From: Zheng Yejian <zhengyejian1@huawei.com>
Date: Wed, 6 Sep 2023 16:19:30 +0800
Subject: ring-buffer: Avoid softlockup in ring_buffer_resize()
Git-commit: f6bd2c92488c30ef53b5bd80c52f0a7eee9d545a
Patch-mainline: v6.6-rc2
References: git-fixes
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@huawei.com
Cc: <mhiramat@kernel.org>
Signed-off-by: Zheng Yejian <zhengyejian1@huawei.com>
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>
Acked-by: Petr Pavlu <petr.pavlu@suse.com>
---
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 78502d4c7214..72ccf75defd0 100644
--- a/kernel/trace/ring_buffer.c
+++ b/kernel/trace/ring_buffer.c
@@ -2198,6 +2198,8 @@ int ring_buffer_resize(struct trace_buffer *buffer, unsigned long size,
err = -ENOMEM;
goto out_err;
}
+
+ cond_resched();
}
get_online_cpus();