c | 21 ++++++++++++++++++--- > 2 files changed, 27 insertions(+), 5 deletions(-) > > diff --git a/Documentation/kernel-parameters.txt > b/Documentation/kernel-parameters.txt > index 9107b38..3bbd92f 100644 > --- a/Documentation/kernel-parameters.txt > +++ b/Documentation/kernel-parameters.txt > @@ -2032,8 +2032,15 @@ and is between 256 and 4096 characters. It is defined in > the file > > print-fatal-signals= > [KNL] debug: print fatal signals > - print-fatal-signals=1: print segfault info to > - the kernel console. > + > + If enabled, warn about various signal handling > + related application anomalies: too many signals, > + too many POSIX.1 timers, fatal signals causing a > + coredump - etc. > + > + If you hit the warning due to signal overflow, > + you might want to try "ulimit -i unlimited". > + > default: off. > > printk.time= Show timing data prefixed to each printk message line > diff --git a/kernel/signal.c b/kernel/signal.c > index 6705320..624a626 100644 > --- a/kernel/signal.c > +++ b/kernel/signal.c > @@ -41,6 +41,8 @@ > > static struct kmem_cache *sigqueue_cachep; > > +int print_fatal_signals __read_mostly; > + > static void __user *sig_handler(struct task_struct *t, int sig) > { > return t->sighand->action[sig - 1].sa.sa_handler; > @@ -188,6 +190,17 @@ int next_signal(struct sigpending *pending, sigset_t *mask) > return sig; > } > > +static void show_reach_rlimit_sigpending(void) > +{ > + DEFINE_RATELIMIT_STATE(printk_rl_state, 5 * HZ, 10);
This needs to have `static' storage. This bug should have been apparent in your testing?
> + if (!__ratelimit(&printk_rl_state)) > + return; > + > + printk(KERN_INFO "%s/%d: reached RLIMIT_SIGPENDING.\n", > + current->comm, current->pid); > +} > ... >
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