Re: [Bug #13371] s2disk hangs with kernel 2.6.29 and later, SATA, Gigabyte EG45M-DS2H

[Richard Atterer <richard-2/EmM+jwkBzwc4Swprx3xw@public.gmane.org>]

Hello,

this bug is still present, but so far (despite lots of useful help by 
Bartlomiej) I have been unable to bisect the issue.

We took some of the discussion off-list - here is a summary, with some new 
results at the end:

* I originally bisected the bug and identified this patch as the culprit:
295f00042aaf6b553b5f37348f89bab463d4a469: ide: don't execute the next 
queued command from the hard-IRQ context (v2)

* The fix for 295f000 (2ea5521: ide: fix suspend regression) did not fix my 
problem either.

* After some mails, I switched to CONFIG_IDE=n in the config I use for 
testing (was CONFIG_IDE=m before), because the problem still occurred in 
that case. The result of this:
295f000 (ide: don't execute the next queued command from the hard-IRQ
        context (v2)): ***Works*** with CONFIG_IDE=n
2ea5521 (ide: fix suspend regression): Hangs with CONFIG_IDE=n
1406de8 (2.6.30-rc6): Hangs with CONFIG_IDE=n

I also disconnected my second (PATA) disk at that point, since it does not 
influence the bug. So my system is SATA-only, both the (single) hard disk 
and my DVD writer are SATA.

* I bisected 295f000..2ea5521 and ended up at this as the first bad commit:
9ea09af3bd3090e8349ca2899ca2011bd94cda85: stop_machine: introduce stop_machine_create/destroy.
This turns out to be a bug that was fixed by
a0e280e0f33f6c859a235fb69a875ed8f3420388: stop_machine/cpu hotplug: fix disable_nonboot_cpus

* a0e280e worked for me, so (with increasing grumpiness;) I bisected 
a0e280e..2ea5521. This bisect didn't work, I ended up with a reported "bad" 
commit which was clearly not the problem. The configs and bisect log are at
<http://atterer.net/s2disk-config/>
The bisect log lines with "OK" mean that I went back and booted the kernel 
a second time, to make sure I hadn't mixed something up. But the second 
tries all had the same result as the first.

* Bart analysed that part of the history and suggested trying out 73d5931, 
and if that worked, bisecting 73d5931..2ea5521.

Today I re-tried both 73d5931 and 2ea5521, and it turns out that in both 
cases, s2disk hangs. :-|

By chance, I noticed that the behaviour during the hang is different from 
what I reported before, at least with these two versions. Initially, I 
said that the system would hang after the "s2disk: Snapshotting system" 
with a blinking cursor.
It turns out that actually it hangs for quite a while (maybe 2 minutes?) 
and only then starts to perform the s2disk!! The last lines written are 
"s2disk: Compression ratio 0.24" or similar, and then a line containing 
just "S¦". Afterwards, the system does *not* power off as it usually does, 
but just seems to hang again. (I think I waited for a few minutes, but 
nothing happened.)

Since the last, third bisect did not work, I'm at a loss what to try next.

Cheers,

  Richard

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