From: Minchan Kim <minchan@kernel.org>
To: Luigi Semenzato <semenzato@google.com>
Cc: linux-mm@kvack.org
Subject: Re: another allocation livelock with zram
Date: Wed, 21 Nov 2012 10:27:26 +0900 [thread overview]
Message-ID: <20121121012726.GA5121@bbox> (raw)
In-Reply-To: <CAA25o9T8cBhuFnesnxHDsv3PmV8tiHKoLz0dGQeUSCvtpBBv3A@mail.gmail.com>
Hi Luigi,
Question.
Is it a 3.4.0 vanilla kernel?
Otherwise, some hacky patches(ex, min_filelist_kbytes) are applied?
On Tue, Nov 20, 2012 at 03:46:34PM -0800, Luigi Semenzato wrote:
> Greetings MM folks,
>
> and thanks again for fixing my previous hang-with-zram problem. I am
> now running into a similar problem and I hope I will not take
> advantage of your kindness by asking for further advice.
>
> By running a few dozen memory-hungry processes on an ARM cpu with 2 Gb
> RAM, with zram enabled, I can easily get into a situation where all
> processes are either:
>
> 1. blocked in a futex
> 2. trying unsuccessfully to allocate memory
>
> This happens when there should still be plenty of memory: the zram
> swap device is about 1/3 full. (The output of SysRq-M is at the end.)
> Yet the SI and SO fields of vmstat stay at 0, and CPU utilization is
> 100% system.
>
> procs -----------memory---------- ---swap-- -----io---- -system-- ----cpu----
> r b swpd free buff cache si so bi bo in cs us sy id wa
> 46 0 1076432 13636 2844 216648 0 0 0 0 621 229 0 100 0 0
> 44 0 1076432 13636 2844 216648 0 0 0 0 618 204 0 100 0 0
>
> I added counters in various places in the page allocator to see which
> paths were being taken and noticed the following facts:
>
> - alloc_page_slowpath is looping, apparently trying to rebalance. It
> calls alloc_pages_direct_reclaim at a rate of about 155 times/second,
> and gets one page about once every 500 calls. Did_some_progress is
> always set to true. Then should_alloc_retry returns true (because
> order < PAGE_ALLOC_COSTLY_ORDER).
>
> - kswapd is asleep and is not woken up because alloc_page_slowpath
> never goes to the "restart" label.
>
> My questions are:
>
> 1. is it obvious to any of you what is going wrong?
> 1.1 is the allocation failing because nobody is waking up kswapd? And
> if so, why not?
>
> 2. if it's not obvious, what are the next things to look into?
>
> 3. is there a better way of debugging this?
>
> Thanks!
> Luigi
>
> [ 0.000000] Linux version 3.4.0
> (semenzato@luigi.mtv.corp.google.com) (gcc version 4.6.x-google
> 20120301 (prerelease) (gcc-4.6.3_cos_gg_2a32ae6) ) #26 SMP Tue Nov 20
> 14:27:15 PST 2012
> [ 0.000000] CPU: ARMv7 Processor [410fc0f4] revision 4 (ARMv7), cr=10c5387d
> [ 0.000000] CPU: PIPT / VIPT nonaliasing data cache, PIPT instruction cache
> [ 0.000000] Machine: SAMSUNG EXYNOS5 (Flattened Device Tree),
> model: Google Snow
> ...
