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([2620:0:1000:8411:170e:a1a5:1887:adb2]) by smtp.gmail.com with ESMTPSA id q11-20020a63e94b000000b005d6a0b2efb3sm200016pgj.21.2024.02.01.11.28.09 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Thu, 01 Feb 2024 11:28:10 -0800 (PST) Message-ID: Date: Thu, 1 Feb 2024 11:28:08 -0800 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH V2] lockdep: fix deadlock issue between lockdep and rcu Content-Language: en-US To: Zhiguo Niu , peterz@infradead.org, mingo@redhat.com, will@kernel.org, longman@redhat.com, boqun.feng@gmail.com Cc: linux-kernel@vger.kernel.org, niuzhiguo84@gmail.com, ke.wang@unisoc.com, xuewen.yan@unisoc.com, Carlos Llamas , Greg Kroah-Hartman References: <1705477714-10467-1-git-send-email-zhiguo.niu@unisoc.com> From: Bart Van Assche In-Reply-To: <1705477714-10467-1-git-send-email-zhiguo.niu@unisoc.com> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit On 1/16/24 23:48, Zhiguo Niu wrote: > -000|queued_spin_lock_slowpath(lock = 0xFFFFFFC08291BBC8, val = 0) > -001|queued_spin_lock() > -001|lockdep_lock() > -001|graph_lock() // try to hold graph lock > -002|lookup_chain_cache_add() > -002|validate_chain() > -003|lock_acquire > -004|_raw_spin_lock_irqsave(lock = 0xFFFFFF817F211D80) > -005|lock_timer_base(inline) > -006|mod_timer(inline) > -006|wake_nocb_gp_defer(inline)// hold nocb_gp_lock > -006|__call_rcu_nocb_wake(rdp = 0xFFFFFF817F2A8680) > -007|__call_rcu_common(inline) > -007|call_rcu(head = 0xFFFFFFC0822E0B58, func = ?) > -008|call_rcu_hurry(inline) > -008|rcu_sync_call(inline) > -008|rcu_sync_func(rhp = 0xFFFFFFC0822E0B58) > -009|rcu_do_batch(rdp = 0xFFFFFF817F266680) > -010|nocb_cb_wait(inline) > -010|rcu_nocb_cb_kthread(arg = 0xFFFFFF817F266680) > -011|kthread(_create = 0xFFFFFF8080363740) > -012|ret_from_fork(asm) The above call trace shows a graph_lock() call from inside lock_timer_base(). How can that happen? In lock_timer_base() I see a raw_spin_lock_irqsave() call. Did I perhaps overlook something? Thanks, Bart.