[patch 070/262] mm/memory.c: avoid unnecessary kernel/user pointer conversion

Andrew Morton
2021-11-05T20:38:21Z

From: Amit Daniel Kachhap <amit.kachhap@arm.com>
Subject: mm/memory.c: avoid unnecessary kernel/user pointer conversion

Annotating a pointer from __user to kernel and then back again might
confuse sparse. In copy_huge_page_from_user() it can be avoided by
removing the intermediate variable since it is never used.

Link: https://lkml.kernel.org/r/20210914150820.19326-1-amit.kachhap@arm.com
Signed-off-by: Amit Daniel Kachhap <amit.kachhap@arm.com>
Acked-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: Vincenzo Frascino <Vincenzo.Frascino@arm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---

mm/memory.c | 4 +---
1 file changed, 1 insertion(+), 3 deletions(-)

--- a/mm/memory.c~mm-memory-avoid-unnecessary-kernel-user-pointer-conversion
+++ a/mm/memory.c
@@ -5421,7 +5421,6 @@ long copy_huge_page_from_user(struct pag
unsigned int pages_per_huge_page,
bool allow_pagefault)
{
- void *src = (void *)usr_src;
void *page_kaddr;
unsigned long i, rc = 0;
unsigned long ret_val = pages_per_huge_page * PAGE_SIZE;
@@ -5434,8 +5433,7 @@ long copy_huge_page_from_user(struct pag
else
page_kaddr = kmap_atomic(subpage);
rc = copy_from_user(page_kaddr,
- (const void __user *)(src + i * PAGE_SIZE),
- PAGE_SIZE);
+ usr_src + i * PAGE_SIZE, PAGE_SIZE);
if (allow_pagefault)
kunmap(subpage);
else
_