[PATCH 1/4] cpusets oom_kill tweaks

Paul Jackson
2005-09-01T09:09:16Z

This patch applies a few comment and code cleanups to mm/oom_kill.c
prior to applying a few small patches to improve cpuset management of
memory placement.

The comment changed in oom_kill.c was seriously misleading. The code
layout change in select_bad_process() makes room for adding another
condition on which a process can be spared the oom killer (see the
subsequent cpuset_nodes_overlap patch for this addition).

Also a couple typos and spellos that bugged me, while I was here.

This patch should have no material affect.

Signed-off-by: Paul Jackson <pj@sgi.com>

Index: linux-2.6.13-mem_exclusive_oom/mm/oom_kill.c
===================================================================
--- linux-2.6.13-mem_exclusive_oom.orig/mm/oom_kill.c
+++ linux-2.6.13-mem_exclusive_oom/mm/oom_kill.c
@@ -6,8 +6,8 @@
* for goading me into coding this file...
*
* The routines in this file are used to kill a process when
- * we're seriously out of memory. This gets called from kswapd()
- * in linux/mm/vmscan.c when we really run out of memory.
+ * we're seriously out of memory. This gets called from __alloc_pages()
+ * in mm/page_alloc.c when we really run out of memory.
*
* Since we won't call these routines often (on a well-configured
* machine) this file will double as a 'coding guide' and a signpost
@@ -26,7 +26,7 @@
/**
* oom_badness - calculate a numeric value for how bad this task has been
* @p: task struct of which task we should calculate
- * @p: current uptime in seconds
+ * @uptime: current uptime in seconds
*
* The formula used is relatively simple and documented inline in the
* function. The main rationale is that we want to select a good task
@@ -57,9 +57,9 @@ unsigned long badness(struct task_struct

/*
* Processes which fork a lot of child processes are likely
- * a good choice. We add the vmsize of the childs if they
+ * a good choice. We add the vmsize of the children if they
* have an own mm. This prevents forking servers to flood the
- * machine with an endless amount of childs
+ * machine with an endless amount of children
*/
list_for_each(tsk, &p->children) {
struct task_struct *chld;
@@ -143,28 +143,32 @@ static struct task_struct * select_bad_p
struct timespec uptime;

do_posix_clock_monotonic_gettime(&uptime);
- do_each_thread(g, p)
- /* skip the init task with pid == 1 */
- if (p->pid > 1 && p->oomkilladj != OOM_DISABLE) {
- unsigned long points;
+ do_each_thread(g, p) {
+ unsigned long points;
+ int releasing;

- /*
- * This is in the process of releasing memory so wait it
- * to finish before killing some other task by mistake.
- */
- if ((unlikely(test_tsk_thread_flag(p, TIF_MEMDIE)) || (p->flags & PF_EXITING)) &&
- !(p->flags & PF_DEAD))
- return ERR_PTR(-1UL);
- if (p->flags & PF_SWAPOFF)
- return p;
-
- points = badness(p, uptime.tv_sec);
- if (points > maxpoints || !chosen) {
- chosen = p;
- maxpoints = points;
- }
+ /* skip the init task with pid == 1 */
+ if (p->pid == 1)
+ continue;
+ if (p->oomkilladj == OOM_DISABLE)
+ continue;
+ /*
+ * This is in the process of releasing memory so for wait it
+ * to finish before killing some other task by mistake.
+ */
+ releasing = test_tsk_thread_flag(p, TIF_MEMDIE) ||
+ p->flags & PF_EXITING;
+ if (releasing && !(p->flags & PF_DEAD))
+ return ERR_PTR(-1UL);
+ if (p->flags & PF_SWAPOFF)
+ return p;
+
+ points = badness(p, uptime.tv_sec);
+ if (points > maxpoints || !chosen) {
+ chosen = p;
+ maxpoints = points;
}
- while_each_thread(g, p);
+ } while_each_thread(g, p);
return chosen;
}

@@ -189,7 +193,8 @@ static void __oom_kill_task(task_t *p)
return;
}
task_unlock(p);
- printk(KERN_ERR "Out of Memory: Killed process %d (%s).\n", p->pid, p->comm);
+ printk(KERN_ERR "Out of Memory: Killed process %d (%s).\n",
+ p->pid, p->comm);

/*
* We give our sacrificial lamb high priority and access to