Re: [Bug 53031] New: kswapd in uninterruptible sleep state

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(switched to email.  Please respond via emailed reply-to-all, not via the
bugzilla web interface).

On Fri, 25 Jan 2013 17:56:25 +0000 (UTC)
bugzilla-daemon@xxxxxxxxxxxxxxxxxxx wrote:

> https://bugzilla.kernel.org/show_bug.cgi?id=53031
> 
>            Summary: kswapd in uninterruptible sleep state
>            Product: Memory Management
>            Version: 2.5
>     Kernel Version: 3.7.3,3.7.4
>           Platform: All
>         OS/Version: Linux
>               Tree: Mainline
>             Status: NEW
>           Severity: normal
>           Priority: P1
>          Component: Other
>         AssignedTo: akpm@xxxxxxxxxxxxxxxxxxxx
>         ReportedBy: dairinin@xxxxxxxxx
>         Regression: No

I'd say "Regression: yes"!

Can you please run sysrq-W (or "echo w > /proc/sysrq-trigger" when
kswapd is stuck so we can see where it is stuck?

Also sysrq-m when it is in that state would be useful, thanks.

[remainder retained for linux-mm to enjoy]

> 
> Created an attachment (id=91781)
>  --> (https://bugzilla.kernel.org/attachment.cgi?id=91781)
> Script do show what has changed in /proc/vmstat
> 
> I have recently upgraded from 3.2 to 3.7.3, and I am seeing, that the
> behavior of kswapd is strange at least.
> 
> The machine is core2duo e7200 with 4G RAM, running 3.7.3 kernel. It has
> compaction and THP (always) enabled.
> 
> The machine is serving files over the network, so it is constantly under
> memory pressure from page cache. The network is not very fast, and average disk
> read rate is between 2 and 8 megabytes per second.
> 
> In normal state, when page cache is filled, the free memory (according
> to free and vmstat) is fluctuating between 100 and 150 megabytes, with
> kswapd stepping in at 100M, quickly freeing to 150M and going to sleep
> again.
> 
> 1) On 3.7.3, after several hours after page cache is filled, kswapd enters
> permanent D-state, with free memory keeping around 150M (high watermark,
> I presume?). I have captured diffs for /proc/vmstat:
> 
> $ ./diffshow 5
> ----8<----
> nr_free_pages:____________________________________38327 -> 38467 (140)
> nr_active_anon:__________________________________110014 -> 110056 (42)
> nr_inactive_file:______________________________526153 -> 526297 (144)
> nr_active_file:__________________________________98802 -> 98864 (62)
> nr_anon_pages:____________________________________103475 -> 103512 (37)
> nr_file_pages:____________________________________627957 -> 628160 (203)
> nr_dirty:______________________________________________15 -> 17 (2)
> nr_page_table_pages:________________________2142 -> 2146 (4)
> nr_kernel_stack:________________________________251 -> 253 (2)
> nr_dirtied:__________________________________________1169312 -> 1169317 (5)
> nr_written:__________________________________________1211979 -> 1211982 (3)
> nr_dirty_threshold:__________________________159540 -> 159617 (77)
> nr_dirty_background_threshold:____79770 -> 79808 (38)
> pgpgin:__________________________________________________564650577 -> 564673241 (22664)
> pgpgout:________________________________________________5117612 -> 5117668 (56)
> pgalloc_dma32:____________________________________105487556 -> 105491067 (3511)
> pgalloc_normal:__________________________________84026173 -> 84029309 (3136)
