Hi, On Wednesday, 6 of April 2005 01:10, Nigel Cunningham wrote: > Hi. > > On Wed, 2005-04-06 at 08:57, Pavel Machek wrote: > > Hi! > > > > > > > 2) We can try to force uninterruptible tasks to get their "signals" anyway using > > > > > wake_up_state() directly on them (which I don't like as much). > > > > > > > > They are probably uninterruptible for a reason... > > > > > > > > If something is staying in UNINTERRUPTIBLE for more than 1 second, it > > > > is going to cause problems elsewhere, anyway. Do you see that happening? > > > > > > Probably. Please see, for example, this message sent to l-k: > > > > > > http://marc.theaimsgroup.com/?l=linux-kernel&m=111268969510393&w=2 > > > > ...hmm, perhaps kseriod needs suspend/resume support, or something; It seems that anything compiled in (ie not as a module) which ends up in call_usermodehelper() during boot is likely to need this kind of handling. > > but that does not mean we should handle *all* uninterruptible tasks > > that way. > > > > > I can easily trigger a similar behavior with an uninterruptible task and I > > > have some problems with freezing tasks on SMP that smell like this too. > > > > > > If we are going to ignore uninterruptible tasks, I'd propose to set PF_FREEZE > > > and TIF_SIGPENDING for them without counting them as "todo" in > > > > You can't just ignore uninterruptible tasks, sorry. > > I don't think Rafael is suggesting ignoring them. Words, words ... ;-) > He's suggesting what I'm already doing: > - Signal so they enter the freezer if they leave the state; > - Don't count them when deciding whether freezing failed; > - Handle the case where they don't leave the state until post resume (I > let them enter the refrigerator, but have code in there to check whether > the freezer is still on). Yup. Actaully, I think of something like this (tested once): --- old/kernel/power/process.c 2005-04-06 08:30:47.000000000 +0200 +++ new/kernel/power/process.c 2005-04-06 08:31:31.000000000 +0200 @@ -18,6 +18,7 @@ */ #define TIMEOUT (6 * HZ) +static int refrigerator_disabled; static inline int freezeable(struct task_struct * p) { @@ -47,9 +48,12 @@ void refrigerator(unsigned long flag) recalc_sigpending(); /* We sent fake signal, clean it up */ spin_unlock_irq(¤t->sighand->siglock); - current->flags |= PF_FROZEN; - while (current->flags & PF_FROZEN) - schedule(); + if (!refrigerator_disabled) { + current->flags |= PF_FROZEN; + while (current->flags & PF_FROZEN) + schedule(); + } + pr_debug("%s left refrigerator\n", current->comm); current->state = save; } @@ -62,6 +66,7 @@ int freeze_processes(void) struct task_struct *g, *p; printk( "Stopping tasks: " ); + refrigerator_disabled = 0; start_time = jiffies; do { todo = 0; @@ -72,6 +77,9 @@ int freeze_processes(void) continue; if (p->flags & PF_FROZEN) continue; + if ((p->flags & PF_FREEZE) && + (p->state == TASK_UNINTERRUPTIBLE)) + continue; /* FIXME: smp problem here: we may not access other process' flags without locking */ @@ -100,6 +108,7 @@ void thaw_processes(void) struct task_struct *g, *p; printk( "Restarting tasks..." ); + refrigerator_disabled = 1; read_lock(&tasklist_lock); do_each_thread(g, p) { if (!freezeable(p)) > > In this way, I handle kseriod and anything else uninterruptible without > any problems. Exactly. :-) Greets, Rafael -- - Would you tell me, please, which way I ought to go from here? - That depends a good deal on where you want to get to. -- Lewis Carroll "Alice's Adventures in Wonderland"
