From: Xuanye Liu <liuqiye2025@163.com>
Date: Thu, 10 Jul 2025 02:58:58 +0000 (+0800)
Subject: mm: simplify min_brk handling in brk()
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=e001ef9652c2d931a1126c9d173ec5ea95e9847a;p=thirdparty%2Flinux.git

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.

Link: https://lkml.kernel.org/r/20250710025859.926355-1-liuqiye2025@163.com
Signed-off-by: Xuanye Liu <liuqiye2025@163.com>
Reviewed-by: Pedro Falcato <pfalcato@suse.de>
Reviewed-by: Lorenzo Stoakes <lorenzo.stoakes@oracle.com>
Cc: Jann Horn <jannh@google.com>
Cc: Liam Howlett <liam.howlett@oracle.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---

diff --git a/mm/mmap.c b/mm/mmap.c
index 74072369e8fde..1287e92ccdda6 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;