Hello,

On Sun, Jun 28, 2026 at 01:04:17PM +0800, Runyu Xiao wrote:

Hi,

On Sat, 27 Jun 2026 14:21:05 -0700 Jakub Kicinski wrote:
> Please provide the stack trace from the report, rather than just saying
> that you can trigger it.

I am really suprised to see this warning. I've been runing this code with
CONFIG_PROVE_RCU_LIST for ages, and I haven't seen anything similar.

Sure, sorry for not including it in the RFC.  The warning was from the
reviewed reproducer used for the CONFIG_PROVE_RCU_LIST triage, not from
a production crash.  The relevant part of the dmesg is:

Reading it, it does not come from the kernel's netpoll code at
all -- it comes from an out-of-tree module (!?)

  WARNING: suspicious RCU usage
  6.1.66 #3 Tainted: G           O
  -----------------------------
  /home/ubuntu22/msv_workspace/shared/vuln_msv.c:45 RCU-list traversed in non-reader section!!

  other info that might help us debug this:

  rcu_scheduler_active = 2, debug_locks = 1
  no locks held by insmod/190.

  stack backtrace:
  CPU: 1 PID: 190 Comm: insmod Tainted: G           O       6.1.66 #3

Have you tested it on a more modern kernel?

  Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.15.0-1 04/01/2014
  Call Trace:
   <task>
   dump_stack_lvl+0x45/0x5d
   lockdep_rcu_suspicious.cold+0x2d/0x64
   poll_napi.constprop.0+0x43/0x71 [vuln_msv]
   netpoll_poll_dev.constprop.0+0x27/0x36 [vuln_msv]
   ? 0xffffffffc0005000
   rcu_list_msv_init+0xe2/0x1000 [vuln_msv]

What is `vuln_msv` exactly?

Could you reproduce this from an in-kernel path instead -- a real
netpoll/netconsole/bonding caller, with the frames resolving to the kernel
rather than [vuln_msv]?

Meanwhile, NAK until the above is clarified

--
pw-bot: rejected