linux-kernel - Re: Fwd: [6.5.1] Slow boot and opening files (RIP: kvfree_rcu

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Message-ID: <ZPYLmm3ih7u95l1a@pc636>
Date:   Mon, 4 Sep 2023 18:53:46 +0200
From:   Uladzislau Rezki <urezki@...il.com>
To:     Marcus Seyfarth <m.seyfarth@...il.com>
Cc:     Uladzislau Rezki <urezki@...il.com>, paulmck@...nel.org,
        Bagas Sanjaya <bagasdotme@...il.com>,
        Ziwei Dai <ziwei.dai@...soc.com>, linux-kernel@...r.kernel.org,
        rcu@...r.kernel.org
Subject: Re: Fwd: [6.5.1] Slow boot and opening files (RIP: kvfree_rcu_bulk)

> 
>     >     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@...38:~/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.
>     This GDB was configured as "x86_64-linux-gnu".
>     Type "show configuration" for configuration details.
>     For bug reporting instructions, please see:
>     <https://www.gnu.org/software/gdb/bugs/>.
>     Find the GDB manual and other documentation resources online at:
>         <http://www.gnu.org/software/gdb/documentation/>.
> 
>     For help, type "help".
>     Type "apropos word" to search for commands related to "word"...
>     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