On 11/03, Rafael J. Wysocki wrote: > > On Wednesday, November 02, 2011, Oleg Nesterov wrote: > > > > Rafael, could you remind why freezer_do_not_count/freezer_count check > > ->mm != NULL ? > > You're asking difficult questions. ;-) I am trying ;) > The intention was to prevent PF_FREEZER_SKIP from having any effect on > kernel threads, IIRC. Anyway, there are only two legitimate users of it > (vfork and apm_ioctl) and in both cases the task in question is user space. Actually CLONE_VFORK is used by call_usermodehelper() paths but this case is fine. The caller is the PF_NOFREEZE workqueue thread. > > The comment says "However, we don't want kernel threads to be frozen", > > but it is not clear anyway. A kernel thread simply shouldn't use this > > interface if it doesn't want to freeze. > > > > And in any case, PF_KTHREAD looks better if we really need to filter > > out the kernel threads. > > PF_FREEZER_SKIP was introduced specifically with vfork in mind and I'm not > sure if it's a good idea to re-use it for something else (at least not for > something entirely obvious). Indeed! So why do we check ->mm != NULL? We can remove this check, right now it doesn't matter. And we are trying to avoid the new users of this interface. Oleg. -- To unsubscribe from this list: send the line "unsubscribe linux-nfs" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
