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Date: Fri, 5 Aug 2016 09:11:10 +1000
From: Dave Chinner <david@...morbit.com>
To: Mel Gorman <mgorman@...hsingularity.net>
Cc: linux-kernel@...r.kernel.org
Subject: Re: [bug, 4.8] /proc/meminfo: counter values are very wrong
On Thu, Aug 04, 2016 at 01:34:58PM +0100, Mel Gorman wrote:
> On Thu, Aug 04, 2016 at 01:24:09PM +0100, Mel Gorman wrote:
> > On Thu, Aug 04, 2016 at 03:10:51PM +1000, Dave Chinner wrote:
> > > Hi folks,
> > >
> > > I just noticed a whacky memory usage profile when running some basic
> > > IO tests on a current 4.8 tree. It looked like there was a massive
> > > memory leak from my monitoring graphs - doing buffered IO was
> > > causing huge amounts of memory to be considered used, but the cache
> > > size was not increasing.
> > >
> > > Looking at /proc/meminfo:
> > >
> > > $ cat /proc/meminfo
> > > MemTotal: 16395408 kB
> > > MemFree: 79424 kB
> > > MemAvailable: 2497240 kB
> > > Buffers: 4372 kB
> > > Cached: 558744 kB
> > > SwapCached: 48 kB
> > > Active: 2127212 kB
> > > Inactive: 100400 kB
> > > Active(anon): 25348 kB
> > > Inactive(anon): 79424 kB
> > > Active(file): 2101864 kB
> > > Inactive(file): 20976 kB
> > > Unevictable: 13612980 kB <<<<<<<<<
> >
> > This? Very quickly done, no boot testing
> >
>
> Or better yet, this. This is aimed at the proc reporting only.
>
> diff --git a/fs/proc/meminfo.c b/fs/proc/meminfo.c
> index 09e18fdf61e5..b9a8c813e5e6 100644
> --- a/fs/proc/meminfo.c
> +++ b/fs/proc/meminfo.c
> @@ -46,7 +46,7 @@ static int meminfo_proc_show(struct seq_file *m, void *v)
> cached = 0;
>
> for (lru = LRU_BASE; lru < NR_LRU_LISTS; lru++)
> - pages[lru] = global_page_state(NR_LRU_BASE + lru);
> + pages[lru] = global_node_page_state(NR_LRU_BASE + lru);
>
> available = si_mem_available();
>
> diff --git a/mm/page_alloc.c b/mm/page_alloc.c
> index fb975cec3518..baa97da3687d 100644
> --- a/mm/page_alloc.c
> +++ b/mm/page_alloc.c
> @@ -4064,7 +4064,7 @@ long si_mem_available(void)
> int lru;
>
> for (lru = LRU_BASE; lru < NR_LRU_LISTS; lru++)
> - pages[lru] = global_page_state(NR_LRU_BASE + lru);
> + pages[lru] = global_node_page_state(NR_LRU_BASE + lru);
>
> for_each_zone(zone)
> wmark_low += zone->watermark[WMARK_LOW];
OK, that makes the /proc accounting match the /sys per-node
accounting, but the output still looks wrong. I remove files with
cached pages from the filesystem (i.e. invalidate and free them),
yet they are apparrently still accounted as being on the
active/inactive LRU.
