Commit 6d014e44b68d for kernel

commit 6d014e44b68ddd43f71288d2a4dbb1a259869149
Author: Vincent Donnefort <vdonnefort@google.com>
Date:   Thu Aug 6 22:13:03 2026 +0100

    ring-buffer: Initialise reader page order in rb_allocate_cpu_buffer()

    In rb_allocate_cpu_buffer(), bpage->order was omitted, leaving it as 0.
    This is an issue for a ring-buffer with subbufs bigger than PAGE_SIZE if
    when freed: free_buffer_page() relies on this value. Align the value
    with the actual allocation size (buffer::subbuf_order).

    Cc: stable@vger.kernel.org
    Fixes: f9b94daa542a ("ring-buffer: Set new size of the ring buffer sub page")
    Link: https://patch.msgid.link/20260806211306.3704194-4-vdonnefort@google.com
    Signed-off-by: Vincent Donnefort <vdonnefort@google.com>
    Signed-off-by: Steven Rostedt <rostedt@goodmis.org>

diff --git a/kernel/trace/ring_buffer.c b/kernel/trace/ring_buffer.c
index 6cbd80ccef37..760a00e8505c 100644
--- a/kernel/trace/ring_buffer.c
+++ b/kernel/trace/ring_buffer.c
@@ -2510,6 +2510,7 @@ rb_allocate_cpu_buffer(struct trace_buffer *buffer, long nr_pages, int cpu)
 	bpage = alloc_cpu_page(cpu);
 	if (!bpage)
 		return NULL;
+	bpage->order = cpu_buffer->buffer->subbuf_order;

 	rb_check_bpage(cpu_buffer, bpage);