linux-kernel - [PATCH] mm: simplify min

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Message-ID: <20250710025859.926355-1-liuqiye2025@163.com>
Date: Thu, 10 Jul 2025 10:58:58 +0800
From: Xuanye Liu <liuqiye2025@....com>
To: Andrew Morton <akpm@...ux-foundation.org>,
	"Liam R. Howlett" <Liam.Howlett@...cle.com>,
	Lorenzo Stoakes <lorenzo.stoakes@...cle.com>
Cc: Xuanye Liu <liuqiye2025@....com>,
	Vlastimil Babka <vbabka@...e.cz>,
	Jann Horn <jannh@...gle.com>,
	Pedro Falcato <pfalcato@...e.de>,
	linux-mm@...ck.org,
	linux-kernel@...r.kernel.org
Subject: [PATCH] mm: simplify min_brk handling in brk()

Set min_brk to mm->start_brk by default, and override it with
mm->end_data only when CONFIG_COMPAT_BRK is enabled and
brk_randomized is false.

This makes the logic clearer with no functional change.

Signed-off-by: Xuanye Liu <liuqiye2025@....com>
---
 mm/mmap.c | 7 ++-----
 1 file changed, 2 insertions(+), 5 deletions(-)

diff --git a/mm/mmap.c b/mm/mmap.c
index d8fa373e4ac1..7306253cc3b5 100644
--- a/mm/mmap.c
+++ b/mm/mmap.c
@@ -127,18 +127,15 @@ SYSCALL_DEFINE1(brk, unsigned long, brk)
 
 	origbrk = mm->brk;
 
+	min_brk = mm->start_brk;
 #ifdef CONFIG_COMPAT_BRK
 	/*
 	 * CONFIG_COMPAT_BRK can still be overridden by setting
 	 * randomize_va_space to 2, which will still cause mm->start_brk
 	 * to be arbitrarily shifted
 	 */
-	if (current->brk_randomized)
-		min_brk = mm->start_brk;
-	else
+	if (!current->brk_randomized)
 		min_brk = mm->end_data;
-#else
-	min_brk = mm->start_brk;
 #endif
 	if (brk < min_brk)
 		goto out;
-- 
2.43.0