lkml.org 
[lkml]   [2010]   [Jan]   [22]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
    /
    From
    SubjectRe: [RFC][PATCH] PM: disable nonboot cpus before suspending devices
    Date
    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.

    The real solution would be to remove the memory allocations from the
    _cpu_down() call path.

    BTW, this is one of the cases I and Ben are talking about where it's not
    practical to rework the code just to avoid memory allocation problems during
    suspend/resume.

    Rafael


    \
     
     \ /
      Last update: 2010-01-22 21:51    [W:0.021 / U:50.652 seconds]
    ©2003-2017 Jasper Spaans. hosted at Digital OceanAdvertise on this site