From: Mark Brown <broonie@kernel.org>
To: Mark Rutland <mark.rutland@arm.com>
Cc: Naresh Kamboju <naresh.kamboju@linaro.org>,
Linux ARM <linux-arm-kernel@lists.infradead.org>,
open list <linux-kernel@vger.kernel.org>,
lkft-triage@lists.linaro.org,
linux-stable <stable@vger.kernel.org>,
Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
Catalin Marinas <catalin.marinas@arm.com>,
Steven Rostedt <rostedt@goodmis.org>,
Masami Hiramatsu <mhiramat@kernel.org>,
Marc Zyngier <maz@kernel.org>
Subject: Re: selftests: ftrace: Internal error: Oops: sve_save_state
Date: Tue, 17 Oct 2023 15:03:24 +0100 [thread overview]
Message-ID: <39b003bc-df89-4e0b-929e-2c42354aaa86@sirena.org.uk> (raw)
In-Reply-To: <ZS6PKYMXDfAVTeLw@FVFF77S0Q05N>
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On Tue, Oct 17, 2023 at 02:42:01PM +0100, Mark Rutland wrote:
> So unless sve_alloc() failed, at the instant the IRQ was taken:
> * `task->thread.sve_state` should be non-NULL
> * `task->thread_info.flags & TIF_SVE` should be 0
> ... so if `task->thread.sve_state` becomes NULL, I wonder if we end up
> accidentally blatting that as part of the context switch? I can't immedaitely
> see how/
We're possibly missing a fpsimd_bind_task_to_cpu() somewhere since all
the hilarity with KVM means that we don't use the task_struct to save
state, though the task that's taking the SVE trap shouldn't be impacted
there if it didn't set TIF_SVE yet. There *is* a window where we have
TIF_SVE set but didn't yet do the rebind but that should be in a preempt
disabled section.
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next prev parent reply other threads:[~2023-10-17 14:03 UTC|newest]
Thread overview: 13+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-10-17 8:04 Naresh Kamboju
2023-10-17 12:22 ` Mark Brown
2023-10-17 13:42 ` Mark Rutland
2023-10-17 14:03 ` Mark Brown [this message]
2023-10-19 15:37 ` Naresh Kamboju
2023-10-19 17:25 ` Mark Brown
2023-12-21 0:06 ` Daniel Díaz
2023-12-21 0:34 ` Masami Hiramatsu
2024-01-30 23:13 ` Daniel Díaz
2023-12-21 1:06 ` Mark Brown
2024-01-31 0:15 ` Daniel Díaz
2024-01-31 12:42 ` Mark Brown
2023-10-17 13:28 ` Steven Rostedt
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