On Tue, Dec 13, 2022 at 12:17 PM Joel Fernandes joel@joelfernandes.org wrote:

Hello,

Please apply to the stable v5.10 kernel, the commit: 29368e093921 ("x86/smpboot: Move rcu_cpu_starting() earlier").

While I am confident this fixes it, I started an overnight test of all rcutorture scenarios. It cherry-picks cleanly.

I will test 5.4 as well as it applies there.

- Joel

It made it into the mainline in 5.11. I am able to reproduce the following splat without it on v5.10 stable, which is identical to the one that the commit fixed:

[ 42.628511] ============================= [ 42.628512] WARNING: suspicious RCU usage [ 42.628513] 5.10.156+ #7 Not tainted [ 42.628514] ----------------------------- [ 42.628516] kernel/locking/lockdep.c:3621 RCU-list traversed in non-reader section!! [ 42.628516] [ 42.628517] other info that might help us debug this: [ 42.628518] [ 42.628519] [ 42.628519] RCU used illegally from offline CPU! [ 42.628520] rcu_scheduler_active = 1, debug_locks = 1 [ 42.628521] no locks held by swapper/1/0. [ 42.628522] [ 42.628522] stack backtrace: [ 42.628523] CPU: 1 PID: 0 Comm: swapper/1 Not tainted 5.10.156+ #7 [ 42.628540] Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.0-debian-1.16.0-4 04/01/2014 [ 42.628541] Call Trace: [ 42.628541] [ 42.628542] ============================= [ 42.628543] WARNING: suspicious RCU usage [ 42.628544] 5.10.156+ #7 Not tainted [ 42.628561] ----------------------------- [ 42.628563] kernel/kprobes.c:300 RCU-list traversed in non-reader section!! [ 42.628563] [ 42.628564] other info that might help us debug this: [ 42.628565] [ 42.628566] [ 42.628567] RCU used illegally from offline CPU! [ 42.628568] rcu_scheduler_active = 1, debug_locks = 1 [ 42.628569] no locks held by swapper/1/0. [ 42.628570] [ 42.628570] stack backtrace: [ 42.628571] CPU: 1 PID: 0 Comm: swapper/1 Not tainted 5.10.156+ #7 [ 42.628573] Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.0-debian-1.16.0-4 04/01/2014 [ 42.628573] Call Trace: [ 42.628574] dump_stack+0x77/0x9b [ 42.628575] __is_insn_slot_addr+0x156/0x170 [ 42.628576] kernel_text_address+0xb1/0xe0 [ 42.628577] ? get_stack_info+0x2b/0x80 [ 42.628578] __kernel_text_address+0x9/0x40 [ 42.628578] show_trace_log_lvl+0x223/0x2f0 [ 42.628579] ? dump_stack+0x77/0x9b [ 42.628580] dump_stack+0x77/0x9b [ 42.628581] __lock_acquire.cold+0x326/0x330 [ 42.628581] lock_acquire+0xbd/0x2a0 [ 42.628582] ? vprintk_emit+0x6c/0x310 [ 42.628583] _raw_spin_lock+0x27/0x40 [ 42.628584] ? vprintk_emit+0x6c/0x310 [ 42.628584] vprintk_emit+0x6c/0x310 [ 42.628585] printk+0x63/0x7e [ 42.628586] start_secondary+0x1c/0xf0 [ 42.628587] secondary_startup_64_no_verify+0xc2/0xcb [ 42.628588] dump_stack+0x77/0x9b [ 42.628588] __lock_acquire.cold+0x326/0x330 [ 42.628589] lock_acquire+0xbd/0x2a0 [ 42.628590] ? vprintk_emit+0x6c/0x310 [ 42.628591] _raw_spin_lock+0x27/0x40 [ 42.628591] ? vprintk_emit+0x6c/0x310 [ 42.628592] vprintk_emit+0x6c/0x310

Thanks,

• Joel