From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-wm1-f69.google.com (mail-wm1-f69.google.com [209.85.128.69]) by kanga.kvack.org (Postfix) with ESMTP id 44FC18E00EE for ; Fri, 25 Jan 2019 16:03:09 -0500 (EST) Received: by mail-wm1-f69.google.com with SMTP id 18so2633189wmw.6 for ; Fri, 25 Jan 2019 13:03:09 -0800 (PST) Received: from mail-sor-f65.google.com (mail-sor-f65.google.com. [209.85.220.65]) by mx.google.com with SMTPS id q4sor74827920wru.28.2019.01.25.13.03.07 for (Google Transport Security); Fri, 25 Jan 2019 13:03:07 -0800 (PST) MIME-Version: 1.0 References: <20190124231441.37A4A305@viggo.jf.intel.com> <20190124231442.EFD29EE0@viggo.jf.intel.com> In-Reply-To: <20190124231442.EFD29EE0@viggo.jf.intel.com> From: Bjorn Helgaas Date: Fri, 25 Jan 2019 15:02:55 -0600 Message-ID: Subject: Re: [PATCH 1/5] mm/resource: return real error codes from walk failures Content-Type: text/plain; charset="UTF-8" Sender: owner-linux-mm@kvack.org List-ID: To: Dave Hansen Cc: Linux Kernel Mailing List , Dan Williams , Dave Jiang , zwisler@kernel.org, vishal.l.verma@intel.com, thomas.lendacky@amd.com, Andrew Morton , mhocko@suse.com, linux-nvdimm@lists.01.org, linux-mm@kvack.org, Huang Ying , Wu Fengguang , Borislav Petkov , baiyaowei@cmss.chinamobile.com, Takashi Iwai , Jerome Glisse On Thu, Jan 24, 2019 at 5:21 PM Dave Hansen wrote: > > > From: Dave Hansen > > walk_system_ram_range() can return an error code either becuase *it* > failed, or because the 'func' that it calls returned an error. The > memory hotplug does the following: > > ret = walk_system_ram_range(..., func); > if (ret) > return ret; > > and 'ret' makes it out to userspace, eventually. The problem is, > walk_system_ram_range() failues that result from *it* failing (as > opposed to 'func') return -1. That leads to a very odd -EPERM (-1) > return code out to userspace. > > Make walk_system_ram_range() return -EINVAL for internal failures to > keep userspace less confused. > > This return code is compatible with all the callers that I audited. > > Signed-off-by: Dave Hansen > Cc: Dan Williams > Cc: Dave Jiang > Cc: Ross Zwisler > Cc: Vishal Verma > Cc: Tom Lendacky > Cc: Andrew Morton > Cc: Michal Hocko > Cc: linux-nvdimm@lists.01.org > Cc: linux-kernel@vger.kernel.org > Cc: linux-mm@kvack.org > Cc: Huang Ying > Cc: Fengguang Wu > Cc: Borislav Petkov > Cc: Bjorn Helgaas > Cc: Yaowei Bai > Cc: Takashi Iwai > Cc: Jerome Glisse > --- > > b/kernel/resource.c | 4 ++-- > 1 file changed, 2 insertions(+), 2 deletions(-) > > diff -puN kernel/resource.c~memory-hotplug-walk_system_ram_range-returns-neg-1 kernel/resource.c > --- a/kernel/resource.c~memory-hotplug-walk_system_ram_range-returns-neg-1 2019-01-24 15:13:13.950199540 -0800 > +++ b/kernel/resource.c 2019-01-24 15:13:13.954199540 -0800 > @@ -375,7 +375,7 @@ static int __walk_iomem_res_desc(resourc > int (*func)(struct resource *, void *)) > { > struct resource res; > - int ret = -1; > + int ret = -EINVAL; > > while (start < end && > !find_next_iomem_res(start, end, flags, desc, first_lvl, &res)) { > @@ -453,7 +453,7 @@ int walk_system_ram_range(unsigned long > unsigned long flags; > struct resource res; > unsigned long pfn, end_pfn; > - int ret = -1; > + int ret = -EINVAL; Can you either make a similar change to the powerpc version of walk_system_ram_range() in arch/powerpc/mm/mem.c or explain why it's not needed? It *seems* like we'd want both versions of walk_system_ram_range() to behave similarly in this respect. > start = (u64) start_pfn << PAGE_SHIFT; > end = ((u64)(start_pfn + nr_pages) << PAGE_SHIFT) - 1; > _ 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=-11.6 required=3.0 tests=DKIMWL_WL_MED,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI, SIGNED_OFF_BY,SPF_PASS,USER_IN_DEF_DKIM_WL autolearn=unavailable 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 D45FBC282C0 for ; Fri, 25 Jan 2019 21:03:10 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id 6BF78218A6 for ; Fri, 25 Jan 2019 21:03:10 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=google.com header.i=@google.com header.b="JRDDhEn8" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 6BF78218A6 Authentication-Results: mail.kernel.org; dmarc=fail (p=reject dis=none) header.from=google.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=owner-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix) id B00AB8E00EF; Fri, 25 Jan 2019 16:03:09 -0500 (EST) Received: by kanga.kvack.org (Postfix, from userid 40) id AB2538E00EE; Fri, 25 Jan 2019 16:03:09 -0500 (EST) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 9C90E8E00EF; Fri, 25 Jan 2019 16:03:09 -0500 (EST) X-Delivered-To: linux-mm@kvack.org Received: from mail-wm1-f69.google.com (mail-wm1-f69.google.com [209.85.128.69]) by kanga.kvack.org (Postfix) with ESMTP id 44FC18E00EE for ; Fri, 25 Jan 2019 16:03:09 -0500 (EST) Received: by mail-wm1-f69.google.com with SMTP id 18so2633189wmw.6 for ; Fri, 25 Jan 2019 13:03:09 -0800 (PST) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:dkim-signature:mime-version:references :in-reply-to:from:date:message-id:subject:to:cc; bh=GlFA8LtVMqJOfnjC7UmYvTFlMlqdaOETYFtC07gL8c8=; b=KU+F18XyoyUXOrQg1qelJrExDLh8pMRzL+mEfJegZJyQCeZxVwVB6ig3XWuvGeuRWe etc0TdNl4cUuKC2yV1pkOr4POnZjB6JujSZr2QKXsC7TpJjXFbiGcyxz3WTgkPVflhFo e8oB4k1fZ428uVtyToSvlL+qCodLDwZKd7XSKdtYclqOs7ruw+ktk2aP5YdWJR3F+O6g BMPPSqOFaMt3mUtcoAi2b4uO7m8bfgJJtGE8PBhlSPeHQlclmHkbvsDxvFkCoimBTZ2Z pm+Nm0hBzsjh9yrtXw5JhcE+SLRkjpNa1kU7WgwaBnz1Vzr0IKG2VdRLErU48mT5X4NH Mf3Q== X-Gm-Message-State: AJcUukcW/E/eH2b1N3NGGFKFFp7EDWuyLBK/aeZ05m70+fdkjBCyj9Zx QJmMRc3EwlZISCei+5Mw2G0AqbY2xDj/DfPQR0GDOlLvBqT15oxiMhaFKEJUfonjCF+Gw/6Jj9l a4S3U8nGgTqu4w5XDt4KNk7/Sl/JLr668Lpm07zk8bZNF3/mJEGQhkGdkiBCuynREfzRpxr+m5X HLz9vwPQ8qSjX60BcePV430ZaMtDP7m8irqRwQwVGdzvLVRCQDS3UU7rcSCgEUS3M0z+3v8vcng sxaASOhsOiLfciA8JtQk729wZ3KKo3IEZbPN5pxf/XuHo6IxFp04Gmo/vWqp8sk4fslnWK3ynYn GZcQUmYKWsXg6QKfLF/1+mjxd3r5+qWxXEChryXZprIFItp1sCwHypHGelSebsVP+Yi/H3wbPXU r X-Received: by 2002:a1c:bc82:: with SMTP id