A soft lockup was observed when loading amdgpu module.
If a module has a lot of tracable functions, multiple calls
to kallsyms_lookup can spend too much time in RCU critical
section and with disabled preemption, causing kernel panic.
This is the same issue that was fixed in
commit d0b24b4e91fc ("ftrace: Prevent RCU stall on PREEMPT_VOLUNTARY
kernels") and commit 42ea22e754ba ("ftrace: Add cond_resched() to
ftrace_graph_set_hash()").Fix it the same way by adding cond_resched() in ftrace_module_enable. Signed-off-by: Vladimir Riabchun <[email protected]> --- Changes since v1: https://lore.kernel.org/all/aMLPm__QGrQCwz1t@vova-pc/ - Move cond_resched below within_module check - Add some details in commit description kernel/trace/ftrace.c | 2 ++ 1 file changed, 2 insertions(+) diff --git a/kernel/trace/ftrace.c b/kernel/trace/ftrace.c index a69067367c29..42bd2ba68a82 100644 --- a/kernel/trace/ftrace.c +++ b/kernel/trace/ftrace.c @@ -7535,6 +7535,8 @@ void ftrace_module_enable(struct module *mod) if (!within_module(rec->ip, mod)) break; + cond_resched(); + /* Weak functions should still be ignored */ if (!test_for_valid_rec(rec)) { /* Clear all other flags. Should not be enabled anyway */ -- 2.43.0
