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 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 C66E6C433DF for ; Fri, 7 Aug 2020 06:26:17 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 9348E22CF6 for ; Fri, 7 Aug 2020 06:26:17 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1596781577; bh=R/J9wYhkC2ROECBjlhXoxiqOfcsT0hjnDSt3+QsEc3Q=; h=Date:From:To:Subject:In-Reply-To:Reply-To:List-ID:From; b=Tw2PbkrZOMe3IImVz0pBWddSA2XpCpxLYYTKD9OFZ16GuxTjCwmtpa/DofZB7VU0r DkcT5H60v4dLvEuXbDc7mln3QeJvvXBBGHzH26KUmO+C9om6ZV2fn6a7RBybzu+Cqw 9rQsUYrUaz/RcT2PXBpjVnDnTCEP3bPrMAxHtPi4= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726401AbgHGG0R (ORCPT ); Fri, 7 Aug 2020 02:26:17 -0400 Received: from mail.kernel.org ([198.145.29.99]:34822 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725805AbgHGG0R (ORCPT ); Fri, 7 Aug 2020 02:26:17 -0400 Received: from localhost.localdomain (c-73-231-172-41.hsd1.ca.comcast.net [73.231.172.41]) (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 0018222D2C; Fri, 7 Aug 2020 06:26:15 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1596781576; bh=R/J9wYhkC2ROECBjlhXoxiqOfcsT0hjnDSt3+QsEc3Q=; h=Date:From:To:Subject:In-Reply-To:From; b=LmJFtiTLFGpWtnjMDkY/FcGBBIZC0Vm+T6XLdRC7IYBoTGQjANHx+Ag4Q0mGYRX59 2LEUWapAdYZpVkFgFNoI9Z+OWIdT9IZwg6NOylgC/YXbOu8D6CY69GGOS77LEcVop2 qw7oOgdBHXCMULZBYx5QyZWnnuyTVJLudlCEwP4A= Date: Thu, 06 Aug 2020 23:26:15 -0700 From: Andrew Morton To: aarcange@redhat.com, akpm@linux-foundation.org, hughd@google.com, kirill.shutemov@linux.intel.com, linux-mm@kvack.org, mike.kravetz@oracle.com, mm-commits@vger.kernel.org, songliubraving@fb.com, stable@vger.kernel.org, torvalds@linux-foundation.org Subject: [patch 158/163] khugepaged: collapse_pte_mapped_thp() flush the right range Message-ID: <20200807062615.qiADx5DeQ%akpm@linux-foundation.org> In-Reply-To: <20200806231643.a2711a608dd0f18bff2caf2b@linux-foundation.org> User-Agent: s-nail v14.8.16 Sender: mm-commits-owner@vger.kernel.org Precedence: bulk Reply-To: linux-kernel@vger.kernel.org List-ID: X-Mailing-List: mm-commits@vger.kernel.org From: Hugh Dickins Subject: khugepaged: collapse_pte_mapped_thp() flush the right range pmdp_collapse_flush() should be given the start address at which the huge page is mapped, haddr: it was given addr, which at that point has been used as a local variable, incremented to the end address of the extent. Found by source inspection while chasing a hugepage locking bug, which I then could not explain by this. At first I thought this was very bad; then saw that all of the page translations that were not flushed would actually still point to the right pages afterwards, so harmless; then realized that I know nothing of how different architectures and models cache intermediate paging structures, so maybe it matters after all - particularly since the page table concerned is immediately freed. Much easier to fix than to think about. Link: http://lkml.kernel.org/r/alpine.LSU.2.11.2008021204390.27773@eggly.anvils Fixes: 27e1f8273113 ("khugepaged: enable collapse pmd for pte-mapped THP") Signed-off-by: Hugh Dickins Acked-by: Kirill A. Shutemov Cc: Andrea Arcangeli Cc: Mike Kravetz Cc: Song Liu Cc: [5.4+] Signed-off-by: Andrew Morton --- mm/khugepaged.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) --- a/mm/khugepaged.c~khugepaged-collapse_pte_mapped_thp-flush-the-right-range +++ a/mm/khugepaged.c @@ -1502,7 +1502,7 @@ void collapse_pte_mapped_thp(struct mm_s /* step 4: collapse pmd */ ptl = pmd_lock(vma->vm_mm, pmd); - _pmd = pmdp_collapse_flush(vma, addr, pmd); + _pmd = pmdp_collapse_flush(vma, haddr, pmd); spin_unlock(ptl); mm_dec_nr_ptes(mm); pte_free(mm, pmd_pgtable(_pmd)); _