On 11/09/2012 04:12 PM, Kamezawa Hiroyuki wrote:

(2012/11/09 0:52), Sha Zhengju wrote:

quoted

From: Sha Zhengju <redacted>

Current when a memcg oom is happening the oom dump messages is still global
state and provides few useful info for users. This patch prints more pointed
memcg page statistics for memcg-oom.


We set up a simple cgroup hierarchy for test:
	root_memcg
	    |
	    1 (use_hierachy=1, with a process)
	    |
	    2 (its process will be killed by memcg oom)

Following are samples of oom output:

(1)Before change:

[  295.754215] mal invoked oom-killer: gfp_mask=0xd0, order=0, oom_score_adj=0
[  295.754219] mal cpuset=/ mems_allowed=0-1
[  295.754221] Pid: 4623, comm: mal Not tainted 3.6.0+ #26
[  295.754223] Call Trace:
[  295.754230]  [<ffffffff8111b9c4>] dump_header+0x84/0xd0
[  295.754233]  [<ffffffff8111c691>] oom_kill_process+0x331/0x350
		..... (call trace)
[  295.754288]  [<ffffffff815171e5>] page_fault+0x25/0x30
[  295.754291] Task in /1/2 killed as a result of limit of /1
[  295.754293] memory: usage 511640kB, limit 512000kB, failcnt 4471
[  295.754294] memory+swap: usage 563200kB, limit 563200kB, failcnt 22
[  295.754296] kmem: usage 0kB, limit 9007199254740991kB, failcnt 0
[  295.754297] Mem-Info:
[  295.754298] Node 0 DMA per-cpu:           <<<<<<<<<<<<<<<<<<<<< print per cpu pageset stat
[  295.754300] CPU    0: hi:    0, btch:   1 usd:   0
	       ......
[  295.754302] CPU    15: hi:    0, btch:   1 usd:   0

[  295.754448] Node 0 DMA32 per-cpu:
[  295.754450] CPU    0: hi:  186, btch:  31 usd: 181
	       ......
[  295.754451] CPU    15: hi:  186, btch:  31 usd:  25

[  295.754470] Node 0 Normal per-cpu:
[  295.754472] CPU    0: hi:  186, btch:  31 usd:  56
	       ......
[  295.754473] CPU    15: hi:  186, btch:  31 usd: 150

[  295.754493] Node 1 Normal per-cpu:
[  295.754495] CPU    0: hi:  186, btch:  31 usd:   0
	       ......
[  295.754496] CPU    15: hi:  186, btch:  31 usd:   0
					     <<<<<<<<<<<<<<<<<<<<< print global page state
[  295.754519] active_anon:57756 inactive_anon:73437 isolated_anon:0
[  295.754519]  active_file:2659 inactive_file:14291 isolated_file:0
[  295.754519]  unevictable:1268 dirty:0 writeback:4961 unstable:0
[  295.754519]  free:5979740 slab_reclaimable:2955 slab_unreclaimable:5460
[  295.754519]  mapped:2478 shmem:62 pagetables:994 bounce:0
[  295.754519]  free_cma:0
					     <<<<<<<<<<<<<<<<<<<<< print per zone page state
[  295.754522] Node 0 DMA free:15884kB min:56kB low:68kB high:84kB active_anon:0kB inactive_anon:0kB active_file:0kB inactive_file:0kB unevictable:0kB isolated(anon):0kB isolated(file):0kB present:15884kB mlocked:0kB dirty:0kB writeback:0kB mapped:0kB shmem:0kB slab_reclaimable:0kB slab_unreclaimable:0kB kernel_stack:0kB pagetables:0kB unstable:0kB bounce:0kB free_cma:0kB writeback_tmp:0kB pages_scanned:0 all_unreclaimable? no
[  295.754527] lowmem_reserve[]: 0 2966 12013 12013
[  295.754530] Node 0 DMA32 free:3041228kB min:11072kB .....
[  295.754535] lowmem_reserve[]: 0 0 9046 9046
[  295.754537] Node 0 Normal free:8616716kB min:33756kB .....
[  295.754542] lowmem_reserve[]: 0 0 0 0
[  295.754545] Node 1 Normal free:12245132kB min:45220kB ....
[  295.754550] lowmem_reserve[]: 0 0 0 0
[  295.754552] Node 0 DMA: 1*4kB (U) 1*8kB (U) 0*16kB 0*32kB 2*64kB (U) 1*128kB (U) 1*256kB (U) 0*512kB 1*1024kB (U) 1*2048kB (R) 3*4096kB (M) = 15884kB
[  295.754563] Node 0 DMA32: 5*4kB (M) 3*8kB (M) 6*16kB (UM) ... 738*4096kB (MR) = 3041228kB
[  295.754574] Node 0 Normal: 16*4kB (EM) 165*8kB (UEM) ... 2101*4096kB (MR) = 8616840kB
[  295.754586] Node 1 Normal: 768*4kB (UEM) 924*8kB (UEM) ... 048kB (EM) 2976*4096kB (MR) = 12245264kB
[  295.754598] 25266 total pagecache pages
[  295.754599] 7227 pages in swap cache
					     <<<<<<<<<<<<<<<<<<<<< print global swap cache stat
[  295.754600] Swap cache stats: add 21474, delete 14247, find 533/576
[  295.754601] Free swap  = 2016000kB
[  295.754602] Total swap = 2096444kB
[  295.816119] 6291440 pages RAM
[  295.816121] 108291 pages reserved
[  295.816122] 9427 pages shared
[  295.816123] 195843 pages non-shared
[  295.816124] [ pid ]   uid  tgid total_vm      rss nr_ptes swapents oom_score_adj name
[  295.816161] [ 4569]     0  4569    16626      475      18       30             0 bash
[  295.816164] [ 4622]     0  4622   103328    87541     208    14950             0 mal
[  295.816167] [ 4623]     0  4623   103328    33468      85     5162             0 mal
[  295.816171] Memory cgroup out of memory: Kill process 4622 (mal) score 699 or sacrifice child
[  295.816173] Killed process 4622 (mal) total-vm:413312kB, anon-rss:349872kB, file-rss:292kB

We can see that messages dumped by show_free_areas() are longsome and can provide so limited info for memcg that just happen oom.

