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    SubjectRe: [PATCH] show message when exceeded rlimit of pending signals
    Hi Ingo,

    > Here's a slightly improved version of the text:

    Thank you for your review and collect my English.

    >> +int print_fatal_signals;
    >
    > i'd suggest __read_mostly.

    > Plus please move variables to the top of the file. (i know this comes
    > from the previous code but we can improve it while we are touching it)

    Of course. You're right, if we found one like it,
    I want to improve the code little by little too.

    How is the following patch.

    Signed-off-by: Naohiro Ooiwa <nooiwa@miraclelinux.com>
    Acked-by: Ingo Molnar <mingo@elte.hu>
    ---
    Documentation/kernel-parameters.txt | 13 ++++++++++---
    kernel/signal.c | 16 +++++++++++++---
    2 files changed, 23 insertions(+), 6 deletions(-)

    diff --git a/Documentation/kernel-parameters.txt b/Documentation/kernel-parameters.txt
    index 9107b38..8492ad3 100644
    --- a/Documentation/kernel-parameters.txt
    +++ b/Documentation/kernel-parameters.txt
    @@ -2032,9 +2032,16 @@ 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.
    - default: off.
    +
    + 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
    Format: <bool> (1/Y/y=enable, 0/N/n=disable)
    diff --git a/kernel/signal.c b/kernel/signal.c
    index 6705320..c913eb7 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 +190,12 @@ int next_signal(struct sigpending *pending, sigset_t *mask)
    return sig;
    }

    +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);
    +}
    +
    /*
    * allocate a new signal queue record
    * - this may be called without locks if and only if t == current, otherwise an
    @@ -209,8 +217,12 @@ 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 +937,6 @@ 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

    Ingo Molnar wrote:
    > * Naohiro Ooiwa <nooiwa@miraclelinux.com> wrote:
    >
    >> Hi Ingo,
    >>
    >> Now that you mention it, I think so, too.
    >> I update my patch.
    >>
    >> How is the following patch.
    >> Could you please review it.
    >>
    >> Thanks you.
    >> Naohiro Ooiwa
    >>
    >>
    >>
    >> Signed-off-by: Naohiro Ooiwa <nooiwa@miraclelinux.com>
    >> ---
    >> Documentation/kernel-parameters.txt | 9 ++++++++-
    >> kernel/signal.c | 16 +++++++++++++---
    >> 2 files changed, 21 insertions(+), 4 deletions(-)
    >>
    >> diff --git a/Documentation/kernel-parameters.txt
    >> b/Documentation/kernel-parameters.txt
    >> index 9107b38..01c2723 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
    >> + If you would like to know what the cause of a coredump
    >> + by signal number, if your working system may have
    >> + too many POSIX.1 timers, and when during the system
    >> + test,you may as well to enable this parameter.
    >> print-fatal-signals=1: print segfault info to
    >> - the kernel console.
    >> + the kernel console, and print caution that reached the
    >> + limit of pending signals to the kernel console.
    >> + When printed the caution messages, you can try
    >> + "ulimit -i unlimited".
    >> default: off.
    >>
    >
    > Here's a slightly improved version of the text:
    >
    > print-fatal-signals=
    > [KNL] debug: print fatal signals
    >
    > 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.
    >
    >> +int print_fatal_signals;
    >
    > i'd suggest __read_mostly.
    >
    > Plus please move variables to the top of the file. (i know this comes
    > from the previous code but we can improve it while we are touching it)
    >
    > With these things addressed it looks good to me:
    >
    > Acked-by: Ingo Molnar <mingo@elte.hu>
    >
    > Ingo
    >



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