From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-0.9 required=3.0 tests=DKIM_SIGNED,DKIM_VALID, DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_PASS, URIBL_BLOCKED autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 248D1ECDE32 for ; Wed, 17 Oct 2018 15:04:06 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id DD7062150F for ; Wed, 17 Oct 2018 15:04:05 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=efficios.com header.i=@efficios.com header.b="OyGFHMOX" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org DD7062150F Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=efficios.com Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727852AbeJQXAJ (ORCPT ); Wed, 17 Oct 2018 19:00:09 -0400 Received: from mail.efficios.com ([167.114.142.138]:51402 "EHLO mail.efficios.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727047AbeJQXAJ (ORCPT ); Wed, 17 Oct 2018 19:00:09 -0400 Received: from localhost (ip6-localhost [IPv6:::1]) by mail.efficios.com (Postfix) with ESMTP id 5961B1CA457; Wed, 17 Oct 2018 11:04:02 -0400 (EDT) Received: from mail.efficios.com ([IPv6:::1]) by localhost (mail02.efficios.com [IPv6:::1]) (amavisd-new, port 10032) with ESMTP id NAY17FcCkkrQ; Wed, 17 Oct 2018 11:04:02 -0400 (EDT) Received: from localhost (ip6-localhost [IPv6:::1]) by mail.efficios.com (Postfix) with ESMTP id ED3171CA44E; Wed, 17 Oct 2018 11:04:01 -0400 (EDT) DKIM-Filter: OpenDKIM Filter v2.10.3 mail.efficios.com ED3171CA44E DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=efficios.com; s=default; t=1539788642; bh=e1OfzSagmyTggYyC443r01uIr2r6Qk2p35af4+oG0I8=; h=Date:From:To:Message-ID:MIME-Version; b=OyGFHMOXQsi927GlUVWIqCE4XccOv5DjGOMFK5RZN/xeRc80ahKM7VYf5gvtsLlQt lbK5YkvzbIB6owCKg9BUydaBCz36vtbCC3MVs8y3L8bEHm3yUvtSwCVx3e3SkhLniN Xh85sd7vL9h7u4gcqF9y98T2Z/0B3GNPPz7QUpJpBk5d9LTvnOMXKy2gHt6VS+q2SX T/uoLYHOzGY/iFodbacb53OrLF1+pcNI2XmQ5XuIDJX8CkTesYXY3+anAIbRX/dcJ7 CFOgJnOJRq2Yra2tkkq+tCADu0+v23+cjzYvA+pVatJCpcqgkc4UWh0PCrVJfxSIwO 4Pg1X4NPkyHYg== X-Virus-Scanned: amavisd-new at efficios.com Received: from mail.efficios.com ([IPv6:::1]) by localhost (mail02.efficios.com [IPv6:::1]) (amavisd-new, port 10026) with ESMTP id 9gRzMb9a_c4U; Wed, 17 Oct 2018 11:04:01 -0400 (EDT) Received: from mail02.efficios.com (mail02.efficios.com [167.114.142.138]) by mail.efficios.com (Postfix) with ESMTP id C0F411CA445; Wed, 17 Oct 2018 11:04:01 -0400 (EDT) Date: Wed, 17 Oct 2018 11:04:01 -0400 (EDT) From: Mathieu Desnoyers To: Sergey Senozhatsky Cc: rostedt , Peter Zijlstra , "Paul E. McKenney" , Boqun Feng , linux-kernel , linux-api , Thomas Gleixner , Andy Lutomirski , Dave Watson , Paul Turner , Andrew Morton , Russell King , Ingo Molnar , "H. Peter Anvin" , Andi Kleen , Chris Lameter , Ben Maurer , Josh Triplett , Linus Torvalds , Catalin Marinas , Will Deacon , Michael Kerrisk , Joel Fernandes Message-ID: <2060193272.771.1539788641739.JavaMail.zimbra@efficios.com> In-Reply-To: <1051015468.759.1539788401096.JavaMail.zimbra@efficios.com> References: <20181010191936.7495-1-mathieu.desnoyers@efficios.com> <20181010191936.7495-5-mathieu.desnoyers@efficios.com> <20181016143016.10da89bd@gandalf.local.home> <20181017002722.GA1068@jagdpanzerIV> <1051015468.759.1539788401096.JavaMail.zimbra@efficios.com> Subject: Re: [RFC PATCH for 4.21 04/16] mm: Introduce vm_map_user_ram, vm_unmap_user_ram MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 7bit X-Originating-IP: [167.114.142.138] X-Mailer: Zimbra 8.8.10_GA_3039 (ZimbraWebClient - FF52 (Linux)/8.8.10_GA_3041) Thread-Topic: Introduce vm_map_user_ram, vm_unmap_user_ram Thread-Index: gPGMSdyLSfgdOsd0mGALLpA4RUrvCVBT8D6q Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org ----- On Oct 17, 2018, at 11:00 AM, Mathieu Desnoyers mathieu.desnoyers@efficios.com wrote: > ----- On Oct 16, 2018, at 8:27 PM, Sergey Senozhatsky > sergey.senozhatsky.work@gmail.com wrote: > >> On (10/16/18 14:30), Steven Rostedt wrote: >>> > +void vm_unmap_user_ram(const void *mem, unsigned int count) >>> > +{ >>> > + unsigned long size = (unsigned long)count << PAGE_SHIFT; >>> > + unsigned long addr = (unsigned long)mem; >>> > + struct vmap_area *va; >>> > + >>> > + might_sleep(); >>> > + BUG_ON(!addr); >>> > + BUG_ON(addr < VMALLOC_START); >>> > + BUG_ON(addr > VMALLOC_END); >>> > + BUG_ON(!PAGE_ALIGNED(addr)); >>> > + >>> > + debug_check_no_locks_freed(mem, size); >>> > + va = find_vmap_area(addr); >>> > + BUG_ON(!va); >>> > + free_unmap_vmap_area(va); >>> > +} >>> > +EXPORT_SYMBOL(vm_unmap_user_ram); >>> > + >>> >>> Noticing this from Sergey's question in another patch, why are you >>> using BUG_ON()? That's rather extreme and something we are trying to >>> avoid adding more of (I still need to remove the BUG_ON()s I've added >>> over ten years ago). I don't see why all these BUG_ON's can't be turned >>> into: >> >> +1 >> >>> if (WARN_ON(x)) >>> return; >> >> Given that this somewhat MM-related, I'd may be say VM_WARN_ON(). I notice that VM_WARN_ON() casts the result of WARN_ON() to (void), so it cannot be used in a if () statement. VM_WARN_ON() will only warn if CONFIG_DEBUG_VM is set. Is it really what we want ? Thanks, Mathieu > > Good point, will do! > > So I'll do one cleanup patch for vm_unmap_ram(), and I'll modify the new > vm_unmap_user_ram(). > > Thanks, > > Mathieu > >> >> -ss > > -- > Mathieu Desnoyers > EfficiOS Inc. > http://www.efficios.com -- Mathieu Desnoyers EfficiOS Inc. http://www.efficios.com