Re: [PATCH 0/2] memcg: add the soft_limit reclaim in global direct reclaim

[Ying Han <yinghan@google.com>]

On Fri, Apr 29, 2011 at 9:44 AM, Minchan Kim <minchan.kim@gmail.com> wrote:
> Hi Ying,
>
> On Thu, Apr 28, 2011 at 03:37:04PM -0700, Ying Han wrote:
>> We recently added the change in global background reclaim which counts the
>> return value of soft_limit reclaim. Now this patch adds the similar logic
>> on global direct reclaim.
>>
>> We should skip scanning global LRU on shrink_zone if soft_limit reclaim does
>> enough work. This is the first step where we start with counting the nr_scanned
>> and nr_reclaimed from soft_limit reclaim into global scan_control.
>>
>> The patch is based on mmotm-04-14 and i triggered kernel BUG at mm/vmscan.c:1058!
>
> Could you tell me exact patches?
> mmtom-04-14 + just 2 patch of this? or + something?
>
> These day, You and Kame produces many patches.
> Do I have to apply something of them?
No, I applied my patch on top of mmotm and here is the last commit
before my patch.

commit 66a3827927351e0f88dc391919cf0cda10d42dd7
Author: Andrew Morton <akpm@linux-foundation.org>
Date:   Thu Apr 14 15:51:34 2011 -0700

>
>>
>> [  938.242033] kernel BUG at mm/vmscan.c:1058!
>> [  938.242033] invalid opcode: 0000 [#1] SMP·
>> [  938.242033] last sysfs file: /sys/devices/pci0000:00/0000:00:1f.2/device
>> [  938.242033] Pid: 546, comm: kswapd0 Tainted: G        W   2.6.39-smp-direct_reclaim
>> [  938.242033] RIP: 0010:[<ffffffff810ed174>]  [<ffffffff810ed174>] isolate_pages_global+0x18c/0x34f
>> [  938.242033] RSP: 0018:ffff88082f83bb50  EFLAGS: 00010082
>> [  938.242033] RAX: 00000000ffffffea RBX: ffff88082f83bc90 RCX: 0000000000000401
>> [  938.242033] RDX: 0000000000000001 RSI: 0000000000000000 RDI: ffffea001ca653e8
>> [  938.242033] RBP: ffff88082f83bc20 R08: 0000000000000000 R09: ffff88085ffb6e00
>> [  938.242033] R10: ffff88085ffb73d0 R11: ffff88085ffb6e00 R12: ffff88085ffb6e00
>> [  938.242033] R13: ffffea001ca65410 R14: 0000000000000001 R15: ffffea001ca653e8
>> [  938.242033] FS:  0000000000000000(0000) GS:ffff88085fd00000(0000) knlGS:0000000000000000
>> [  938.242033] CS:  0010 DS: 0000 ES: 0000 CR0: 000000008005003b
>> [  938.242033] CR2: 00007f5c3405c320 CR3: 0000000001803000 CR4: 00000000000006e0
>> [  938.242033] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
>> [  938.242033] DR3: 0000000000000000 DR6: 00000000ffff0ff0 DR7: 0000000000000400
>> [  938.242033] Process kswapd0 (pid: 546, threadinfo ffff88082f83a000, task ffff88082fe52080)
>> [  938.242033] Stack:
>> [  938.242033]  ffff88085ffb6e00 ffffea0000000002 0000000000000021 0000000000000000
>> [  938.242033]  0000000000000000 ffff88082f83bcb8 ffffea00108eec80 ffffea00108eecb8
>> [  938.242033]  ffffea00108eecf0 0000000000000004 fffffffffffffffc 0000000000000020
>> [  938.242033] Call Trace:
>> [  938.242033]  [<ffffffff810ee8a5>] shrink_inactive_list+0x185/0x418
>> [  938.242033]  [<ffffffff810366cc>] ? __switch_to+0xea/0x212
>> [  938.242033]  [<ffffffff810e8b35>] ? determine_dirtyable_memory+0x1a/0x2c
>> [  938.242033]  [<ffffffff810ef19b>] shrink_zone+0x380/0x44d
>> [  938.242033]  [<ffffffff810e5188>] ? zone_watermark_ok_safe+0xa1/0xae
>> [  938.242033]  [<ffffffff810efbd8>] kswapd+0x41b/0x76b
>> [  938.242033]  [<ffffffff810ef7bd>] ? zone_reclaim+0x2fb/0x2fb
>> [  938.242033]  [<ffffffff81088569>] kthread+0x82/0x8a
>> [  938.242033]  [<ffffffff8141b0d4>] kernel_thread_helper+0x4/0x10
>> [  938.242033]  [<ffffffff810884e7>] ? kthread_worker_fn+0x112/0x112
>> [  938.242033]  [<ffffffff8141b0d0>] ? gs_change+0xb/0xb
>>
>
> It seems there is active page in inactive list.
> As I look deactivate_page, lru_deactivate_fn clears PageActive before
> add_page_to_lru_list and it should be protected by zone->lru_lock.
> In addiion, PageLRU would protect with race with isolation functions.
>
> Hmm, I don't have any clue now.
> Is it reproducible easily?
I can manage to reproduce it on my host by adding lots of memory
pressure and then trigger the global
reclaim.

