5.4-stable review patch. If anyone has any objections, please let me know.
------------------
From: Zheng Yejian zhengyejian1@huawei.com
[ 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-zhengyej...
Cc: mhiramat@kernel.org Signed-off-by: Zheng Yejian zhengyejian1@huawei.com Signed-off-by: Steven Rostedt (Google) rostedt@goodmis.org Signed-off-by: Sasha Levin sashal@kernel.org --- kernel/trace/ring_buffer.c | 2 ++ 1 file changed, 2 insertions(+)
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();