From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by smtp.subspace.kernel.org (Postfix) with ESMTP id 716C1606A32E for ; Sat, 14 Nov 2026 18:56:24 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.a=rsa-sha256 header.s=k20260515 header.b=hFXT4w+R Received: by kanga.kvack.org (Postfix) id 873B96B00EF; Sat, 14 Nov 2026 13:56:23 -0500 (EST) Received: by kanga.kvack.org (Postfix, from userid 40) id 824866B05B0; Sat, 14 Nov 2026 13:56:23 -0500 (EST) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 73D8F6B05B1; Sat, 14 Nov 2026 13:56:23 -0500 (EST) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0011.hostedemail.com [216.40.44.11]) by kanga.kvack.org (Postfix) with ESMTP id 5596A6B00EF for ; Sat, 14 Nov 2026 13:56:23 -0500 (EST) Received: from smtpin20.hostedemail.com (lb01a-stub [10.200.18.249]) by unirelay04.hostedemail.com (Postfix) with ESMTP id 5E6BE1A0458 for ; Sat, 14 Nov 2026 18:56:22 +0000 (UTC) X-FDA: 85434630204.20.7E5156A Received: from tor.source.kernel.org (tor.source.kernel.org [172.105.4.254]) by imf02.hostedemail.com (Postfix) with ESMTP id BCA6A80004 for ; Sat, 14 Nov 2026 18:56:20 +0000 (UTC) Authentication-Results: imf02.hostedemail.com; dkim=pass header.d=kernel.org header.s=k20260515 header.b=hFXT4w+R; spf=pass (imf02.hostedemail.com: domain of ljs@kernel.org designates 172.105.4.254 as permitted sender) smtp.mailfrom=ljs@kernel.org; dmarc=pass (policy=quarantine) header.from=kernel.org ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1794682580; h=from:from:sender:reply-to:subject:subject:date:date: message-id:message-id:to:to:cc:cc:mime-version:mime-version: content-type:content-type:content-transfer-encoding: in-reply-to:in-reply-to:references:references:dkim-signature; bh=//GruLIthFISZCy43B0WDxoPfxAVchEQzL1ze90Ia1U=; b=jkNaPwhFpPX8xsU1gzUEAISolFkXFo9CNRmUI+XKvlXCdA6X07fn6vrhARxR4uYPlUoEk4 tUw2/DEuRXZy09oa8zNfYhIPhUePj+//nespUzw3oWi95SfMrJrgWvnmtKp1T5sG5Hiauw NXoPLjkG+CgibkMz7Ff6UkLVi6z/TuI= ARC-Seal: i=1; a=rsa-sha256; d=hostedemail.com; s=arc-20220608; cv=none; t=1794682580; b=Aq0MAfj6ItiRBHVTvViKyMQtIMv1PET9fLgyJ6ABQVLaB/OyQUwIT+0oYpkuGNt+XtZsck Q0lnyt7FEfdmC5/P6TzknojJe4SNWiPE6KetcVZdKiftyoISxo6xjA7ZCfHehflCZxgAaE tict2plqJcyN5Y1cRuEXbJ9BAzlCmTY= ARC-Authentication-Results: i=1; imf02.hostedemail.com; dkim=pass header.d=kernel.org header.s=k20260515 header.b=hFXT4w+R; spf=pass (imf02.hostedemail.com: domain of ljs@kernel.org designates 172.105.4.254 as permitted sender) smtp.mailfrom=ljs@kernel.org; dmarc=pass (policy=quarantine) header.from=kernel.org Received: from smtp.kernel.org (quasi.space.kernel.org [100.103.45.18]) by tor.source.kernel.org (Postfix) with ESMTP id 4E18561265; Sat, 14 Nov 2026 18:56:20 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 3BC5C1F000C4; Sat, 14 Nov 2026 18:56:13 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1794682580; bh=//GruLIthFISZCy43B0WDxoPfxAVchEQzL1ze90Ia1U=; h=Date:From:To:Cc:Subject:References:In-Reply-To; b=hFXT4w+RF00hYPkv+JLeIEZAjbBCTc5CY95xB7nG2ZeZC6xVNc/tyLfLCXLXXfzU/ 0xwjpH4uqHfJv3b9jTPfEDI05f7epSGY7WNGrFU65nrM599kdWjAEstILA4u/ArbNH FTR5pcJyhgtGykdCgnB9yTDQlTEGPmVB2LhUyMM/DydIocWWISlDCPO5SdDwgRJIHN 4wq5xnK84S73I5MUqu84dXHgKrRnMmjnl0JRhFS++dhSPVoIn0UZspmNkPF5QG60KR Pr81J5yjOzly8Xwkbx+5AcxopvUR+FkweegBHOBezVZ17Bld0ubFOCo/dvixMRJFbK Aqop4pp6GTflA== Date: Sat, 14 Nov 2026 18:56:10 +0000 From: "Lorenzo Stoakes (ARM)" To: "David Hildenbrand (Arm)" Cc: "Liam