On Tue, Jan 06, 2026 at 08:33:52PM -0500, Steven Rostedt wrote:
> On Tue, 6 Jan 2026 16:54:27 -0800
> Guenter Roeck <[email protected]> wrote:
>
> > > Don't remove this block. It's still needed. A lot of entries are
> > > skipped when adding the records. Weak functions and zero'd pointers
> > > that were part of the count are skipped. This is the code that handles
> > > that. It has nothing to do with rounding errors.
> > >
> > Sorry, misunderstanding. I thought that is what you meant with "This will
> > make pages equal the number of pages that were allocated. Then I'm not sure
> > we need this extra logic."
> >
> > What is the no longer needed extra logic ?
>
> I meant the added logic you had there, as I was a bit confused by the
> "spaces" part.
>
That was just to avoid "skip" going negative in the for loop.
The code below should work as well. I'll give it a try.
Thanks,
Guenter
> The logic still needs to be updated, but I think it can be done with the
> following:
>
> if (pg_unuse) {
> unsigned long pg_remaining, remaining = 0;
> long skip;
>
> /* Count the number of entries unused and compare it to
> skipped. */
> pg_remaining = (PAGE_SIZE << pg->order) / ENTRIES_SIZE -
> pg->index;
>
> if (!WARN(skipped < pg_remaining, "Extra allocated pages for
> ftrace")) {
>
> skip = skipped - pg_remaining;
>
> for (pg = pg_unuse; pg && skip > 0; pg = pg->next) {
> remaining += 1 << pg->order;
> skip -= (PAGE_SIZE << pg->order) / ENTRIES_SIZE;
> }
>
> pages -= remaining;
>
> /*
> * Check to see if the number of pages remaining would
> * just fit the number of entries skipped.
> */
> WARN(pg || skip > 0, "Extra allocated pages for ftrace:
> %lu with %lu skipped",
> remaining, skipped);
> }
> /* Need to synchronize with ftrace_location_range() */
> synchronize_rcu();
> ftrace_free_pages(pg_unuse);
> }
>
> -- Steve