> pgfree:__________________________________________________190134573 -> 190141394 (6821)
> pgactivate:__________________________________________2750244 -> 2750283 (39)
> pgfault:________________________________________________67214984 -> 67216222 (1238)
> pgsteal_kswapd_dma32:______________________45793109 -> 45795077 (1968)
> pgsteal_kswapd_normal:____________________61391466 -> 61394464 (2998)
> pgscan_kswapd_dma32:________________________45812628 -> 45814596 (1968)
> pgscan_kswapd_normal:______________________61465283 -> 61468281 (2998)
> slabs_scanned:____________________________________30783104 -> 30786432 (3328)
> pageoutrun:__________________________________________2936967 -> 2937033 (66)
> 
> vmstat:
> procs -----------memory---------- ---swap-- -----io---- -system-- ----cpu----
> __r__ b____ swpd____ free____ buff__ cache____ si____ so______ bi______ bo____ in____ cs us sy id wa
> __1__ 1 296924 153064____ 6936 2479664______ 0______ 0__ 5408________ 0 11711 1350__ 1__ 2 44 53
> __0__ 1 296924 152448____ 6928 2480048______ 0______ 0__ 6760________ 0 9723 1127__ 1__ 4 47 48
> __0__ 1 296924 152948____ 6916 2479464______ 0______ 0__ 3512______ 16 10392 1231__ 1__ 2 48 49
> __0__ 1 296924 153616____ 6916 2478804______ 0______ 0__ 2724________ 0 10279 1078__ 0__ 2 48 49
> __0__ 1 296924 152972____ 6916 2480132______ 0______ 0__ 3584________ 0 11289 1252__ 1__ 3 49 48
> __0__ 1 296924 155348____ 6916 2478396______ 0______ 0__ 6472________ 0 11285 1132__ 1__ 2 45 53
> __0__ 1 296924 152988____ 6916 2481024______ 0______ 0__ 5112______ 20 10039 1257__ 0__ 2 46 52
> __0__ 1 296924 152968____ 6916 2481016______ 0______ 0__ 3244________ 0 9586 1127__ 1__ 3 46 51
> __0__ 1 296924 153500____ 6916 2481196______ 0______ 0__ 3516________ 0 10899 1127__ 1__ 1 48 49
> __0__ 1 296924 152860____ 6916 2481688______ 0______ 0__ 4240________ 0 10418 1245__ 1__ 3 47 49
> __0__ 2 296924 153016____ 6912 2478584______ 0______ 0__ 5632________ 0 12136 1516__ 2__ 3 46 49
> __0__ 2 296924 153292____ 6912 2480984______ 0______ 0__ 4668________ 0 10872 1248__ 1__ 2 49 48
> __0__ 1 296924 152420____ 6916 2481844______ 0______ 0__ 4764______ 56 11236 1402__ 1__ 3 45 51
> __0__ 1 296924 152652____ 6916 2481204______ 0______ 0__ 4628________ 0 9422 1208__ 0__ 3 46 51
> 
> buddyinfo:
> $ cat /proc/buddyinfo; sleep 1; cat /proc/buddyinfo 
> Node 0, zone__________ DMA__________ 0__________ 0__________ 0__________ 1__________ 2__________ 1__________ 1__________ 0____
> ____ 1__________ 1__________ 3 
> Node 0, zone______ DMA32______ 515______ 205______ 242______ 201____ 1384______ 116________ 21__________ 8____
> ____ 1__________ 0__________ 0 
> Node 0, zone____ Normal____ 1779__________ 0__________ 0________ 18________ 11__________ 3__________ 1__________ 3____
> ____ 0__________ 0__________ 0 
> Node 0, zone__________ DMA__________ 0__________ 0__________ 0__________ 1__________ 2__________ 1__________ 1__________ 0____
> ____ 1__________ 1__________ 3 
> Node 0, zone______ DMA32______ 480______ 197______ 227______ 176____ 1384______ 116________ 21__________ 8____
> ____ 1__________ 0__________ 0 
> Node 0, zone____ Normal____ 1792__________ 9__________ 0________ 18________ 11__________ 3__________ 1__________ 3____
> ____ 0__________ 0__________ 0
> 
> 2) Also from time to time situation switches, where free memory is fixed at
> some random point, fluctuating around this values at +-1 megabyte. 
