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commit f21f7fa263ac005713f0a7a43179c5aea0fabe85
parent eba2d6b34a32bdc3585c5810633ec38f9472380c
Author: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Date:   Wed, 19 Sep 2018 07:41:46 +0200

Merge tag 'trace-v4.19-rc4' of git://git.kernel.org/pub/scm/linux/kernel/git/rostedt/linux-trace

Steven writes:
  "Vaibhav Nagarnaik found that modifying the ring buffer size could cause
   a huge latency in the system because it does a while loop to free pages
   without releasing the CPU (on non preempt kernels). In a case where there
   are hundreds of thousands of pages to free it could actually cause a system
   stall. A properly place cond_resched() solves this issue."

Diffstat:
Mkernel/trace/ring_buffer.c | 2++
1 file changed, 2 insertions(+), 0 deletions(-)

diff --git a/kernel/trace/ring_buffer.c b/kernel/trace/ring_buffer.c @@ -1546,6 +1546,8 @@ rb_remove_pages(struct ring_buffer_per_cpu *cpu_buffer, unsigned long nr_pages) tmp_iter_page = first_page; do { + cond_resched(); + to_remove_page = tmp_iter_page; rb_inc_page(cpu_buffer, &tmp_iter_page);