From: "Arnd Bergmann" <arnd@arndb.de>
To: "Finn Thain" <fthain@linux-m68k.org>,
"Peter Zijlstra" <peterz@infradead.org>
Cc: "Will Deacon" <will@kernel.org>,
"Andrew Morton" <akpm@linux-foundation.org>,
"Boqun Feng" <boqun.feng@gmail.com>,
"Jonathan Corbet" <corbet@lwn.net>,
"Mark Rutland" <mark.rutland@arm.com>,
linux-kernel@vger.kernel.org,
Linux-Arch <linux-arch@vger.kernel.org>,
"Geert Uytterhoeven" <geert@linux-m68k.org>,
linux-m68k@vger.kernel.org
Subject: Re: [RFC v2 3/3] atomic: Add alignment check to instrumented atomic operations
Date: Mon, 15 Sep 2025 13:20:18 +0200 [thread overview]
Message-ID: <57bca164-4e63-496d-9074-79fd89feb835@app.fastmail.com> (raw)
In-Reply-To: <8247e3bd-13c2-e28c-87d8-5fd1bfed7104@linux-m68k.org>
On Mon, Sep 15, 2025, at 12:37, Finn Thain wrote:
> On Mon, 15 Sep 2025, Peter Zijlstra wrote:
>>
>> > When you do atomic operations on atomic_t or atomic64_t, (sizeof(long)
>> > - 1) probably doesn't make much sense. But atomic operations get used on
>> > scalar types (aside from atomic_t and atomic64_t) that don't have natural
>> > alignment. Please refer to the other thread about this:
>> > https://lore.kernel.org/all/ed1e0896-fd85-5101-e136-e4a5a37ca5ff@linux-m68k.org/
>>
>> Perhaps set ARCH_SLAB_MINALIGN ?
>>
>
> That's not going to help much. The 850 byte offset of task_works into
> struct task_struct and the 418 byte offset of exit_state in struct
> task_struct are already misaligned.
Has there been any progress on building m68k kernels with -mint-align?
IIRC there are only a small number of uapi structures that need
__packed annotations to maintain the existing syscall ABI.
Arnd
next prev parent reply other threads:[~2025-09-15 11:20 UTC|newest]
Thread overview: 44+ messages / expand[flat|nested] mbox.gz Atom feed top
2025-09-14 0:45 [RFC v2 0/3] Align atomic storage Finn Thain
2025-09-14 0:45 ` [RFC v2 1/3] documentation: Discourage alignment assumptions Finn Thain
2025-09-14 0:45 ` [RFC v2 3/3] atomic: Add alignment check to instrumented atomic operations Finn Thain
2025-09-15 8:00 ` Peter Zijlstra
2025-09-15 9:38 ` Finn Thain
2025-09-15 10:06 ` Peter Zijlstra
2025-09-15 10:37 ` Finn Thain
2025-09-15 11:20 ` Arnd Bergmann [this message]
2025-09-16 0:16 ` Finn Thain
2025-09-16 10:10 ` Geert Uytterhoeven
2025-09-17 1:23 ` Finn Thain
2025-09-16 12:37 ` Arnd Bergmann
2025-09-16 21:38 ` Brad Boyer
2025-09-17 16:54 ` Andreas Schwab
2025-09-17 2:14 ` Finn Thain
2025-09-22 15:49 ` Arnd Bergmann
2025-09-23 6:39 ` Finn Thain
2025-09-14 0:45 ` [RFC v2 2/3] atomic: Specify alignment for atomic_t and atomic64_t Finn Thain
2025-09-15 7:13 ` Geert Uytterhoeven
2025-09-15 7:35 ` Arnd Bergmann
2025-09-15 8:06 ` Peter Zijlstra
2025-09-15 9:26 ` Finn Thain
2025-09-15 9:29 ` Arnd Bergmann
2025-09-22 7:06 ` Geert Uytterhoeven
2025-09-22 8:16 ` Finn Thain
2025-09-22 9:29 ` Geert Uytterhoeven
2025-09-22 15:21 ` Arnd Bergmann
2025-09-23 6:28 ` Finn Thain
2025-09-23 6:41 ` Arnd Bergmann
2025-09-23 8:05 ` Finn Thain
2025-09-23 19:11 ` Arnd Bergmann
2025-09-30 2:18 ` Finn Thain
2025-09-30 6:35 ` Arnd Bergmann
2025-10-01 1:03 ` Finn Thain
2025-10-01 6:44 ` Arnd Bergmann
2025-10-06 9:25 ` Finn Thain
2025-10-06 9:25 ` Finn Thain
2025-10-06 10:07 ` Arnd Bergmann
2025-10-06 10:22 ` Peter Zijlstra
2025-10-06 11:09 ` Arnd Bergmann
2025-10-06 9:37 ` Peter Zijlstra
2025-09-30 7:41 ` Geert Uytterhoeven
2025-10-01 1:46 ` Finn Thain
2025-10-01 7:08 ` Geert Uytterhoeven
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