6.6-stable review patch. If anyone has any objections, please let me know.
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From: Vladimir Riabchun ferr.lambarginio@gmail.com
[ Upstream commit 4099b98203d6b33d990586542fa5beee408032a3 ]
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.
Link: https://lore.kernel.org/aMQD9_lxYmphT-up@vova-pc Signed-off-by: Vladimir Riabchun ferr.lambarginio@gmail.com Signed-off-by: Steven Rostedt (Google) rostedt@goodmis.org Signed-off-by: Sasha Levin sashal@kernel.org --- kernel/trace/ftrace.c | 2 ++ 1 file changed, 2 insertions(+)
diff --git a/kernel/trace/ftrace.c b/kernel/trace/ftrace.c index 15785a729a0cd..398992597685b 100644 --- a/kernel/trace/ftrace.c +++ b/kernel/trace/ftrace.c @@ -6873,6 +6873,8 @@ 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 */