> [ 198.564328] SysRq : Show Memory
> [ 198.564347] Mem-info:
> [ 198.564355] Normal per-cpu:
> [ 198.564364] CPU 0: hi: 186, btch: 31 usd: 0
> [ 198.564373] CPU 1: hi: 186, btch: 31 usd: 0
> [ 198.564381] HighMem per-cpu:
> [ 198.564389] CPU 0: hi: 90, btch: 15 usd: 0
> [ 198.564397] CPU 1: hi: 90, btch: 15 usd: 0
> [ 198.564411] active_anon:196868 inactive_anon:66835 isolated_anon:47
> [ 198.564415] active_file:13931 inactive_file:11043 isolated_file:0
> [ 198.564419] unevictable:0 dirty:4 writeback:1 unstable:0
> [ 198.564423] free:3409 slab_reclaimable:2583 slab_unreclaimable:3337
> [ 198.564427] mapped:137910 shmem:29899 pagetables:3972 bounce:0
> [ 198.564449] Normal free:13384kB min:5380kB low:6724kB high:8068kB
> active_anon:782052kB inactive_anon:261808kB active_file:25020kB
> inactive_file:24900kB unevictable:0kB isolated(anon):16kB
> isolated(file):0kB present:1811520kB mlocked:0kB dirty:12kB
> writeback:0kB mapped:461296kB shmem:115892kB slab_reclaimable:10332kB
> slab_unreclaimable:13348kB kernel_stack:3008kB pagetables:15888kB
> unstable:0kB bounce:0kB writeback_tmp:0kB pages_scanned:107282320
> all_unreclaimable? no
> [ 198.564474] lowmem_reserve[]: 0 2095 2095
> [ 198.564499] HighMem free:252kB min:260kB low:456kB high:656kB
> active_anon:5420kB inactive_anon:5532kB active_file:30704kB
> inactive_file:19272kB unevictable:0kB isolated(anon):172kB
> isolated(file):0kB present:268224kB mlocked:0kB dirty:4kB
> writeback:4kB mapped:90344kB shmem:3704kB slab_reclaimable:0kB
> slab_unreclaimable:0kB kernel_stack:0kB pagetables:0kB unstable:0kB
> bounce:0kB writeback_tmp:0kB pages_scanned:7081406 all_unreclaimable?
> no
> [ 198.564523] lowmem_reserve[]: 0 0 0
> [ 198.564536] Normal: 1570*4kB 6*8kB 1*16kB 0*32kB 0*64kB 1*128kB
> 1*256kB 1*512kB 0*1024kB 1*2048kB 1*4096kB = 13384kB
> [ 198.564574] HighMem: 59*4kB 2*8kB 0*16kB 0*32kB 0*64kB 0*128kB
> 0*256kB 0*512kB 0*1024kB 0*2048kB 0*4096kB = 252kB
> [ 198.564610] 123112 total pagecache pages
> [ 198.564616] 68239 pages in swap cache
> [ 198.564622] Swap cache stats: add 466115, delete 397876, find 31817/56350
> [ 198.564630] Free swap = 1952336kB
> [ 198.564635] Total swap = 3028768kB
> [ 198.564640] xxcount_nr_reclaimed 358488
> [ 198.564646] xxcount_nr_reclaims 6201
> [ 198.564651] xxcount_aborted_reclaim 0
> [ 198.564656] xxcount_more_to_do 5137
> [ 198.564662] xxcount_direct_reclaims 17065
> [ 198.564667] xxcount_failed_direct_reclaims 10708
> [ 198.564673] xxcount_no_progress 5696
> [ 198.564678] xxcount_restarts 5696
> [ 198.564683] xxcount_should_alloc_retry 5008
> [ 198.564688] xxcount_direct_compact 1
> [ 198.564693] xxcount_alloc_failed 115
> [ 198.564699] xxcount_gfp_nofail 0
> [ 198.564704] xxcount_costly_order 5009
> [ 198.564709] xxcount_repeat 0
> [ 198.564714] xxcount_kswapd_nap 2210
> [ 198.564719] xxcount_kswapd_sleep 17
> [ 198.564724] xxcount_kswapd_loop 2211
> [ 198.564729] xxcount_kswapd_try_to_sleep 2210
> [ 198.575349] 524288 pages of RAM
> [ 198.575358] 4420 free pages
> [ 198.575365] 7122 reserved pages
> [ 198.575371] 4091 slab pages
> [ 198.575378] 302549 pages shared
> [ 198.575384] 68239 pages swap cached
>
> --
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--
Kind regards,
Minchan Kim
--
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next prev parent reply other threads:[~2012-11-21 1:27 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-11-20 23:46 another allocation livelock with zram Luigi Semenzato
2012-11-21 1:27 ` Minchan Kim [this message]
2012-11-21 1:47 ` Luigi Semenzato
2012-11-21 13:59 ` Minchan Kim
2012-11-21 18:21 ` Luigi Semenzato
2012-11-23 5:44 ` Minchan Kim
2012-11-27 1:00 ` Luigi Semenzato
2012-11-28 6:12 ` Minchan Kim
2013-02-17 3:33 ` Jaegeuk Hanse
2013-02-17 4:55 ` Luigi Semenzato
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