> There is vmstat:
> procs -----------memory---------- ---swap-- -----io---- -system-- ----cpu----
> __r__ b____ swpd____ free____ buff__ cache____ si____ so______ bi______ bo____ in____ cs us sy id wa
> __0__ 0 296480 381052____ 9732 2481324______ 1______ 2__ 2022______ 19____ 45____ 44__ 1__ 2 81 16
> __0__ 0 296480 382040____ 9732 2481180______ 0______ 0__ 2324________ 0 6505__ 825__ 1__ 2 96__ 1
> __0__ 0 296480 382500____ 9732 2481060______ 0______ 0__ 3824________ 0 5941 1046__ 1__ 2 96__ 1
> __0__ 0 296480 382092____ 9740 2480976______ 0______ 0__ 2048______ 16 7701__ 862__ 0__ 2 97__ 1
> __0__ 0 296480 382160____ 9740 2481896______ 0______ 0__ 5008________ 0 6443 1017__ 1__ 2 93__ 5
> __0__ 0 296480 382484____ 9740 2481668______ 0______ 0__ 2764________ 0 6972__ 799__ 0__ 2 97__ 1
> __0__ 0 296480 381912____ 9740 2481620______ 0______ 0__ 3780________ 0 7632 1036__ 1__ 2 96__ 1
> __0__ 0 296480 382240____ 9744 2481632______ 0______ 0__ 2796________ 0 7533__ 981__ 1__ 2 95__ 3
> __1__ 0 296480 382372____ 9748 2481756______ 0______ 0__ 2940________ 0 6565 1048__ 2__ 2 95__ 2
> __0__ 0 296480 383064____ 9748 2480320______ 0______ 0__ 5980________ 0 6352__ 979__ 0__ 3 92__ 5
> __0__ 0 296480 381380____ 9748 2481752______ 0______ 0__ 2732________ 0 6322__ 999__ 1__ 2 96__ 1
> __0__ 0 296480 381640____ 9748 2481992______ 0______ 0__ 2468________ 0 5640__ 849__ 0__ 2 97__ 2
> __0__ 0 296480 381684____ 9748 2481856______ 0______ 0__ 2760________ 0 7064__ 944__ 2__ 2 95__ 1
> __0__ 0 296480 381908____ 9748 2481664______ 0______ 0__ 2608________ 0 6797__ 952__ 0__ 2 94__ 4
> __0__ 0 296480 384024____ 9748 2479424______ 0______ 0__ 4804________ 0 6342 2767__ 1__ 2 94__ 4
> __0__ 0 296480 381948____ 9748 2481080______ 0______ 0__ 1868________ 0 6428__ 803__ 0__ 2 97__ 2
> __0__ 0 296480 382088____ 9748 2481524______ 0______ 0__ 3252________ 0 6464__ 990__ 1__ 1 98__ 1
> __0__ 0 296480 381884____ 9748 2481816______ 0______ 0__ 2892________ 0 7880__ 858__ 1__ 2 94__ 3
> __0__ 0 296480 382120____ 9748 2481848______ 0______ 0__ 2500________ 0 6207__ 905__ 1__ 1 96__ 2
> __0__ 1 296480 381976____ 9748 2479876______ 0______ 0__ 5188________ 0 6691__ 908__ 1__ 2 94__ 4
> __0__ 0 296480 381708____ 9748 2481584______ 0______ 0__ 2692________ 0 7904 1030__ 1__ 2 94__ 3
> __0__ 0 296480 382196____ 9748 2481704______ 0______ 0__ 2092________ 0 6715__ 722__ 1__ 1 97__ 1
> 
> 
> The /proc/vmstat diff is like this:
> 
> $ ./diffshow 5
> ----8<----
> nr_free_pages:____________________________________94999 -> 95630 (631)
> nr_inactive_anon:______________________________47076 -> 47196 (120)
> nr_inactive_file:______________________________347048 -> 347080 (32)
> nr_active_file:__________________________________270128 -> 270462 (334)
> nr_file_pages:____________________________________619886 -> 620314 (428)
> nr_dirty:______________________________________________10 -> 109 (99)
> nr_kernel_stack:________________________________248 -> 249 (1)
> nr_isolated_file:______________________________0 -> 10 (10)
> nr_dirtied:__________________________________________1147486 -> 1147659 (173)
> nr_written:__________________________________________1189947 -> 1190013 (66)
> nr_dirty_threshold:__________________________168770 -> 168974 (204)
> nr_dirty_background_threshold:____84385 -> 84487 (102)
> pgpgin:__________________________________________________528729753 -> 528750521 (20768)
> pgpgout:________________________________________________5013688 -> 5014216 (528)
> pswpin:__________________________________________________77715 -> 77827 (112)
> pgalloc_dma32:____________________________________95912002 -> 95912631 (629)
> pgalloc_normal:__________________________________82241808 -> 82247860 (6052)
> pgfree:__________________________________________________178827810 -> 178834939 (7129)
> pgactivate:__________________________________________2644761 -> 2645104 (343)
> pgfault:________________________________________________63365808 -> 63369261 (3453)
> pgmajfault:__________________________________________23571 -> 23591 (20)
> pgsteal_kswapd_normal:____________________60067802 -> 60072006 (4204)
> pgscan_kswapd_normal:______________________60141548 -> 60145753 (4205)
> slabs_scanned:____________________________________28914432 -> 28915456 (1024)
> kswapd_low_wmark_hit_quickly:______589343 -> 589376 (33)
> kswapd_high_wmark_hit_quickly:____763703 -> 763752 (49)
> pageoutrun:__________________________________________2852120 -> 2852305 (185)
> compact_blocks_moved:______________________10852682 -> 10852847 (165)
> compact_pagemigrate_failed:__________39862700 -> 39865324 (2624)
> 
> kswapd is stuck on normal zone!
