The documentation incorrectly calculate the pfn value as 0x3fffff, which should be 0x3ffff instead. It is obtained by right-shifting 0xffffc000 by 14 bits. This patch corrects the value to prevent any potential confusion for developers referencing this document. Reviewed-by: Mike Rapoport (Microsoft) <rppt@xxxxxxxxxx> Reviewed-by: Linus Walleij <linus.walleij@xxxxxxxxxx> Reviewed-by: Zenghui Yu <zenghui.yu@xxxxxxxxx> Signed-off-by: Pengyu Zhang <zpenya1314@xxxxxxxxx> --- Documentation/mm/page_tables.rst | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/Documentation/mm/page_tables.rst b/Documentation/mm/page_tables.rst index be47b192a596..e7c69cc32493 100644 --- a/Documentation/mm/page_tables.rst +++ b/Documentation/mm/page_tables.rst @@ -29,7 +29,7 @@ address. With a page granularity of 4KB and a address range of 32 bits, pfn 0 is at address 0x00000000, pfn 1 is at address 0x00001000, pfn 2 is at 0x00002000 and so on until we reach pfn 0xfffff at 0xfffff000. With 16KB pages pfs are -at 0x00004000, 0x00008000 ... 0xffffc000 and pfn goes from 0 to 0x3fffff. +at 0x00004000, 0x00008000 ... 0xffffc000 and pfn goes from 0 to 0x3ffff. As you can see, with 4KB pages the page base address uses bits 12-31 of the address, and this is why `PAGE_SHIFT` in this case is defined as 12 and -- 2.25.1
