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 43A53606A31A for ; Wed, 28 Oct 2026 16:20:10 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key, unprotected) header.d=kernel.org header.i=@kernel.org header.a=rsa-sha256 header.s=k20260515 header.b=Od2jCajZ Received: by kanga.kvack.org (Postfix) id 413286B05BD; Wed, 28 Oct 2026 12:20:09 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 3C4BB6B05BE; Wed, 28 Oct 2026 12:20:09 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 2B33F6B05BF; Wed, 28 Oct 2026 12:20:09 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0016.hostedemail.com [216.40.44.16]) by kanga.kvack.org (Postfix) with ESMTP id EF05E6B05BD for ; Wed, 28 Oct 2026 12:20:08 -0400 (EDT) Received: from smtpin01.hostedemail.com (lb01a-stub [10.200.18.249]) by unirelay06.hostedemail.com (Postfix) with ESMTP id 82261A6EB2 for ; Wed, 28 Oct 2026 16:20:08 +0000 (UTC) X-FDA: 85372546896.01.F44F5B8 Received: from sea.source.kernel.org (sea.source.kernel.org [172.234.252.31]) by imf15.hostedemail.com (Postfix) with ESMTP id 74F51A000C for ; Wed, 28 Oct 2026 16:20:06 +0000 (UTC) Authentication-Results: imf15.hostedemail.com; dkim=pass header.d=kernel.org header.s=k20260515 header.b=Od2jCajZ; dmarc=pass (policy=quarantine) header.from=kernel.org; spf=pass (imf15.hostedemail.com: domain of kas@kernel.org designates 172.234.252.31 as permitted sender) smtp.mailfrom=kas@kernel.org ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1793204406; 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=0rATnQQTJ72YrBkABg0cEBhwiSsSBn8AUhfECRfpTKo=; b=QK8frgUO+6cuquJyDzHdKsk1V4bnoAEL/WIFprTOrGoAfqCspgsk4NM7hjp6EbPEmi7G/w sgioDEJwwjA/D0wozik28sbl75DmNy69qJoRciuu6iBpaALRQ3UULpkFlhA8JnFOzcNWkV GV9pHVdEcgq3VdrcLOw1Exnlpe1QwR0= ARC-Authentication-Results: i=1; imf15.hostedemail.com; dkim=pass header.d=kernel.org header.s=k20260515 header.b=Od2jCajZ; dmarc=pass (policy=quarantine) header.from=kernel.org; spf=pass (imf15.hostedemail.com: domain of kas@kernel.org designates 172.234.252.31 as permitted sender) smtp.mailfrom=kas@kernel.org ARC-Seal: i=1; a=rsa-sha256; d=hostedemail.com; s=arc-20220608; cv=none; t=1793204406; b=DJeupdpmslj7ZswiMF01K54UAmZ/9JvnnILMtfZXVoRcY73hXB0K7eG8+Hu5QISvzwT9OM O/O5K4oUd0/hYkteWHjWKBQOAzJO9VLA85Za08mY1Rzw/AieJ++3SLnSFIbkM3QZSeTeoi d9I60u1YcKG1IrgRFbJfFg4BdzymFiY= Received: from smtp.kernel.org (quasi.space.kernel.org [100.103.45.18]) by sea.source.kernel.org (Postfix) with ESMTP id 9297643681; Wed, 28 Oct 2026 16:20:05 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id B24D31F01825; Wed, 28 Oct 2026 16:20:00 