alloc_tag: move memory_allocation_profiling_sysctls into .rodata

[PATCH] alloc_tag: move memory_allocation_profiling_sysctls into .rodata

Posted by Joel Granados 1 month, 3 weeks ago

Remove the change in file mode permissions done before initializing the
sysctl. It is not necessary as the writing of the kernel variable will
be blocked by the proc_mem_profiling_handler when writing is disallowed
(also controlled by mem_profiling_support).

Signed-off-by: Joel Granados <joel.granados@kernel.org>
---
 lib/alloc_tag.c | 5 +----
 1 file changed, 1 insertion(+), 4 deletions(-)

diff --git a/lib/alloc_tag.c b/lib/alloc_tag.c
index 27fee57a5c91db8067c05bff974a9e801e0ef6a0..846a5b5b44a4e5f530605c97a200e03260e73d77 100644
--- a/lib/alloc_tag.c
+++ b/lib/alloc_tag.c
@@ -783,7 +783,7 @@ static int proc_mem_profiling_handler(const struct ctl_table *table, int write,
 }
 
 
-static struct ctl_table memory_allocation_profiling_sysctls[] = {
+static const struct ctl_table memory_allocation_profiling_sysctls[] = {
 	{
 		.procname	= "mem_profiling",
 		.data		= &mem_alloc_profiling_key,
@@ -798,9 +798,6 @@ static struct ctl_table memory_allocation_profiling_sysctls[] = {
 
 static void __init sysctl_init(void)
 {
-	if (!mem_profiling_support)
-		memory_allocation_profiling_sysctls[0].mode = 0444;
-
 	register_sysctl_init("vm", memory_allocation_profiling_sysctls);
 }
 #else /* CONFIG_SYSCTL */

---
base-commit: 8f0b4cce4481fb22653697cced8d0d04027cb1e8
change-id: 20251215-jag-alloc_tag_const-dc9d7c3f7a8f

Best regards,
-- 
Joel Granados <joel.granados@kernel.org>

Re: [PATCH] alloc_tag: move memory_allocation_profiling_sysctls into .rodata

Posted by Suren Baghdasaryan 1 month, 2 weeks ago

On Mon, Dec 15, 2025 at 7:47 AM Joel Granados <joel.granados@kernel.org> wrote:
>
> Remove the change in file mode permissions done before initializing the
> sysctl. It is not necessary as the writing of the kernel variable will
> be blocked by the proc_mem_profiling_handler when writing is disallowed
> (also controlled by mem_profiling_support).

Right. When this code was written,
memory_allocation_profiling_sysctls.proc_handler was using
proc_do_static_key(), so this mode update was needed. But now that we
use proc_mem_profiling_handler(), it can be indeed removed.
Thanks for the cleanup!

>
> Signed-off-by: Joel Granados <joel.granados@kernel.org>

Acked-by: Suren Baghdasaryan <surenb@google.com>

> ---
>  lib/alloc_tag.c | 5 +----
>  1 file changed, 1 insertion(+), 4 deletions(-)
>
> diff --git a/lib/alloc_tag.c b/lib/alloc_tag.c
> index 27fee57a5c91db8067c05bff974a9e801e0ef6a0..846a5b5b44a4e5f530605c97a200e03260e73d77 100644
> --- a/lib/alloc_tag.c
> +++ b/lib/alloc_tag.c
> @@ -783,7 +783,7 @@ static int proc_mem_profiling_handler(const struct ctl_table *table, int write,
>  }
>
>
> -static struct ctl_table memory_allocation_profiling_sysctls[] = {
> +static const struct ctl_table memory_allocation_profiling_sysctls[] = {
>         {
>                 .procname       = "mem_profiling",
>                 .data           = &mem_alloc_profiling_key,
> @@ -798,9 +798,6 @@ static struct ctl_table memory_allocation_profiling_sysctls[] = {
>
>  static void __init sysctl_init(void)
>  {
> -       if (!mem_profiling_support)
> -               memory_allocation_profiling_sysctls[0].mode = 0444;
> -
>         register_sysctl_init("vm", memory_allocation_profiling_sysctls);
>  }
>  #else /* CONFIG_SYSCTL */
>
> ---
> base-commit: 8f0b4cce4481fb22653697cced8d0d04027cb1e8
> change-id: 20251215-jag-alloc_tag_const-dc9d7c3f7a8f
>
> Best regards,
> --
> Joel Granados <joel.granados@kernel.org>
>
>