Messages in this thread Patch in this message | | | Date | Fri, 7 Sep 2018 11:21:31 -0700 | Subject | [PATCH] ring-buffer: Allow for rescheduling when removing pages | From | Vaibhav Nagarnaik <> |
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When reducing ring buffer size, pages are removed by scheduling a work item on each CPU for the corresponding CPU ring buffer. After the pages are removed from ring buffer linked list, the pages are free()d in a tight loop. The loop does not give up CPU until all pages are removed. In a worst case behavior, when lot of pages are to be freed, it can cause system stall.
After the pages are removed from the list, the free() can happen while the work is rescheduled. Add a check for need_sched() within the loop to prevent the system hangup.
Reported-by: Jason Behmer <jbehmer@google.com> Signed-off-by: Vaibhav Nagarnaik <vnagarnaik@google.com> --- kernel/trace/ring_buffer.c | 3 +++ 1 file changed, 3 insertions(+)
diff --git a/kernel/trace/ring_buffer.c b/kernel/trace/ring_buffer.c index 1d92d4a982fd..bc1789df7c53 100644 --- a/kernel/trace/ring_buffer.c +++ b/kernel/trace/ring_buffer.c @@ -1546,6 +1546,9 @@ rb_remove_pages(struct ring_buffer_per_cpu *cpu_buffer, unsigned long nr_pages) tmp_iter_page = first_page; do { + if (need_resched()) + schedule(); + to_remove_page = tmp_iter_page; rb_inc_page(cpu_buffer, &tmp_iter_page); -- 2.19.0.rc2.392.g5ba43deb5a-goog
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