Messages in this thread | | | Date | Tue, 24 Sep 2013 02:21:11 +0200 | From | Pavel Machek <> | Subject | Re: [Suspend-devel] [BUG] 3.7-rc regression bisected: s2disk fails to resume image: Processes could not be frozen, cannot continue resuming |
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Hi!
> > And from suspend_ioctls.h: > > #define SNAPSHOT_IOC_MAGIC '3' > > #define SNAPSHOT_FREEZE _IO(SNAPSHOT_IOC_MAGIC, 1) > > > > My mistake, should be '3' instead of 3. > > OK... The thing to test, then, is what does __usermodehelper_disable() > return to freeze_processes(). If that's where this -EAGAIN comes from, > we at least have a plausible theory re what's going on. > > freeze_processes() uses __usermodehelper_disable() to stop any new userland > processes spawned by UMH (modprobe, etc.) and waits for ones it might be > waiting for to complete. Then it does try_to_freeze_tasks(), which > freezes remaining userland, carefully skipping the current thread. > However, it misses the possibility that current thread might have been > spawned by something that had been launched by UMH, with UMH waiting > for it. Which is the case of everything spawned by linuxrc. > > I'd try something like diff below, but I'm *NOT* familiar with swsusp at > all; it's not for mainline until ACKed by swsusp folks. > > diff --git a/kernel/kmod.c b/kernel/kmod.c > index fb32636..d968882 100644 > --- a/kernel/kmod.c > +++ b/kernel/kmod.c > @@ -571,7 +571,8 @@ int call_usermodehelper_exec(struct subprocess_info *sub_info, int wait) > DECLARE_COMPLETION_ONSTACK(done); > int retval = 0; > > - helper_lock(); > + if (!(current->flags & PF_FREEZER_SKIP)) > + helper_lock(); > if (!khelper_wq || usermodehelper_disabled) { > retval = -EBUSY; > goto out; > @@ -611,7 +612,8 @@ wait_done: > out: > call_usermodehelper_freeinfo(sub_info); > unlock: > - helper_unlock(); > + if (!(current->flags & PF_FREEZER_SKIP)) > + helper_unlock(); > return retval; > } > EXPORT_SYMBOL(call_usermodehelper_exec);
PF_FREEZER_SKIP flag is manipulated at about 1000 places, so I'm not sure this will nest correctly. They seem to be in form of
|= FREEZER_SKIP schedule() &= ~FREEZER_SKIP
so this should be safe, but...
Pavel -- (english) http://www.livejournal.com/~pavelmachek (cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html
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