> 
> Also there is raw vmstat:
> nr_free_pages 95343
> nr_inactive_anon 47196
> nr_active_anon 114110
> nr_inactive_file 348142
> nr_active_file 272638
> nr_unevictable 552
> nr_mlock 552
> nr_anon_pages 100386
> nr_mapped 6158
> nr_file_pages 623530
> nr_dirty 0
> nr_writeback 0
> nr_slab_reclaimable 21356
> nr_slab_unreclaimable 15570
> nr_page_table_pages 2045
> nr_kernel_stack 244
> nr_unstable 0
> nr_bounce 0
> nr_vmscan_write 149405
> nr_vmscan_immediate_reclaim 13896
> nr_writeback_temp 0
> nr_isolated_anon 0
> nr_isolated_file 4
> nr_shmem 48
> nr_dirtied 1147666
> nr_written 1190129
> nr_anon_transparent_hugepages 116
> nr_free_cma 0
> nr_dirty_threshold 169553
> nr_dirty_background_threshold 84776
> pgpgin 529292001
> pgpgout 5014788
> pswpin 77827
> pswpout 148890
> pgalloc_dma 0
> pgalloc_dma32 95940824
> pgalloc_normal 82395157
> pgalloc_movable 0
> pgfree 179010711
> pgactivate 2647284
> pgdeactivate 2513412
> pgfault 63427189
> pgmajfault 23606
> pgrefill_dma 0
> pgrefill_dma32 1915983
> pgrefill_normal 430939
> pgrefill_movable 0
> pgsteal_kswapd_dma 0
> pgsteal_kswapd_dma32 39927548
> pgsteal_kswapd_normal 60180622
> pgsteal_kswapd_movable 0
> pgsteal_direct_dma 0
> pgsteal_direct_dma32 14062458
> pgsteal_direct_normal 1894412
> pgsteal_direct_movable 0
> pgscan_kswapd_dma 0
> pgscan_kswapd_dma32 39946808
> pgscan_kswapd_normal 60254407
> pgscan_kswapd_movable 0
> pgscan_direct_dma 0
> pgscan_direct_dma32 14260652
> pgscan_direct_normal 1895350
> pgscan_direct_movable 0
> pgscan_direct_throttle 0
> pginodesteal 25301
> slabs_scanned 28931968
> kswapd_inodesteal 26119
> kswapd_low_wmark_hit_quickly 591050
> kswapd_high_wmark_hit_quickly 766006
> kswapd_skip_congestion_wait 15
> pageoutrun 2858733
> allocstall 156938
> pgrotated 161518
> compact_blocks_moved 10860505
> compact_pages_moved 411760
> compact_pagemigrate_failed 39987369
> compact_stall 29399
> compact_fail 23718
> compact_success 5681
> htlb_buddy_alloc_success 0
> htlb_buddy_alloc_fail 0
> unevictable_pgs_culled 6416
> unevictable_pgs_scanned 0
> unevictable_pgs_rescued 5337
> unevictable_pgs_mlocked 6672
> unevictable_pgs_munlocked 6120
> unevictable_pgs_cleared 0
> unevictable_pgs_stranded 0
> thp_fault_alloc 41
> thp_fault_fallback 302
> thp_collapse_alloc 507
> thp_collapse_alloc_failed 3704
> thp_split 111
> 
> Buddyinfo:
> $ cat /proc/buddyinfo; sleep 1; cat /proc/buddyinfo 
> Node 0, zone__________ DMA__________ 0__________ 0__________ 0__________ 1__________ 2__________ 1__________ 1__________ 0____
> ____ 1__________ 1__________ 3 
> Node 0, zone______ DMA32__ 29527__ 26916______ 489______ 221________ 40__________ 5__________ 0__________ 0____
> ____ 0__________ 0__________ 0 
> Node 0, zone____ Normal____ 3158__________ 0__________ 0__________ 2__________ 1__________ 1__________ 1__________ 1____
> ____ 0__________ 0__________ 0 
> Node 0, zone__________ DMA__________ 0__________ 0__________ 0__________ 1__________ 2__________ 1__________ 1__________ 0____
> ____ 1__________ 1__________ 3 
> Node 0, zone______ DMA32__ 29527__ 26909______ 489______ 211________ 41__________ 5__________ 0__________ 0____
