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Subject: Re: PATCH: Re: LOCKDEP customizable numbers upper limit
To:     hooanon05g@gmail.com
Cc:     linux-kernel@vger.kernel.org, peterz@infradead.org
References: <30795.1620913191@jrobl>
 <f323397b-dbe7-b655-4624-d243c2f68d81@i-love.sakura.ne.jp>
 <19935.1621016564@jrobl>
From:   Tetsuo Handa <penguin-kernel@i-love.sakura.ne.jp>
Message-ID: <11faf952-c0f8-6e1d-3560-12d77847a8ac@i-love.sakura.ne.jp>
Date:   Sat, 15 May 2021 07:41:02 +0900
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On 2021/05/15 3:22, hooanon05g@gmail.com wrote:
> Tetsuo Handa:
>> Please submit a patch that avoids only BUILD_BUG_ON().
> 
> Here it is.

Thank you. In practice, nobody will increase by more than 5 bits.

Acked-by: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>

> 
> J. R. Okajima
> 
> ----------------------------------------
> commit 43e103e1a5975c61334811d16e207e6d0ac57b77
> Author: J. R. Okajima <hooanon05g@gmail.com>
> Date:   Sat May 15 03:17:10 2021 +0900
> 
>     LOCKDEP: upper limit LOCKDEP_CHAINS_BITS
>     
>     CONFIG_LOCKDEP_CHAINS_BITS value decides the size of chain_hlocks[] in
>     kernel/locking/lockdep.c, and it is checked by add_chain_cache() with
>             BUILD_BUG_ON((1UL << 24) <= ARRAY_SIZE(chain_hlocks));
>     This patch is just to silence BUILD_BUG_ON().
>     
>     See-also: https://marc.info/?l=linux-kernel&m=162091320503900&w=2
>     Cc: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>
>     Cc: Peter Zijlstra <peterz@infradead.org>
>     Signed-off-by: J. R. Okajima <hooanon05g@gmail.com>
> 
> diff --git a/lib/Kconfig.debug b/lib/Kconfig.debug
> index 678c13967580e..999ed5aa6bcee 100644
> --- a/lib/Kconfig.debug
> +++ b/lib/Kconfig.debug
> @@ -1390,7 +1390,7 @@ config LOCKDEP_BITS
>  config LOCKDEP_CHAINS_BITS
>  	int "Bitsize for MAX_LOCKDEP_CHAINS"
>  	depends on LOCKDEP && !LOCKDEP_SMALL
> -	range 10 30
> +	range 10 21
>  	default 16
>  	help
>  	  Try increasing this value if you hit "BUG: MAX_LOCKDEP_CHAINS too low!" message.
>