[PATCH 6.19 192/220] ring-buffer: Fix to update per-subbuf entries of persistent ring buffer

Greg Kroah-Hartman
2026-03-23T13:59:18Z

From: Masami Hiramatsu (Google) <mhiramat@kernel.org>

commit f35dbac6942171dc4ce9398d1d216a59224590a9 upstream.

Since the validation loop in rb_meta_validate_events() updates the same
cpu_buffer->head_page->entries, the other subbuf entries are not updated.
Fix to use head_page to update the entries field, since it is the cursor
in this loop.

Cc: stable@vger.kernel.org
Cc: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Cc: Ian Rogers <irogers@google.com>
Fixes: 5f3b6e839f3c ("ring-buffer: Validate boot range memory events")
Link: https://patch.msgid.link/177391153882.193994.17158784065013676533.stgit@mhiramat.tok.corp.google.com
Signed-off-by: Masami Hiramatsu (Google) <mhiramat@kernel.org>
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
kernel/trace/ring_buffer.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)

--- a/kernel/trace/ring_buffer.c
+++ b/kernel/trace/ring_buffer.c
@@ -2052,7 +2052,7 @@ static void rb_meta_validate_events(stru

entries += ret;
entry_bytes += local_read(&head_page->page->commit);
- local_set(&cpu_buffer->head_page->entries, ret);
+ local_set(&head_page->entries, ret);

if (head_page == cpu_buffer->commit_page)
break;