Recent CMA change "cma: make number of CMA areas dynamic, remove CONFIG_CMA_AREAS" breaks the boot of arm64 kernel in linux-next. Knic is like: Unable to handle kernel paging request at virtual address ffff0000438fff70 Mem abort info: ESR = 0x96000044 EC = 0x25: DABT (current EL), IL = 32 bits SET = 0, FnV = 0 EA = 0, S1PTW = 0 Data abort info: ISV = 0, ISS = 0x00000044 CM = 0, WnR = 1 swapper pgtable: 4k pages, 48-bit VAs, pgdp=0000000041f61000 [ffff0000438fff70] pgd=0000000000000000, p4d=0000000000000000 Internal error: Oops: 96000044 [#1] PREEMPT SMP Modules linked in: CPU: 0 PID: 0 Comm: swapper Not tainted 5.9.0-rc3-00020-ge1bce3d64c48 #2 Hardware name: linux,dummy-virt (DT) pstate: 20000085 (nzCv daIf -PAN -UAO BTYPE=--) pc : __memset+0x148/0x188 lr : memblock_alloc_try_nid+0xbc/0xd4 sp : ffff800011ab3d10 x29: ffff800011ab3d10 x28: 0000000041710018 x27: 0000000040000000 x26: ffff8000115d1000 x25: 0000000000000000 x24: ffff800011300428 x23: ffff800011d1bd60 x22: 0000000000000000 x21: 00000000ffffffff x20: ffff0000438fff70 x19: 0000000000000090 x18: 0000000000000010 x17: 0000000000001400 x16: 0000000000001c00 x15: ffff800011ac3530 x14: ffff800011ac3530 x13: fffffdfffe600000 x12: ffff800011ab3e44 x11: 0000000000000004 x10: 0000000000000018 x9 : 0000000000000000 x8 : ffff0000438fff70 x7 : 0000000000000000 x6 : 000000000000003f x5 : 0000000000000040 x4 : 0000000000000010 x3 : 0000000000000080 x2 : 0000000000000080 x1 : 0000000000000000 x0 : ffff0000438fff70 Call trace: __memset+0x148/0x188 cma_init_reserved_mem+0x94/0x154 cma_declare_contiguous_nid+0x240/0x2bc dma_contiguous_reserve_area+0x48/0x78 dma_contiguous_reserve+0x78/0x88 arm64_memblock_init+0x424/0x45c setup_arch+0x270/0x5f0 start_kernel+0x84/0x4dc Code: f101007f fa45a068 54fffc0b aa0303e2 (a9001d07) random: get_random_bytes called from print_oops_end_marker+0x2c/0x68 with crng_init=0 ---[ end trace 0000000000000000 ]--- Kernel panic - not syncing: Attempted to kill the idle task! ---[ end Kernel panic - not syncing: Attempted to kill the idle task! ]--- The virtual address returned from memblock_alloc() is not ready till paging_init() is done. Cc: Roman Gushchin <guro@xxxxxx> Cc: Mike Kravetz <mike.kravetz@xxxxxxxxxx> Cc: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> Cc: Will Deacon <will@xxxxxxxxxx> Cc: Stephen Rothwell <sfr@xxxxxxxxxxxxxxxx> Signed-off-by: Barry Song <song.bao.hua@xxxxxxxxxxxxx> --- -v1: to fix the knic during boot after applying Mike's patch: https://lore.kernel.org/linux-mm/20200915205703.34572-1-mike.kravetz@xxxxxxxxxx/ arch/arm64/mm/init.c | 9 +++++++-- 1 file changed, 7 insertions(+), 2 deletions(-) diff --git a/arch/arm64/mm/init.c b/arch/arm64/mm/init.c index f1c75957ff3c..8dd61d07fff5 100644 --- a/arch/arm64/mm/init.c +++ b/arch/arm64/mm/init.c @@ -402,8 +402,6 @@ void __init arm64_memblock_init(void) reserve_elfcorehdr(); high_memory = __va(memblock_end_of_DRAM() - 1) + 1; - - dma_contiguous_reserve(arm64_dma32_phys_limit); } void __init bootmem_init(void) @@ -415,6 +413,13 @@ void __init bootmem_init(void) early_memtest(min << PAGE_SHIFT, max << PAGE_SHIFT); + /* + * CMA is using memblock_alloc(), the virtual address returned + * from memblock_alloc() isn't ready till paging_init(). + * So this has to happen after paging_init() + */ + dma_contiguous_reserve(arm64_dma32_phys_limit); + max_pfn = max_low_pfn = max; min_low_pfn = min; -- 2.25.1
