From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755448AbaIDUbB (ORCPT ); Thu, 4 Sep 2014 16:31:01 -0400 Received: from mail.linuxfoundation.org ([140.211.169.12]:55488 "EHLO mail.linuxfoundation.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755311AbaIDUbA (ORCPT ); Thu, 4 Sep 2014 16:31:00 -0400 Date: Thu, 4 Sep 2014 13:30:58 -0700 From: Andrew Morton To: Sasha Levin Cc: oleg@redhat.com, riel@redhat.com, kirill.shutemov@linux.intel.com, luto@amacapital.net, linux-mm@kvack.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH] mm: mmap: use pr_emerg when printing BUG related information Message-Id: <20140904133058.37ca7aa2e46a607eed94df3b@linux-foundation.org> In-Reply-To: <1409855782-15089-1-git-send-email-sasha.levin@oracle.com> References: <1409855782-15089-1-git-send-email-sasha.levin@oracle.com> X-Mailer: Sylpheed 3.2.0beta5 (GTK+ 2.24.10; x86_64-pc-linux-gnu) Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu, 4 Sep 2014 14:36:22 -0400 Sasha Levin wrote: > Make sure we actually see the output of validate_mm() and browse_rb() > before triggering a BUG(). pr_info isn't shown by default so the reason > for the BUG() isn't obvious. > yup, I'll scoot that into 3.17. That code's actually pretty cruddy. How does this look? From: Andrew Morton Subject: mm/mmap.c: clean up CONFIG_DEBUG_VM_RB checks - be consistent in printing the test which failed - one message was actually wrong (aa) - don't print second bogus warning if browse_rb() failed Cc: Sasha Levin Signed-off-by: Andrew Morton --- mm/mmap.c | 17 +++++++++++------ 1 file changed, 11 insertions(+), 6 deletions(-) diff -puN mm/mmap.c~mm-mmapc-clean-up-config_debug_vm_rb-checks mm/mmap.c --- a/mm/mmap.c~mm-mmapc-clean-up-config_debug_vm_rb-checks +++ a/mm/mmap.c @@ -369,16 +369,18 @@ static int browse_rb(struct rb_root *roo struct vm_area_struct *vma; vma = rb_entry(nd, struct vm_area_struct, vm_rb); if (vma->vm_start < prev) { - pr_emerg("vm_start %lx prev %lx\n", vma->vm_start, prev); + pr_emerg("vm_start %lx < prev %lx\n", + vma->vm_start, prev); bug = 1; } if (vma->vm_start < pend) { - pr_emerg("vm_start %lx pend %lx\n", vma->vm_start, pend); + pr_emerg("vm_start %lx < pend %lx\n", + vma->vm_start, pend); bug = 1; } if (vma->vm_start > vma->vm_end) { - pr_emerg("vm_end %lx < vm_start %lx\n", - vma->vm_end, vma->vm_start); + pr_emerg("vm_start %lx > vm_end %lx\n", + vma->vm_start, vma->vm_end); bug = 1; } if (vma->rb_subtree_gap != vma_compute_subtree_gap(vma)) { @@ -420,8 +422,10 @@ static void validate_mm(struct mm_struct int i = 0; unsigned long highest_address = 0; struct vm_area_struct *vma = mm->mmap; + while (vma) { struct anon_vma_chain *avc; + vma_lock_anon_vma(vma); list_for_each_entry(avc, &vma->anon_vma_chain, same_vma) anon_vma_interval_tree_verify(avc); @@ -436,12 +440,13 @@ static void validate_mm(struct mm_struct } if (highest_address != mm->highest_vm_end) { pr_emerg("mm->highest_vm_end %lx, found %lx\n", - mm->highest_vm_end, highest_address); + mm->highest_vm_end, highest_address); bug = 1; } i = browse_rb(&mm->mm_rb); if (i != mm->map_count) { - pr_emerg("map_count %d rb %d\n", mm->map_count, i); + if (i != -1) + pr_emerg("map_count %d rb %d\n", mm->map_count, i); bug = 1; } BUG_ON(bug); _