oom-kill: show virtual size and rss information of the killed process

In a typical oom analysis scenario, we frequently want to know whether the
killed process has a memory leak or not at the first step.  This patch
adds vsz and rss information to the oom log to help this analysis.  To
save time for the debugging.

example:
===================================================================
rsyslogd invoked oom-killer: gfp_mask=0x201da, order=0, oom_adj=0
Pid: 1308, comm: rsyslogd Not tainted 2.6.32-rc6 #24
Call Trace:
[<ffffffff8132e35b>] ?_spin_unlock+0x2b/0x40
[<ffffffff810f186e>] oom_kill_process+0xbe/0x2b0

(snip)

492283 pages non-shared
Out of memory: kill process 2341 (memhog) score 527276 or a child
Killed process 2341 (memhog) vsz:1054552kB, anon-rss:970588kB, file-rss:4kB
===========================================================================
                             ^
                             |
                            here

[rientjes@google.com: fix race, add pid & comm to message]
Signed-off-by: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Signed-off-by: David Rientjes <rientjes@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

mm/oom_kill.c

@@ -352,6 +352,8 @@ static void dump_header(gfp_t gfp_mask, int order, struct mem_cgroup *mem)
 		dump_tasks(mem);
 }
 
+#define K(x) ((x) << (PAGE_SHIFT-10))
+
 /*
  * Send SIGKILL to the selected  process irrespective of  CAP_SYS_RAW_IO
  * flag though it's unlikely that  we select a process with CAP_SYS_RAW_IO
@@ -365,15 +367,23 @@ static void __oom_kill_task(struct task_struct *p, int verbose)
 		return;
 	}
 
+	task_lock(p);
 	if (!p->mm) {
 		WARN_ON(1);
-		printk(KERN_WARNING "tried to kill an mm-less task!\n");
+		printk(KERN_WARNING "tried to kill an mm-less task %d (%s)!\n",
+			task_pid_nr(p), p->comm);
+		task_unlock(p);
 		return;
 	}
 
 	if (verbose)
-		printk(KERN_ERR "Killed process %d (%s)\n",
-				task_pid_nr(p), p->comm);
+		printk(KERN_ERR "Killed process %d (%s) "
+		       "vsz:%lukB, anon-rss:%lukB, file-rss:%lukB\n",
+		       task_pid_nr(p), p->comm,
+		       K(p->mm->total_vm),
+		       K(get_mm_counter(p->mm, anon_rss)),
+		       K(get_mm_counter(p->mm, file_rss)));
+	task_unlock(p);
 
 	/*
 	 * We give our sacrificial lamb high priority and access to