R. Howlett" , Vlastimil Babka , Mike Rapoport , Suren Baghdasaryan , Michal Hocko , Andrew Morton , Willy Tarreau , Jani Nikula , Joonas Lahtinen , Rodrigo Vivi , Tvrtko Ursulin , David Airlie , Simona Vetter , Chris Wilson , Matthew Auld , Madhavan Srinivasan , Michael Ellerman , Nicholas Piggin , "Christophe Leroy (CS GROUP)" , "Ritesh Harjani (IBM)" , Shrikanth Hegde , Rik van Riel , Benjamin Herrenschmidt , linux-mm@kvack.org, linux-kernel@vger.kernel.org, intel-gfx@lists.freedesktop.org, dri-devel@lists.freedesktop.org, linuxppc-dev@lists.ozlabs.org, Chris Mason , stable@vger.kernel.org Subject: Re: [PATCH 1/5] mm: do not call vm_ops->access with FOLL_ANON Message-ID: References: <20261112-access_shite-v1-0-988a5c470db2@kernel.org> <20261112-access_shite-v1-1-988a5c470db2@kernel.org> X-Archived-By: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20261112-access_shite-v1-1-988a5c470db2@kernel.org> X-Spam-Status: No, score=-15.8 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_CR_TRAILER,INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_PASS, SPF_PASS autolearn=ham autolearn_force=no version=4.0.1 X-Rspamd-Server: rspam09 X-Stat-Signature: btusoz77gs61bsdqee97eqzqqc569wam X-Rspamd-Queue-Id: BCA6A80004 X-Rspam-User: X-HE-Tag: 1794682580-293533 X-HE-Meta: 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 BT/nQUkm 1IytrzvPQGypF4EsP6sgrrq+VhW5oqzJ4w8pASFK/fe12hT9y0cMJdEfKux4kQELrMWaeRs7f8AewqzGAWwHlgSiFzL+hyrwwz0isrC7cZDKKMsyCfJAHli2oU0iYuzXPkKq+y+0HXKdwoXKDF/fu7TmPY6JAz21mQw5h/pe4UKgT1ygCzGTKE2m25t+0hoFiQnrGCwlgNbdR4tSIoNrCNGeQaRolqRhPWCsP3qjBLuCRMGRUtKlm2BgrEIxzP+YzyDEZuzjWoXKKMzL9BIrVMVioOlIaHUrzOZMH7O2+obpBwXnkqPvNPfbXINzaEX7LENljQcTgzKNq1VKdr+7VBO2Tb1Or3FJq65kjchUnyDEpentITVDisnFkHivQUs3tN7j5YXMhPcWUfyugzyavYKsSBPgE8JD2fdi8gWVIiqOW5fGqBJW1tdaCiA== Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: X-Spam-Checker-Version: SpamAssassin 4.0.1 (2024-03-26) on aws-us-west-2-korg-listserv-alma10-1 On Thu, Nov 12, 2026 at 11:08:57PM +0100, David Hildenbrand (Arm) wrote: > From: Chris Mason > > Reading /proc//cmdline or /proc//environ can block in a device > driver, or read device memory, if the virtual addresses point at a device > mapping. > > Ever since commit 7f7ccc2ccc2e ("proc: do not access cmdline nor environ > from file-backed areas") we use FOLL_ANON to only read from anonymous > memory. While GUP properly handles FOLL_ANON, __access_remote_vm() > will fall back on GUP errors to vma->vm_ops->access() without similarly > considering the flag. > > Fix it by not calling vm_ops->access if FOLL_ANON was specified, to > truly limit it to anonymous memory only. > > Fixes: 7f7ccc2ccc2e ("proc: do not access cmdline nor environ from file-backed areas") > Signed-off-by: Chris Mason > Cc: stable@vger.kernel.org > [ david: simplify description; slightly rework implementation ] > Signed-off-by: David Hildenbrand (Arm) LGTM so: Reviewed-by: Lorenzo Stoakes (ARM) > --- > mm/memory.c | 3 +++ > 1 file changed, 3 insertions(+) > > diff --git a/mm/memory.c b/mm/memory.c > index 1a0ec09c56fd7..d4370c1b331c9 100644 > --- a/mm/memory.c > +++ b/mm/memory.c > @@ -7398,6 +7398,9 @@ static int __access_remote_vm(struct mm_struct *mm, unsigned long addr, > continue; > } > > + if (gup_flags & FOLL_ANON) > + break; > + > /* > * Check if this is a VM_IO | VM_PFNMAP VMA, which > * we can access using slightly different code. > > -- > 2.43.0 > -- Cheers, Lorenzo