I found another bug on this (or persistent ring buffer itself)
Let me fix it first.
On Tue, 13 Jan 2026 15:52:13 +0900
"Masami Hiramatsu (Google)" <mhiramat@kernel.org> wrote:
> Hi,
>
> Here is the 3rd version of the series to improve backup instances of
> the persistent ring buffer. The previous version is here:
>
> https://lore.kernel.org/all/176788217131.1398317.11144318616426272901.stgit@mhiramat.tok.corp.google.com/
>
> In this version, I updated [1/2] to back to checking readonly
> flag and consolidate the eventfs_entries.
>
> Since backup instances are a kind of snapshot of the persistent
> ring buffer, it should be readonly. And if it is readonly
> there is no reason to keep it after reading all data via trace_pipe
> because the data has been consumed.
> Thus, [1/2] makes backup instances readonly (not able to write any
> events, cleanup trace, change buffer size). Also, [2/2] removes the
> backup instance after consuming all data via trace_pipe.
> With this improvements, even if we makes a backup instance (using
> the same amount of memory of the persistent ring buffer), it will
> be removed after reading the data automatically.
>
> ---
>
> Masami Hiramatsu (Google) (2):
> tracing: Make the backup instance readonly
> tracing: Add autoremove feature to the backup instance
>
>
> kernel/trace/trace.c | 164 +++++++++++++++++++++++++++++++++++--------
> kernel/trace/trace.h | 14 +++-
> kernel/trace/trace_boot.c | 5 +
> kernel/trace/trace_events.c | 68 +++++++++++-------
> 4 files changed, 191 insertions(+), 60 deletions(-)
>
> --
> Masami Hiramatsu (Google) <mhiramat@kernel.org>
--
Masami Hiramatsu (Google) <mhiramat@kernel.org>