Reboot, then run dbench for a minute:
$ sudo mkfs.xfs -f /dev/pmem1
meta-data=/dev/pmem1 isize=512 agcount=4, agsize=524288 blks
= sectsz=4096 attr=2, projid32bit=1
= crc=1 finobt=1, sparse=0
data = bsize=4096 blocks=2097152, imaxpct=25
= sunit=0 swidth=0 blks
naming =version 2 bsize=4096 ascii-ci=0 ftype=1
log =internal log bsize=4096 blocks=2560, version=2
= sectsz=4096 sunit=1 blks, lazy-count=1
realtime =none extsz=4096 blocks=0, rtextents=0
$ sudo mount /dev/pmem1 /mnt/scratch
$ sudo dbench -t 60 -D /mnt/scratch/ 16
dbench version 4.00 - Copyright Andrew Tridgell 1999-2004
Running for 60 seconds with load '/usr/share/dbench/client.txt' and minimum warmup 12 secs
13 of 16 processes prepared for launch 0 sec
16 of 16 processes prepared for launch 0 sec
releasing clients
16 21754 2147.77 MB/sec warmup 1 sec latency 17.381 ms
16 53021 2426.23 MB/sec warmup 2 sec latency 7.557 ms
16 79871 2389.22 MB/sec warmup 3 sec latency 13.746 ms
16 110047 2441.00 MB/sec warmup 4 sec latency 7.685 ms
16 141388 2495.74 MB/sec warmup 5 sec latency 10.877 ms
16 172085 2519.72 MB/sec warmup 6 sec latency 14.059 ms
16 205794 2574.78 MB/sec warmup 7 sec latency 8.034 ms
16 245632 2682.26 MB/sec warmup 8 sec latency 6.851 ms
16 286074 2771.92 MB/sec warmup 9 sec latency 6.495 ms
16 317664 2767.22 MB/sec warmup 10 sec latency 10.318 ms
16 345883 2736.86 MB/sec warmup 11 sec latency 14.107 ms
16 407209 2491.90 MB/sec execute 1 sec latency 14.000 ms
16 434075 2416.98 MB/sec execute 2 sec latency 14.067 ms
16 460773 2405.59 MB/sec execute 3 sec latency 10.984 ms
16 489597 2438.34 MB/sec execute 4 sec latency 12.759 ms
16 516526 2432.47 MB/sec execute 5 sec latency 11.068 ms
16 550227 2511.25 MB/sec execute 6 sec latency 8.156 ms
16 592814 2677.03 MB/sec execute 7 sec latency 5.571 ms
16 633506 2781.02 MB/sec execute 8 sec latency 6.116 ms
16 668733 2808.95 MB/sec execute 9 sec latency 8.357 ms
16 706375 2853.15 MB/sec execute 10 sec latency 14.133 ms
16 738346 2843.96 MB/sec execute 11 sec latency 9.305 ms
16 766890 2812.90 MB/sec execute 12 sec latency 9.677 ms
16 795720 2788.20 MB/sec execute 13 sec latency 11.019 ms
16 827221 2783.46 MB/sec execute 14 sec latency 9.281 ms
16 857404 2774.13 MB/sec execute 15 sec latency 7.055 ms
16 886224 2756.10 MB/sec execute 16 sec latency 9.445 ms
16 915254 2744.52 MB/sec execute 17 sec latency 10.447 ms
16 949089 2757.18 MB/sec execute 18 sec latency 18.721 ms
16 982041 2763.18 MB/sec execute 19 sec latency 12.401 ms
16 1013375 2762.66 MB/sec execute 20 sec latency 10.355 ms
16 1045294 2763.22 MB/sec execute 21 sec latency 11.896 ms
16 1083431 2786.87 MB/sec execute 22 sec latency 8.539 ms
16 1121150 2807.17 MB/sec execute 23 sec latency 11.574 ms
16 1152589 2803.24 MB/sec execute 24 sec latency 9.669 ms
16 1189106 2816.73 MB/sec execute 25 sec latency 10.104 ms
16 1222171 2819.00 MB/sec execute 26 sec latency 15.502 ms
16 1253029 2813.85 MB/sec execute 27 sec latency 10.030 ms
16 1283695 2808.15 MB/sec execute 28 sec latency 14.520 ms
16 1310353 2791.60 MB/sec execute 29 sec latency 10.559 ms
16 1339147 2781.06 MB/sec execute 30 sec latency 10.048 ms
16 1367932 2772.66 MB/sec execute 31 sec latency 8.283 ms
16 1397614 2766.76 MB/sec execute 32 sec latency 18.411 ms
16 1424115 2753.46 MB/sec execute 33 sec latency 10.346 ms
16 1450474 2739.71 MB/sec execute 34 sec latency 14.018 ms
16 1477712 2729.13 MB/sec execute 35 sec latency 13.977 ms
