On Friday 22 January 2010, Rafael J. Wysocki wrote: > On Friday 22 January 2010, Sebastian Ott wrote: > > hi Rafael, > > > > on s390 we have a reproduceable testcase where, after all devices were > > suspended, a memory allocation results in disk IO. I know that this is > > similar to the current discussion about magically changing the gpf mask, > > but in our case the related allocation is triggered not by a device driver > > but directly by hibernation_snapshot. The call chain looks like this: > > > > STACK: > > 0 schedule+1796 [0x5a7af0] > > 1 io_schedule+98 [0x5a82ce] > > 2 sync_page_killable+4 [0x1ec424] > > 3 __wait_on_bit+204 [0x5a8bc4] > > 4 add_to_page_cache_locked+2 [0x1ec766] > > 5 shrink_page_list+2372 [0x1fc5b0] > > 6 shrink_list+2496 [0x1fd02c] > > 7 shrink_zone+932 [0x1fd3e0] > > 8 try_to_free_pages+668 [0x1fe4bc] > > 9 __alloc_pages_nodemask+1346 [0x1f5056] > > 10 __get_free_pages+76 [0x1f52dc] > > 11 __build_sched_domains+60 [0x144f98] > > 12 partition_sched_domains+696 [0x145dcc] > > 13 update_sched_domains+100 [0x146104] > > 14 notifier_call_chain+166 [0x5ae112] > > 15 raw_notifier_call_chain+44 [0x1800c4] > > 16 _cpu_down+586 [0x59f212] > > 17 disable_nonboot_cpus+354 [0x155ad2] > > 18 hibernation_snapshot+324 [0x1a7938] > > 19 hibernate+304 [0x1a7bcc] > > 20 state_store+130 [0x1a645e] > > 21 sysfs_write_file+264 [0x2b551c] > > 22 vfs_write+190 [0x23f98a] > > 23 sys_write+100 [0x23fb50] > > 24 sysc_noemu+16 [0x118ff6] > > > > a possible fix would be to call disable_nonboot_cpus before suspending the > > devices.. > > This is going against the changes attempting to speed-up suspend and resume, > such as the asynchronous suspend/resume patchset, so I don't agree with it. In fact there's more to it. enable_nonboot_cpus() has to be called before suspend_ops->wake() (and analogously for hibernation), because of some ACPI-related ordering constraints (calling them in the reverse orther leads to _serious_ problems during resume). In turn, suspend_ops->wake() should be called before we resume devices, for similar reasons. So, your patch really would break things. Rafael _______________________________________________ linux-pm mailing list linux-pm@xxxxxxxxxxxxxxxxxxxxxxxxxx https://lists.linux-foundation.org/mailman/listinfo/linux-pm
