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

[Nathan Chancellor <nathan@kernel.org>]

Hi Kefeng,

On Mon, Oct 30, 2023 at 05:34:32PM +0800, Kefeng Wang wrote:
> On 2023/10/26 0:37, Nathan Chancellor wrote:
> > 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:
> > 
> 
> I think the root cause is the bad node info of memory address, meanwhile,
> the riscv's cma reserve is before numa init, see the following log,
> 
> [    0.000000] cma: Reserved 16 MiB at 0x000000009f000000 on node 4
> [    0.000000] NUMA: Faking a node at [mem
> 0x0000000080000000-0x000000009fffffff]
> [    0.000000] NUMA: NODE_DATA [mem 0x9eff2780-0x9eff3fff]
> [    0.000000] NUMA: NODE_DATA(0) on node 4		// should be node 0
> [    0.000000] [ff1c000002000000-ff1c000002000fff] potential offnode
> page_structs
> 
> additional, early_pfn_to_nid will cache the recent lookups of pfn-to-nid,
> which
> led to the next early_pfn_to_nid get the cache nid, not the new nid(changed
> by numa init),
> 
> setup_arch
>  paging_init
>   dma_contiguous_reserve
>    cma_declare_contiguous_nid // 9f000000 node 4
>     early_pfn_to_nid		  // 1. lookup memblk, pfn=9f000, nid=4 cached
>  misc_mem_init
>   arch_numa_init
>    numa_init
>     dummy_numa_init
>      numa_add_memblk		  // 2. setup new nid of memblk
>     numa_register_nodes
>      setup_node_data
>       early_pfn_to_nid        // 3. *but still use cached pfn,nid*
> mm_core_init
>  mem_init
>   memblock_free_all
>    __free_pages_core		  // 4. check page and find bad page
> 
> Firstly, 9f000000 on nid=4 should be fixed in firmware(I don't know where
> store this infomation), secondly, if we want to fix it or avoid

I believe the firmware for QEMU is just OpenSBI but that is about all I
know, I am not a RISC-V developer.

I've explicitly added some RISC-V folks, the start of the thread is
available at
https://lore.kernel.org/20231025163703.GA2440148@dev-arch.thelio-3990X/.

Cheers,
Nathan

> similar issue happened in other scene,a reset function to cleanup the
> cached pfn-nid should be added, I try following diff, it should work.
> 
> diff --git a/drivers/base/arch_numa.c b/drivers/base/arch_numa.c
> index eaa31e567d1e..24100e45971c 100644
> --- a/drivers/base/arch_numa.c
> +++ b/drivers/base/arch_numa.c
> @@ -210,6 +210,7 @@ int __init numa_add_memblk(int nid, u64 start, u64 end)
>  	}
> 
>  	node_set(nid, numa_nodes_parsed);
> +	early_pfn_reset_nid();
>  	return ret;
>  }
> 
> diff --git a/include/linux/mm.h b/include/linux/mm.h
> index 418d26608ece..f20a8da22b35 100644
> --- a/include/linux/mm.h
> +++ b/include/linux/mm.h
> @@ -3173,9 +3173,11 @@ static inline int early_pfn_to_nid(unsigned long pfn)
>  {
>  	return 0;
>  }
> +static inline void early_pfn_reset_nid(void) {}
>  #else
>  /* please see mm/page_alloc.c */
>  extern int __meminit early_pfn_to_nid(unsigned long pfn);
> +extern void __meminit early_pfn_reset_nid(void);
>  #endif
> 
>  extern void set_dma_reserve(unsigned long new_dma_reserve);
> diff --git a/mm/mm_init.c b/mm/mm_init.c
> index 077bfe393b5e..fb7751b233c4 100644
> --- a/mm/mm_init.c
> +++ b/mm/mm_init.c
> @@ -586,6 +586,7 @@ struct mminit_pfnnid_cache {
>  };
> 
>  static struct mminit_pfnnid_cache early_pfnnid_cache __meminitdata;
> +static DEFINE_SPINLOCK(early_pfn_lock);
> 
>  /*
>   * Required by SPARSEMEM. Given a PFN, return what node the PFN is on.
> @@ -611,7 +612,6 @@ static int __meminit __early_pfn_to_nid(unsigned long
> pfn,
> 
>  int __meminit early_pfn_to_nid(unsigned long pfn)
>  {
> -	static DEFINE_SPINLOCK(early_pfn_lock);
>  	int nid;
> 
>  	spin_lock(&early_pfn_lock);
> @@ -623,6 +623,15 @@ int __meminit early_pfn_to_nid(unsigned long pfn)
>  	return nid;
>  }
> 
> +void __meminit early_pfn_reset_nid(void)
> +{
> +	spin_lock(&early_pfn_lock);
> +	early_pfnnid_cache.last_start = 0;
> +	early_pfnnid_cache.last_end = 0;
> +	early_pfnnid_cache.last_nid = 0;
> +	spin_unlock(&early_pfn_lock);
> +}
> +
>  int hashdist = HASHDIST_DEFAULT;
> 
>  static int __init set_hashdist(char *str)
> 
> 
> 
> > 
> > <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