Re: lib/maple_tree.c:4056:1: error: the frame size of 1144 bytes is larger than 1024 bytes

[Wei Yang <richard.weiyang@gmail.com>]

On Thu, Jan 30, 2025 at 11:31:50PM +0100, Scall wrote:
>On 1/30/25 5:13 PM, Liam R. Howlett wrote:
>> Do you have KASAN or lock debugging on?
>
>No, I don't.
>
>> Does the issue go away when reverting 8c7904a8cd0df ("maple_tree: i is
>> always less than or equal to mas_end") ?
>
>That commit has not been backported to the kernel version I tried to build
>(6.12.11, currently the latest stable version).
>
>Good news: I learned that the issue has already been solved in the mainline
>version with commit 5059aa6334fcf ("maple_tree: memset maple_big_node as a
>whole") and backporting it is the solution.

Hmm... I tried to reproduce this and found different gcc version may behave
differently. An old version doesn't report warning while a later version does.

With GCC 8.2.1, the latest master looks good. Even I use -O3.

    7004a2e46d16 2025-01-22 Merge tag 'linux_kselftest-nolibc-6.14-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/shuah/linux-kselftest

But with GCC 11.4.0(I don't have the exact version as yours), the latest
master still get a warning. But the message is a little bit different from
yours:

  lib/maple_tree.c: In function ‘mas_wr_spanning_store’:
  lib/maple_tree.c:3804:1: warning: the frame size of 1040 bytes is larger than 1024 bytes [-Wframe-larger-than=]
   3804 | }
        | ^
  lib/maple_tree.c: In function ‘mas_wr_bnode’:
  lib/maple_tree.c:4065:1: warning: the frame size of 1048 bytes is larger than 1024 bytes [-Wframe-larger-than=]
   4065 | }
        | ^

Then I tried to bisect it. And found similar warning even at the first maple
tree commit 54a611b60590 ("Maple Tree: add new data structure"). Below is the
warning message:

  lib/maple_tree.c: In function ‘mas_wr_spanning_store.isra’:
  lib/maple_tree.c:4047:1: warning: the frame size of 1032 bytes is larger than 1024 bytes [-Wframe-larger-than=]
   4047 | }
        | ^
  lib/maple_tree.c: In function ‘mas_wr_bnode’:
  lib/maple_tree.c:4325:1: warning: the frame size of 1040 bytes is larger than 1024 bytes [-Wframe-larger-than=]
   4325 | }
        | ^

Hi, Liam

Do you have some suggestion on what I can do to help?

-- 
Wei Yang
Help you, Help me