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 4F5A2C77B7A for ; Wed, 7 Jun 2023 17:49:27 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S232288AbjFGRt0 (ORCPT ); Wed, 7 Jun 2023 13:49:26 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:47066 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S232208AbjFGRtZ (ORCPT ); Wed, 7 Jun 2023 13:49:25 -0400 Received: from dfw.source.kernel.org (dfw.source.kernel.org [IPv6:2604:1380:4641:c500::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id BA46E196 for ; Wed, 7 Jun 2023 10:49:24 -0700 (PDT) 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 dfw.source.kernel.org (Postfix) with ESMTPS id 4E03164239 for ; Wed, 7 Jun 2023 17:49:24 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 90C1CC433EF; Wed, 7 Jun 2023 17:49:23 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linux-foundation.org; s=korg; t=1686160163; bh=WIbBHz8WgHl1EzfoLZjvV+vV39RKvW1iTffsmXrABN4=; h=Date:To:From:Subject:From; b=15vE3IyicLOBHbnJ+mVw+97wm0zm78YH47kMtxqX4hrSRFvMH7Bzd2VDBbqjC2Ftt EBr1I5n1Emxh8wo7BHgcnZx0OQW8ejB2RaL4/dpmvXXogYXZIWPoWj6lYWe1TzVicP lNhVYD6zCXl708MMujx8Ue07F0wKoLI3JSF/nl8Y= Date: Wed, 07 Jun 2023 10:49:22 -0700 To: mm-commits@vger.kernel.org, willy@infradead.org, shy828301@gmail.com, peterx@redhat.com, mike.kravetz@oracle.com, kirill@shutemov.name, jiaqiyan@google.com, hughd@google.com, david@redhat.com, stevensd@chromium.org, akpm@linux-foundation.org From: Andrew Morton Subject: + mm-khugepaged-fix-iteration-in-collapse_file.patch added to mm-hotfixes-unstable branch Message-Id: <20230607174923.90C1CC433EF@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/khugepaged: fix iteration in collapse_file has been added to the -mm mm-hotfixes-unstable branch. Its filename is mm-khugepaged-fix-iteration-in-collapse_file.patch This patch will shortly appear at https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches/mm-khugepaged-fix-iteration-in-collapse_file.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: David Stevens Subject: mm/khugepaged: fix iteration in collapse_file Date: Wed, 7 Jun 2023 14:31:35 +0900 Remove an unnecessary call to xas_set(index) when iterating over the target range in collapse_file. The extra call to xas_set reset the xas cursor to the top of the tree, causing the xas_next call on the next iteration to walk the tree to index instead of advancing to index+1. This returned the same page again, which would cause collapse_file to fail because the page is already locked. This bug was hidden when CONFIG_DEBUG_VM was set. When that config was used, the xas_load in a subsequent VM_BUG_ON assert would walk xas from the top of the tree to index, causing the xas_next call on the next loop iteration to advance the cursor as expected. Link: https://lkml.kernel.org/r/20230607053135.2087354-1-stevensd@google.com Fixes: a2e17cc2efc7 ("mm/khugepaged: maintain page cache uptodate flag") Signed-off-by: David Stevens Cc: David Hildenbrand Cc: Hugh Dickins Cc: Jiaqi Yan Cc: Kirill A . Shutemov Cc: Matthew Wilcox Cc: Peter Xu Cc: Yang Shi Cc: Mike Kravetz Signed-off-by: Andrew Morton --- mm/khugepaged.c | 1 - 1 file changed, 1 deletion(-) --- a/mm/khugepaged.c~mm-khugepaged-fix-iteration-in-collapse_file +++ a/mm/khugepaged.c @@ -2070,7 +2070,6 @@ static int collapse_file(struct mm_struc TTU_IGNORE_MLOCK | TTU_BATCH_FLUSH); xas_lock_irq(&xas); - xas_set(&xas, index); VM_BUG_ON_PAGE(page != xas_load(&xas), page); _ Patches currently in -mm which might be from stevensd@chromium.org are mm-shmem-fix-race-in-shmem_undo_range-w-thp.patch mm-khugepaged-fix-iteration-in-collapse_file.patch