I may have stumbled into a kernel memory leak during reshaping of a RAID 10
from offset to near layout:
I have a RAID 10 array which was previously in offset layout. I decided to
reshape to a near layout. Eventually the machine had become very sluggish,
the load average shot up, and the reshape slowed down to nearly nothing.
md127 : active raid10 sdh1[2] sdk1[3] sdf1[0] sdg1[1]
7813771264 blocks super 1.2 512K chunks 2 near-copies [4/4] [UUUU]
[=========>...........] reshape = 49.5% (3872227840/7813771264) finish=63624.5min speed=1032K/sec
A look at slabtop appears to show that there is an allocation that is
larger than the physical RAM (16GB):
Active / Total Objects (% used) : 61551490 / 61918456 (99.4%)
Active / Total Slabs (% used) : 2209811 / 2209811 (100.0%)
Active / Total Caches (% used) : 76 / 99 (76.8%)
Active / Total Size (% used) : 15241504.92K / 15319798.41K (99.5%)
Minimum / Average / Maximum Object : 0.01K / 0.25K / 15.69K
OBJS ACTIVE USE OBJ SIZE SLABS OBJ/SLAB CACHE SIZE NAME
60511744 60511219 29% 0.25K 2183366 32 17466928K kmalloc-256
193408 82391 42% 0.06K 3022 64 12088K kmalloc-64
154880 129949 83% 0.03K 1210 128 4840K kmalloc-32
154624 152783 98% 0.01K 302 512 1208K kmalloc-8
144160 143412 99% 0.02K 848 170 3392K fsnotify_event_holder
125103 34053 27% 0.08K 2453 51 9812K selinux_inode_security
Output of mdadm -D:
/dev/md127:
Version : 1.2
Creation Time : Wed Dec 20 19:41:25 2013
Raid Level : raid10
Array Size : 7813771264 (7451.79 GiB 8001.30 GB)
Used Dev Size : 3906885632 (3725.90 GiB 4000.65 GB)
Raid Devices : 4
Total Devices : 4
Persistence : Superblock is persistent
Update Time : Sat Jul 19 22:20:55 2014
State : active, reshaping
Active Devices : 4
Working Devices : 4
Failed Devices : 0
Spare Devices : 0
Layout : offset=2
Chunk Size : 512K
Reshape Status : 49% complete
New Layout : near=2, far=1
Name : local:home (local to host local)
UUID : 3102a888:f08888a8:da88e888:c6288888
Events : 70841
Number Major Minor RaidDevice State
0 8 81 0 active sync /dev/sdf1
1 8 97 1 active sync /dev/sdg1
2 8 113 2 active sync /dev/sdh1
3 8 161 3 active sync /dev/sdk1
uname -r output:
3.13.6-200.fc20.x86_64
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