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 52DF5606A331 for ; Tue, 27 Oct 2026 13:56:08 +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=jIhYLNBN Received: by kanga.kvack.org (Postfix) id 607A36B0759; Tue, 27 Oct 2026 09:56:07 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 5DFBE6B075B; Tue, 27 Oct 2026 09:56:07 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 51C956B075C; Tue, 27 Oct 2026 09:56:07 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0012.hostedemail.com [216.40.44.12]) by kanga.kvack.org (Postfix) with ESMTP id 309DC6B0759 for ; Tue, 27 Oct 2026 09:56:07 -0400 (EDT) Received: from smtpin27.hostedemail.com (lb01a-stub [10.200.18.249]) by unirelay03.hostedemail.com (Postfix) with ESMTP id C9B90A0935 for ; Tue, 27 Oct 2026 13:56:06 +0000 (UTC) X-FDA: 85368555132.27.42AEFF3 Received: from tor.source.kernel.org (tor.source.kernel.org [172.105.4.254]) by imf11.hostedemail.com (Postfix) with ESMTP id 3936B40007 for ; Tue, 27 Oct 2026 13:56:05 +0000 (UTC) Authentication-Results: imf11.hostedemail.com; dkim=pass header.d=kernel.org header.s=k20260515 header.b=jIhYLNBN; dmarc=pass (policy=quarantine) header.from=kernel.org; spf=pass (imf11.hostedemail.com: domain of harry@kernel.org designates 172.105.4.254 as permitted sender) smtp.mailfrom=harry@kernel.org ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1793109365; 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=Zr1jTThDFAddOSK457sc66293xmVyHCCi9iGlWUeddU=; b=eBvEbKof9RAWRv7T77xDc5jF9UR2U5Y7DbY7v5hstc4vkQXliBP+5V35WDJFSHiO0J02h9 EXrVLiiRPZFj4fGYueqy2YQt/sHU1H9mhJVoACaM3iXiq4ysxHaS0cWFdRw4Q2ps8m4AI0 M7Wjlvw6YrMche4l1h+HSs5AgFs0iiE= ARC-Authentication-Results: i=1; imf11.hostedemail.com; dkim=pass header.d=kernel.org header.s=k20260515 header.b=jIhYLNBN; dmarc=pass (policy=quarantine) header.from=kernel.org; spf=pass (imf11.hostedemail.com: domain of harry@kernel.org designates 172.105.4.254 as permitted sender) smtp.mailfrom=harry@kernel.org ARC-Seal: i=1; a=rsa-sha256; d=hostedemail.com; s=arc-20220608; cv=none; t=1793109365; b=qtpKih127KwkmyF+8nz1iK/g9bmNC3/QEMgIBJYlWAoPCW1lmnbd3M5Hb5QLDx9KhYWQ5U skZY+qzIDXGu5BtbOOYX6pbqEqcM8QenujfpGxfCMkqPSuUCzwZRouzWju6gi+zG0Un48Y A1qPChxTEsDHWkKahz9UtHbWhktFNeo= Received: from smtp.kernel.org (quasi.space.kernel.org [100.103.45.18]) by tor.source.kernel.org (Postfix) with ESMTP id 94C686020A; Tue, 27 Oct 2026 13:56:04 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id B17E81F01825; Tue, 27 Oct 2026 13:56:03 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1793109364; bh=Zr1jTThDFAddOSK457sc66293xmVyHCCi9iGlWUeddU=; h=Date:From:To:Cc:Subject:References:In-Reply-To; b=jIhYLNBNpp0NexZNmMUHOUCY+eEy16NfWjuSuwLJqmFHwNWPY9BdmcaHZW+1fGIg9 fiBkl7KehfwTpd4R+QE8pIbz2ex/lWNl//inoU+svKsu/oI0sqh9JGs4nayk/63cZa PuQtRNz2s2eqW5o62hUTfQo+difIHb2bfTQI3wmFE48eH1hqvasX2J061wIVJ/8XLp B8iwzzJIHvVnrgkO1CLMhM/dtnxK1pMp932wcPpTyDMf/mtjlI6T7bM2e0ImgLpb5G itjSlM0i78ybkEbvAJ0jTU2GNXWaOjkHSgMcq3b5iw8EB94IUavJ0yBcssBsMi8xzh 0HHSAVhaSG0Nw== Date: Tue, 27 Oct 2026 13:56:02 +0000 From: Harry Yoo 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 , 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 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: rspam12 X-Rspamd-Queue-Id: 3936B40007 X-Stat-Signature: jsaf9esokjiw8oiognwpp34wg5bhouk5 X-Spam-Status: No, score=-11.1 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: 1793109365-479024 X-HE-Meta: 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 ayR9wdf3 AnNiURJyje/0aDGBTiKFu+IrQ1zIZpdsV4N6E3eEUlVr6KPadku1h5oMxSVtasBUsnEisGrdQ3ZVGs9eynrj1fNq3iZ1KmCVFeR7aFrcQQvpXZCp5dkR5jxLK9KiXEkYRX4s9x1E97lu0jfqH/paAX//GAJO0jOAMJnHUyLDY6+B/sTPXjXbQsG1MPBYQ5ux0gqIL/4+coIopr3dCBazSuxD/QhrxqnkCf6OcxWhE39Irh33tb3i9UcWZg0i2u/TKMaHDvhSnQWyHJdv2tBsPmTE39wGTfyCAJrGw4ttpcUVByd6h5Xr1gignBbukyLbZg9cEHau4YTwOceCJY2pIvIrS2wfcajEkrXE5igDfGs2zEVBiIo87WJtnFdJlMyRCnVTBV4GyjPic6HrhwXoq8oL8xs3R5N5WsIWRotl1Bsx4r0PrZmejZp/tlsG891NXi6Kt1alWCMBO/y0= 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) > --- Looks good to me, Reviewed-by: Harry Yoo (Meta) -- Cheers, Harry / Hyeonggon