Re: Andrea VM changes

From: Dan Kegel (dank_at_kegel.com)
Date: 08/31/03

  • Next message: Andrea Arcangeli: "Re: Andrea VM changes" 
    Date:	Sun, 31 Aug 2003 09:19:35 -0700
To: Jörn Engel <joern@wohnheim.fh-wedel.de>

    Jörn Engel wrote:
    > On Sun, 31 August 2003 08:51:55 -0700, Dan Kegel wrote:
    >
    >>In the test-and-measurement system I'm developing,
    >>it turned out the sanest thing to do with OOM conditions
    >>was to consider them user errors, and to handle them
    >>by dumping memory usage info about processes and slab caches,
    >>then halt. It's been very helpful because it turns flaky
    >>conditions into rock-solid failures. Too bad this drastic
    >>approach isn't appropriate for general use.
    >
    >
    > Sound interesting. Can you send a patch for the interested and
    > unafraid?

    This is against 2.4.21 or so.

    --- mm.old/oom_kill.c Mon Apr 28 17:23:19 2003
    +++ mm/oom_kill.c Mon Apr 28 20:22:23 2003
    @@ -20,9 +20,13 @@
      #include <linux/swap.h>
      #include <linux/swapctl.h>
      #include <linux/timex.h>
    +#include <asm/uaccess.h>

      /* #define DEBUG */

    +#define CONFIG_OOM_HALT
    +#ifndef CONFIG_OOM_HALT
    +
      /**
       * int_sqrt - oom_kill.c internal function, rough approximation to sqrt
       * @x: integer of which to calculate the sqrt
    @@ -193,6 +197,62 @@
              return;
      }

    +#else
    +
    +/**
    + * oom_halt - log out of memory condition, then halt system.
    + *
    + * For embedded systems which can't tolerate the chance that
    + * the oom killer will kill the wrong process, and would rather
    + * simply log the event in detail and halt.
    + */
    +static void
    +oom_halt(void)
    +{
    + struct task_struct *p;
    + struct file *file;
    + int ret;
    +
    + printk(KERN_EMERG "oom: Out of memory!\n");
    +
    + printk(KERN_EMERG "oom: VM and RSS in KB, pid, and mm ptr for each task:\n");
    + read_lock(&tasklist_lock);
    + for_each_task(p) {
    + if (p->mm)
    + printk(KERN_EMERG "oom> vm %5d rss %5d pid %5d mm %p (%s)\n",
    + p->mm->total_vm * (PAGE_SIZE / 1024),
    + p->mm->rss * (PAGE_SIZE / 1024), p->pid, p->mm, p->comm);
    + }
    + read_unlock(&tasklist_lock);
    +
    + file = filp_open("/proc/slabinfo", O_RDONLY, 0);
    + if (IS_ERR(file) || !file->f_op || !file->f_op->read)
    + goto out;
    + printk(KERN_EMERG "oom: Contents of /proc/slabinfo:\n");
    + do {
    + char buf[128];
    + int pos;
    + mm_segment_t fs = get_fs();
    + /* read one line */
    + for (pos = 0; pos < sizeof (buf); pos++) {
    + set_fs(KERNEL_DS);
    + ret = file->f_op->read(file, buf + pos, 1, &file->f_pos);
    + set_fs(fs);
    + if (ret != 1 || buf[pos] == '\n')
    + break;
    + }
    + buf[pos] = 0;
    + printk(KERN_EMERG "oom> %s\n", buf);
    + } while (ret == 1);
    + /* filp_close(file, NULL); */
    +out:
    + printk(KERN_EMERG "oom: Halting.\n");
    + cli();
    + machine_halt();
    +}
    +
    +#endif
    +
      /**
       * out_of_memory - is the system out of memory?
       */
    @@ -237,7 +297,11 @@
              /*
               * Ok, really out of memory. Kill something.
               */
              lastkill = now;
    +#ifdef CONFIG_OOM_HALT
    + oom_halt();
    +#else
              oom_kill();
    +#endif

      reset:
              first = now; 

    -- 
Dan Kegel
http://www.kegel.com
http://counter.li.org/cgi-bin/runscript/display-person.cgi?user=78045
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  • Next message: Andrea Arcangeli: "Re: Andrea VM changes"