Hi,
On (24/08/29 10:42), Andrii Nakryiko wrote:
> Now that build ID related internals in kernel/bpf/stackmap.c can be used
> both in sleepable and non-sleepable contexts, we need to add additional
> rcu_read_lock()/rcu_read_unlock() protection around fetching
> perf_callchain_entry, but with the refactoring in previous commit it's
> now pretty straightforward. We make sure to do rcu_read_unlock (in
> sleepable mode only) right before stack_map_get_build_id_offset() call
> which can sleep. By that time we don't have any more use of
> perf_callchain_entry.
Shouldn't this be backported to stable kernels? It seems that those still
do suspicious-RCU deference:
__bpf_get_stack()
get_perf_callchain()
perf_callchain_user()
perf_get_guest_cbs()
