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SubjectRe: [BUG] Code reordering in swsusp breaks suspend on SMP systems

> 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. 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?
(cesky, pictures)
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