m124mr8038102wmf.77.1548450188724; Fri, 25 Jan 2019 13:03:08 -0800 (PST) X-Received: by 2002:a1c:bc82:: with SMTP id m124mr8038057wmf.77.1548450187564; Fri, 25 Jan 2019 13:03:07 -0800 (PST) ARC-Seal: i=1; a=rsa-sha256; t=1548450187; cv=none; d=google.com; s=arc-20160816; b=TnXZDApGUdIYeMN2S9T8huz4kQ8CjVe1PyOp977ITXetzwtKG7Dhxq6WYKBZICYJG/ mwc53X4Wa7KqMYdgfuPXUaWT/iGfBw5IAy8UWLp66fpQCYwzoI1GtA98sm6RLggTy9UJ 6K4+HEDuOknG21FlEz10uTYO14v6L3XsLRAtUmr7WZRRF1Ae4DqOq8C1Ysy4dHShZ0+y EPo6IMoXn3zMm/MC9KTxUMyoi8yHSQAUCZklEgEnfaJrltOqwF1V2lCmmFxoYtCKDv8R GVGhAEUwgXoZECCZ3FxntUeDyIPrx4RQEc5T8wAcuk9KHSrs+IjSLy8CBQjUygRnLBsu vdpA== ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=arc-20160816; h=cc:to:subject:message-id:date:from:in-reply-to:references :mime-version:dkim-signature; bh=GlFA8LtVMqJOfnjC7UmYvTFlMlqdaOETYFtC07gL8c8=; b=uwLTEctNbIk2Tl4tBzPxTuwqistcFVaBpEs2bzAzp8bMRjgZ9LGVJR8+PWUaopjAiy 4m4PKwNARtd4pp3xyeCUybzqkq0zPwJu7thcsarAcZ1cyvKTQgPQvOt5Bo8xmsfk6HrG TOwLlCM5XcuH3f4j2ZYG90ynlpIECXkRJwng4HRvKsgWv3DEJHvuN+fHf8XN3nfZCZxp 0+aIVTObftxaaZdKrNGyVy3zrtUwiAsjf8xN1QFxdx5kYA4VxAsZtTcBolDWnxlT/U+K rW/oyfsE04JBZoXQ58ITM0O5xaU5ss3w1+uvGV0JNB56bjEbhCdBUDhPzyYclOae8mzK H/EQ== ARC-Authentication-Results: i=1; mx.google.com; dkim=pass header.i=@google.com header.s=20161025 header.b=JRDDhEn8; spf=pass (google.com: domain of bhelgaas@google.com designates 209.85.220.65 as permitted sender) smtp.mailfrom=bhelgaas@google.com; dmarc=pass (p=REJECT sp=REJECT dis=NONE) header.from=google.com Received: from mail-sor-f65.google.com (mail-sor-f65.google.com. [209.85.220.65]) by mx.google.com with SMTPS id q4sor74827920wru.28.2019.01.25.13.03.07 for (Google Transport Security); Fri, 25 Jan 2019 13:03:07 -0800 (PST) Received-SPF: pass (google.com: domain of bhelgaas@google.com designates 209.85.220.65 as permitted sender) client-ip=209.85.220.65; Authentication-Results: mx.google.com; dkim=pass header.i=@google.com header.s=20161025 header.b=JRDDhEn8; spf=pass (google.com: domain of bhelgaas@google.com designates 209.85.220.65 as permitted sender) smtp.mailfrom=bhelgaas@google.com; dmarc=pass (p=REJECT sp=REJECT dis=NONE) header.from=google.com DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20161025; h=mime-version:references:in-reply-to:from:date:message-id:subject:to :cc; bh=GlFA8LtVMqJOfnjC7UmYvTFlMlqdaOETYFtC07gL8c8=; b=JRDDhEn8/pBLDYMXq+rCIIkS2PvE/vCc8+Vgigg/VxRv1eyxQObLuf9Ql56fZebign hZZqX3LZTlxh4qtYJaHRX2ZnZzRI7SNdQMloqP3An+Di6jaSMBjtcI/JkdMlqzFC7BEj tkjLMRL0VYIJA0AfWf3mSFlXN8mfnFRs1vQPOThm+lQyqR7/DIeHKPd2b+iEhtmP8cNq 4SJIynT+/KmTQu69nps1hVdBtXq267EqcDrobJaMrTFCskCvhU1WRvRJrO1Hf8U8jAuH 0OQeoiMxMDs+Md0Ca0wNaQmVQZ/n7I0rK2cPmMM6IwHp4d2nC7eHBJYVhXFM8VCGru71 w3TA== X-Google-Smtp-Source: ALg8bN4YSnU8ocVyHeD54PjkgUNpLaNRE+Av0um87TRh1jxbNHujScXrZ+6dCqJZAqSI4YIMKMgZIpl7xkOcH+hyQDg= X-Received: by 2002:adf:9b11:: with SMTP id b17mr13033849wrc.168.1548450186690; Fri, 25 Jan 2019 13:03:06 -0800 (PST) MIME-Version: 1.0 References: <20190124231441.37A4A305@viggo.jf.intel.com> <20190124231442.EFD29EE0@viggo.jf.intel.com> In-Reply-To: <20190124231442.EFD29EE0@viggo.jf.intel.com> From: Bjorn Helgaas Date: Fri, 25 Jan 2019 15:02:55 -0600 Message-ID: Subject: Re: [PATCH 1/5] mm/resource: return real error codes from walk failures To: Dave Hansen Cc: Linux Kernel Mailing List , Dan Williams , Dave Jiang , zwisler@kernel.org, vishal.l.verma@intel.com, thomas.lendacky@amd.com, Andrew Morton , mhocko@suse.com, linux-nvdimm@lists.01.org, linux-mm@kvack.org, Huang Ying , Wu Fengguang , Borislav Petkov , baiyaowei@cmss.chinamobile.com, Takashi Iwai , Jerome Glisse Content-Type: text/plain; charset="UTF-8" X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: Message-ID: <20190125210255.jbLi420NiT-v90pqIqiT9QEpj5bRiJJbaukIjFmmAfs@z> On Thu, Jan 24, 2019 at 5:21 PM Dave Hansen wrote: > > > From: Dave Hansen > > walk_system_ram_range() can return an error code either becuase *it* > failed, or because the 'func' that it calls returned an error. The > memory hotplug does the following: > > ret = walk_system_ram_range(..., func); > if (ret) > return ret; > > and 'ret' makes it out to userspace, eventually. The problem is, > walk_system_ram_range() failues that result from *it* failing (as > opposed to 'func') return -1. That leads to a very odd -EPERM (-1) > return code out to userspace. > > Make walk_system_ram_range() return -EINVAL for internal failures to > keep userspace less confused. > > This return code is compatible with all the callers that I audited. > > Signed-off-by: Dave Hansen > Cc: Dan Williams > Cc: Dave Jiang > Cc: Ross Zwisler > Cc: Vishal Verma > Cc: Tom Lendacky > Cc: Andrew Morton > Cc: Michal Hocko > Cc: linux-nvdimm@lists.01.org > Cc: linux-kernel@vger.kernel.org > Cc: linux-mm@kvack.org > Cc: Huang Ying > Cc: Fengguang Wu > Cc: Borislav Petkov > Cc: Bjorn Helgaas > Cc: Yaowei Bai > Cc: Takashi Iwai > Cc: Jerome Glisse > --- > > b/kernel/resource.c | 4 ++-- > 1 file changed, 2 insertions(+), 2 deletions(-) > > diff -puN kernel/resource.c~memory-hotplug-walk_system_ram_range-returns-neg-1 kernel/resource.c > --- a/kernel/resource.c~memory-hotplug-walk_system_ram_range-returns-neg-1 2019-01-24 15:13:13.950199540 -0800 > +++ b/kernel/resource.c 2019-01-24 15:13:13.954199540 -0800 > @@ -375,7 +375,7 @@ static int __walk_iomem_res_desc(resourc > int (*func)(struct resource *, void *)) > { > struct resource res; > - int ret = -1; > + int ret = -EINVAL; > > while (start < end && > !find_next_iomem_res(start, end, flags, desc, first_lvl, &res)) { > @@ -453,7 +453,7 @@ int walk_system_ram_range(unsigned long > unsigned long flags; > struct resource res; > unsigned long pfn, end_pfn; > - int ret = -1; > + int ret = -EINVAL; Can you either make a similar change to the powerpc version of walk_system_ram_range() in arch/powerpc/mm/mem.c or explain why it's not needed? It *seems* like we'd want both versions of walk_system_ram_range() to behave similarly in this respect. > start = (u64) start_pfn << PAGE_SHIFT; > end = ((u64)(start_pfn + nr_pages) << PAGE_SHIFT) - 1; > _