2024년 4월 17일 (수) 오후 3:03, Mike Rapoport <rppt@xxxxxxxxxx>님이 작성: > > On Tue, Apr 16, 2024 at 09:06:35PM +0900, skseofh@xxxxxxxxx wrote: > > From: Daero Lee <daero_le.lee@xxxxxxxxxxx> > > > > Like reserved-memory with the 'no-map' property and only 'size' property > > (w/o 'reg' property), there are memory regions need to be allocated in > > memblock.memory marked with the MEMBLOCK_NOMAP flag, but should not be > > allocated in memblock.reserved. > > This still does not explain why you need such regions. > > As Wei Yang explained, memblock does not allocate memory from > memblock.reserved. The memblock.reserved array represents memory that is in > use by firmware or by early kernel allocations and cannot be freed to page > allocator. Thank you for your comments. I used the wrong word. When I use 'allocate', I mean that the region 'adds' to the memblock.reserved. > > If you have a region that's _NOMAP in memblock.memory and is absent in > memblock.reserved it will not be mapped by the kernel page tables, but it > will be considered as free memory by the core mm. > > Is this really what you want? If my understanding is right, before freeing (memory && !reserved) area, we marked the memblock.reserved regions and memblock.memory regions with no-map flag. And when we free (memory && !reserved) area, we skip the memblock.memory regions with no-map(see should_skip_region). So, I think that the memory regions with no-map flag will not be considered as free memory. If there is anything I think is wrong, feel free to correct me. Regards, DaeRo Lee
