From patchwork Mon Aug 10 02:40:38 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Andrew Morton X-Patchwork-Id: 266714 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-7.0 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED, DKIM_VALID, HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI, SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED autolearn=no autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 02817C433DF for ; Mon, 10 Aug 2020 02:40:40 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id D4606206C3 for ; Mon, 10 Aug 2020 02:40:39 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1597027239; bh=Ys0/M/e4c+ztPxWabqnPrC0t7EJildHk22QjwPtP9OM=; h=Date:From:To:Subject:List-ID:From; b=Duxgh1gdKp0bfM8kCoZ0tXcF1HNHVbEfbqQR6ulu2l0vLUEgNk4h8w0Kg1w44dJk9 fAOCMVBQ/rU5WZbwsgo+Wyr6eOMjDMD1o2r9gInF9oP379t3+nVww/NylQ/TsBN06a qS91YTsRFG3FPLi4rTyYa6995aRX1f2awPVhv9PM= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726403AbgHJCkj (ORCPT ); Sun, 9 Aug 2020 22:40:39 -0400 Received: from mail.kernel.org ([198.145.29.99]:43660 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726219AbgHJCkj (ORCPT ); Sun, 9 Aug 2020 22:40:39 -0400 Received: from localhost.localdomain (c-71-198-47-131.hsd1.ca.comcast.net [71.198.47.131]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id 93F3D206CD; Mon, 10 Aug 2020 02:40:38 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1597027238; bh=Ys0/M/e4c+ztPxWabqnPrC0t7EJildHk22QjwPtP9OM=; h=Date:From:To:Subject:From; b=HqIViE1X68mU05r3hYgC7+Vv1TOvXz5m5ApVMVNCbjNwMgZZWSNgH/Y9Rm7ChYo+/ DkpDm5CPjBDuibFLZnniBBjX6dzBEqqqeABjlEKwUXqIPnwvk2G4OaNlPqlP/eCx2+ eOL9ffWFtVLtIe832doutx/9Y7YlRXoKWYzmCEQ0= Date: Sun, 09 Aug 2020 19:40:38 -0700 From: akpm@linux-foundation.org To: aarcange@redhat.com, hughd@google.com, kirill.shutemov@linux.intel.com, mike.kravetz@oracle.com, mm-commits@vger.kernel.org, songliubraving@fb.com, stable@vger.kernel.org Subject: [merged] khugepaged-khugepaged_test_exit-check-mmget_still_valid.patch removed from -mm tree Message-ID: <20200810024038.911dk9nR7%akpm@linux-foundation.org> User-Agent: s-nail v14.8.16 Sender: stable-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: stable@vger.kernel.org The patch titled Subject: khugepaged: khugepaged_test_exit() check mmget_still_valid() has been removed from the -mm tree. Its filename was khugepaged-khugepaged_test_exit-check-mmget_still_valid.patch This patch was dropped because it was merged into mainline or a subsystem tree ------------------------------------------------------ From: Hugh Dickins Subject: khugepaged: khugepaged_test_exit() check mmget_still_valid() Move collapse_huge_page()'s mmget_still_valid() check into khugepaged_test_exit() itself. collapse_huge_page() is used for anon THP only, and earned its mmget_still_valid() check because it inserts a huge pmd entry in place of the page table's pmd entry; whereas collapse_file()'s retract_page_tables() or collapse_pte_mapped_thp() merely clears the page table's pmd entry. But core dumping without mmap lock must have been as open to mistaking a racily cleared pmd entry for a page table at physical page 0, as exit_mmap() was. And we certainly have no interest in mapping as a THP once dumping core. Link: http://lkml.kernel.org/r/alpine.LSU.2.11.2008021217020.27773@eggly.anvils Fixes: 59ea6d06cfa9 ("coredump: fix race condition between collapse_huge_page() and core dumping") Signed-off-by: Hugh Dickins Cc: Andrea Arcangeli Cc: Song Liu Cc: Mike Kravetz Cc: Kirill A. Shutemov Cc: [4.8+] Signed-off-by: Andrew Morton --- mm/khugepaged.c | 5 +---- 1 file changed, 1 insertion(+), 4 deletions(-) --- a/mm/khugepaged.c~khugepaged-khugepaged_test_exit-check-mmget_still_valid +++ a/mm/khugepaged.c @@ -431,7 +431,7 @@ static void insert_to_mm_slots_hash(stru static inline int khugepaged_test_exit(struct mm_struct *mm) { - return atomic_read(&mm->mm_users) == 0; + return atomic_read(&mm->mm_users) == 0 || !mmget_still_valid(mm); } static bool hugepage_vma_check(struct vm_area_struct *vma, @@ -1100,9 +1100,6 @@ static void collapse_huge_page(struct mm * handled by the anon_vma lock + PG_lock. */ mmap_write_lock(mm); - result = SCAN_ANY_PROCESS; - if (!mmget_still_valid(mm)) - goto out; result = hugepage_vma_revalidate(mm, address, &vma); if (result) goto out;