Greetings, Nowadays I'm working on 'IRQ Stack' on ARM64 [1]. Like x86, I'd like to utilize percpu infrastructure for stack allocation, but I've got a challenge. ARM64 uses a generic setup_per_cpu_areas() described in mm/percpu.c. IOW, __per_cpu_offset[] is PAGE_SIZE aligned, and it is not possible to allocate stack with an alignment which is bigger than PAGE_SIZE. At first glance, the alignment of __per_cpu_offset[] looks controlled by 'atom_size' argument of pcpu_embed_first_chunk(), but I soon realize that the 'atom_size' is not configurable in this case. It would be redundant to introduce ARM64-specific setup_per_cpu_areas() for a single parameter, atom_size, change. At the same time, it is doubtable to define an interface, like PERCPU_ENOUGH_ROOM [2], for a single arch support. I'm not sure which approach is better than the other. Any comments are greatly welcome. Thanks in advance! [1] https://lkml.org/lkml/2015/10/17/75 [2] Since no code uses PERCPU_ENOUGH_ROOM, it could be dropped as clean-up. -- Best Regards Jungseok Lee -- 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>