Re: [PATCH] selftests/mm: fix khugepaged_race build with older glibc

["Lorenzo Stoakes (ARM)" <ljs@kernel.org>]

On Tue, Oct 27, 2026 at 08:20:13PM +0800, Zenghui Yu wrote:
> From: "Zenghui Yu (Huawei)" <zenghui.yu@linux.dev>
>
> glibc versions before 2.37 do not define MADV_COLLAPSE in <sys/mman.h>, so
> khugepaged_race fails to build against them (e.g. glibc 2.34):
>
> [root@localhost mm]# make
>   CC       khugepaged_race
> khugepaged_race.c: In function 'main':
> khugepaged_race.c:506:23: error: 'MADV_COLLAPSE' undeclared (first use in this function); did you mean 'MADV_COLD'?
>   506 |       hpage_pmd_size, MADV_COLLAPSE);
>       |                       ^~~~~~~~~~~~~
>       |                       MADV_COLD
> khugepaged_race.c:506:23: note: each undeclared identifier is reported only once for each function it appears in
> make: *** [../lib.mk:225: /data/code/mm/tools/testing/selftests/mm/khugepaged_race] Error 1
>
> Include <linux/mman.h> to get the UAPI definition of MADV_COLLAPSE.
>
> Fixes: 66c374464438 ("selftests/mm: add khugepaged race harness")
> Signed-off-by: Zenghui Yu (Huawei) <zenghui.yu@linux.dev>

Seems sensible enough so:

Acked-by: Lorenzo Stoakes (ARM) <ljs@kernel.org>

> ---
>  tools/testing/selftests/mm/khugepaged_race.c | 1 +
>  1 file changed, 1 insertion(+)
>
> diff --git a/tools/testing/selftests/mm/khugepaged_race.c b/tools/testing/selftests/mm/khugepaged_race.c
> index abb0678522cd..1a27cb39745b 100644
> --- a/tools/testing/selftests/mm/khugepaged_race.c
> +++ b/tools/testing/selftests/mm/khugepaged_race.c
> @@ -8,6 +8,7 @@
>  #define _GNU_SOURCE
>  #include <errno.h>
>  #include <fcntl.h>
> +#include <linux/mman.h>
>  #include <pthread.h>
>  #include <stdio.h>
>  #include <stdlib.h>
> --
> 2.56.0
>

--
Cheers, Lorenzo