From: Oleg Nesterov <oleg@redhat.com>
To: Ingo Molnar <mingo@kernel.org>
Cc: linux-kernel@vger.kernel.org,
Andy Lutomirski <luto@amacapital.net>,
Andrew Morton <akpm@linux-foundation.org>,
Dave Hansen <dave@sr71.net>,
Peter Zijlstra <peterz@infradead.org>,
Borislav Petkov <bp@alien8.de>, "H . Peter Anvin" <hpa@zytor.com>,
Linus Torvalds <torvalds@linux-foundation.org>,
Thomas Gleixner <tglx@linutronix.de>,
Uros Bizjak <ubizjak@gmail.com>
Subject: Re: [PATCH 2/3] x86/fpu: Remove the thread::fpu pointer
Date: Sat, 8 Jun 2024 12:10:40 +0200 [thread overview]
Message-ID: <20240608101040.GA7947@redhat.com> (raw)
In-Reply-To: <ZmQHrHqQUVTRtjSz@gmail.com>
On 06/08, Ingo Molnar wrote:
>
> On a third thought, while more readable, this doesn't work in practice with
> the current scheme, because x86_task_fpu() gets called on kthreads in
> fpu_clone(), which trips up the new debugging code.
Yes, yes, I even mentioned this in reply to 3/3.
> We could resolve it by special-casing PF_KTHREAD here too, but that weakens
> the whole readability argument. I'll leave it as-is for now.
Agreed.
Note that PF_KTHREAD | PF_USER_WORKER is already a special case in fpu_clone(),
see the "if (minimal)" check. We can probably do more changes later, for example
I don't even understand why do we need to initialize dst_fpu->fpstate->regs,
switch_fpu_return() is only called by arch_exit_to_user_mode_prepare().
Oleg.
next prev parent reply other threads:[~2024-06-08 10:12 UTC|newest]
Thread overview: 30+ messages / expand[flat|nested] mbox.gz Atom feed top
2024-06-05 8:35 [PATCH 0/3, v3] x86/fpu: Remove the thread::fpu pointer Ingo Molnar
2024-06-05 8:35 ` [PATCH 1/3] x86/fpu: Make task_struct::thread constant size Ingo Molnar
2024-06-05 19:04 ` Chang S. Bae
2024-06-06 9:30 ` [PATCH] x86/fpu: Fix stale comment in ex_handler_fprestore() Ingo Molnar
2024-06-06 15:55 ` Chang S. Bae
2024-06-05 8:35 ` [PATCH 2/3] x86/fpu: Remove the thread::fpu pointer Ingo Molnar
2024-06-05 13:38 ` Oleg Nesterov
2024-06-06 8:53 ` Ingo Molnar
2024-06-08 6:55 ` Ingo Molnar
2024-06-08 7:26 ` Ingo Molnar
2024-06-08 10:10 ` Oleg Nesterov [this message]
2024-06-25 5:26 ` Edgecombe, Rick P
2024-06-25 13:45 ` Edgecombe, Rick P
2024-06-05 8:35 ` [PATCH 3/3] x86/fpu: Remove init_task FPU state dependencies, add debugging warning Ingo Molnar
2024-06-05 14:17 ` Oleg Nesterov
2024-06-05 16:08 ` Linus Torvalds
2024-06-05 16:26 ` Oleg Nesterov
2024-06-05 17:28 ` Linus Torvalds
2024-06-06 8:30 ` [PATCH 3/3, v4] x86/fpu: Remove init_task FPU state dependencies, add debugging warning for PF_KTHREAD tasks Ingo Molnar
2024-06-06 8:46 ` [PATCH 4/3] x86/fpu: Push 'fpu' pointer calculation into the fpu__drop() call Ingo Molnar
2024-06-06 8:47 ` [PATCH 5/3] x86/fpu: Make sure x86_task_fpu() doesn't get called for PF_KTHREAD tasks during exit Ingo Molnar
2024-06-06 8:48 ` [PATCH 3/3, v4] x86/fpu: Remove init_task FPU state dependencies, add debugging warning for PF_KTHREAD tasks Ingo Molnar
2024-06-06 12:00 ` Oleg Nesterov
2024-06-07 10:56 ` Ingo Molnar
2024-06-24 6:47 ` [PATCH 3/3] x86/fpu: Remove init_task FPU state dependencies, add debugging warning Ning, Hongyu
2024-06-27 3:50 ` Ning, Hongyu
2024-06-05 21:21 ` [PATCH 0/3, v3] x86/fpu: Remove the thread::fpu pointer Brian Gerst
2024-06-06 9:06 ` [PATCH] x86/fpu: Introduce the x86_task_fpu() helper method Ingo Molnar
2024-06-06 15:35 ` Brian Gerst
2024-06-07 11:38 ` Ingo Molnar
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