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 B2802C4332F for ; Mon, 6 Nov 2023 18:28:46 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S232132AbjKFS2r (ORCPT ); Mon, 6 Nov 2023 13:28:47 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:56936 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231773AbjKFS2q (ORCPT ); Mon, 6 Nov 2023 13:28:46 -0500 Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 1DA2AD47; Mon, 6 Nov 2023 10:28:44 -0800 (PST) Received: by smtp.kernel.org (Postfix) with ESMTPSA id A9F4AC433C8; Mon, 6 Nov 2023 18:28:43 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linux-foundation.org; s=korg; t=1699295323; bh=cfLKtmPTASsY/mXd3KyqzMORK9r2N0qAhcYDQEPAbGY=; h=Date:To:From:Subject:From; b=U4tdbuyNCC0Q1Djfzq6vrIDtxl85IwplXHVapwIhIXfG/x/EL8gZbaETayZbdeTcc Mi4vixzCN8HAlry7IocJ8ueo1sCCSs4K72h9Hr2BOWsToQPELdvHdmP2D8+qigialO DBvqokhAkOHVKm+3ZfCLIkjmPHJQH0KP70m7Tn34= Date: Mon, 06 Nov 2023 10:28:43 -0800 To: mm-commits@vger.kernel.org, stable@vger.kernel.org, riel@surriel.com, hannes@cmpxchg.org, shr@devkernel.io, akpm@linux-foundation.org From: Andrew Morton Subject: + mm-fix-for-negative-counter-nr_file_hugepages.patch added to mm-hotfixes-unstable branch Message-Id: <20231106182843.A9F4AC433C8@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: fix for negative counter: nr_file_hugepages has been added to the -mm mm-hotfixes-unstable branch. Its filename is mm-fix-for-negative-counter-nr_file_hugepages.patch This patch will shortly appear at https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches/mm-fix-for-negative-counter-nr_file_hugepages.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: Stefan Roesch Subject: mm: fix for negative counter: nr_file_hugepages Date: Mon, 6 Nov 2023 10:19:18 -0800 While qualifiying the 6.4 release, the following warning was detected in messages: vmstat_refresh: nr_file_hugepages -15664 The warning is caused by the incorrect updating of the NR_FILE_THPS counter in the function split_huge_page_to_list. The if case is checking for folio_test_swapbacked, but the else case is missing the check for folio_test_pmd_mappable. The other functions that manipulate the counter like __filemap_add_folio and filemap_unaccount_folio have the corresponding check. I have a test case, which reproduces the problem. It can be found here: https://github.com/sroeschus/testcase/blob/main/vmstat_refresh/madv.c The test case reproduces on an XFS filesystem. Running the same test case on a BTRFS filesystem does not reproduce the problem. AFAIK version 6.1 until 6.6 are affected by this problem. Link: https://lkml.kernel.org/r/20231106181918.1091043-1-shr@devkernel.io Signed-off-by: Stefan Roesch Co-debugged-by: Johannes Weiner Cc: Johannes Weiner Cc: Rik van Riel Cc: Signed-off-by: Andrew Morton --- mm/huge_memory.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) --- a/mm/huge_memory.c~mm-fix-for-negative-counter-nr_file_hugepages +++ a/mm/huge_memory.c @@ -2772,7 +2772,8 @@ int split_huge_page_to_list(struct page if (folio_test_swapbacked(folio)) { __lruvec_stat_mod_folio(folio, NR_SHMEM_THPS, -nr); - } else { + } else if (folio_test_pmd_mappable(folio)) { + __lruvec_stat_mod_folio(folio, NR_FILE_THPS, -nr); filemap_nr_thps_dec(mapping); _ Patches currently in -mm which might be from shr@devkernel.io are mm-fix-for-negative-counter-nr_file_hugepages.patch