Kernel Bug Tracker – Bug 11050
software suspend does not work when mounted cifs share inaccessible
Last modified: 2012-05-22 12:44:11 UTC
Latest working kernel version: unknown
Earliest failing kernel version: 2.6.25
Hardware Environment: hp nc4010 notebook
Software suspend does not work when there is a mounted cifs share, and the server that serves the share is inaccessible.
Steps to reproduce:
0) make a local network where the local DHCP points to a local DNS that resolves a name such as nonexistent.nodomain to a private ip such as 10.0.0.1.
connect the PC to the local network.
1) mount //nonexistent/someshare
2) move the PC to a public network
1) make an alias address such as
ifconfig eth0:0 10.0.0.1
Note: does not work with 127.0.0.1 for some reason (another cifs bug?)
2) mount //10.0.0.1/someshare
3) disable access to the server: iptables -P OUTPUT DROP
In either case the suspend does not complete - it attempts to stop the tasks, prints a lot of backtraces and scheduler debug info, and then resumes the tasks again.
Created attachment 16758 [details]
the kernel messages from my log that seem relevant
Created attachment 17515 [details]
patch to allow cifsnotifyd thread to be suspended
Let me know if this fixes the problem
I have not been able to reproduce the original problem yet (which may be a good sign as I am running current code, 2.6.27-rc4) - but it may turn out that suspend is failing when cifs is in the process of reconnecting to the server (which might happen in the situation you describe).
You note that this fails to localhost as well - could you describe the steps you followed for failure when mounted to localhost?
You cannot make it fail with localhost, at least not with my current kernel + cifs.
However, you may try to reproduce with a local interface alias address as describe above in B).
It may take some time to apply the patch and build a kernel, I currently do not have compiled kernel sources due to disk space limitations, sorry.
With 2.6.27-rc5 I can reproduce the problem using the above steps (under B).
AFAICT the patch makes no difference.
I ran command 'suspend' on a Linux workstation and it tells me
-bash: suspend: cannot suspend a login shell
Do I need a Linux laptop for this to try out?
no, it should work equally poorly on any hardware.
However, this problem would not normally manifest on a desktop because it is typically connected to a single network only and does not move elsewhere.
If you cannot suspend your machine to disk either your suspend script or your kernel is broken.
The command to suspend is probably not 'suspend', however. 'suspend' in bash is equivalent of Ctrl+Z.
It would be something like '/sbin/hibernate' or 'echo disk > /sys/power/state'
linux-1t9o:~ # uname -r
//192.168.1.71/winshare on /mnt/smb_a type cifs (rw,mand)
linux-1t9o:~ # echo disk > /sys/power/state
bash: echo: write error: Function not implemented
linux-1t9o:~ # suspend
The pty is not responding to any commands. Do not know what to make
out of this. I could do other things on this desktop i.e. open a new tty
and execute commands in it.
I created an alias like 10.0.0.1 on my eth0 interface, I can ping it but a
command like this fails:
mount -t cifs //10.0.0.1/<sambashare> <mountpoint> -o user=user,pass=password
fails with the error mount error 112 = Host is down
I did start samba daemons with command like this /usr/sbin/smbd start on
this very same machine.
(In reply to comment #8)
> linux-1t9o:~ # uname -r
> //192.168.1.71/winshare on /mnt/smb_a type cifs (rw,mand)
> linux-1t9o:~ # echo disk > /sys/power/state
> bash: echo: write error: Function not implemented\
Perhaps you did not compile software suspned into your kernel?
> linux-1t9o:~ # suspend
This is a bash command that is equivalent to sending SIGSTOP to the current shell.
> The pty is not responding to any commands. Do not know what to make
> out of this. I could do other things on this desktop i.e. open a new tty
> and execute commands in it.
That it did exactly what it is supposed to do.
In case it was not clear enough from comment #7:
In the steps to reproduce I use 'suspend' to mean putting the system into a deep sleep state such as using 'echo disk > /sys/power/state', invoking a suspend script such as '/usr/sbin/hibernate', invoking the 'Hibernate' option in some GUI or pressing a hardware button which is configured to perform one of the above.
It does *not* mean invoking the bash command 'suspend' which is completely unrelated to system state and only stops that single shell.