16 1504889 2719.33 MB/sec execute 36 sec latency 12.919 ms
16 1541168 2731.19 MB/sec execute 37 sec latency 7.316 ms
16 1576119 2738.48 MB/sec execute 38 sec latency 7.054 ms
16 1607758 2738.84 MB/sec execute 39 sec latency 8.155 ms
16 1640821 2742.17 MB/sec execute 40 sec latency 6.686 ms
16 1672161 2741.02 MB/sec execute 41 sec latency 10.458 ms
16 1701658 2736.87 MB/sec execute 42 sec latency 13.877 ms
16 1731166 2732.70 MB/sec execute 43 sec latency 12.307 ms
16 1759926 2726.88 MB/sec execute 44 sec latency 9.745 ms
16 1785855 2716.11 MB/sec execute 45 sec latency 12.085 ms
16 1815083 2712.64 MB/sec execute 46 sec latency 8.048 ms
16 1843967 2708.13 MB/sec execute 47 sec latency 13.302 ms
16 1871199 2701.24 MB/sec execute 48 sec latency 10.160 ms
16 1898231 2694.15 MB/sec execute 49 sec latency 16.625 ms
16 1929620 2694.67 MB/sec execute 50 sec latency 10.693 ms
16 1968670 2708.80 MB/sec execute 51 sec latency 20.115 ms
16 2001738 2711.94 MB/sec execute 52 sec latency 7.594 ms
16 2038135 2720.41 MB/sec execute 53 sec latency 12.177 ms
16 2069687 2721.12 MB/sec execute 54 sec latency 8.222 ms
16 2097545 2715.63 MB/sec execute 55 sec latency 14.536 ms
16 2122502 2705.52 MB/sec execute 56 sec latency 14.738 ms
16 2148142 2697.19 MB/sec execute 57 sec latency 14.473 ms
16 2178085 2695.15 MB/sec execute 58 sec latency 8.586 ms
16 2210608 2697.11 MB/sec execute 59 sec latency 10.013 ms
16 cleanup 60 sec
0 cleanup 60 sec
Operation Count AvgLat MaxLat
----------------------------------------
NTCreateX 5153313 0.048 15.558
Close 3785702 0.003 8.334
Rename 218238 0.041 9.738
Unlink 1040545 0.336 18.710
Deltree 136 11.999 65.636
Mkdir 68 0.004 0.007
Qpathinfo 4670973 0.007 8.336
Qfileinfo 818833 0.001 8.544
Qfsinfo 856506 0.005 4.494
Sfileinfo 419850 0.013 8.224
Find 1806064 0.018 13.301
WriteX 2570636 0.032 16.620
ReadX 8078906 0.005 12.453
LockX 16782 0.004 1.633
UnlockX 16782 0.002 0.179
Flush 361228 0.171 20.110
Throughput 2697.11 MB/sec 16 clients 16 procs max_latency=20.115 ms
$ cat /proc/meminfo
MemTotal: 16395372 kB
MemFree: 74092 kB
MemAvailable: 16090152 kB
Buffers: 59348 kB
Cached: 142660 kB
SwapCached: 0 kB
Active: 3098852 kB
Inactive: 12669128 kB
Active(anon): 21580 kB
Inactive(anon): 25288 kB
Active(file): 3077272 kB
Inactive(file): 12643840 kB
Unevictable: 3516 kB
Mlocked: 3516 kB
SwapTotal: 497976 kB
SwapFree: 497976 kB
Dirty: 0 kB
Writeback: 0 kB
AnonPages: 39248 kB
Mapped: 36596 kB
Shmem: 8968 kB
Slab: 462224 kB
SReclaimable: 428468 kB
SUnreclaim: 33756 kB
KernelStack: 6256 kB
PageTables: 6852 kB
NFS_Unstable: 0 kB
Bounce: 0 kB
WritebackTmp: 0 kB
CommitLimit: 8695660 kB
Committed_AS: 187528 kB
VmallocTotal: 34359738367 kB
VmallocUsed: 0 kB
VmallocChunk: 0 kB
HugePages_Total: 0
HugePages_Free: 0
HugePages_Rsvd: 0
HugePages_Surp: 0
Hugepagesize: 2048 kB
DirectMap4k: 14204 kB
DirectMap2M: 16762880 kB
$
dbench completely removes the files it uses during the test.
Aparently I have 15GB of cached file lru pages in the system now,
which should be impossible because the filesystem is only 8GB in
size. It also doesn't match the "cached" accounting, so free
considers all these lru pages as used, not free:
$ free
total used free shared buff/cache available
Mem: 16395372 15652956 78264 8968 664152 16094336
Swap: 497976 0 497976
$
So there's still something screwed up....
Cheers,
Dave.
--
Dave Chinner
david@...morbit.com
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