On Tue, 2007-11-06 at 17:46 +1100, Stephen Rothwell wrote:
> On Mon, 05 Nov 2007 18:23:07 +0000 David <david@unsolicited.net> wrote:
> >
> > I've been testing rc1 for a week or so, and about 25% of the time I'm
> > seeing Firefox and Thunderbird getting stuck in 'D' state as they startup.
> > 
> > I've attached the output of Sysrq-T to this mail... system is a
> > dual-core AMD64, and files are on a RAID-1 root partition connected two
> > SATA disks on the on-board NVidia controller. I've had no problems
> > before .24 rc1
> 
> I am seeing something very similar on a PowerPC machine where copying a
> file from an LVM volume with ext3 on it to a simple scsi partition (again
> ext3) on the same disk will hang in congestion_wait.  If I am patient
> enough, the copy makes very slow progress.  A kill -9 will kill it
> eventually, but a simple control-C will not.
> 
> This hang occurs more often than not (and usually when I am trying to
> install a new kernel into /boot for testing :-)).
> 
> I don't have access to the machine today, but if more information would
> be useful, I could boot into 2.6.24-rc1-<mumble> again tomorrow.

LVM will provide a different BDI even though it could be on the same
disk as another 'real' partition. Still that should not make the copy
take that long.

I tried copying a 1M file from the lvm to a real partition on the same
disk (after ensuring the lvm had all the dirty limit), works like
advertised.

x86_64 SMP PREEMPT v2.6.24-rc1-748-g2655e2c + the four attached patches
rawhide x86_64 userland

To test this scenario I made an lvm thingy /dev/lvm/foo on /dev/sdb6

/ -> /dev/sda3
/dev/sdb1 /mnt/sdb1
/dev/lvm/foo -> /mnt/foo

All ext3 for this test.

The pretty numbers come from:

# while sleep 1; do cat /sys/class/bdi/*/bdi_dirty_kb | awk '{t=$0; n+=
$0; while (getline) { t=t " " $0; n+=$0; } ; getline total <
"/sys/class/bdi/sda/dirty_kb" ; print t " : " n "/" total }' ; done

while doing:

# dd if=/dev/zero of=/mnt/foo/zero bs=4096 count=$((1024*1024/4))

dm-0 ............................................. sda sdb ..........

0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 159440 0 0 0 0 0 0 : 159440/193540
5848 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 89588 0 0 0 0 0 0 : 95436/193092
41488 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 82908 0 0 0 0 0 0 : 124396/192576
69984 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 62100 0 0 0 0 0 0 : 132084/191952
93488 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 67132 0 0 0 0 0 0 : 160620/191752
114452 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 57676 0 0 0 0 0 0 : 172128/191696
124260 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 53508 0 0 0 0 0 0 : 177768/191544
138072 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 53140 0 0 0 0 0 0 : 191212/191252
145004 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 45748 0 0 0 0 0 0 : 190752/190804
155408 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 35508 0 0 0 0 0 0 : 190916/190920
162252 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 29192 0 0 0 0 0 0 : 191444/191392
165968 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 25108 0 0 0 0 0 0 : 191076/191036
168480 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 22316 0 0 0 0 0 0 : 190796/190768
173308 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 17428 0 0 0 0 0 0 : 190736/190640
177504 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 13784 0 0 0 0 0 0 : 191288/191240
179792 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 12036 0 0 0 0 0 0 : 191828/191768
179976 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 11920 0 0 0 0 0 0 : 191896/191836
179956 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 11920 0 0 0 0 0 0 : 191876/191828
179996 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 11900 0 0 0 0 0 0 : 191896/191836
180088 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 11904 0 0 0 0 0 0 : 191992/191932
180084 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 11904 0 0 0 0 0 0 : 191988/191928
180092 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 11904 0 0 0 0 0 0 : 191996/191948
180108 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 11904 0 0 0 0 0 0 : 192012/191952
180128 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 11904 0 0 0 0 0 0 : 192032/191976
180112 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 11904 0 0 0 0 0 0 : 192016/191968
180124 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 11904 0 0 0 0 0 0 : 192028/191972
180120 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 11904 0 0 0 0 0 0 : 192024/191964
180116 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 11904 0 0 0 0 0 0 : 192020/191960
180108 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 11904 0 0 0 0 0 0 : 192012/191952
180116 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 11904 0 0 0 0 0 0 : 192020/191960
180112 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 11904 0 0 0 0 0 0 : 192016/191956
180116 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 11904 0 0 0 0 0 0 : 192020/191960
180108 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 11904 0 0 0 0 0 0 : 192012/191964
182444 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 9344 0 0 0 0 0 0 : 191788/191744
182436 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 9344 0 0 0 0 0 0 : 191780/191736
182452 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 9344 0 0 0 0 0 0 : 191796/191752
182412 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 9340 0 0 0 0 0 0 : 191752/191712
182436 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 9344 0 0 0 0 0 0 : 191780/191736
182620 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 9352 0 0 0 0 0 0 : 191972/191940
182616 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 9352 0 0 0 0 0 0 : 191968/191924
182600 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 9352 0 0 0 0 0 0 : 191952/191920
182636 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 9352 0 0 0 0 0 0 : 191988/191948

