From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-pf0-f199.google.com (mail-pf0-f199.google.com [209.85.192.199]) by kanga.kvack.org (Postfix) with ESMTP id EA3096B0003 for ; Thu, 29 Mar 2018 06:27:24 -0400 (EDT) Received: by mail-pf0-f199.google.com with SMTP id u8so3971114pfm.21 for ; Thu, 29 Mar 2018 03:27:24 -0700 (PDT) Received: from www262.sakura.ne.jp (www262.sakura.ne.jp. [202.181.97.72]) by mx.google.com with ESMTPS id w23-v6si3536174plk.649.2018.03.29.03.27.22 for (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Thu, 29 Mar 2018 03:27:23 -0700 (PDT) Subject: Re: [PATCH v2] lockdep: Show address of "struct lockdep_map" at print_lock(). From: Tetsuo Handa References: <1522059513-5461-1-git-send-email-penguin-kernel@I-love.SAKURA.ne.jp> <20180326160549.GL4043@hirez.programming.kicks-ass.net> <201803270558.HCA41032.tVFJOFOMOFLHSQ@I-love.SAKURA.ne.jp> <201803271941.GBE57310.tVSOJLQOFFOHFM@I-love.SAKURA.ne.jp> In-Reply-To: <201803271941.GBE57310.tVSOJLQOFFOHFM@I-love.SAKURA.ne.jp> Message-Id: <201803291926.FEH43221.VSOQHOtFJFLMOF@I-love.SAKURA.ne.jp> Date: Thu, 29 Mar 2018 19:26:52 +0900 Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Sender: owner-linux-mm@kvack.org List-ID: To: akpm@linux-foundation.org Cc: peterz@infradead.org, mhocko@suse.com, mingo@redhat.com, linux-kernel@vger.kernel.org, linux-mm@kvack.org, bp@suse.de, rientjes@google.com, tglx@linutronix.de >>From 91c081c4c5f6a99402542951e7de661c38f928ab Mon Sep 17 00:00:00 2001 From: Tetsuo Handa Date: Tue, 27 Mar 2018 19:38:33 +0900 Subject: [PATCH v2] lockdep: Show address of "struct lockdep_map" at print_lock(). Since "struct lockdep_map" is embedded into lock objects, we can know which instance of a lock object is acquired using hlock->instance field. This will help finding which threads are causing a lock contention. Currently, print_lock() is printing hlock->acquire_ip field in both "[<%px>]" and "%pS" format. But "[<%px>]" is little useful nowadays, for we use scripts/faddr2line which receives "%pS" for finding the location in the source code. And I want to reduce amount of output, for debug_show_all_locks() might print a lot. Therefore, this patch replaces "[<%px>]" for printing hlock->acquire_ip field with "%p" for printing hlock->instance field. [ 251.305475] 3 locks held by a.out/31106: [ 251.308949] #0: 00000000b0f753ba (&mm->mmap_sem){++++}, at: copy_process.part.41+0x10d5/0x1fe0 [ 251.314283] #1: 00000000ef64d539 (&mm->mmap_sem/1){+.+.}, at: copy_process.part.41+0x10fe/0x1fe0 [ 251.319618] #2: 00000000b41a282e (&mapping->i_mmap_rwsem){++++}, at: copy_process.part.41+0x12f2/0x1fe0 Signed-off-by: Tetsuo Handa Acked-by: Michal Hocko Acked-by: David Rientjes Cc: Peter Zijlstra Cc: Ingo Molnar Cc: Borislav Petkov Cc: Thomas Gleixner --- kernel/locking/lockdep.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff --git a/kernel/locking/lockdep.c b/kernel/locking/lockdep.c index 12a2805..0233863 100644 --- a/kernel/locking/lockdep.c +++ b/kernel/locking/lockdep.c @@ -556,9 +556,9 @@ static void print_lock(struct held_lock *hlock) return; } + printk(KERN_CONT "%p", hlock->instance); print_lock_name(lock_classes + class_idx - 1); - printk(KERN_CONT ", at: [<%px>] %pS\n", - (void *)hlock->acquire_ip, (void *)hlock->acquire_ip); + printk(KERN_CONT ", at: %pS\n", (void *)hlock->acquire_ip); } static void lockdep_print_held_locks(struct task_struct *curr) -- 1.8.3.1