[Samba] Many "smbd" process with "D" uninterruptible sleep status

[Simon Wang]

I got a samba server(Linux) to store some data in my PC(windows)
frequently.  And last night I found that samba can't work. After logined to
samba server and found that there's 91 smbd processes with status "D"
totally.
# ps
    169 root         0        SW   [pdflush]
    170 root         0        DW   [pdflush]
....
29534 simon  20608 D    /sbin/smbd -D
29548 root       2792 D    /bin/sync
30160 simon  20608 D    /sbin/smbd -D
30474 simon  20608 D    /sbin/smbd -D
30496 simon  18676 D    /sbin/smbd -D
30673 simon  20504 D    /sbin/smbd -D
30810 simon  20504 D    /sbin/smbd -D
31302 simon  20608 D    /sbin/smbd -D
31965 simon  20608 D    /sbin/smbd -D
32288 simon  20608 D    /sbin/smbd -D
...
And after 5 mins the result of "ps" is the same.

The result of "top" shows below. The load average is VERY HIGHT and CPU is
busy for io.
# top
Mem: 366504K used, 143900K free, 0K shrd, 14216K buff, 293224K cached
CPU:  1.7% usr  3.5% sys  0.0% nic  0.0% idle 92.9% io  1.7% irq  0.0% sirq
Load average: 103.10 103.03 102.65 1/149 5614
PID  PPID USER     STAT   VSZ %MEM %CPU COMMAND
 5532  3325 root     R     3000  0.5  3.5 top
 2421     1 simon  D    20712  4.0  0.0 /sbin/smbd -D
  594     1 simon  D    20712  4.0  0.0 /sbin/smbd -D
 4130     1 simon  D    20712  4.0  0.0 /sbin/smbd -D
 1261     1 simon  D    20608  4.0  0.0 /sbin/smbd -D
23452     1 simon  D    20608  4.0  0.0 /sbin/smbd -D
30474     1 simon  D    20608  4.0  0.0 /sbin/smbd -D
21641     1 simon  D    20608  4.0  0.0 /sbin/smbd -D
 9053     1 simon  D    20608  4.0  0.0 /sbin/smbd -D
 3068     1 simon  D    20608  4.0  0.0 /sbin/smbd -D

After reboot, the samba works fine. Until now I cannot reproduce yet.
I can't figure out what's going on.
Is it kind of bugs in kernel or samba?
Does pdflush crash first, then affect smbd and sync to crash?

Please help,
Thanks very much.


I used some options in smb.conf:
  max smbd process = 100
  max connections = 100

Linux Samba Server:
  Linux 2.6.31.8
  Samba 3.5.6
  Software RAID 1


Simon