From: Muchun Song <muchun.song@linux.dev>
To: Chuyi Zhou <zhouchuyi@bytedance.com>
Cc: tglx@linutronix.de, mingo@redhat.com, luto@kernel.org,
peterz@infradead.org, paulmck@kernel.org, bp@alien8.de,
dave.hansen@linux.intel.com, pbonzini@redhat.com,
bigeasy@linutronix.de, clrkwllms@kernel.org, rostedt@goodmis.org,
nadav.amit@gmail.com, linux-kernel@vger.kernel.org
Subject: Re: [PATCH v5 05/12] smp: Alloc percpu csd data in smpcfd_prepare_cpu() only once
Date: Thu, 23 Apr 2026 15:29:55 +0800 [thread overview]
Message-ID: <5E373C0D-EB29-4F57-9DB7-AD3BBD0CE0F0@linux.dev> (raw)
In-Reply-To: <20260422064022.3791652-6-zhouchuyi@bytedance.com>
> On Apr 22, 2026, at 14:40, Chuyi Zhou <zhouchuyi@bytedance.com> wrote:
>
> Later patch would enable preemption during csd_lock_wait() in
> smp_call_function_many_cond(), which may cause access cfd->csd data that
> has already been freed in smpcfd_dead_cpu().
>
> One way to fix the above issue is to use the RCU mechanism to protect the
> csd data and wait for all read critical sections to exit before freeing
> the memory in smpcfd_dead_cpu(), but this could delay CPU shutdown. This
> patch chooses a simpler approach: allocate the percpu csd on the UP side
> only once and skip freeing the csd memory in smpcfd_dead_cpu().
>
> Suggested-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
> Signed-off-by: Chuyi Zhou <zhouchuyi@bytedance.com>
Acked-by: Muchun Song <muchun.song@linux.dev>
Thanks.
next prev parent reply other threads:[~2026-04-23 7:30 UTC|newest]
Thread overview: 14+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-04-22 6:40 [PATCH v5 00/12] Allow preemption during IPI completion waiting to improve real-time performance Chuyi Zhou
2026-04-22 6:40 ` [PATCH v5 01/12] smp: Disable preemption explicitly in __csd_lock_wait Chuyi Zhou
2026-04-22 6:40 ` [PATCH v5 02/12] smp: Enable preemption early in smp_call_function_single Chuyi Zhou
2026-04-22 6:40 ` [PATCH v5 03/12] smp: Refactor remote CPU selection in smp_call_function_any() Chuyi Zhou
2026-04-22 6:40 ` [PATCH v5 04/12] smp: Use task-local IPI cpumask in smp_call_function_many_cond() Chuyi Zhou
2026-04-22 6:40 ` [PATCH v5 05/12] smp: Alloc percpu csd data in smpcfd_prepare_cpu() only once Chuyi Zhou
2026-04-23 7:29 ` Muchun Song [this message]
2026-04-22 6:40 ` [PATCH v5 06/12] smp: Enable preemption early in smp_call_function_many_cond Chuyi Zhou
2026-04-22 6:40 ` [PATCH v5 07/12] smp: Remove preempt_disable from smp_call_function Chuyi Zhou
2026-04-22 6:40 ` [PATCH v5 08/12] smp: Remove preempt_disable from on_each_cpu_cond_mask Chuyi Zhou
2026-04-22 6:40 ` [PATCH v5 09/12] scftorture: Remove preempt_disable in scftorture_invoke_one Chuyi Zhou
2026-04-22 6:40 ` [PATCH v5 10/12] x86/mm: Move flush_tlb_info back to the stack Chuyi Zhou
2026-04-22 6:40 ` [PATCH v5 11/12] x86/mm: Enable preemption during native_flush_tlb_multi Chuyi Zhou
2026-04-22 6:40 ` [PATCH v5 12/12] x86/mm: Enable preemption during flush_tlb_kernel_range Chuyi Zhou
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