lkml.org 
[lkml]   [2017]   [Mar]   [20]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
    /
    Date
    From
    Subjectmemory hotplug and force_remove
    Hi Rafael,
    we have been chasing the following BUG() triggering during the memory
    hotremove (remove_memory):
    ret = walk_memory_range(PFN_DOWN(start), PFN_UP(start + size - 1), NULL,
    check_memblock_offlined_cb);
    if (ret)
    BUG();

    and it took a while to learn that the issue is caused by
    /sys/firmware/acpi/hotplug/force_remove being enabled. I was really
    surprised to see such an option because at least for the memory hotplug
    it cannot work at all. Memory hotplug fails when the memory is still
    in use. Even if we do not BUG() here enforcing the hotplug operation
    will lead to problematic behavior later like crash or a silent memory
    corruption if the memory gets onlined back and reused by somebody else.

    I am wondering what was the motivation for introducing this behavior and
    whether there is a way to disallow it for memory hotplug. Or maybe drop
    it completely. What would break in such a case?

    Thanks!
    --
    Michal Hocko
    SUSE Labs

    \
     
     \ /
      Last update: 2017-03-20 20:30    [W:4.432 / U:0.280 seconds]
    ©2003-2017 Jasper Spaans. hosted at Digital OceanAdvertise on this site