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In sparse vmemmap model, the virtual address of vmemmap is calculated as: '(struct page *)VMEMMAP_START - (phys_ram_base >> PAGE_SHIFT)'. And the struct page's va can be calculated with an offset: 'vmemmap + (pfn)'. However, when initializing struct pages, kernel actually starts from the first page from the same section that phys_ram_base belongs to. If the first page's physical address is not 'phys_ram_base >> PAGE_SHIFT', then we get an va below VMEMMAP_START when calculating va for it's struct page. For example, if phys_ram_base starts from 0x82000000 with pfn 0x82000, the first page in the same section is actually pfn 0x80000. During init_unavailage_range, we will initialize struct page for pfn 0x80000 with virtual address '(struct page *)VMEMMAP_START - 0x2000', which is below VMEMMAP_START as well as PCI_IO_END. This commit fixes this bug by aligning phys_ram_base with SECTION_SIZE. Signed-off-by: Xu Lu --- arch/riscv/mm/init.c | 5 ++++- 1 file changed, 4 insertions(+), 1 deletion(-) diff --git a/arch/riscv/mm/init.c b/arch/riscv/mm/init.c index 0e8c20adcd98..9866de267b74 100644 --- a/arch/riscv/mm/init.c +++ b/arch/riscv/mm/init.c @@ -59,6 +59,8 @@ EXPORT_SYMBOL(pgtable_l4_enabled); EXPORT_SYMBOL(pgtable_l5_enabled); #endif =20 +#define RISCV_MEMSTART_ALIGN (1UL << SECTION_SIZE_BITS) + phys_addr_t phys_ram_base __ro_after_init; EXPORT_SYMBOL(phys_ram_base); =20 @@ -241,7 +243,8 @@ static void __init setup_bootmem(void) * at worst, we map the linear mapping with PMD mappings. */ if (!IS_ENABLED(CONFIG_XIP_KERNEL)) - phys_ram_base =3D memblock_start_of_DRAM() & PMD_MASK; + phys_ram_base =3D round_down(memblock_start_of_DRAM(), + RISCV_MEMSTART_ALIGN); =20 /* * In 64-bit, any use of __va/__pa before this point is wrong as we --=20 2.20.1