On Monday, March 20, 2017 03:29:39 PM Michal Hocko wrote: > Hi Rafael, Hi, > 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? Honestly, I don't remember from the top of my head and I haven't looked at that code for several months. I need some time to recall that. Thanks, Rafael -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@xxxxxxxxx. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>
