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 Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 4159AC6FD19 for ; Wed, 8 Mar 2023 23:01:55 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S230041AbjCHXBy (ORCPT ); Wed, 8 Mar 2023 18:01:54 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:38806 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S230180AbjCHXBH (ORCPT ); Wed, 8 Mar 2023 18:01:07 -0500 Received: from ams.source.kernel.org (ams.source.kernel.org [IPv6:2604:1380:4601:e00::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id CDEBBD49E2; Wed, 8 Mar 2023 15:00:36 -0800 (PST) Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by ams.source.kernel.org (Postfix) with ESMTPS id 8A28FB81E1E; Wed, 8 Mar 2023 23:00:34 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 482BDC433D2; Wed, 8 Mar 2023 23:00:33 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linux-foundation.org; s=korg; t=1678316433; bh=UNBiEptSI6HARhfxoCic4dbFRHGuMqDaeZaCeEINN/I=; h=Date:To:From:Subject:From; b=N8rdGiWuhyU0avoul5cTsrFonp/KAjka3KZyiYys/qZyIebkGPjIs1Ybdn/aBkqik 3hYTaGzoRqelyILxUcanubFL4evWD95BNfgkzpSg/fu+S7BPsAsm0N8TSaQmU75UB1 7XMa9kIjkoFFS9ZteuEFVkewb5/jVvX0334uVLgA= Date: Wed, 08 Mar 2023 15:00:32 -0800 To: mm-commits@vger.kernel.org, willy@infradead.org, stable@vger.kernel.org, pengfei.xu@intel.com, heng.su@intel.com, david@redhat.com, Liam.Howlett@oracle.com, akpm@linux-foundation.org From: Andrew Morton Subject: + mm-ksm-fix-race-with-vma-iteration-and-mm_struct-teardown.patch added to mm-hotfixes-unstable branch Message-Id: <20230308230033.482BDC433D2@smtp.kernel.org> Precedence: bulk Reply-To: linux-kernel@vger.kernel.org List-ID: X-Mailing-List: mm-commits@vger.kernel.org The patch titled Subject: mm/ksm: fix race with VMA iteration and mm_struct teardown has been added to the -mm mm-hotfixes-unstable branch. Its filename is mm-ksm-fix-race-with-vma-iteration-and-mm_struct-teardown.patch This patch will shortly appear at https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches/mm-ksm-fix-race-with-vma-iteration-and-mm_struct-teardown.patch This patch will later appear in the mm-hotfixes-unstable branch at git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm Before you just go and hit "reply", please: a) Consider who else should be cc'ed b) Prefer to cc a suitable mailing list as well c) Ideally: find the original patch on the mailing list and do a reply-to-all to that, adding suitable additional cc's *** Remember to use Documentation/process/submit-checklist.rst when testing your code *** The -mm tree is included into linux-next via the mm-everything branch at git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm and is updated there every 2-3 working days ------------------------------------------------------ From: "Liam R. Howlett" Subject: mm/ksm: fix race with VMA iteration and mm_struct teardown Date: Wed, 8 Mar 2023 17:03:10 -0500 exit_mmap() will tear down the VMAs and maple tree with the mmap_lock held in write mode. Ensure that the maple tree is still valid by checking ksm_test_exit() after taking the mmap_lock in read mode, but before the for_each_vma() iterator dereferences a destroyed maple tree. Since the maple tree is destroyed, the flags telling lockdep to check an external lock has been cleared. Skip the for_each_vma() iterator to avoid dereferencing a maple tree without the external lock flag, which would create a lockdep warning. Link: https://lkml.kernel.org/r/20230308220310.3119196-1-Liam.Howlett@oracle.com Fixes: a5f18ba07276 ("mm/ksm: use vma iterators instead of vma linked list") Signed-off-by: Liam R. Howlett Reported-by: Pengfei Xu Link: https://lore.kernel.org/lkml/ZAdUUhSbaa6fHS36@xpf.sh.intel.com/ Reported-by: syzbot+2ee18845e89ae76342c5@syzkaller.appspotmail.com Link: https://syzkaller.appspot.com/bug?id=64a3e95957cd3deab99df7cd7b5a9475af92c93e Acked-by: David Hildenbrand Cc: Matthew Wilcox (Oracle) Cc: Cc: Signed-off-by: Andrew Morton --- --- a/mm/ksm.c~mm-ksm-fix-race-with-vma-iteration-and-mm_struct-teardown +++ a/mm/ksm.c @@ -988,9 +988,15 @@ static int unmerge_and_remove_all_rmap_i mm = mm_slot->slot.mm; mmap_read_lock(mm); + + /* + * Exit right away if mm is exiting to avoid lockdep issue in + * the maple tree + */ + if (ksm_test_exit(mm)) + goto mm_exiting; + for_each_vma(vmi, vma) { - if (ksm_test_exit(mm)) - break; if (!(vma->vm_flags & VM_MERGEABLE) || !vma->anon_vma) continue; err = unmerge_ksm_pages(vma, @@ -999,6 +1005,7 @@ static int unmerge_and_remove_all_rmap_i goto error; } +mm_exiting: remove_trailing_rmap_items(&mm_slot->rmap_list); mmap_read_unlock(mm); _ Patches currently in -mm which might be from Liam.Howlett@oracle.com are maple_tree-fix-mas_skip_node-end-slot-detection.patch test_maple_tree-add-more-testing-for-mas_empty_area.patch mm-ksm-fix-race-with-vma-iteration-and-mm_struct-teardown.patch maple_tree-be-more-cautious-about-dead-nodes.patch maple_tree-detect-dead-nodes-in-mas_start.patch maple_tree-fix-freeing-of-nodes-in-rcu-mode.patch maple_tree-remove-extra-smp_wmb-from-mas_dead_leaves.patch maple_tree-fix-write-memory-barrier-of-nodes-once-dead-for-rcu-mode.patch maple_tree-add-smp_rmb-to-dead-node-detection.patch maple_tree-add-rcu-lock-checking-to-rcu-callback-functions.patch mm-enable-maple-tree-rcu-mode-by-default.patch