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[66.111.4.227]) by smtp.gmail.com with ESMTPSA id v1sm1390941ilo.81.2021.06.18.10.01.43 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Fri, 18 Jun 2021 10:01:44 -0700 (PDT) Received: from compute4.internal (compute4.nyi.internal [10.202.2.44]) by mailauth.nyi.internal (Postfix) with ESMTP id 78E7627C005A; Fri, 18 Jun 2021 13:01:43 -0400 (EDT) Received: from mailfrontend1 ([10.202.2.162]) by compute4.internal (MEProxy); Fri, 18 Jun 2021 13:01:43 -0400 X-ME-Sender: X-ME-Received: X-ME-Proxy-Cause: gggruggvucftvghtrhhoucdtuddrgeduledrfeeffedguddtgecutefuodetggdotefrod ftvfcurfhrohhfihhlvgemucfhrghsthforghilhdpqfgfvfdpuffrtefokffrpgfnqfgh necuuegrihhlohhuthemuceftddtnecusecvtfgvtghiphhivghnthhsucdlqddutddtmd enucfjughrpefhvffufffkofgjfhgggfestdekredtredttdenucfhrhhomhepuehoqhhu nhcuhfgvnhhguceosghoqhhunhdrfhgvnhhgsehgmhgrihhlrdgtohhmqeenucggtffrrg htthgvrhhnpeehvdevteefgfeiudettdefvedvvdelkeejueffffelgeeuhffhjeetkeei ueeuleenucevlhhushhtvghrufhiiigvpedtnecurfgrrhgrmhepmhgrihhlfhhrohhmpe gsohhquhhnodhmvghsmhhtphgruhhthhhpvghrshhonhgrlhhithihqdeiledvgeehtdei gedqudejjeekheehhedvqdgsohhquhhnrdhfvghngheppehgmhgrihhlrdgtohhmsehfih igmhgvrdhnrghmvg X-ME-Proxy: Received: by mail.messagingengine.com (Postfix) with ESMTPA; Fri, 18 Jun 2021 13:01:42 -0400 (EDT) From: Boqun Feng To: Peter Zijlstra Cc: Ingo Molnar , Will Deacon , Waiman Long , Boqun Feng , linux-kernel@vger.kernel.org, Johannes Berg Subject: [PATCH 2/4] locking/lockdep: Remove the unnecessary trace saving Date: Sat, 19 Jun 2021 01:01:08 +0800 Message-Id: <20210618170110.3699115-3-boqun.feng@gmail.com> X-Mailer: git-send-email 2.30.2 In-Reply-To: <20210618170110.3699115-1-boqun.feng@gmail.com> References: <20210618170110.3699115-1-boqun.feng@gmail.com> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org In print_bad_irq_dependency(), save_trace() is called to set the ->trace for @prev_root as the current call trace, however @prev_root corresponds to the the held lock, which may not be acquired in current call trace, therefore it's wrong to use save_trace() to set ->trace of @prev_root. Moreover, with our adjustment of printing backwards dependency path, the ->trace of @prev_root is unncessary, so remove it. Reported-by: Johannes Berg Signed-off-by: Boqun Feng --- kernel/locking/lockdep.c | 3 --- 1 file changed, 3 deletions(-) diff --git a/kernel/locking/lockdep.c b/kernel/locking/lockdep.c index 3b32cd9cdfd0..74d084a398be 100644 --- a/kernel/locking/lockdep.c +++ b/kernel/locking/lockdep.c @@ -2550,9 +2550,6 @@ print_bad_irq_dependency(struct task_struct *curr, lockdep_print_held_locks(curr); pr_warn("\nthe dependencies between %s-irq-safe lock and the holding lock:\n", irqclass); - prev_root->trace = save_trace(); - if (!prev_root->trace) - return; print_shortest_lock_dependencies_backwards(backwards_entry, prev_root); pr_warn("\nthe dependencies between the lock to be acquired"); -- 2.30.2