[PATCH] tracing: Fix unload_page for simple_ring_buffer init rollback

[PATCH] tracing: Fix unload_page for simple_ring_buffer init rollback

[Vincent Donnefort]

The unload_page callback expects the return value of load_page() as its
argument: ret = load_page(va); unload(ret). Fix the rollback code in
simple_ring_buffer_init_mm() where the descriptor's VA is used instead
of the loaded page address.

Fixes: 635923081c79 ("tracing: load/unload page callbacks for simple_ring_buffer")
Signed-off-by: Vincent Donnefort <vdonnefort@google.com>

diff --git a/kernel/trace/simple_ring_buffer.c b/kernel/trace/simple_ring_buffer.c
index 02af2297ae5a..38cf9abe0be8 100644
--- a/kernel/trace/simple_ring_buffer.c
+++ b/kernel/trace/simple_ring_buffer.c
@@ -431,7 +431,7 @@ int simple_ring_buffer_init_mm(struct simple_rb_per_cpu *cpu_buffer,
 
 	if (ret) {
 		for (i--; i >= 0; i--)
-			unload_page((void *)desc->page_va[i]);
+			unload_page(bpages[i].page);
 		unload_page(cpu_buffer->meta);
 
 		return ret;

base-commit: 5d6919055dec134de3c40167a490f33c74c12581
-- 
2.54.0.563.g4f69b47b94-goog

Re: [PATCH] tracing: Fix unload_page for simple_ring_buffer init rollback

[Steven Rostedt]

On Tue, 12 May 2026 15:16:14 +0100
Vincent Donnefort <vdonnefort@google.com> wrote:

> The unload_page callback expects the return value of load_page() as its
> argument: ret = load_page(va); unload(ret). Fix the rollback code in
> simple_ring_buffer_init_mm() where the descriptor's VA is used instead
> of the loaded page address.
> 
> Fixes: 635923081c79 ("tracing: load/unload page callbacks for simple_ring_buffer")
> Signed-off-by: Vincent Donnefort <vdonnefort@google.com>
> 
> diff --git a/kernel/trace/simple_ring_buffer.c b/kernel/trace/simple_ring_buffer.c
> index 02af2297ae5a..38cf9abe0be8 100644
> --- a/kernel/trace/simple_ring_buffer.c
> +++ b/kernel/trace/simple_ring_buffer.c
> @@ -431,7 +431,7 @@ int simple_ring_buffer_init_mm(struct simple_rb_per_cpu *cpu_buffer,
>  
>  	if (ret) {
>  		for (i--; i >= 0; i--)
> -			unload_page((void *)desc->page_va[i]);
> +			unload_page(bpages[i].page);
>  		unload_page(cpu_buffer->meta);
>  
>  		return ret;
> 
> base-commit: 5d6919055dec134de3c40167a490f33c74c12581

Vincent,

Did you make this patch because of the Sashiko report?

  https://sashiko.dev/?list=org.kernel.vger.linux-trace-kernel#/patchset/20260512135420.99194-1-devnexen%40gmail.com

If so, I think we can add a: Reported-by: Sashiko <sashiko-bot@kernel.org>

-- Steve

Re: [PATCH] tracing: Fix unload_page for simple_ring_buffer init rollback

[Vincent Donnefort]

On Thu, May 21, 2026 at 08:31:07AM -0400, Steven Rostedt wrote:
> On Tue, 12 May 2026 15:16:14 +0100
> Vincent Donnefort <vdonnefort@google.com> wrote:
> 
> > The unload_page callback expects the return value of load_page() as its
> > argument: ret = load_page(va); unload(ret). Fix the rollback code in
> > simple_ring_buffer_init_mm() where the descriptor's VA is used instead
> > of the loaded page address.
> > 
> > Fixes: 635923081c79 ("tracing: load/unload page callbacks for simple_ring_buffer")
> > Signed-off-by: Vincent Donnefort <vdonnefort@google.com>
> > 
> > diff --git a/kernel/trace/simple_ring_buffer.c b/kernel/trace/simple_ring_buffer.c
> > index 02af2297ae5a..38cf9abe0be8 100644
> > --- a/kernel/trace/simple_ring_buffer.c
> > +++ b/kernel/trace/simple_ring_buffer.c
> > @@ -431,7 +431,7 @@ int simple_ring_buffer_init_mm(struct simple_rb_per_cpu *cpu_buffer,
> >  
> >  	if (ret) {
> >  		for (i--; i >= 0; i--)
> > -			unload_page((void *)desc->page_va[i]);
> > +			unload_page(bpages[i].page);
> >  		unload_page(cpu_buffer->meta);
> >  
> >  		return ret;
> > 
> > base-commit: 5d6919055dec134de3c40167a490f33c74c12581
> 
> Vincent,
> 
> Did you make this patch because of the Sashiko report?
> 
>   https://sashiko.dev/?list=org.kernel.vger.linux-trace-kernel#/patchset/20260512135420.99194-1-devnexen%40gmail.com
> 
> If so, I think we can add a: Reported-by: Sashiko <sashiko-bot@kernel.org>

I did not for this one, but I have used this tag few times since yesterday [1] though :) 

https://lore.kernel.org/all/20260521102149.804874-2-vdonnefort@google.com/
https://lore.kernel.org/all/20260521124613.911067-4-vdonnefort@google.com/

> 
> -- Steve