Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753903AbZJaIuW (ORCPT ); Sat, 31 Oct 2009 04:50:22 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1752594AbZJaIuV (ORCPT ); Sat, 31 Oct 2009 04:50:21 -0400 Received: from mailgw.miraclelinux.com ([122.216.84.157]:11952 "EHLO mailgw.miraclelinux.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751435AbZJaIuU (ORCPT ); Sat, 31 Oct 2009 04:50:20 -0400 Message-ID: <4AEBFA46.8070709@miraclelinux.com> Date: Sat, 31 Oct 2009 17:50:14 +0900 From: Naohiro Ooiwa User-Agent: Thunderbird 2.0.0.23 (Windows/20090812) MIME-Version: 1.0 To: Andrew Morton CC: Ingo Molnar , Hiroshi Shimamoto , roland@redhat.com, Peter Zijlstra , Thomas Gleixner , LKML , oleg@redhat.com Subject: Re: [PATCH] show message when exceeded rlimit of pending signals References: <4AEACFBF.4060108@miraclelinux.com> <20091030143333.414ea29c.akpm@linux-foundation.org> <4AEBEE38.50108@miraclelinux.com> In-Reply-To: <4AEBEE38.50108@miraclelinux.com> Content-Type: text/plain; charset=ISO-2022-JP Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 4072 Lines: 136 Naohiro Ooiwa wrote: > Andrew Morton wrote: >> On Fri, 30 Oct 2009 20:36:31 +0900 >> Naohiro Ooiwa 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. Thanks you. Naohiro Ooiwa Signed-off-by: Naohiro Ooiwa Acked-by: Ingo Molnar --- 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); + + if (!__ratelimit(&printk_rl_state)) + return; + + printk(KERN_INFO "%s/%d: reached RLIMIT_SIGPENDING.\n", + current->comm, current->pid); +} + /* * allocate a new signal queue record * - this may be called without locks if and only if t == current, otherwise an @@ -209,8 +222,12 @@ 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_fatal_signals) + show_reach_rlimit_sigpending(); + } if (unlikely(q == NULL)) { atomic_dec(&user->sigpending); free_uid(user); @@ -925,8 +942,6 @@ static int send_signal(int sig, struct siginfo *info, struct task_struct *t, return __send_signal(sig, info, t, group, from_ancestor_ns); } -int print_fatal_signals; - static void print_fatal_signal(struct pt_regs *regs, int signr) { printk("%s/%d: potentially unexpected fatal signal %d.\n", -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/