From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753226AbeC2MCx (ORCPT ); Thu, 29 Mar 2018 08:02:53 -0400 Received: from merlin.infradead.org ([205.233.59.134]:34380 "EHLO merlin.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751008AbeC2MCv (ORCPT ); Thu, 29 Mar 2018 08:02:51 -0400 Date: Thu, 29 Mar 2018 14:01:56 +0200 From: Peter Zijlstra To: Tetsuo Handa Cc: akpm@linux-foundation.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 Subject: Re: [PATCH v2] lockdep: Show address of "struct lockdep_map" at print_lock(). Message-ID: <20180329120156.GY4043@hirez.programming.kicks-ass.net> 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> <201803291926.FEH43221.VSOQHOtFJFLMOF@I-love.SAKURA.ne.jp> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <201803291926.FEH43221.VSOQHOtFJFLMOF@I-love.SAKURA.ne.jp> User-Agent: Mutt/1.9.3 (2018-01-21) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu, Mar 29, 2018 at 07:26:52PM +0900, Tetsuo Handa wrote: > >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 Acked-by: Peter Zijlstra (Intel) Ingo, can you merge this? > 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 >