Messages in this thread | | | Date | Sun, 5 Feb 2006 01:38:59 -0800 | From | Andrew Morton <> | Subject | Re: [PATCH -mm] swsusp: freeze user space processes first |
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"Rafael J. Wysocki" <rjw@sisk.pl> wrote: > > Hi, > > This patch allows swsusp to freeze processes successfully under heavy load > by freezing userspace processes before kernel threads. > > ... > > /* 0 = success, else # of processes that we failed to stop */ > int freeze_processes(void) > { > - int todo; > + int todo, nr_user, user_frozen; > unsigned long start_time; > struct task_struct *g, *p; > unsigned long flags; > > printk( "Stopping tasks: " ); > start_time = jiffies; > + user_frozen = 0; > do { > - todo = 0; > + nr_user = todo = 0; > read_lock(&tasklist_lock); > do_each_thread(g, p) { > if (!freezeable(p)) > continue; > if (frozen(p)) > continue; > - > - freeze(p); > - spin_lock_irqsave(&p->sighand->siglock, flags); > - signal_wake_up(p, 0); > - spin_unlock_irqrestore(&p->sighand->siglock, flags); > - todo++; > + if (p->mm && !(p->flags & PF_BORROWED_MM)) { > + /* The task is a user-space one. > + * Freeze it unless there's a vfork completion > + * pending > + */ > + if (!p->vfork_done) > + freeze_process(p); > + nr_user++; > + } else { > + /* Freeze only if the user space is frozen */ > + if (user_frozen) > + freeze_process(p); > + todo++; > + } > } while_each_thread(g, p); > read_unlock(&tasklist_lock); > + todo += nr_user; > + if (!user_frozen && !nr_user) { > + sys_sync(); > + start_time = jiffies; > + } > + user_frozen = !nr_user; > yield(); /* Yield is okay here */ > - if (todo && time_after(jiffies, start_time + TIMEOUT)) { > - printk( "\n" ); > - printk(KERN_ERR " stopping tasks timed out (%d tasks remaining)\n", todo ); > + if (todo && time_after(jiffies, start_time + TIMEOUT)) > break;
The logic in that loop makes my brain burst.
What happens if a process does vfork();sleep(100000000)?
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