On Thursday 22 March 2007 01:53:54 Rafael J. Wysocki wrote:
> On Thursday, 22 March 2007 00:39, Maxim wrote:
> > On Thursday 22 March 2007 01:24:25 Rafael J. Wysocki wrote:
> > > On Thursday, 22 March 2007 00:09, Maxim wrote:
> > > > On Thursday 22 March 2007 00:39:02 you wrote:
> > > > > On Wednesday, 21 March 2007 23:21, Pavel Machek wrote:
> > > > > > Hi!
> > > > > >
> > > > > > > Starting with 2.6.21-rc1 suspend to ram and disk doesn't work
> > > > > > > anymore on my system.
> > > > > > >
> > > > > > > I did a git-bisect and found that those commits break it:
> > > > > > >
> > > > > > > e3c7db621bed4afb8e231cb005057f2feb5db557 - [PATCH] [PATCH] PM:
> > > > > > > Change code ordering in main.c
> > > > > > > ed746e3b18f4df18afa3763155972c5835f284c5 - [PATCH] [PATCH]
> > > > > > > swsusp: Change code ordering in disk.c
> > > > > > > 259130526c267550bc365d3015917d90667732f1 - [PATCH] [PATCH]
> > > > > > > swsusp: Change code ordering in user.c
> > > > > > >
> > > > > >
> > > > > > (Yep, it was in my "to analyze" queue).
> > > > > >
> > > > > > > I already reported about it, but now i know the reason why
> > > > > > > suspend breaks.
> > > > > > >
> > > > > > > The problem is that both cpu_up/cpu_down were allowed to sleep
> > > > > > > until now,
> > > > > > > and it did work because those functions could be called only in
> > > > > > > process context
> > > > > > > (the one that writes to /sys/devices/system/cpu/cpu*/online) or
> > > > > > > idle thread that does smp_init()).
> > > > > > >
> > > > > > > But now they are called _after_ all tasks were suspended, so if
> > > > > > > cpu_down tries for example to take a lock
> > > > > > > that is taken by different process, it can't since the different
> > > > > > > proccess is frozen and can't release the lock.
> > > > > > >
> > > > > >
> > > > > > Thanks for detailed explanation.
> > > > > >
> > > > > > ...but, on my machine suspend works ok in -rc4. I'm not seeing this.
> > > > > >
> > > > > > ...by design, "frozen" tasks must not hold any locks. If frozen task
> > > > > > holds a lock, that's a bug.
> > > > > >
> > > > > > > Or, it is also possible to revert this change.
> > > > > >
> > > > > > Are you using xfs?
> > > > >
> > > > > Well, this is the only case that can trigger it. There are no other
> > > > > freezable
> > > > > workqueues.
> > > > >
> > > > > Greetings,
> > > > > Rafael
> > > > >
> > > >
> > > > Hello,
> > > >
> > > > Yes, you are right and it is XFS
> > > >
> > > > System suspends and resumes with xfs and your patch correctly,
> > >
> > > Could you please sent this information to the list? I'd like it to reach
> > > all
> > > of the CCed parites. ;-)
> >
> > I did now ( sorry I just keep using this Answer command, instead of Answer
> > to everybody)
> > I didn't intend to send private email.
> > >
> > > > Of course I need to mention that I had to unload microcode
> > > > update driver because it prevented resume,
> > > > because it calls firmware loader helper, and again sleeps on
> > > > lock
> > >
> > > This is interesting. Did it happen before or is it a regression?
> >
> > It is from the same group of bugs , I mean hang because cpu_up/down is
> > called with frozen tasks
> > Of course it didn't happen before those reordering commits were introduced
>
> Well, we want cpu_up/down to be called after processes have been frozen, for
> various reasons (one of them being that applications shouldn't see us playing
> with the CPUs).
>
> Thanks for reporting this, I'll have a look at the microcode update driver.
>
> > > > And also I noticed now that system oopses on second attempt to
> > > > suspend ether to ram or disk
> > > > in pci_restore_msi_state which is called indirectly by
> > > > ahci_pci_device_resume, I will investigate this soon.
> > >
> > > Thanks. We've had such reports earlier, but I think the problem is still
> > > unresolved. Any
> > > additional information will be valuable.
> >
> > I will do my best,
> > Also I want to note that the above problem is 100% repeatable, and happens
> > independently whenever suspend to disk
> > or suspend to ram was used in first successful try ( or at least, I got
> > back-trace using kdb, after suspend to disk, after
> > suspend to ram system hang, so I assume, that this it is same problem ,
> > because it didn't hang of first try)
>
> Thanks for the information.
>
> BTW, what's the last kernel you have tested?
>
> Rafael
>
Hello,
Thanks for quick response,
I will continue to test my system
I use literally latest Linus's git tree.
The kernel that works is 2.6.20 , and except very weird hang that happens
sometimes (1 in 5~6 times) on resume from ram, everything works
I described it in http://lkml.org/lkml/2007/3/16/126
Regards,
Maxim Levitsky
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