# dd if=/dev/zero of=/mnt/sdb1/zero bs=4096 count=$((1024*1024/4))

dm-0 ............................................. sda sdb ..........

107608 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 9344 0 0 0 0 0 0 : 116952/191732
78824 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 7984 27644 0 0 0 0 0 : 114452/191544
77372 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 6548 56972 0 0 0 0 0 : 140892/191400
81412 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 5392 80476 0 0 0 0 0 : 167280/191224
76444 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 4252 104060 0 0 0 0 0 : 184756/191492
63408 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 3412 121332 0 0 0 0 0 : 188152/191464
57868 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 2976 130160 0 0 0 0 0 : 191004/191368
49324 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 2520 139324 0 0 0 0 0 : 191168/191192
40516 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 2072 148420 0 0 0 0 0 : 191008/191020
33748 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 1724 156288 0 0 0 0 0 : 191760/191772
29280 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 1496 160896 0 0 0 0 0 : 191672/191688
26288 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 1344 163744 0 0 0 0 0 : 191376/191400
21440 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 1096 168844 0 0 0 0 0 : 191380/191372
17796 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 908 172452 0 0 0 0 0 : 191156/191164
16004 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 816 174636 0 0 0 0 0 : 191456/191468
15048 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 768 175836 0 0 0 0 0 : 191652/191664
15052 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 768 175896 0 0 0 0 0 : 191716/191728
12904 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 660 178228 0 0 0 0 0 : 191792/191812
12880 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 656 178264 0 0 0 0 0 : 191800/191812
12884 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 656 178284 0 0 0 0 0 : 191824/191832
12900 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 656 178512 0 0 0 0 0 : 192068/192092
12900 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 656 178528 0 0 0 0 0 : 192084/192096
12900 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 656 178516 0 0 0 0 0 : 192072/192084
9256 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 472 182184 0 0 0 0 0 : 191912/191892
9256 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 472 182156 0 0 0 0 0 : 191884/191860
9256 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 472 182180 0 0 0 0 0 : 191908/191888
9256 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 472 182172 0 0 0 0 0 : 191900/191880
9260 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 472 182192 0 0 0 0 0 : 191924/191900
9268 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 472 182352 0 0 0 0 0 : 192092/192080
9268 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 472 182384 0 0 0 0 0 : 192124/192100
9268 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 472 182372 0 0 0 0 0 : 192112/192100
9268 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 472 182380 0 0 0 0 0 : 192120/192096
9268 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 472 182364 0 0 0 0 0 : 192104/192092
9268 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 472 182396 0 0 0 0 0 : 192136/192112
9268 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 472 182392 0 0 0 0 0 : 192132/192108