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authorVaibhav Nagarnaik <vnagarnaik@google.com>2018-09-07 15:31:29 -0700
committerSteven Rostedt (VMware) <rostedt@goodmis.org>2018-09-17 18:15:11 -0400
commit83f365554e47997ec68dc4eca3f5dce525cd15c3 (patch)
tree66a9f5651bb4d5b99a2ccb9e639b1fbd76487524
parent7876320f88802b22d4e2daf7eb027dd14175a0f8 (diff)
ring-buffer: Allow for rescheduling when removing pages
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. Call cond_resched() in the loop to prevent the system hangup. Link: http://lkml.kernel.org/r/20180907223129.71994-1-vnagarnaik@google.com Cc: stable@vger.kernel.org Fixes: 83f40318dab00 ("ring-buffer: Make removal of ring buffer pages atomic") Reported-by: Jason Behmer <jbehmer@google.com> Signed-off-by: Vaibhav Nagarnaik <vnagarnaik@google.com> Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
-rw-r--r--kernel/trace/ring_buffer.c2
1 files changed, 2 insertions, 0 deletions
diff --git a/kernel/trace/ring_buffer.c b/kernel/trace/ring_buffer.c
index 1d92d4a982fd..65bd4616220d 100644
--- 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);