> ____ 0__________ 0__________ 0 
> Node 0, zone____ Normal____ 2790________ 29__________ 0__________ 8__________ 1__________ 1__________ 1__________ 1____
> ____ 0__________ 0__________ 0 
> 
> Zoneinfo:
> $ cat /proc/zoneinfo 
> Node 0, zone__________ DMA
> __ pages free________ 3976
> ______________ min__________ 64
> ______________ low__________ 80
> ______________ high________ 96
> ______________ scanned__ 0
> ______________ spanned__ 4080
> ______________ present__ 3912
> ______ nr_free_pages 3976
> ______ nr_inactive_anon 0
> ______ nr_active_anon 0
> ______ nr_inactive_file 0
> ______ nr_active_file 0
> ______ nr_unevictable 0
> ______ nr_mlock________ 0
> ______ nr_anon_pages 0
> ______ nr_mapped______ 0
> ______ nr_file_pages 0
> ______ nr_dirty________ 0
> ______ nr_writeback 0
> ______ nr_slab_reclaimable 0
> ______ nr_slab_unreclaimable 0
> ______ nr_page_table_pages 0
> ______ nr_kernel_stack 0
> ______ nr_unstable__ 0
> ______ nr_bounce______ 0
> ______ nr_vmscan_write 0
> ______ nr_vmscan_immediate_reclaim 0
> ______ nr_writeback_temp 0
> ______ nr_isolated_anon 0
> ______ nr_isolated_file 0
> ______ nr_shmem________ 0
> ______ nr_dirtied____ 0
> ______ nr_written____ 0
> ______ nr_anon_transparent_hugepages 0
> ______ nr_free_cma__ 0
> ______________ protection: (0, 3503, 4007, 4007)
> __ pagesets
> ______ cpu: 0
> __________________________ count: 0
> __________________________ high:__ 0
> __________________________ batch: 1
> __ vm stats threshold: 8
> ______ cpu: 1
> __________________________ count: 0
> __________________________ high:__ 0
> __________________________ batch: 1
> __ vm stats threshold: 8
> __ all_unreclaimable: 1
> __ start_pfn:________________ 16
> __ inactive_ratio:______ 1
> Node 0, zone______ DMA32
> __ pages free________ 87395
> ______________ min__________ 14715
> ______________ low__________ 18393
> ______________ high________ 22072
> ______________ scanned__ 0
> ______________ spanned__ 1044480
> ______________ present__ 896960
> ______ nr_free_pages 87395
> ______ nr_inactive_anon 18907
> ______ nr_active_anon 92242
> ______ nr_inactive_file 325044
> ______ nr_active_file 267577
> ______ nr_unevictable 0
> ______ nr_mlock________ 0
> ______ nr_anon_pages 51703
> ______ nr_mapped______ 4369
> ______ nr_file_pages 593009
> ______ nr_dirty________ 17
> ______ nr_writeback 0
> ______ nr_slab_reclaimable 14988
> ______ nr_slab_unreclaimable 11515
> ______ nr_page_table_pages 1305
> ______ nr_kernel_stack 133
> ______ nr_unstable__ 0
> ______ nr_bounce______ 0
> ______ nr_vmscan_write 140220
> ______ nr_vmscan_immediate_reclaim 62
> ______ nr_writeback_temp 0
> ______ nr_isolated_anon 0
> ______ nr_isolated_file 0
> ______ nr_shmem________ 10
> ______ nr_dirtied____ 810741
> ______ nr_written____ 862763
> ______ nr_anon_transparent_hugepages 116
> ______ nr_free_cma__ 0
> ______________ protection: (0, 0, 504, 504)
> __ pagesets
> ______ cpu: 0
> __________________________ count: 123
> __________________________ high:__ 186
> __________________________ batch: 31
