Re: [PATCH] tools/sched_ext: Fix data header access during free in scx_sdt

[Andrea Righi <arighi@nvidia.com>]

Hi Emil,

On Sun, Feb 01, 2026 at 07:42:08PM -0500, Emil Tsalapatis wrote:
> Fix a pointer arithmetic error in scx_sdt during freeing that
> causes the allocator to use the wrong memory address for the
> allocation's data header.
> 
> Fixes: f0262b102c7 ("tools/sched_ext: add scx_pair scheduler")

I think this is fixing commig 36929ebd17ae6 ("tools/sched_ext: add arena
based scheduler") in sched_ext/for-6.20, right?

Apart than that, LGTM:

Acked-by: Andrea Righi <arighi@nvidia.com>

Thanks,
-Andrea

> Signed-off-by: Emil Tsalapatis <emil@etsalapatis.com>
> ---
>  tools/sched_ext/scx_sdt.bpf.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/tools/sched_ext/scx_sdt.bpf.c b/tools/sched_ext/scx_sdt.bpf.c
> index d965f7d209de..31b09958e8d5 100644
> --- a/tools/sched_ext/scx_sdt.bpf.c
> +++ b/tools/sched_ext/scx_sdt.bpf.c
> @@ -312,7 +312,7 @@ int scx_alloc_free_idx(struct scx_allocator *alloc, __u64 idx)
>  	pos = idx & mask;
>  	data = chunk->data[pos];
>  	if (likely(data)) {
> -		data[pos] = (struct sdt_data) {
> +		*data = (struct sdt_data) {
>  			.tid.genn = data->tid.genn + 1,
>  		};
>  
> -- 
> 2.49.0
>