From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature ECDSA (prime256v1) server-digest SHA256) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 6474C606A31C for ; Fri, 30 Oct 2026 00:34:53 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key, unprotected) header.d=lists.infradead.org header.i=@lists.infradead.org header.a=rsa-sha256 header.s=bombadil.20210309 header.b=Q+1gqBSx; dkim=pass (2048-bit key, unprotected) header.d=kernel.org header.i=@kernel.org header.a=rsa-sha256 header.s=k20260515 header.b=DduHRuPY DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20210309; h=Sender:List-Subscribe:List-Help :List-Post:List-Archive:List-Unsubscribe:List-Id:Content-Transfer-Encoding: MIME-Version:References:In-Reply-To:Message-ID:Date:Subject:Cc:To:From: Reply-To:Content-Type:Content-ID:Content-Description:Resent-Date:Resent-From: Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Unsubscribe-Post: List-Owner; bh=J6qvhedKX/gt9L39bpVgRBd7A0g16i9D1HZNiTvqkfw=; b=Q+1gqBSxT6WPtu C0TbNgKq7sl8SAXlQLnobNh+uJrDGsDzKOEbktFsl7g1hbWfANK0zC73f3qWKV4poGYkL5k7rpbHb X+nGtmSK5CZfphE7uZnppEptZPealy9D5GXdoUszAVR92evpZNbvhg3qvtw2RXmRFR60KZJRDlU9o UGOgVn65XUAVKH7RVVs9imTlzPKvE2wvStvcMkZWaj2wQUb4E81b7sbj9uNcygtGxFhP6Bw0g8ctK OVS+mgPbUtvKynTa3HBar7Wi9eFooHiJgm/U5VQI3nvdjrbqx3TBZsgJmSMPBiTzmb6dR3a/RPy8h TdIb40zPSilrAOEjksmQ==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.100.1 #2 (Red Hat Linux)) id 1xMaa3-0000000AZys-1MlB; Fri, 30 Oct 2026 00:34:51 +0000 Received: from sea.source.kernel.org ([172.234.252.31]) by bombadil.infradead.org with esmtps (Exim 4.100.1 #2 (Red Hat Linux)) id 1xMaZw-0000000AZyf-1iRG for kexec@lists.infradead.org; Fri, 30 Oct 2026 00:34:45 +0000 Received: from smtp.kernel.org (quasi.space.kernel.org [100.103.45.18]) by sea.source.kernel.org (Postfix) with ESMTP id 3F6AC438A6; Fri, 30 Oct 2026 00:34:43 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 03BF11F000C1; Fri, 30 Oct 2026 00:34:40 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1793320483; bh=J6qvhedKX/gt9L39bpVgRBd7A0g16i9D1HZNiTvqkfw=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=DduHRuPYmFLQVXIsNcNjApO97/T8X2q8UAfCyYP1FbDA55gYCiFqIxgKlBRMzDPCT Eqs2Hx8NW5JNHHOwoaWAREmZ9P3g0DpqSD6ZIAALIBan8uNdEC7bloNBM6ojVGEYVk FENFOG2Gdb/Pe7A0j+ozRR73EUaDH16qGjtXlvUo9kWAgkt1QHi+VdagnEw8C8T74j Yr8bysC4D0OxTeYJFfW5QuO9Da+Ehdf3XvdtWlh8G5C0H/tFFCwNzQnltS9dLOayxj OH44Anbtpxbx/w1SEQjMZhJc6+ynBnLLft0fXjVDgMDV3v73CICkPnVUjb7wRDMMx3 S8ms98yTtaxtw== From: SJ Park To: "David Hildenbrand (Arm)" Cc: SJ Park , 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 , Kiryl Shutsemau , 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 v2 02/47] fork: take mmap_lock before copying mm_struct Date: Thu, 29 Oct 2026 17:34:33 -0700 Message-ID: <20261030003434.154864-1-sj@kernel.org> X-Mailer: git-send-email 2.47.3 In-Reply-To: <20261029-fixes_core-v2-2-a64ce7f83abb@kernel.org> References: X-Archived-By: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-BeenThere: kexec@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Archive: List-Post: List-Help: List-Subscribe: , Sender: "kexec" X-Spam-Status: No, score=-13.9 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,DKIM_VALID_EF, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,MAILING_LIST_MULTI, SPF_HELO_NONE,SPF_PASS,USER_AGENT_GIT autolearn=unavailable autolearn_force=no version=4.0.1 X-Spam-Checker-Version: SpamAssassin 4.0.1 (2024-03-26) on aws-us-west-2-korg-listserv-alma10-1 On Thu, 29 Oct 2026 21:32:57 +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. Looks good and makes sense to me. > > Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2") > Cc: stable@vger.kernel.org > Reported-by: Josef Bacik > Reviewed-by: Lorenzo Stoakes (ARM) > Reviewed-by: Rik van Riel > Reviewed-by: Vlastimil Babka (SUSE) > Reviewed-by: Barry Song > Reviewed-by: Pedro Falcato > Reviewed-by: Harry Yoo (Meta) > Reviewed-by: Kiryl Shutsemau (Meta) > Signed-off-by: David Hildenbrand (Arm) Reviewed-by: SJ Park Thanks, SJ [...]