On Mon, 22 Jul 2013 16:55:58 -0700 Colin Cross <ccross@xxxxxxxxxxx> wrote: > On Mon, Jul 22, 2013 at 4:02 PM, Michael Leun > <lkml20130126@xxxxxxxxxxxxxxx> wrote: > > On Mon, 6 May 2013 16:50:18 -0700 > > Colin Cross <ccross@xxxxxxxxxxx> wrote: > > > >> Avoid waking up every thread sleeping in a futex_wait call during > > [...] > > > > With 3.11-rc s2disk from suspend-utils stopped working: Frozen at > > displaying 0% of saving image to disk. > > > > echo "1" >/sys/power/state still works. > > > > Bisecting yielded 88c8004fd3a5fdd2378069de86b90b21110d33a4, > > reverting that from 3.11-rc2 makes s2disk working again. > > > > I think the expanded use of the freezable_* helpers is exposing an > existing bug in hibernation. The SNAPSHOT_FREEZE ioctl calls > freeze_processes(), which sets the global system_freezing_cnt and > pm_freezing. try_to_freeze_tasks then sends every process except > current a signal which causes them all to end up in the refrigerator. > The current task then returns back to userspace and continues its work > to suspend to disk. If that task ever hits a call to try_to_freeze() > in the kernel, it will see system_freezing_cnt and pm_freezing=true > and freeze, and suspend to disk will hang forever. It could hit > try_to_freeze() because of a signal delivered to the task, or from > calling any syscall that uses a freezable_* helper like the one I > added to sys_futex. > > I think the right solution is to add a flag to the freezing task that > marks it unfreezable. I think PF_NOFREEZE would work, although it is > normally used on kernel threads, can you see if the attached patch > helps? That patch helps. BTW, the only machine I can reproduce this bug with is an i7-3630QM notebook. Cannot reproduce on an Core Duo U1400 and cannot reproduce on an i7 M 620. Are the sysreq backtraces still wanted? If so, any tip, how I could get them saved? -- MfG, Michael Leun -- 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
