Re: Fwd: [6.5.1] Slow boot and opening files (RIP: kvfree_rcu_bulk)

From: Uladzislau Rezki
Date: Mon Sep 04 2023 - 12:53:55 EST


>
> >     Could you please clarify some items:
> >
> >     1.
> >     <snip>
> >     if (!WARN_ON_ONCE(!poll_state_synchronize_rcu_full(&bnode->gp_snap)))
> {
> >             debug_rcu_bhead_unqueue(bnode);
> >             rcu_lock_acquire(&rcu_callback_map);
> >     <snip>
> >
> >     Do you see this warning? I mean the one that is in the if()?
> >
> >
> > Hi! From my limited understanding, the warning points to that snippet: [
>  
> >  7.108424] WARNING: CPU: 13 PID: 338 at kernel/rcu/tree.c:2952
> > kvfree_rcu_bulk+0x13b/0x160
> >
> OK. Since you have a compiled vmlinux. Just to be sure, could you please
> perform below steps:
>
> <snip>
> urezki@pc638:~/data/raid0/coding/linux.git$ gdb ./vmlinux
> GNU gdb (Debian 10.1-1.7) 10.1.90.20210103-git
> Copyright (C) 2021 Free Software Foundation, Inc.
> License GPLv3+: GNU GPL version 3 or later <http://gnu.org/licenses/
> gpl.html>
> This is free software: you are free to change and redistribute it.
> There is NO WARRANTY, to the extent permitted by law.
> Type "show copying" and "show warranty" for details.
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> Type "show configuration" for configuration details.
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> Reading symbols from ./vmlinux...
> (gdb) l *kvfree_rcu_bulk+0x13b
> <snip>
>
> and post the output here?
>
>
> I guess that is with my self-compiled 6.5.1 installed, right? I might come back
> to this task with the asked data later, but as that machine is used in
> production for daily tasks this might take a couple of days.
>
Yes, please.

>
> I don't have an SHA1 but you can take the vanilla 6.5.1 kernel and apply all
> seven 0001-*.patch files from my repo that are available here: https://
> github.com/ms178/archpkgbuilds/tree/main/packages/linux-cachyos to get it into
> the same state.
>
Sounds good. I will try my best to reproduce it locally with set of
extra patches + your .config + 6.5.1 kernel.

Thank you for the help to debug it!

--
Uladzislau Rezki