The commit is pushed to "branch-rh7-3.10.0-1160.6.1.vz7.171.x-ovz" and will appear at https://src.openvz.org/scm/ovz/vzkernel.git after rh7-3.10.0-1160.6.1.vz7.171.2 ------> commit d0b2f7cda662987572c5f84e7a8831d8c1135bd1 Author: Vasily Averin <v...@virtuozzo.com> Date: Thu Dec 3 15:31:57 2020 +0300
ms/tracing: Fix race in trace_open and buffer resize call Author: Gaurav Kohli <gko...@codeaurora.org> backported upstream commit bbeb97464eefc65f506084fd9f18f21653e01137 Below race can come, if trace_open and resize of cpu buffer is running parallely on different cpus CPUX CPUY ring_buffer_resize atomic_read(&buffer->resize_disabled) tracing_open tracing_reset_online_cpus ring_buffer_reset_cpu rb_reset_cpu rb_update_pages remove/insert pages resetting pointer This race can cause data abort or some times infinte loop in rb_remove_pages and rb_insert_pages while checking pages for sanity. Take buffer lock to fix this. Signed-off-by: Gaurav Kohli <gko...@codeaurora.org> Signed-off-by: Steven Rostedt (VMware) <rost...@goodmis.org> backport changes: ring_buffer_reset_cpu() fixed only ring_buffer_reset_online_cpus() is not present in this kernel https://jira.sw.ru/browse/PSBM-122343 Signed-off-by: Vasily Averin <v...@virtuozzo.com> --- kernel/trace/ring_buffer.c | 5 +++++ 1 file changed, 5 insertions(+) diff --git a/kernel/trace/ring_buffer.c b/kernel/trace/ring_buffer.c index 8b3df28..7b1afd1 100644 --- a/kernel/trace/ring_buffer.c +++ b/kernel/trace/ring_buffer.c @@ -4170,6 +4170,9 @@ void ring_buffer_reset_cpu(struct ring_buffer *buffer, int cpu) if (!cpumask_test_cpu(cpu, buffer->cpumask)) return; + /* prevent another thread from changing buffer sizes */ + mutex_lock(&buffer->mutex); + atomic_inc(&buffer->resize_disabled); atomic_inc(&cpu_buffer->record_disabled); @@ -4192,6 +4195,8 @@ void ring_buffer_reset_cpu(struct ring_buffer *buffer, int cpu) atomic_dec(&cpu_buffer->record_disabled); atomic_dec(&buffer->resize_disabled); + + mutex_unlock(&buffer->mutex); } EXPORT_SYMBOL_GPL(ring_buffer_reset_cpu); _______________________________________________ Devel mailing list Devel@openvz.org https://lists.openvz.org/mailman/listinfo/devel