This is a note to let you know that I've just added the patch titled
ring-buffer: Avoid softlockup in ring_buffer_resize()
to the 5.4-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
ring-buffer-avoid-softlockup-in-ring_buffer_resize.patch
and it can be found in the queue-5.4 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
commit 9c229928b6d195526d78f514e4656b6d68930d73
Author: Zheng Yejian <zhengyejian1@xxxxxxxxxx>
Date: Wed Sep 6 16:19:30 2023 +0800
ring-buffer: Avoid softlockup in ring_buffer_resize()
[ Upstream commit f6bd2c92488c30ef53b5bd80c52f0a7eee9d545a ]
When user resize all trace ring buffer through file 'buffer_size_kb',
then in ring_buffer_resize(), kernel allocates buffer pages for each
cpu in a loop.
If the kernel preemption model is PREEMPT_NONE and there are many cpus
and there are many buffer pages to be allocated, it may not give up cpu
for a long time and finally cause a softlockup.
To avoid it, call cond_resched() after each cpu buffer allocation.
Link: https://lore.kernel.org/linux-trace-kernel/20230906081930.3939106-1-zhengyejian1@xxxxxxxxxx
Cc: <mhiramat@xxxxxxxxxx>
Signed-off-by: Zheng Yejian <zhengyejian1@xxxxxxxxxx>
Signed-off-by: Steven Rostedt (Google) <rostedt@xxxxxxxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
diff --git a/kernel/trace/ring_buffer.c b/kernel/trace/ring_buffer.c
index 445475c229b3a..2a4fb4f1e3cad 100644
--- a/kernel/trace/ring_buffer.c
+++ b/kernel/trace/ring_buffer.c
@@ -1821,6 +1821,8 @@ int ring_buffer_resize(struct ring_buffer *buffer, unsigned long size,
err = -ENOMEM;
goto out_err;
}
+
+ cond_resched();
}
get_online_cpus();
