Re: [PATCH 09/32] locking/lockdep: Save stack trace for each softirq vector involved

[Linus Torvalds]

On Tue, Feb 12, 2019 at 9:15 AM Frederic Weisbecker <frederic@xxxxxxxxxx> wrote:
>
>
> +static int save_trace_mask(struct lock_class *class, u64 mask)
> +{
> +       int bit = 0;
> +
> +       while (mask) {
> +               long fs = __ffs64(mask) + 1;
> +
> +               mask >>= fs;
> +               bit += fs;

Same buggy pattern of "ffs+1" and overflow of shift count.

                 Linus