(2012/11/09 0:52), Sha Zhengju wrote:
> From: Sha Zhengju <handai....@taobao.com>
> 
> 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.

> 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 <handai....@taobao.com>
> ---
>   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


> +     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 ?

Thanks,
-Kame

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