>
> Could you apply below debugging patch and report the result?
>
> diff --git a/include/linux/mm_inline.h b/include/linux/mm_inline.h
> index 8f7d247..f39b53a 100644
> --- a/include/linux/mm_inline.h
> +++ b/include/linux/mm_inline.h
> @@ -25,6 +25,8 @@ static inline void
>  __add_page_to_lru_list(struct zone *zone, struct page *page, enum lru_list l,
>                       struct list_head *head)
>  {
> +       VM_BUG_ON(PageActive(page) && (
> +                       l == LRU_INACTIVE_ANON || l == LRU_INACTIVE_FILE));
>        list_add(&page->lru, head);
>        __mod_zone_page_state(zone, NR_LRU_BASE + l, hpage_nr_pages(page));
>        mem_cgroup_add_lru_list(page, l);
> diff --git a/mm/swap.c b/mm/swap.c
> index a83ec5a..5f7c3c8 100644
> --- a/mm/swap.c
> +++ b/mm/swap.c
> @@ -454,6 +454,8 @@ static void lru_deactivate_fn(struct page *page, void *arg)
>                 * The page's writeback ends up during pagevec
>                 * We moves tha page into tail of inactive.
>                 */
> +               VM_BUG_ON(PageActive(page) && (
> +                       lru == LRU_INACTIVE_ANON || lru == LRU_INACTIVE_FILE));
>                list_move_tail(&page->lru, &zone->lru[lru].list);
>                mem_cgroup_rotate_reclaimable_page(page);
>                __count_vm_event(PGROTATED);
> diff --git a/mm/vmscan.c b/mm/vmscan.c
> index b3a569f..3415896 100644
> --- a/mm/vmscan.c
> +++ b/mm/vmscan.c
> @@ -963,7 +963,7 @@ int __isolate_lru_page(struct page *page, int mode, int file)
>
>        /* Only take pages on the LRU. */
>        if (!PageLRU(page))
> -               return ret;
> +               return 1;
>
>        /*
>         * When checking the active state, we need to be sure we are
> @@ -971,10 +971,10 @@ int __isolate_lru_page(struct page *page, int mode, int file)
>         * of each.
>         */
>        if (mode != ISOLATE_BOTH && (!PageActive(page) != !mode))
> -               return ret;
> +               return 2;
>
>        if (mode != ISOLATE_BOTH && page_is_file_cache(page) != file)
> -               return ret;
> +               return 3;
>
>        /*
>         * When this function is being called for lumpy reclaim, we
> @@ -982,7 +982,7 @@ int __isolate_lru_page(struct page *page, int mode, int file)
>         * unevictable; only give shrink_page_list evictable pages.
>         */
>        if (PageUnevictable(page))
> -               return ret;
> +               return 4;
>
>        ret = -EBUSY;
>
> @@ -1035,13 +1035,14 @@ static unsigned long isolate_lru_pages(unsigned long nr_to_scan,
>                unsigned long end_pfn;
>                unsigned long page_pfn;
>                int zone_id;
> +               int ret;
>
>                page = lru_to_page(src);
>                prefetchw_prev_lru_page(page, src, flags);
>
>                VM_BUG_ON(!PageLRU(page));
>
> -               switch (__isolate_lru_page(page, mode, file)) {
> +               switch (ret = __isolate_lru_page(page, mode, file)) {
>                case 0:
>                        list_move(&page->lru, dst);
>                        mem_cgroup_del_lru(page);
> @@ -1055,6 +1056,7 @@ static unsigned long isolate_lru_pages(unsigned long nr_to_scan,
>                        continue;
>
>                default:
> +                       printk(KERN_ERR "ret %d\n", ret);
>                        BUG();
>                }
>
>> Thank you Minchan for the pointer. I reverted the following commit and I
>> haven't seen the problem with the same operation. I haven't looked deeply
>> on the patch yet, but figured it would be a good idea to post the dump.
>> The dump looks not directly related to this patchset, but ppl can use it to
>> reproduce the problem.
>
> I tested the patch with rsync + fadvise several times
> in my machine(2P, 2G DRAM) but I didn't have ever seen the BUG.
> But I didn't test it in memcg. As I look dump, it seems not related to memcg.
> Anyway, I tried it to reproduce it in my machine.
> Maybe I will start testing after next week. Sorry.
>
> I hope my debugging patch givse some clues.
> Thanks for the reporting, Ying.

Sure, i will try the patch and post the result.

--Ying

> --
> Kind regards,
> Minchan Kim
>

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