linux-kernel - Re: linux-next: manual merge of the akpm-current tree with the risc-v tree

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Date:   Tue, 06 Oct 2020 21:32:01 -0700 (PDT)
From:   Palmer Dabbelt <palmer@...belt.com>
To:     Stephen Rothwell <sfr@...b.auug.org.au>
CC:     akpm@...ux-foundation.org, Paul Walmsley <paul@...an.com>,
        Atish Patra <Atish.Patra@....com>,
        linux-kernel@...r.kernel.org, linux-next@...r.kernel.org,
        rppt@...ux.ibm.com, Stephen Rothwell <sfr@...b.auug.org.au>
Subject:     Re: linux-next: manual merge of the akpm-current tree with the risc-v tree

On Tue, 06 Oct 2020 03:39:06 PDT (-0700), Stephen Rothwell wrote:
> Hi all,
>
> Today's linux-next merge of the akpm-current tree got a conflict in:
>
>   arch/riscv/mm/init.c
>
> between commit:
>
>   c29c38fa2a8b ("RISC-V: Remove any memblock representing unusable memory area")
>
> from the risc-v tree and commits:
>
>   3520eeb79142 ("arch, drivers: replace for_each_membock() with for_each_mem_range()")
>
> from the akpm-current tree.
>
> I fixed it up (see below) and can carry the fix as necessary. This
> is now fixed as far as linux-next is concerned, but any non trivial
> conflicts should be mentioned to your upstream maintainer when your tree
> is submitted for merging.  You may also want to consider cooperating
> with the maintainer of the conflicting tree to minimise any particularly
> complex conflicts.
>
> It also looks like there is a bug in that risc-v tree patch: mem_start
> is used uninitialised in setup_bootmem().
> -- 
> Cheers,
> Stephen Rothwell
>
> diff --cc arch/riscv/mm/init.c
> index 812a48c91a95,bc72bb6b5fe0..000000000000
> --- a/arch/riscv/mm/init.c
> +++ b/arch/riscv/mm/init.c
> @@@ -152,20 -141,25 +152,20 @@@ disable
>   }
>   #endif /* CONFIG_BLK_DEV_INITRD */
>   
>  -static phys_addr_t dtb_early_pa __initdata;
>  -
>   void __init setup_bootmem(void)
>   {
> - 	struct memblock_region *reg;
> - 	phys_addr_t mem_start, end = 0;
>  -	phys_addr_t mem_size = 0;
>  -	phys_addr_t total_mem = 0;
> + 	phys_addr_t mem_start, start, end = 0;
>   	phys_addr_t vmlinux_end = __pa_symbol(&_end);
>   	phys_addr_t vmlinux_start = __pa_symbol(&_start);
> + 	u64 i;
>   
>   	/* Find the memory region containing the kernel */
> - 	for_each_memblock(memory, reg) {
> - 		end = reg->base + reg->size;
> + 	for_each_mem_range(i, &start, &end) {
> + 		phys_addr_t size = end - start;
>  -		if (!total_mem)
>  +		if (!mem_start)
> - 			mem_start = reg->base;
> - 		if (reg->base <= vmlinux_start && vmlinux_end <= end)
> - 			BUG_ON(reg->size == 0);
> + 			mem_start = start;
> + 		if (start <= vmlinux_start && vmlinux_end <= end)
> + 			BUG_ON(size == 0);
>  -		total_mem = total_mem + size;
>   	}
>   
>   	/*
> @@@ -542,18 -455,11 +533,18 @@@ static void __init setup_vm_final(void
>   {
>   	uintptr_t va, map_size;
>   	phys_addr_t pa, start, end;
> - 	struct memblock_region *reg;
> + 	u64 i;
>   
>  -	/* Set mmu_enabled flag */
>  -	mmu_enabled = true;
>  -
>  +	/**
>  +	 * MMU is enabled at this point. But page table setup is not complete yet.
>  +	 * fixmap page table alloc functions should be used at this point
>  +	 */
>  +	pt_ops.alloc_pte = alloc_pte_fixmap;
>  +	pt_ops.get_pte_virt = get_pte_virt_fixmap;
>  +#ifndef __PAGETABLE_PMD_FOLDED
>  +	pt_ops.alloc_pmd = alloc_pmd_fixmap;
>  +	pt_ops.get_pmd_virt = get_pmd_virt_fixmap;
>  +#endif
>   	/* Setup swapper PGD for fixmap */
>   	create_pgd_mapping(swapper_pg_dir, FIXADDR_START,
>   			   __pa_symbol(fixmap_pgd_next),

Thanks for pointing this out.  Given that this is the tip of my for-next I'm
just going to drop it, we'll sort out the bug and the conflict.