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 A85F0C433F5 for ; Mon, 7 Mar 2022 00:16:13 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S233168AbiCGARF (ORCPT ); Sun, 6 Mar 2022 19:17:05 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:40816 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S232426AbiCGARE (ORCPT ); Sun, 6 Mar 2022 19:17:04 -0500 Received: from dfw.source.kernel.org (dfw.source.kernel.org [139.178.84.217]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 4FDA55D671 for ; Sun, 6 Mar 2022 16:16:11 -0800 (PST) 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 D93E660FA7 for ; Mon, 7 Mar 2022 00:16:10 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 3B187C340EC; Mon, 7 Mar 2022 00:16:10 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linux-foundation.org; s=korg; t=1646612170; bh=7JB1eAP+XaxmDeO7P8zR/nWqLd2xak9dSqgaEKfNirY=; h=Date:To:From:Subject:From; b=LK1vpYHaKonAjZvvhQDqPtp/DpDKMC1D9+meKZs3YpEQrIEiwI/yGShrzFdZ2F+uo DyaNAFEkACCcNN2D/XMMyEOvlfYGdHeUNpVWX/DMx38RlEyRu8W0M7DjKzKyTJ8LTd Mp0ynQqyRFVafLyFM+qbgAXd8FAyks8G7RXA0gCk= Date: Sun, 06 Mar 2022 16:16:09 -0800 To: mm-commits@vger.kernel.org, willy@infradead.org, hughd@google.com, akpm@linux-foundation.org From: Andrew Morton Subject: + mm-filemap_unaccount_folio-large-skip-mapcount-fixup.patch added to -mm tree Message-Id: <20220307001610.3B187C340EC@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: filemap_unaccount_folio() large skip mapcount fixup has been added to the -mm tree. Its filename is mm-filemap_unaccount_folio-large-skip-mapcount-fixup.patch This patch should soon appear at https://ozlabs.org/~akpm/mmots/broken-out/mm-filemap_unaccount_folio-large-skip-mapcount-fixup.patch and later at https://ozlabs.org/~akpm/mmotm/broken-out/mm-filemap_unaccount_folio-large-skip-mapcount-fixup.patch 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 and is updated there every 3-4 working days ------------------------------------------------------ From: Hugh Dickins Subject: mm: filemap_unaccount_folio() large skip mapcount fixup The page_mapcount_reset() when folio_mapped() while mapping_exiting() was devised long before there were huge or compound pages in the cache. It is still valid for small pages, but not at all clear what's right to check and reset on large pages. Just don't try when folio_test_large(). Link: https://lkml.kernel.org/r/879c4426-4122-da9c-1a86-697f2c9a083@google.com Signed-off-by: Hugh Dickins Cc: Matthew Wilcox Signed-off-by: Andrew Morton --- mm/filemap.c | 26 +++++++++++++------------- 1 file changed, 13 insertions(+), 13 deletions(-) --- a/mm/filemap.c~mm-filemap_unaccount_folio-large-skip-mapcount-fixup +++ a/mm/filemap.c @@ -152,25 +152,25 @@ static void filemap_unaccount_folio(stru VM_BUG_ON_FOLIO(folio_mapped(folio), folio); if (!IS_ENABLED(CONFIG_DEBUG_VM) && unlikely(folio_mapped(folio))) { - int mapcount; - pr_alert("BUG: Bad page cache in process %s pfn:%05lx\n", current->comm, folio_pfn(folio)); dump_page(&folio->page, "still mapped when deleted"); dump_stack(); add_taint(TAINT_BAD_PAGE, LOCKDEP_NOW_UNRELIABLE); - mapcount = page_mapcount(&folio->page); - if (mapping_exiting(mapping) && - folio_ref_count(folio) >= mapcount + 2) { - /* - * All vmas have already been torn down, so it's - * a good bet that actually the folio is unmapped, - * and we'd prefer not to leak it: if we're wrong, - * some other bad page check should catch it later. - */ - page_mapcount_reset(&folio->page); - folio_ref_sub(folio, mapcount); + if (mapping_exiting(mapping) && !folio_test_large(folio)) { + int mapcount = page_mapcount(&folio->page); + + if (folio_ref_count(folio) >= mapcount + 2) { + /* + * All vmas have already been torn down, so it's + * a good bet that actually the page is unmapped + * and we'd rather not leak it: if we're wrong, + * another bad page check should catch it later. + */ + page_mapcount_reset(&folio->page); + folio_ref_sub(folio, mapcount); + } } } _ Patches currently in -mm which might be from hughd@google.com are mm-fs-delete-pf_swapwrite.patch tmpfs-support-for-file-creation-time-fix.patch shmem-mapping_set_exiting-to-help-mapped-resilience.patch mm-_install_special_mapping-apply-vm_locked_clear_mask.patch mm-thp-refix-__split_huge_pmd_locked-for-migration-pmd.patch mm-thp-clearpagedoublemap-in-first-page_add_file_rmap.patch mm-delete-__clearpagewaiters.patch mm-filemap_unaccount_folio-large-skip-mapcount-fixup.patch mm-thp-fix-nr_file_mapped-accounting-in-page__file_rmap.patch