> I think it again, and found that this check is necessary. Because we only > lock memory hotplug when offlining pages. Here is the steps to offline and > remove memory: > > 1. lock memory hotplug > 2. offline a memory section > 3. unlock memory hotplug > 4. repeat 1-3 to offline all memory sections > 5. lock memory hotplug > 6. remove memory > 7. unlock memory hotplug > > All memory sections must be offlined before removing memory. But we don't > hold > the lock in the whole operation. So we should check whether all memory > sections > are offlined before step6. You should describe the race scenario in the patch description. OK? -- 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>