From: Christoph Hellwig <hch@infradead.org>
To: Dave Hansen <dave.hansen@intel.com>
Cc: Sohil Mehta <sohil.mehta@intel.com>,
Fushuai Wang <wangfushuai@baidu.com>,
aruna.ramakrishna@oracle.com, aubrey.li@intel.com, bp@alien8.de,
brgerst@gmail.com, chang.seok.bae@intel.com,
dave.hansen@linux.intel.com, hpa@zytor.com,
linux-kernel@vger.kernel.org, mingo@redhat.com, oleg@redhat.com,
peterz@infradead.org, rick.p.edgecombe@intel.com,
seanjc@google.com, tglx@linutronix.de, vigbalas@amd.com,
x86@kernel.org
Subject: Re: [PATCH] x86/fpu: Fix potential NULL dereference in avx512_status()
Date: Mon, 21 Jul 2025 22:35:17 -0700 [thread overview]
Message-ID: <aH8jFcoU0C82QkNS@infradead.org> (raw)
In-Reply-To: <b3dbca94-8603-44ea-b778-97483fbbba94@intel.com>
On Mon, Jul 21, 2025 at 07:09:52AM -0700, Dave Hansen wrote:
> On 7/18/25 16:48, Sohil Mehta wrote:
> > + /* Do not report AVX512 usage for kernel threads */
> > + if (!(task->flags & (PF_KTHREAD | PF_USER_WORKER)))
> > + timestamp = READ_ONCE(x86_task_fpu(task)->avx512_timestamp);
>
> But the original reason that folks wanted this was so they can go find
> all the AVX-512 users and cluster them together. They obviously can't do
> that today if they're oopsing their kernels.
>
> But the real question to ask here is whether kernel threads can use
> AVX-512, and whether it's important to let userspace know which threads
> are using it.
>
> Let's fix the oops, then circle around and figure out whether tracking
> AVX-512 use in kernel threads is needed.
The RAID6 Q-stripe calculation has a AVX512 implementation which
usually is called from workqueue context.
prev parent reply other threads:[~2025-07-22 5:35 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
2025-07-17 9:43 Fushuai Wang
2025-07-17 19:21 ` Sohil Mehta
2025-07-18 6:21 ` Sohil Mehta
2025-07-18 7:12 ` Fushuai Wang
2025-07-18 23:48 ` Sohil Mehta
2025-07-21 14:09 ` Dave Hansen
2025-07-22 5:35 ` Christoph Hellwig [this message]
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