From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-qt0-f199.google.com (mail-qt0-f199.google.com [209.85.216.199]) by kanga.kvack.org (Postfix) with ESMTP id 458556B0005 for ; Wed, 4 Apr 2018 06:29:02 -0400 (EDT) Received: by mail-qt0-f199.google.com with SMTP id y1so12234529qti.10 for ; Wed, 04 Apr 2018 03:29:02 -0700 (PDT) Received: from mx0a-001b2d01.pphosted.com (mx0a-001b2d01.pphosted.com. [148.163.156.1]) by mx.google.com with ESMTPS id 8si3255514qtw.118.2018.04.04.03.29.01 for (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Wed, 04 Apr 2018 03:29:01 -0700 (PDT) Received: from pps.filterd (m0098399.ppops.net [127.0.0.1]) by mx0a-001b2d01.pphosted.com (8.16.0.22/8.16.0.22) with SMTP id w34ARaGc088240 for ; Wed, 4 Apr 2018 06:29:00 -0400 Received: from e06smtp15.uk.ibm.com (e06smtp15.uk.ibm.com [195.75.94.111]) by mx0a-001b2d01.pphosted.com with ESMTP id 2h4vs6gn8b-1 (version=TLSv1.2 cipher=AES256-SHA256 bits=256 verify=NOT) for ; Wed, 04 Apr 2018 06:28:59 -0400 Received: from localhost by e06smtp15.uk.ibm.com with IBM ESMTP SMTP Gateway: Authorized Use Only! Violators will be prosecuted for from ; Wed, 4 Apr 2018 11:28:56 +0100 Subject: Re: [mm] b1f0502d04: INFO:trying_to_register_non-static_key References: <20180317075119.u6yuem2bhxvggbz3@inn> <792c0f75-7e7f-cd81-44ae-4205f6e4affc@linux.vnet.ibm.com> From: Laurent Dufour Date: Wed, 4 Apr 2018 12:28:44 +0200 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit Message-Id: <964ecdb1-3a2a-96b5-5a9c-5c12f874ea84@linux.vnet.ibm.com> Sender: owner-linux-mm@kvack.org List-ID: To: David Rientjes Cc: kernel test robot , paulmck@linux.vnet.ibm.com, peterz@infradead.org, akpm@linux-foundation.org, kirill@shutemov.name, ak@linux.intel.com, mhocko@kernel.org, dave@stgolabs.net, jack@suse.cz, Matthew Wilcox , benh@kernel.crashing.org, mpe@ellerman.id.au, paulus@samba.org, Thomas Gleixner , Ingo Molnar , hpa@zytor.com, Will Deacon , Sergey Senozhatsky , Andrea Arcangeli , Alexei Starovoitov , kemi.wang@intel.com, sergey.senozhatsky.work@gmail.com, Daniel Jordan , linux-kernel@vger.kernel.org, linux-mm@kvack.org, haren@linux.vnet.ibm.com, khandual@linux.vnet.ibm.com, npiggin@gmail.com, bsingharora@gmail.com, Tim Chen , linuxppc-dev@lists.ozlabs.org, x86@kernel.org, lkp@01.org On 04/04/2018 03:03, David Rientjes wrote: > On Tue, 3 Apr 2018, David Rientjes wrote: > >>>>> I found the root cause of this lockdep warning. >>>>> >>>>> In mmap_region(), unmap_region() may be called while vma_link() has not been >>>>> called. This happens during the error path if call_mmap() failed. >>>>> >>>>> The only to fix that particular case is to call >>>>> seqcount_init(&vma->vm_sequence) when initializing the vma in mmap_region(). >>>>> >>>> >>>> Ack, although that would require a fixup to dup_mmap() as well. >>> >>> You're right, I'll fix that too. >>> >> >> I also think the following is needed: >> >> diff --git a/fs/exec.c b/fs/exec.c >> --- a/fs/exec.c >> +++ b/fs/exec.c >> @@ -312,6 +312,10 @@ static int __bprm_mm_init(struct linux_binprm *bprm) >> vma->vm_flags = VM_SOFTDIRTY | VM_STACK_FLAGS | VM_STACK_INCOMPLETE_SETUP; >> vma->vm_page_prot = vm_get_page_prot(vma->vm_flags); >> INIT_LIST_HEAD(&vma->anon_vma_chain); >> +#ifdef CONFIG_SPECULATIVE_PAGE_FAULT >> + seqcount_init(&vma->vm_sequence); >> + atomic_set(&vma->vm_ref_count, 0); >> +#endif >> >> err = insert_vm_struct(mm, vma); >> if (err) >> > > Ugh, I think there are a number of other places where this is needed as > well in mm/mmap.c. I think it would be better to just create a new > alloc_vma(unsigned long flags) that all vma allocators can use and for > CONFIG_SPECULATIVE_PAGE_FAULT will initialize the seqcount_t and atomic_t. > I don't think this is really needed, most of the time the vma structure is allocated cleared and is then link to rb tree via vma_link. The only case generating a locked warning is when the vma is referenced in the error path before being linked in the mm tree and that is not usual.