Messages in this thread Patch in this message | | | Date | Mon, 09 Nov 2009 00:46:42 +0900 | From | Naohiro Ooiwa <> | Subject | [PATCH] extend print_fatal_signals for reached RLIMIT_SIGPENDING |
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When the system has too many timers or too many aggregate queued signals, the EAGAIN error is returned to application from kernel, including timer_create(). It means that exceeded limit of pending signals at all. But we can't imagine it.
This patch show the message when reached limit of pending signals and enabled print_fatal_signals. If you see this message and your system behaved unexpectedly, you can run following command. # ulimit -i unlimited
With help from Hiroshi Shimamoto <h-shimamoto@ct.jp.nec.com>.
Signed-off-by: Naohiro Ooiwa <nooiwa@miraclelinux.com> Acked-by: Ingo Molnar <mingo@elte.hu> --- 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..56e9c00 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) +{ + static 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", -- 1.5.4.1
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