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1793204405; bh=0rATnQQTJ72YrBkABg0cEBhwiSsSBn8AUhfECRfpTKo=; h=Date:From:To:Cc:Subject:References:In-Reply-To; b=Od2jCajZKWKTDmGKxuYQxCznLzK5lE5I82XP6kHR/pVw15VviXOu0f+rBJztE2sWt aHB1YXF7LuPYHU40KtFSmxWKD6wxnYzbFJeWxCtv5kmvj0IwusDwG6I8dKNYl5hbAX qHQic4MJqltiIVHxUe3brboc9KewZxE/aWUva6VSi7IMJ81oP7hTDulOU8yLFxWP4u W3jZr5qZ7IvLut3ypzOXBw5SA0Vx7r0s7K9pRjlpSjQpPHMhmwn5yGGklOO6EJ9nTi wgAJwgkpfhsVSNks3KTWED/hZ081N4N8oDSY/jJ5jMBOtMs1oL4u97xlwL0bgFticW VC7cHA1IM/c3g== Received: from phl-compute-02.internal (phl-compute-02.internal [10.202.2.42]) by mailfauth.ams.internal (Postfix) with ESMTP id 29073198005A; Wed, 28 Oct 2026 12:19:49 -0400 (EDT) Received: from phl-frontend-03 ([10.202.2.162]) by phl-compute-02.internal (MEProxy); Wed, 28 Oct 2026 12:19:59 -0400 X-ME-Sender: X-ME-Received: X-ME-Proxy-Cause: dmFkZTGclD1JbppB9HJ+wc+PBYUc7y+dixlkOiA2HsCm5bBLjgZcXtU5z4GDtO5noWzmDd ORQFP5u9B2gtbQIzAfn62HyoZPZzOaRlPLXMJbRuOKsJfFDAVc93Ms6EaNrHWEq6z6wsvt Vwv7YGYHYp1DmH0JFFFqpqagIBWKJjdY8K+9fHquSKFVK4QpWZo3/X+8b1lo1wJj7cOP/0 UxPerUKzYQfYIPe0+zZpOe+dudiR/ZmyEvfhO+buEi+HLpafl9BeNw9D79/rT5MOLUUGeC H20VI38/59YkMmPnP0Lyu8v9OMGay2+0LMnea7uAS3uuq0rtJ908MMUpIuTf0GbHo8UsAY ua+t7Qev6BT8kMHCeyM4V1m6u5YQwDA4moRebSE73U9F3vqd/sLjELfF2vONZb+ZcW5TQB 94GQy7Qy9EYuo6vu61hPJ1VjyjuMJ99xhWVMI+3gZz6H3VQ84mHv5w8TE9tnJChUhoUUP9 4BpLr6gQs04DR36/rOYGy/+LZjcGIu/GNpIN099cOSZ+EN2zqtR43z7EhAL94X1B/ytyyp oo/rRFI886c55KcN4on3qj6HWPCrIJtfc0D4lmBumEi5I8lrnU3HxQLS8Z22AYR9GbRHTz 75P/PVpblWhTAf4127jPQ1kO6sZzgqCljd55hkW2aMHmD3LDpX4z8/2t8a7Q X-ME-Proxy: Feedback-ID: i10464835:Fastmail Received: by mail.messagingengine.com (Postfix) with ESMTPA; Wed, 28 Oct 2026 12:19:46 -0400 (EDT) Date: Wed, 28 Oct 2026 16:19:45 +0000 From: Kiryl Shutsemau To: "David Hildenbrand (Arm)" Cc: Andrew Morton , Johannes Weiner , Michal Hocko , Qi Zheng , Shakeel Butt , Lorenzo Stoakes , Kairui Song , Barry Song , Axel Rasmussen , Yuanchu Xie , Wei Xu , Baoquan He , Baolin Wang , "Liam R. Howlett" , Vlastimil Babka , Mike Rapoport , Suren Baghdasaryan , Michal Hocko , Kees Cook , Peter Zijlstra , Jann Horn , Pedro Falcato , Hugh Dickins , Pasha Tatashin , Pratyush Yadav , "Matthew Wilcox (Oracle)" , Jan Kara , Zi Yan , Lance Yang , Rik van Riel , Harry Yoo , Alistair Popple , Nico Pache , Ryan Roberts , Dev Jain , Usama Arif , Matthew Brost , John Hubbard , Peter Xu , Will Deacon , "Aneesh Kumar K.V" , Nick Piggin , Oscar Salvador , Minchan Kim , Muchun Song , Xu Xin , Chengming Zhou , Chris Li , Kemeng Shi , Nhat Pham , Youngjun Park , Gregory Price , Joshua Hahn , Rakie Kim , Ying Huang , Jason Gunthorpe , linux-mm@kvack.org, linux-kernel@vger.kernel.org, kexec@lists.infradead.org, linux-fsdevel@vger.kernel.org, linux-arch@vger.kernel.org, linux-cxl@vger.kernel.org, stable@vger.kernel.org, Josef Bacik Subject: Re: [PATCH 02/46] fork: take mmap_lock before copying mm_struct Message-ID: References: <20261027-fixes_core-v1-0-6f74bec9a5bb@kernel.org> <20261027-fixes_core-v1-2-6f74bec9a5bb@kernel.org> X-Archived-By: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20261027-fixes_core-v1-2-6f74bec9a5bb@kernel.org> X-Rspamd-Server: rspam10 X-Rspamd-Queue-Id: 74F51A000C X-Stat-Signature: yhcw57eewijhdajoucfmqy3t6dt6j3ws X-Spam-Status: No, score=-10.8 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_CR_TRAILER,MAILING_LIST_MULTI,SPF_HELO_PASS,SPF_PASS autolearn=unavailable autolearn_force=no version=4.0.1 X-Rspam-User: X-HE-Tag: 1793204406-75545 X-HE-Meta: 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 d31kfBQQ X4OXgmta9bRg27f4jOOFX9AtUQIRn5cPevDT+9ZafJgjolJm00pYYgvOBY5q7kr3gercnbF4x9aIz7pdG6SJYtfpZnDtx46brrXAeEw7BdIxxRkP7WqptzG9Bqfa9SjcuDipfZjLYh6c0NfQBMboWTwXnHRTf7cGDld27KGtmrpKfWZyyMWjnbVpdysdLw9s1wMt8SPxxAWShdx85aix6xho6UHKlVEimAd04jw28d8H0n7V0aD6XrKbuAKs9/NJ4OwdqMA0id67xSL08TlcoJx7yhrDRd3C/zZIp9Fj/Pq+Hpo9zi/DmwUyTVWP695GKAzsizvfyyQ0NyIn96McYOKEjZGV2glzCrC9Zhe0Pt/v/DDktPa4Od6cM8Vx6yWIeBOxwUBNMDDo69VxS71XizA1FWXpIf6ukdXFzssIZxTK5DsMqFbe9XDvxNkPs6w8oJXvOpx/EH1q3oINBi8pMb7IVYwCMF4n5rDeBQ21k8f6eBiw= 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 Tue, Oct 27, 2026 at 12:17:22AM +0100, David Hildenbrand (Arm) wrote: > dup_mm() copies the parent's mm_struct before dup_mmap() takes the > mmap_lock. A concurrent brk() can leave the child with a stale mm->brk > and newer heap mappings, causing later brk() requests to fail. > > Other operations (e.g., PR_SET_MM) on the parent's mm_struct can similarly > cause inconsistencies. > > As a simple and robust fix, grab the parent's mmap_lock earlier. This > way we don't need to update individual mm fields in dup_mmap() and > keep missing ones. Stop updating the 4 existing members (total_vm, data_vm, > exec_vm, stack_vm), as that is now no longer required. > > Keep releasing the parent's mmap_lock in dup_mmap(), before > userfaultfd completion, to avoid moving the userfaultfd handling into the > caller. This should get cleaned up later. > > Move uprobe_start_dup_mmap() to preserve the lock ordering. > > Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2") > Cc: stable@vger.kernel.org > Reported-by: Josef Bacik > Reviewed-by: Lorenzo Stoakes (ARM) > Signed-off-by: David Hildenbrand (Arm) Reviewed-by: Kiryl Shutsemau (Meta) -- Kiryl Shutsemau / Kirill A. Shutemov