(In reply to comment #9)
> I created an alias like 10.0.0.1 on my eth0 interface, I can ping it but a
> command like this fails:
> mount -t cifs //10.0.0.1/<sambashare> <mountpoint> -o user=user,pass=password
> fails with the error mount error 112 = Host is down
> I did start samba daemons with command like this /usr/sbin/smbd start on
> this very same machine.
Did you actually configure your samba server to export the share?
Can you mount the share on any other IP (127.0.0.1, your normal outside IP)?
Do you have any firewall in place?
Is the server actually running (some distributions require modifying some settings to actually start services)?
For me mounting a share like this works so there must be something wrong with your networking or samba server.
Thanks Michael, much clearer.
I can mount the samba share on a Windows XP box (over eth0) but can't mount
over eth0, eth0 alias, and loopback interfaces on this 2.6.25-rc6 kernel box.
On a 18.104.22.168, I can do all i.e. mount a local samba share over eth0, eth0
alias, and loopback interfaces.
Will continue debugging.
I am using 2.6.24 kernel, everything is fine i.e. I can create an alias,
mount a share using that alias.
But the .config does not have ip_tables module so I iptables command fails.
Then I issue command echo disk > /sys/power/state, whole system
suspends (i.e. screen blanks out and system does not respond the
keyboard/mouse etc.) and comes back when I push the power button.
Will repeat this on a 2.6.27 machine I have which has ip_tables module built.
Scenario B listed in the first comment, does not quite recreate on 2.6.27.
For suspend, I am using command echo disk > /sys/power/state.
With or without a cifs mount, after the echo disk command is executed, the
screen blanks out but returns with a message on pty,
bash: echo: write error. Device or resource busy
I take it back, I did execute scenario B with all the steps this 2.6.27 kernel
and like I see on 2.6.24, the kernel suspends and resumes when powere button is
It is broken on 2.6.27-rc5 but I cannot reproduce on another machine running 22.214.171.124.
I will try to upgrade the laptop to a later kernel.
I'm sorry I put you through so much trouble to test a problem that seems fixed in current kernels.
I could not reproduce it (scenario b) on 2.6.29-rc3. Suspend worked fine (although the subsequent wakeup from suspended state failed a few minutes later, in what I believe, is an unrelated problem with video drivers).
It is possible that the change to the send handling or the change to remove dir_notify from the kernel (which affected one of cifs's background threads) may be the reason why it now works.
I cannot test on the laptop because 126.96.36.199 does not recognize my dm volumes.
Michael, any luck on testing this on later kernels on laptop or otherwise
as per your comment #18?
Yes, I installed a 2.6.29 from Debian which sees my volumes.
However, it still has the bug (using scenario A to reproduce).
Perhaps I should look what patches Debian applies and how the other scenario works.
Created attachment 22577 [details]
kernel output during suspend attempt
I've hit this accidentally on 2.6.31-rc4 by doing the following:
1. Connect to a friend's Windows laptop using smb4k through his WLAN.
2. Suspend. (no problem yet)
3. Go to my home and continue working on my WLAN.
4. Suspend triggers the bug now (because my friend's laptop cannot be reached)
So far I haven't tried to re-produce, but I will, if that helps.
If this is reproducible let us know (and if possible let us know the stack trace of the failing process)
*** Bug 20442 has been marked as a duplicate of this bug. ***
This bug is 100% reproducible; just mount a share from another computer; then shut down (or suspend) that computer, then try to suspend the first computer; it won't suspend.
Created attachment 43632 [details]
patch -- set send and receive timeouts before attempting to connect
Does this patch happen to fix the issue? It should apply cleanly to current mainline tree.
Bug #15165 refers to much the same symptoms but with NFS (and it's not actually resolved). I wonder if it's worth making it a duplicate of this bug? They're obviously quite related. Although, sometimes I see the bug even without a share mounted: my suspicion in this case is that the nfs.mount is trying to reach the server at the time suspend is run.
Steve, I would love to see this bug (assuming it is the same one) resolved and can afford a bit of time to work on the code if I understand it. Please let me/us know where/how to direct our efforts! Thanks, cheers.
OK, please ignore what I said about bug #15165, I must have been high (or low) when I wrote that.
What I was trying to say is that I have seen the same symptoms that this bug describes but with NFS instead CIFS.
Jeff, I tried to find the equivalent code in the NFS client that your patch for CIFS affects but without success. If you (or someone) can provide a patch for NFS, I can test it fairly soon.
Or, should I open a new bug, since I'm talking about NFS, not CIFS?