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    SubjectRe: swapper: page allocation failure. order:3, mode:0x20

    > So sure, ratelimit it, make it KERN_INFO and maybe add a dump_stack()?

    Sounds good, I always end up adding a dump_stack there when debugging
    these problems anyway.

    > (printk_ratelimit() may be a suitable name)

    How does this look?

    Anton

    ===== Documentation/sysctl/kernel.txt 1.7 vs edited =====
    --- 1.7/Documentation/sysctl/kernel.txt Wed Apr 9 18:01:38 2003
    +++ edited/Documentation/sysctl/kernel.txt Thu Jan 1 23:52:10 2004
    @@ -251,6 +251,25 @@

    ==============================================================

    +printk_ratelimit:
    +
    +Some warning messages are rate limited. printk_ratelimit specifies
    +the minimum length of time between these messages, by default we
    +allow one every 5 seconds.
    +
    +A value of 0 will disable rate limiting.
    +
    +==============================================================
    +
    +printk_ratelimit_burst:
    +
    +While long term we enforce one message per printk_ratelimit
    +seconds, we do allow a burst of messages to pass through.
    +printk_ratelimit_burst specifies the number of messages we can
    +send before ratelimiting kicks in.
    +
    +==============================================================
    +
    reboot-cmd: (Sparc only)

    ??? This seems to be a way to give an argument to the Sparc
    ===== include/linux/kernel.h 1.43 vs edited =====
    --- 1.43/include/linux/kernel.h Tue Dec 30 08:37:26 2003
    +++ edited/include/linux/kernel.h Thu Jan 1 23:52:10 2004
    @@ -89,6 +89,8 @@

    unsigned long int_sqrt(unsigned long);

    +extern int printk_ratelimit(void);
    +
    static inline void console_silent(void)
    {
    console_loglevel = 0;
    ===== include/linux/sysctl.h 1.54 vs edited =====
    --- 1.54/include/linux/sysctl.h Thu Dec 25 14:32:23 2003
    +++ edited/include/linux/sysctl.h Thu Jan 1 23:53:11 2004
    @@ -127,6 +127,8 @@
    KERN_PANIC_ON_OOPS=57, /* int: whether we will panic on an oops */
    KERN_HPPA_PWRSW=58, /* int: hppa soft-power enable */
    KERN_HPPA_UNALIGNED=59, /* int: hppa unaligned-trap enable */
    + KERN_PRINTK_RATELIMIT=60, /* int: tune printk ratelimiting */
    + KERN_PRINTK_RATELIMIT_BURST=61, /* int: tune printk ratelimiting */
    };


    ===== kernel/printk.c 1.29 vs edited =====
    --- 1.29/kernel/printk.c Tue Dec 30 12:01:55 2003
    +++ edited/kernel/printk.c Thu Jan 1 23:53:51 2004
    @@ -762,3 +762,45 @@
    tty->driver->write(tty, 0, msg, strlen(msg));
    return;
    }
    +
    +/* minimum time in jiffies between messages */
    +int printk_ratelimit_jiffies = 5*HZ;
    +
    +/* number of messages we send before ratelimiting */
    +int printk_ratelimit_burst = 10;
    +
    +/*
    + * printk rate limiting, lifted from the networking subsystem.
    + *
    + * This enforces a rate limit: not more than one kernel message
    + * every printk_ratelimit_jiffies to make a denial-of-service
    + * attack impossible.
    + */
    +int printk_ratelimit(void)
    +{
    + static spinlock_t ratelimit_lock = SPIN_LOCK_UNLOCKED;
    + static unsigned long toks = 10*5*HZ;
    + static unsigned long last_msg;
    + static int missed;
    + unsigned long flags;
    + unsigned long now = jiffies;
    +
    + spin_lock_irqsave(&ratelimit_lock, flags);
    + toks += now - last_msg;
    + last_msg = now;
    + if (toks > (printk_ratelimit_burst * printk_ratelimit_jiffies))
    + toks = printk_ratelimit_burst * printk_ratelimit_jiffies;
    + if (toks >= printk_ratelimit_jiffies) {
    + int lost = missed;
    + missed = 0;
    + toks -= printk_ratelimit_jiffies;
    + spin_unlock_irqrestore(&ratelimit_lock, flags);
    + if (lost)
    + printk(KERN_WARNING "printk: %d messages suppressed.\n", lost);
    + return 1;
    + }
    + missed++;
    + spin_unlock_irqrestore(&ratelimit_lock, flags);
    + return 0;
    +}
    +EXPORT_SYMBOL(printk_ratelimit);
    ===== kernel/sysctl.c 1.55 vs edited =====
    --- 1.55/kernel/sysctl.c Thu Oct 2 17:12:07 2003
    +++ edited/kernel/sysctl.c Thu Jan 1 23:52:11 2004
    @@ -60,6 +60,8 @@
    extern int pid_max;
    extern int sysctl_lower_zone_protection;
    extern int min_free_kbytes;
    +extern int printk_ratelimit_jiffies;
    +extern int printk_ratelimit_burst;

    /* this is needed for the proc_dointvec_minmax for [fs_]overflow UID and GID */
    static int maxolduid = 65535;
    @@ -575,6 +577,22 @@
    .ctl_name = KERN_PANIC_ON_OOPS,
    .procname = "panic_on_oops",
    .data = &panic_on_oops,
    + .maxlen = sizeof(int),
    + .mode = 0644,
    + .proc_handler = &proc_dointvec,
    + },
    + {
    + .ctl_name = KERN_PRINTK_RATELIMIT,
    + .procname = "printk_ratelimit",
    + .data = &printk_ratelimit_jiffies,
    + .maxlen = sizeof(int),
    + .mode = 0644,
    + .proc_handler = &proc_dointvec_jiffies,
    + },
    + {
    + .ctl_name = KERN_PRINTK_RATELIMIT_BURST,
    + .procname = "printk_ratelimit_burst",
    + .data = &printk_ratelimit_burst,
    .maxlen = sizeof(int),
    .mode = 0644,
    .proc_handler = &proc_dointvec,
    ===== mm/page_alloc.c 1.176 vs edited =====
    --- 1.176/mm/page_alloc.c Tue Dec 30 08:38:05 2003
    +++ edited/mm/page_alloc.c Thu Jan 1 23:52:11 2004
    @@ -670,10 +670,11 @@
    }

    nopage:
    - if (!(gfp_mask & __GFP_NOWARN)) {
    - printk("%s: page allocation failure."
    + if (!(gfp_mask & __GFP_NOWARN) && printk_ratelimit()) {
    + printk(KERN_WARNING "%s: page allocation failure."
    " order:%d, mode:0x%x\n",
    p->comm, order, gfp_mask);
    + dump_stack();
    }
    return NULL;
    got_pg:
    -
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