linux-kernel - [PATCH v2] Docs/mm: Fix a mistake for pfn in page

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Message-Id: <20241009144135.12453-1-zpenya1314@gmail.com>
Date: Wed,  9 Oct 2024 22:41:35 +0800
From: Pengyu Zhang <zpenya1314@...il.com>
To: corbet@....net
Cc: rppt@...nel.org,
	linus.walleij@...aro.org,
	fmdefrancesco@...il.com,
	linux-doc@...r.kernel.org,
	linux-kernel@...r.kernel.org,
	yaxin_wang_uestc@....com,
	Pengyu Zhang <zpenya1314@...il.com>
Subject: [PATCH v2] Docs/mm: Fix a mistake for pfn in page_tables.rst

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.

Signed-off-by: Pengyu Zhang <zpenya1314@...il.com>
---
 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