* [PATCH] mm: simplify min_brk handling in brk()
@ 2025-07-10 2:58 Xuanye Liu
2025-07-10 7:56 ` Pedro Falcato
2025-07-10 8:24 ` Lorenzo Stoakes
0 siblings, 2 replies; 3+ messages in thread
From: Xuanye Liu @ 2025-07-10 2:58 UTC (permalink / raw)
To: Andrew Morton, Liam R. Howlett, Lorenzo Stoakes
Cc: Xuanye Liu, Vlastimil Babka, Jann Horn, Pedro Falcato, linux-mm,
linux-kernel
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@163.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
^ permalink raw reply [flat|nested] 3+ messages in thread
* Re: [PATCH] mm: simplify min_brk handling in brk()
2025-07-10 2:58 [PATCH] mm: simplify min_brk handling in brk() Xuanye Liu
@ 2025-07-10 7:56 ` Pedro Falcato
2025-07-10 8:24 ` Lorenzo Stoakes
1 sibling, 0 replies; 3+ messages in thread
From: Pedro Falcato @ 2025-07-10 7:56 UTC (permalink / raw)
To: Xuanye Liu
Cc: Andrew Morton, Liam R. Howlett, Lorenzo Stoakes, Vlastimil Babka,
Jann Horn, linux-mm, linux-kernel
On Thu, Jul 10, 2025 at 10:58:58AM +0800, Xuanye Liu wrote:
> 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@163.com>
Reviewed-by: Pedro Falcato <pfalcato@suse.de>
Small little simplification, looks good, thanks!
--
Pedro
^ permalink raw reply [flat|nested] 3+ messages in thread
* Re: [PATCH] mm: simplify min_brk handling in brk()
2025-07-10 2:58 [PATCH] mm: simplify min_brk handling in brk() Xuanye Liu
2025-07-10 7:56 ` Pedro Falcato
@ 2025-07-10 8:24 ` Lorenzo Stoakes
1 sibling, 0 replies; 3+ messages in thread
From: Lorenzo Stoakes @ 2025-07-10 8:24 UTC (permalink / raw)
To: Xuanye Liu
Cc: Andrew Morton, Liam R. Howlett, Vlastimil Babka, Jann Horn,
Pedro Falcato, linux-mm, linux-kernel
On Thu, Jul 10, 2025 at 10:58:58AM +0800, Xuanye Liu wrote:
> 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@163.com>
LGTM thanks, nice cleanup:
Reviewed-by: Lorenzo Stoakes <lorenzo.stoakes@oracle.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
>
^ permalink raw reply [flat|nested] 3+ messages in thread
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2025-07-10 2:58 [PATCH] mm: simplify min_brk handling in brk() Xuanye Liu
2025-07-10 7:56 ` Pedro Falcato
2025-07-10 8:24 ` Lorenzo Stoakes
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