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    SubjectRe: [BUG] Code reordering in swsusp breaks suspend on SMP systems
    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?
    Pavel
    --
    (english) http://www.livejournal.com/~pavelmachek
    (cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html
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