On 08.10.24 15:27, Ritesh Harjani (IBM) wrote:
During early init CMA_MIN_ALIGNMENT_BYTES can be PAGE_SIZE, since pageblock_order is still zero and it gets initialized later during paging_init() e.g. paging_init() -> free_area_init() -> set_pageblock_order(). One such use case is - early_setup() -> early_init_devtree() -> fadump_reserve_mem() This causes CMA memory alignment check to be bypassed in cma_init_reserved_mem(). Then later cma_activate_area() can hit a VM_BUG_ON_PAGE(pfn & ((1 << order) - 1)) if the reserved memory area was not pageblock_order aligned. Instead of fixing it locally for fadump case on PowerPC, I believe this should be fixed for CMA_MIN_ALIGNMENT_BYTES.
I think we should add a way to catch the usage of CMA_MIN_ALIGNMENT_BYTES before it actually has meaning (before pageblock_order was set) and fix the PowerPC usage by reshuffling the code accordingly.
-- Cheers, David / dhildenb
