ring-buffer: Stop remote reader update when page swap fails

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The remote swap_reader_page callback can return -EBUSY when the writer
moves the head before the remote catches it, particularly during an event
storm on a small buffer. __rb_get_reader_page_from_remote() currently
warns about that failure but continues with the unchanged reader ID and
rearranges the local page list as though the swap succeeded.

Handle the callback failure as a recoverable error. Report it with
pr_warn_ratelimited() and return NULL. Callers already handle a NULL reader
page as a failed attempt. This avoids splicing the same page as both the
previous and new reader without flooding the log under contention.

Cc: stable@vger.kernel.org
Fixes: 2e67fabd8b ("ring-buffer: Introduce ring-buffer remotes")
Link: https://patch.msgid.link/20260825-kernel-patch-1-v2-2-bb3461807a32@gmail.com
Assisted-by: LLM sparse
Signed-off-by: Ivan Immanuel Shaji <ivanimmanuel1234@gmail.com>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>

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Ivan Immanuel Shaji 2026-08-25 12:52:50 -04:00 • committed by Steven Rostedt

parent e0d3aed7b1

commit 5eab74874d

1 changed files with 5 additions and 2 deletions

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kernel/trace/ring_buffer.c

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