Re: oom killer in 2.4.23

[Kristian Peters]

Andrea Arcangeli <andrea@xxxxxxx> schrieb:
> what you're complaining is the 'selection of the task to be killed'.
> That's not solvable. the kernel can't read your brain period. Only if
> the kernel could read the brain of the adminstrator then you would be
> happy, there is no way the kernel can know which is the task you really
> want to have killed first.

I agree. On a server the most likely application to be killed would be the service with the most pages in memory. And those services tend to be the important ones.

However, for a simple desktop-linux that statistical approach seems to be wrong. Your vm has even killed /sbin/getty sometimes, so that I can't login via a simple console.

Re-enabling the oom-killer gives a good result for me:

Dec  6 09:46:19 adlib kernel: Out of Memory: Killed process 643 (khexedit).
Dec  6 09:48:42 adlib kernel: Out of Memory: Killed process 645 (khexedit).

What I complain is that your vm kills some processes without mentioning in the logs. How can I determine what processes the kernel has killed ?


I hope that fairly simple patch does things right for all people that want the old behaviour. It's already a year ago I last hacked on the kernel.

diff -rauN linux-2.4.23/include/linux/sched.h linux-2.4.23-kp1/include/linux/sched.h
--- linux-2.4.23/include/linux/sched.h  Fri Nov 28 19:26:21 2003
+++ linux-2.4.23-kp1/include/linux/sched.h      Sat Dec  6 09:57:04 2003
@@ -429,6 +429,7 @@
 #define PF_DUMPCORE    0x00000200      /* dumped core */
 #define PF_SIGNALED    0x00000400      /* killed by a signal */
 #define PF_MEMALLOC    0x00000800      /* Allocating memory */
+#define PF_MEMDIE      0x00001000      /* Killed for out-of-memory */
 #define PF_FREE_PAGES  0x00002000      /* per process page freeing */
 #define PF_NOIO                0x00004000      /* avoid generating further I/O */
 
diff -rauN linux-2.4.23/mm/oom_kill.c linux-2.4.23-kp1/mm/oom_kill.c
--- linux-2.4.23/mm/oom_kill.c  Fri Nov 28 19:26:21 2003
+++ linux-2.4.23-kp1/mm/oom_kill.c      Fri Dec  5 20:31:39 2003
@@ -21,8 +21,6 @@
 #include <linux/swapctl.h>
 #include <linux/timex.h>
 
-#if 0          /* Nothing in this file is used */
-
 /* #define DEBUG */
 
 /**
@@ -257,5 +255,3 @@
        first = now;
        count = 0;
 }
-
-#endif /* Unused file */
diff -rauN linux-2.4.23/mm/vmscan.c linux-2.4.23-kp1/mm/vmscan.c
--- linux-2.4.23/mm/vmscan.c    Fri Nov 28 19:26:21 2003
+++ linux-2.4.23-kp1/mm/vmscan.c        Sat Dec  6 10:21:55 2003
@@ -649,13 +649,7 @@
                                failed_swapout = !swap_out(classzone);
                } while (--tries);
 
-       if (likely(current->pid != 1))
-               break;
-       if (!check_classzone_need_balance(classzone))
-               break;
-
-       __set_current_state(TASK_RUNNING);
-       yield();
+       out_of_memory();
        }
 
        return 0;



*Kristian

     _o)
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