From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-ig0-f173.google.com (mail-ig0-f173.google.com [209.85.213.173]) by kanga.kvack.org (Postfix) with ESMTP id EDE0C6B0254 for ; Wed, 23 Sep 2015 11:42:00 -0400 (EDT) Received: by igbkq10 with SMTP id kq10so102214858igb.0 for ; Wed, 23 Sep 2015 08:42:00 -0700 (PDT) Received: from mx1.redhat.com (mx1.redhat.com. [209.132.183.28]) by mx.google.com with ESMTPS id nq5si922682igb.89.2015.09.23.08.41.59 for (version=TLSv1.2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Wed, 23 Sep 2015 08:41:59 -0700 (PDT) Date: Wed, 23 Sep 2015 17:38:57 +0200 From: Oleg Nesterov Subject: Re: Multiple potential races on vma->vm_flags Message-ID: <20150923153857.GA20233@redhat.com> References: <55EC9221.4040603@oracle.com> <20150907114048.GA5016@node.dhcp.inet.fi> <55F0D5B2.2090205@oracle.com> <20150910083605.GB9526@node.dhcp.inet.fi> <20150911103959.GA7976@node.dhcp.inet.fi> <20150923153416.GA18973@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20150923153416.GA18973@redhat.com> Sender: owner-linux-mm@kvack.org List-ID: To: "Kirill A. Shutemov" Cc: Andrey Konovalov , Sasha Levin , Rik van Riel , Andrew Morton , Dmitry Vyukov , linux-mm@kvack.org, linux-kernel@vger.kernel.org, Vlastimil Babka , Hugh Dickins On 09/23, Oleg Nesterov wrote: > > On 09/11, Kirill A. Shutemov wrote: > > > > This one is tricky. I *assume* the mm cannot be generally accessible after > > mm_users drops to zero, but I'm not entirely sure about it. > > procfs? ptrace? > > Well, all I can say is that proc/ptrace look fine afaics... > > This is off-topic, but how about the patch below? Different threads can > expand different vma's at the same time under read_lock(mmap_sem), so > vma_lock_anon_vma() can't help to serialize "locked_vm += grow". perhaps vm_stat_account() should be moved too, but total_vm/etc is less important. Or I missed something? Oleg. > --- x/mm/mmap.c > +++ x/mm/mmap.c > @@ -2146,9 +2146,6 @@ static int acct_stack_growth(struct vm_a > if (security_vm_enough_memory_mm(mm, grow)) > return -ENOMEM; > > - /* Ok, everything looks good - let it rip */ > - if (vma->vm_flags & VM_LOCKED) > - mm->locked_vm += grow; > vm_stat_account(mm, vma->vm_flags, vma->vm_file, grow); > return 0; > } > @@ -2210,6 +2207,8 @@ int expand_upwards(struct vm_area_struct > * against concurrent vma expansions. > */ > spin_lock(&vma->vm_mm->page_table_lock); > + if (vma->vm_flags & VM_LOCKED) > + mm->locked_vm += grow; > anon_vma_interval_tree_pre_update_vma(vma); > vma->vm_end = address; > anon_vma_interval_tree_post_update_vma(vma); > @@ -2281,6 +2280,8 @@ int expand_downwards(struct vm_area_stru > * against concurrent vma expansions. > */ > spin_lock(&vma->vm_mm->page_table_lock); > + if (vma->vm_flags & VM_LOCKED) > + mm->locked_vm += grow; > anon_vma_interval_tree_pre_update_vma(vma); > vma->vm_start = address; > vma->vm_pgoff -= grow; -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: email@kvack.org