linux-kernel - Re: [PATCH 1/1] hung_task: fix warnings by enforcing alignment on lock structures

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Message-ID: <5ff7bea5-185f-458e-9ae6-ddfcbdf29b7a@linux.dev>
Date: Sun, 24 Aug 2025 14:18:54 +0800
From: Lance Yang <lance.yang@...ux.dev>
To: Finn Thain <fthain@...ux-m68k.org>
Cc: akpm@...ux-foundation.org, mhiramat@...nel.org,
 kernel test robot <lkp@...el.com>, geert@...ux-m68k.org,
 senozhatsky@...omium.org, oe-kbuild-all@...ts.linux.dev,
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 kent.overstreet@...ux.dev, leonylgao@...cent.com,
 linux-kernel@...r.kernel.org, linux-m68k@...ts.linux-m68k.org,
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 will@...nel.org, stable@...r.kernel.org
Subject: Re: [PATCH 1/1] hung_task: fix warnings by enforcing alignment on
 lock structures



On 2025/8/24 13:57, Finn Thain wrote:
> 
> On Sun, 24 Aug 2025, Lance Yang wrote:
> 
>>
>> The blocker tracking mechanism operates on pointers to higher-level
>> locks (like struct mutex), as that is what is stored in the
>> task_struct->blocker field. It does not operate on the lower-level
>> arch_spinlock_t inside it.
>>
> 
> Perhaps you are aware that the minimum alignment of the struct is at least
> the minimum alignment of the first member. I believe that the reason why

Yes, that's how it should work in theory.

> the lock is always the first member is that misaligned accesses would harm
> performance.
> 
> I really don't know why you want to argue about fixing this.

Okay, arguing further isn't productive. Looking forward to seeing
your patch ;)

Thanks,
Lance