(2) After change
[  269.225628] mal invoked oom-killer: gfp_mask=0xd0, order=0, oom_score_adj=0
[  269.225633] mal cpuset=/ mems_allowed=0-1
[  269.225636] Pid: 4616, comm: mal Not tainted 3.6.0+ #25
[  269.225637] Call Trace:
[  269.225647]  [<ffffffff8111b9c4>] dump_header+0x84/0xd0
[  269.225650]  [<ffffffff8111c691>] oom_kill_process+0x331/0x350
[  269.225710]  .......(call trace)
[  269.225713]  [<ffffffff81517325>] page_fault+0x25/0x30
[  269.225716] Task in /1/2 killed as a result of limit of /1
[  269.225718] memory: usage 511732kB, limit 512000kB, failcnt 5071
[  269.225720] memory+swap: usage 563200kB, limit 563200kB, failcnt 57
[  269.225721] kmem: usage 0kB, limit 9007199254740991kB, failcnt 0
[  269.225722] Memory cgroup stats:cache:8KB rss:511724KB mapped_file:4KB swap:51468KB inactive_anon:265864KB active_anon:245832KB inactive_file:0KB active_file:0KB unevictable:0KB
[  269.225741] [ pid ]   uid  tgid total_vm      rss nr_ptes swapents oom_score_adj name
[  269.225757] [ 4554]     0  4554    16626      473      17       25             0 bash
[  269.225759] [ 4611]     0  4611   103328    90231     208    12260             0 mal
[  269.225762] [ 4616]     0  4616   103328    32799      88     7562             0 mal
[  269.225764] Memory cgroup out of memory: Kill process 4611 (mal) score 699 or sacrifice child
[  269.225766] Killed process 4611 (mal) total-vm:413312kB, anon-rss:360632kB, file-rss:292kB

This version provides more pointed info for memcg in "Memory cgroup stats" section.

seems very nice !
some nitpicks below.

quoted

Change log:
v3 <--- v2
	1. fix towards hierarchy
	2. undo rework dump_tasks
v2 <--- v1
	1. some modification towards hierarchy
	2. rework dump_tasks
	3. rebased on Michal's mm tree since-3.6

Signed-off-by: Sha Zhengju <redacted>
---
  mm/memcontrol.c |   41 +++++++++++++++++++++++++++++++----------
  mm/oom_kill.c   |    6 ++++--
  2 files changed, 35 insertions(+), 12 deletions(-)

diff --git a/mm/memcontrol.c b/mm/memcontrol.c
index 0eab7d5..17317fa 100644
--- a/mm/memcontrol.c
+++ b/mm/memcontrol.c

@@ -118,6 +118,14 @@ static const char * const mem_cgroup_events_names[] = {
  	"pgmajfault",
  };
  
+static const char * const mem_cgroup_lru_names[] = {
+	"inactive_anon",
+	"active_anon",
+	"inactive_file",
+	"active_file",
+	"unevictable",
+};
+
  /*
   * Per memcg event counter is incremented at every pagein/pageout. With THP,
   * it will be incremated by the number of pages. This counter is used for

@@ -1501,8 +1509,8 @@ static void move_unlock_mem_cgroup(struct mem_cgroup *memcg,
  	spin_unlock_irqrestore(&memcg->move_lock, *flags);
  }
  
+#define K(x) ((x) << (PAGE_SHIFT-10))
  /**
- * mem_cgroup_print_oom_info: Called from OOM with tasklist_lock held in read mode.
   * @memcg: The memory cgroup that went over limit
   * @p: Task that is going to be killed
   *

@@ -1520,8 +1528,10 @@ void mem_cgroup_print_oom_info(struct mem_cgroup *memcg, struct task_struct *p)
  	 */
  	static char memcg_name[PATH_MAX];
  	int ret;
+	struct mem_cgroup *mi;

A nitpick but I prefer using 'iter' as variable name as other for_each_mem_cgroup_tree()
in memcontrol.c

Okay, got it.

quoted

+	unsigned int i;
  
-	if (!memcg || !p)
+	if (!p)
  		return;
  
  	rcu_read_lock();

@@ -1569,6 +1579,25 @@ done:
  		res_counter_read_u64(&memcg->kmem, RES_USAGE) >> 10,
  		res_counter_read_u64(&memcg->kmem, RES_LIMIT) >> 10,
  		res_counter_read_u64(&memcg->kmem, RES_FAILCNT));
+
+	printk(KERN_INFO "Memory cgroup stats:");

why KERN_INFO rather than default_log_level ?

Err, I just keep the level consistent with the upper part of this
function. But the log levels
in oom are various: default, KERN_WARNING, KERN_INFO... etc. How about
reconcile them
in another individual patch? : )


Thanks,
Sha