Re: [PATCH] mm: cma: report correct node id

[Nathan Chancellor <nathan@kernel.org>]

Hi Kefeng,

On Thu, Oct 19, 2023 at 09:32:53AM +0800, Kefeng Wang wrote:
> Use early_pfn_to_nid() to get correct node id from base instead of
> the default NUMA_NO_NODE in cma_declare_contiguous_nid().
> 
> Signed-off-by: Kefeng Wang <wangkefeng.wang@huawei.com>
> ---
>  mm/cma.c | 3 +++
>  1 file changed, 3 insertions(+)
> 
> diff --git a/mm/cma.c b/mm/cma.c
> index 2b2494fd6b59..97c27e5fe1a2 100644
> --- a/mm/cma.c
> +++ b/mm/cma.c
> @@ -375,6 +375,9 @@ int __init cma_declare_contiguous_nid(phys_addr_t base,
>  	if (ret)
>  		goto free_mem;
>  
> +	if (nid == NUMA_NO_NODE)
> +		nid = early_pfn_to_nid(PHYS_PFN(base));
> +
>  	pr_info("Reserved %ld MiB at %pa on node %d\n", (unsigned long)size / SZ_1M,
>  		&base, nid);
>  	return 0;
> -- 
> 2.27.0
> 

I bisected a RISC-V boot failure in QEMU to this change in -next. It
happens with OpenSUSE's RISC-V configuration [1], which I was able to
narrow down to the follow configurations on top of defconfig:

CONFIG_ACPI_SPCR_TABLE=y
CONFIG_CMA=y
CONFIG_DEFERRED_STRUCT_PAGE_INIT=y
CONFIG_DMA_CMA=y
CONFIG_NUMA=y

To easily reproduce:

$ echo 'CONFIG_ACPI_SPCR_TABLE=y
CONFIG_CMA=y
CONFIG_DEFERRED_STRUCT_PAGE_INIT=y
CONFIG_DMA_CMA=y
CONFIG_NUMA=y' >kernel/configs/repro.config

$ make -skj"$(nproc)" ARCH=riscv CROSS_COMPILE=riscv64-linux- defconfig repro.config Image

$ qemu-system-riscv64 \
    -display none \
    -nodefaults \
    -bios default \
    -M virt \
    -append earlycon \
    -kernel arch/riscv/boot/Image \
    -initrd riscv-rootfs.cpio \
    -m 512m \
    -serial mon:stdio

OpenSBI v1.3.1
...

<hangs after OpenSBI output>

Without CONFIG_ACPI_SPCR_TABLE=y, there is a visible crash.

[    0.000000] Linux version 6.6.0-rc7-next-20231025 (nathan@dev-fedora.c3-large-arm64) (riscv64-linux-gcc (GCC) 13.2.0, GNU ld (GNU Binutils) 2.41) #1 SMP Wed Oct 25 16:14:59 UTC 2023
...
[    0.000000] mem auto-init: stack:all(zero), heap alloc:off, heap free:off
[    0.000000] page:ff1c000002200000 is uninitialized and poisoned
[    0.000000] page dumped because: VM_BUG_ON_PAGE(1 && PageCompound(page))
[    0.000000] ------------[ cut here ]------------
[    0.000000] kernel BUG at include/linux/page-flags.h:493!
[    0.000000] Kernel BUG [#1]
[    0.000000] Modules linked in:
[    0.000000] CPU: 0 PID: 0 Comm: swapper Not tainted 6.6.0-rc7-next-20231025 #1
[    0.000000] Hardware name: riscv-virtio,qemu (DT)
[    0.000000] epc : __free_pages_core+0x78/0x126
[    0.000000]  ra : __free_pages_core+0x78/0x126
[    0.000000] epc : ffffffff8018dd8e ra : ffffffff8018dd8e sp : ffffffff81403d40
[    0.000000]  gp : ffffffff815013a0 tp : ffffffff8140db00 t0 : 6d75642065676170
[    0.000000]  t1 : 0000000000000070 t2 : 706d756420656761 s0 : ffffffff81403d50
[    0.000000]  s1 : 0000000000000004 a0 : 000000000000003c a1 : ffffffff814866a8
[    0.000000]  a2 : 0000000000000000 a3 : 0000000000000001 a4 : 0000000000000000
[    0.000000]  a5 : 0000000000000000 a6 : 0000000000000008 a7 : 0000000000000038
[    0.000000]  s2 : 0000000000088000 s3 : ff1c000002200000 s4 : 0000000000000009
[    0.000000]  s5 : 00000000ffffffff s6 : 0000000000081800 s7 : 0000000000088200
[    0.000000]  s8 : 00000000000001c0 s9 : 0040000000000000 s10: ffffffff81500bdd
[    0.000000]  s11: ffffffff81500bdc t3 : ffffffff81515aa7 t4 : ffffffff81515aa7
[    0.000000]  t5 : ffffffff81515aa8 t6 : ffffffff81403b58
[    0.000000] status: 0000000200000100 badaddr: 0000000000000000 cause: 0000000000000003
[    0.000000] [<ffffffff8018dd8e>] __free_pages_core+0x78/0x126
[    0.000000] [<ffffffff80a12fee>] memblock_free_pages+0x52/0x62
[    0.000000] [<ffffffff80a15f02>] memblock_free_all+0x1fc/0x27e
[    0.000000] [<ffffffff80a061fa>] mem_init+0x34/0x22c
[    0.000000] [<ffffffff80a13114>] mm_core_init+0x116/0x2d0
[    0.000000] [<ffffffff80a00a6e>] start_kernel+0x3c6/0x742
[    0.000000] Code: 0405 8399 8b85 d7f1 9597 00e2 8593 2ae5 90ef e5dd (9002) 6597
[    0.000000] ---[ end trace 0000000000000000 ]---
[    0.000000] Kernel panic - not syncing: Fatal exception in interrupt

The rootfs is available at [2] if necessary. If there is any more
information I can provide or patches I can test, I am more than happy to
do so.

[1]: https://github.com/openSUSE/kernel-source/raw/master/config/riscv64/default
[2]: https://github.com/ClangBuiltLinux/boot-utils/releases

Cheers,
Nathan