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From:   Will Deacon <will@kernel.org>
To:     Junhao He <hejunhao3@huawei.com>, linux-kernel@vger.kernel.org,
        mark.rutland@arm.com, jonathan.cameron@huawei.com
Cc:     catalin.marinas@arm.com, kernel-team@android.com,
        Will Deacon <will@kernel.org>, shenyang39@huawei.com,
        yangyicong@huawei.com, linux-doc@vger.kernel.org,
        linux-arm-kernel@lists.infradead.org, prime.zeng@hisilicon.com,
        linuxarm@huawei.com
Subject: Re: [PATCH] drivers/perf: hisi: Don't migrate perf to the CPU going to teardown
Date:   Fri,  9 Jun 2023 12:16:45 +0100
Message-Id: <168630624940.3062264.11759068131610200967.b4-ty@kernel.org>
In-Reply-To: <20230608114326.27649-1-hejunhao3@huawei.com>
References: <20230608114326.27649-1-hejunhao3@huawei.com>
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On Thu, 8 Jun 2023 19:43:26 +0800, Junhao He wrote:
> The driver needs to migrate the perf context if the current using CPU going
> to teardown. By the time calling the cpuhp::teardown() callback the
> cpu_online_mask() hasn't updated yet and still includes the CPU going to
> teardown. In current driver's implementation we may migrate the context
> to the teardown CPU and leads to the below calltrace:
> 
> ...
> [  368.104662][  T932] task:cpuhp/0         state:D stack:    0 pid:   15 ppid:     2 flags:0x00000008
> [  368.113699][  T932] Call trace:
> [  368.116834][  T932]  __switch_to+0x7c/0xbc
> [  368.120924][  T932]  __schedule+0x338/0x6f0
> [  368.125098][  T932]  schedule+0x50/0xe0
> [  368.128926][  T932]  schedule_preempt_disabled+0x18/0x24
> [  368.134229][  T932]  __mutex_lock.constprop.0+0x1d4/0x5dc
> [  368.139617][  T932]  __mutex_lock_slowpath+0x1c/0x30
> [  368.144573][  T932]  mutex_lock+0x50/0x60
> [  368.148579][  T932]  perf_pmu_migrate_context+0x84/0x2b0
> [  368.153884][  T932]  hisi_pcie_pmu_offline_cpu+0x90/0xe0 [hisi_pcie_pmu]
> [  368.160579][  T932]  cpuhp_invoke_callback+0x2a0/0x650
> [  368.165707][  T932]  cpuhp_thread_fun+0xe4/0x190
> [  368.170316][  T932]  smpboot_thread_fn+0x15c/0x1a0
> [  368.175099][  T932]  kthread+0x108/0x13c
> [  368.179012][  T932]  ret_from_fork+0x10/0x18
> ...
> 
> [...]

Applied to will (for-next/perf), thanks!

[1/1] drivers/perf: hisi: Don't migrate perf to the CPU going to teardown
      https://git.kernel.org/will/c/7a6a9f1c5a0a

Cheers,
-- 
Will

https://fixes.arm64.dev
https://next.arm64.dev
https://will.arm64.dev