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 ADDCBC83F01 for ; Sun, 27 Aug 2023 14:55:55 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229557AbjH0OzZ (ORCPT ); Sun, 27 Aug 2023 10:55:25 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:57910 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S230123AbjH0OzW (ORCPT ); Sun, 27 Aug 2023 10:55:22 -0400 Received: from mgamail.intel.com (mgamail.intel.com [192.55.52.115]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 8EDE0B5 for ; Sun, 27 Aug 2023 07:55:19 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=intel.com; i=@intel.com; q=dns/txt; s=Intel; t=1693148119; x=1724684119; h=from:to:cc:subject:date:message-id:in-reply-to: references:mime-version:content-transfer-encoding; bh=jeF58AELVOfc3hfokcBCXag6pG1i98ss9u7CduLLyno=; b=aPl3natekMUHnmjqLQSUNc+AwT3lgG0IVz+SJ1pRf/VHRiwmAFDlFfC4 c8VooPZCljLwsw/6Qu0SD2kXIW7a/s3DvgxDenzIm1+XanCPp9CWbALyT LqXLkXzk+0EucnxkvEaS6I6/PkQqTyu7/exf4AhfIAgnScr0FwBJq5vzq PPEnEC2KaG0IGZnhogxcddB0bghtR2RxkntekiKntb+j9CSXylZakknCc 7sPLggkU9g5GPx6r8dUAmGR7Y7GaLqxurnmTdFmwD67z4wwD2vanYJ6kS YBX43VBe5ozymh3L3dhhcXfrIQNV/pw4DyMiAgOBvnVv8+yJx+kB/3ZlF A==; X-IronPort-AV: E=McAfee;i="6600,9927,10815"; a="374923313" X-IronPort-AV: E=Sophos;i="6.02,205,1688454000"; d="scan'208";a="374923313" Received: from orsmga002.jf.intel.com ([10.7.209.21]) by fmsmga103.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 27 Aug 2023 07:55:19 -0700 X-ExtLoop1: 1 X-IronPort-AV: E=McAfee;i="6600,9927,10815"; a="737987321" X-IronPort-AV: E=Sophos;i="6.02,205,1688454000"; d="scan'208";a="737987321" Received: from fyin-dev.sh.intel.com ([10.239.159.24]) by orsmga002.jf.intel.com with ESMTP; 27 Aug 2023 07:55:16 -0700 From: Yin Fengwei To: stable@vger.kernel.org Cc: Yu Zhao , Ryan Roberts , David Hildenbrand , Kefeng Wang , Matthew Wilcox , Minchan Kim , Vishal Moola , Yang Shi , Andrew Morton Subject: [PATCH 6.4.y] madvise:madvise_free_pte_range(): don't use mapcount() against large folio for sharing check Date: Sun, 27 Aug 2023 22:53:02 +0800 Message-Id: <20230827145302.2407183-1-fengwei.yin@intel.com> X-Mailer: git-send-email 2.39.2 In-Reply-To: <2023082614-choice-mongoose-0731@gregkh> References: <2023082614-choice-mongoose-0731@gregkh> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: stable@vger.kernel.org Commit 98b211d6415f ("madvise: convert madvise_free_pte_range() to use a folio") replaced the page_mapcount() with folio_mapcount() to check whether the folio is shared by other mapping. It's not correct for large folios. folio_mapcount() returns the total mapcount of large folio which is not suitable to detect whether the folio is shared. Use folio_estimated_sharers() which returns a estimated number of shares. That means it's not 100% correct. It should be OK for madvise case here. User-visible effects is that the THP is skipped when user call madvise. But the correct behavior is THP should be split and processed then. NOTE: this change is a temporary fix to reduce the user-visible effects before the long term fix from David is ready. Link: https://lkml.kernel.org/r/20230808020917.2230692-4-fengwei.yin@intel.com Fixes: 98b211d6415f ("madvise: convert madvise_free_pte_range() to use a folio") Signed-off-by: Yin Fengwei Reviewed-by: Yu Zhao Reviewed-by: Ryan Roberts Cc: David Hildenbrand Cc: Kefeng Wang Cc: Matthew Wilcox Cc: Minchan Kim Cc: Vishal Moola (Oracle) Cc: Yang Shi Cc: Signed-off-by: Andrew Morton (cherry picked from commit 0e0e9bd5f7b9d40fd03b70092367247d52da1db0) --- mm/madvise.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff --git a/mm/madvise.c b/mm/madvise.c index b5ffbaf616f5..584ff190bf90 100644 --- a/mm/madvise.c +++ b/mm/madvise.c @@ -664,8 +664,8 @@ static int madvise_free_pte_range(pmd_t *pmd, unsigned long addr, * deactivate all pages. */ if (folio_test_large(folio)) { - if (folio_mapcount(folio) != 1) - goto out; + if (folio_estimated_sharers(folio) != 1) + break; folio_get(folio); if (!folio_trylock(folio)) { folio_put(folio); -- 2.39.2