[PATCH] add OOM debug

This patch provides more debug info when the system is OOM.  It displays
memory stats (basically sysrq-m info) from __alloc_pages() when page
allocation fails and during OOM kill.

Thanks to Dave Jones for coming up with the idea.

Signed-off-by: Janet Morgan <janetmor@us.ibm.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

2 files changed, 5 insertions, 3 deletions

diff --git a/mm/oom_kill.c b/mm/oom_kill.c
index 4bbb1cb10495..59666d905f19 100644
--- a/mm/oom_kill.c
+++ b/mm/oom_kill.c
@@ -258,6 +258,10 @@ void out_of_memory(unsigned int __nocast gfp_mask)
         struct mm_struct *mm = NULL;
         task_t * p;
 
+        printk("oom-killer: gfp_mask=0x%x\n", gfp_mask);
+        /* print memory stats */
+        show_mem();
+
         read_lock(&tasklist_lock);
 retry:
         p = select_bad_process();
@@ -268,12 +272,9 @@ retry:
         /* Found nothing?!?! Either we hang forever, or we panic. */
         if (!p) {
                 read_unlock(&tasklist_lock);
-                show_free_areas();
                 panic("Out of memory and no killable processes...\n");
         }
 
-        printk("oom-killer: gfp_mask=0x%x\n", gfp_mask);
-        show_free_areas();
         mm = oom_kill_process(p);
         if (!mm)
                 goto retry;
diff --git a/mm/page_alloc.c b/mm/page_alloc.c
index 10446a646374..be05d17bd7df 100644
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -935,6 +935,7 @@ nopage:
                         " order:%d, mode:0x%x\n",
                         p->comm, order, gfp_mask);
                 dump_stack();
+                show_mem();
         }
         return NULL;
 got_pg: