On Wed, Jul 08, 2026 at 12:59:06PM -0400, Steven Rostedt wrote:
> On Wed, 8 Jul 2026 14:32:01 +0100
> Vincent Donnefort <[email protected]> wrote:
>
> > If page allocation fails in trace_remote_alloc_buffer(), desc->nr_cpus
> > is not yet incremented for the current CPU. As a consequence, on error,
> > half-allocated rb_desc will not be freed in trace_remote_free_buffer().
> >
> > Include the failing CPU in desc->nr_cpus before going to the error path.
> >
>
> Looks like Sashiko found other issues you may want to address:
>
>
> https://sashiko.dev/#/patchset/20260708133201.295072-1-vdonnefort%40google.com
Yeah I saw it, the dreaded "This isn't a bug introduced by this patch" ...
Let me send a follow-up. After looking at the other issue, I think I want to
slightly modify this one actually!
>
> -- Steve
>
> > Fixes: 96e43537af54 ("tracing: Introduce trace remotes")
> > Reported-by: Sashiko <[email protected]>
> > Signed-off-by: Vincent Donnefort <[email protected]>
> >
> > diff --git a/kernel/trace/trace_remote.c b/kernel/trace/trace_remote.c
> > index 2a6cc000ec98..62d3d431c309 100644
> > --- a/kernel/trace/trace_remote.c
> > +++ b/kernel/trace/trace_remote.c
> > @@ -1008,8 +1008,10 @@ int trace_remote_alloc_buffer(struct
> > trace_buffer_desc *desc, size_t desc_size,
> >
> > for (id = 0; id < nr_pages; id++) {
> > rb_desc->page_va[id] = (unsigned
> > long)__get_free_page(GFP_KERNEL);
> > - if (!rb_desc->page_va[id])
> > + if (!rb_desc->page_va[id]) {
> > + desc->nr_cpus++; /* Free this
> > partially-allocated rb_desc */
> > goto err;
> > + }
> >
> > rb_desc->nr_page_va++;
> > }
> >
> > base-commit: 8cdeaa50eae8dad34885515f62559ee83e7e8dda
>