> __ vm stats threshold: 24
> ______ cpu: 1
> __________________________ count: 29
> __________________________ high:__ 186
> __________________________ batch: 31
> __ vm stats threshold: 24
> __ all_unreclaimable: 0
> __ start_pfn:________________ 4096
> __ inactive_ratio:______ 5
> Node 0, zone____ Normal
> __ pages free________ 3200
> ______________ min__________ 2116
> ______________ low__________ 2645
> ______________ high________ 3174
> ______________ scanned__ 0
> ______________ spanned__ 131072
> ______________ present__ 129024
> ______ nr_free_pages 3200
> ______ nr_inactive_anon 25943
> ______ nr_active_anon 24590
> ______ nr_inactive_file 23132
> ______ nr_active_file 10275
> ______ nr_unevictable 552
> ______ nr_mlock________ 552
> ______ nr_anon_pages 49050
> ______ nr_mapped______ 2088
> ______ nr_file_pages 35785
> ______ nr_dirty________ 3
> ______ nr_writeback 0
> ______ nr_slab_reclaimable 2340
> ______ nr_slab_unreclaimable 3926
> ______ nr_page_table_pages 786
> ______ nr_kernel_stack 114
> ______ nr_unstable__ 0
> ______ nr_bounce______ 0
> ______ nr_vmscan_write 9297
> ______ nr_vmscan_immediate_reclaim 13835
> ______ nr_writeback_temp 0
> ______ nr_isolated_anon 0
> ______ nr_isolated_file 10
> ______ nr_shmem________ 38
> ______ nr_dirtied____ 338110
> ______ nr_written____ 328638
> ______ nr_anon_transparent_hugepages 0
> ______ nr_free_cma__ 0
> ______________ protection: (0, 0, 0, 0)
> __ pagesets
> ______ cpu: 0
> __________________________ count: 152
> __________________________ high:__ 186
> __________________________ batch: 31
> __ vm stats threshold: 12
> ______ cpu: 1
> __________________________ count: 172
> __________________________ high:__ 186
> __________________________ batch: 31
> __ vm stats threshold: 12
> __ all_unreclaimable: 0
> __ start_pfn:________________ 1048576
> __ inactive_ratio:______ 1
> 
> I have tried disabling compaction (1000
> > /proc/sys/vm/extdefrag_threshold), and symptoms do change. There is no
> kswapd stuck in D, but instead page cache is almost cleaned from time to
> time 
> 
> Also I have a piece of code, which can reproduce the first problem with
> kswapd in D state on another amd64 system, which has normal zone
> artificially limited to the same ratio against dma32 zone. It needs a
> large file, which is at least twice as large as system RAM (the larger
> the better):
> dd if=/dev/zero of=tf bs=1M count=$((1024*8))
> 
> Then start smth like this:
> ./a.out tf 32
> and let it run for some time to fill the page cache.
> 
> The code will random read the file in fixed chunks at fixed rate in two
> "streams": one stream of 1/3 rate will be scattered across the whole
> file and mark pages with WILLNEED. Another stream at 2/3 rate is
> contained in 1/10 of a file and will not pass any hints.
> 
> 3) Now I am running 3.7.4, and atm I see the second problem again, i.e. kswapd
> is stuck on zone normal.
> 
> -- 
> Configure bugmail: https://bugzilla.kernel.org/userprefs.cgi?tab=email
> ------- You are receiving this mail because: -------
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