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=-15.8 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER, INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS autolearn=ham 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 3FA55C49EA7 for ; Fri, 25 Jun 2021 01:39:34 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 2C2F0610A7 for ; Fri, 25 Jun 2021 01:39:34 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S233028AbhFYBlx (ORCPT ); Thu, 24 Jun 2021 21:41:53 -0400 Received: from mail.kernel.org ([198.145.29.99]:60688 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S232973AbhFYBlv (ORCPT ); Thu, 24 Jun 2021 21:41:51 -0400 Received: by mail.kernel.org (Postfix) with ESMTPSA id 74235610A7; Fri, 25 Jun 2021 01:39:30 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linux-foundation.org; s=korg; t=1624585170; bh=/GefFZigdsm2FtIHaSvFs3pKxmOWfTVavc1bwNdWQCE=; h=Date:From:To:Subject:In-Reply-To:From; b=j1XKhgy78aHkVkJeNV1zNhB6H7sjECYHuiXakAKeHLSfO32ObeDJxYFLx/AErSsG3 WsJz3Xi0oo3SCpVrNz0CpinVe9wGkhw0UTHrtlWf/LjM2o/WiFMR0mI4Cq3FAdng3I rY6GvIZI7LQwcO0mX5hV5c5EKPhF+oaNYdvrwpag= Date: Thu, 24 Jun 2021 18:39:30 -0700 From: Andrew Morton To: akpm@linux-foundation.org, apopple@nvidia.com, hughd@google.com, kirill.shutemov@linux.intel.com, linux-mm@kvack.org, mm-commits@vger.kernel.org, peterx@redhat.com, rcampbell@nvidia.com, shy828301@gmail.com, stable@vger.kernel.org, torvalds@linux-foundation.org, wangyugui@e16-tech.com, will@kernel.org, willy@infradead.org, ziy@nvidia.com Subject: [patch 10/24] mm/thp: another PVMW_SYNC fix in page_vma_mapped_walk() Message-ID: <20210625013930.b8M_U9WL0%akpm@linux-foundation.org> In-Reply-To: <20210624183838.ac3161ca4a43989665ac8b2f@linux-foundation.org> User-Agent: s-nail v14.8.16 Precedence: bulk Reply-To: linux-kernel@vger.kernel.org List-ID: X-Mailing-List: mm-commits@vger.kernel.org From: Hugh Dickins Subject: mm/thp: another PVMW_SYNC fix in page_vma_mapped_walk() Aha! Shouldn't that quick scan over pte_none()s make sure that it holds ptlock in the PVMW_SYNC case? That too might have been responsible for BUGs or WARNs in split_huge_page_to_list() or its unmap_page(), though I've never seen any. Link: https://lkml.kernel.org/r/1bdf384c-8137-a149-2a1e-475a4791c3c@google.com Link: https://lore.kernel.org/linux-mm/20210412180659.B9E3.409509F4@e16-tech.com/ Fixes: ace71a19cec5 ("mm: introduce page_vma_mapped_walk()") Signed-off-by: Hugh Dickins Acked-by: Kirill A. Shutemov Tested-by: Wang Yugui Cc: Alistair Popple Cc: Matthew Wilcox Cc: Peter Xu Cc: Ralph Campbell Cc: Will Deacon Cc: Yang Shi Cc: Zi Yan Cc: Signed-off-by: Andrew Morton --- mm/page_vma_mapped.c | 4 ++++ 1 file changed, 4 insertions(+) --- a/mm/page_vma_mapped.c~mm-thp-another-pvmw_sync-fix-in-page_vma_mapped_walk +++ a/mm/page_vma_mapped.c @@ -276,6 +276,10 @@ next_pte: goto restart; } pvmw->pte++; + if ((pvmw->flags & PVMW_SYNC) && !pvmw->ptl) { + pvmw->ptl = pte_lockptr(mm, pvmw->pmd); + spin_lock(pvmw->ptl); + } } while (pte_none(*pvmw->pte)); if (!pvmw->ptl) { _