From nobody Fri Dec 19 03:08:52 2025 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 2F0F5C5AE5C for ; Sun, 19 Nov 2023 19:48:15 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231317AbjKSTsP (ORCPT ); Sun, 19 Nov 2023 14:48:15 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:34146 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229665AbjKSTsM (ORCPT ); Sun, 19 Nov 2023 14:48:12 -0500 Received: from mail-yw1-x1136.google.com (mail-yw1-x1136.google.com [IPv6:2607:f8b0:4864:20::1136]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 3749111A for ; Sun, 19 Nov 2023 11:48:09 -0800 (PST) Received: by mail-yw1-x1136.google.com with SMTP id 00721157ae682-5c9d850a0dbso6658997b3.2 for ; Sun, 19 Nov 2023 11:48:09 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20230601; t=1700423288; x=1701028088; darn=vger.kernel.org; h=content-transfer-encoding:mime-version:reply-to:references :in-reply-to:message-id:date:subject:cc:to:from:from:to:cc:subject :date:message-id:reply-to; bh=cduqWiCMIKVDQKzalcbjrj5u/UZrGRNgI9eE9WPHu3A=; b=Y9sAFqwPPdpUQXqbpYpZjJ/bJFuU5qndB3eaipJ94VTJIKWoYM50djbzA8SIXrJp0E IQB+DXITZVEmKmCwo/wFMp1N+qG6z0btZOGJVXKggy+SgcgidRpVGvdBG4xhV4FE7AkJ l4rixv+zfi2XOjZY8M7Z/7CO8AVI+XwvjCe6aBACRlKbXd72bHRyilUuKRc5lIYCDts1 8HNy+kHE3SV6ZJvDbF9sGSrswumW19xFIu7juY64z337qf3doIndP5V1a1OyCwmyU5sA PF5ITZ1VZkihNjhzdlLL6Df5ZWehP+u2rGd4pmS2P/flRVc9zWrd6aZlwiFW9dJQcnAQ +PUA== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1700423288; x=1701028088; h=content-transfer-encoding:mime-version:reply-to:references :in-reply-to:message-id:date:subject:cc:to:from:x-gm-message-state :from:to:cc:subject:date:message-id:reply-to; bh=cduqWiCMIKVDQKzalcbjrj5u/UZrGRNgI9eE9WPHu3A=; b=Yj3eNh5jUBAYPYvV47npF8G3aojkyElxcmw0nAUeXqjHu5dzbTX2PMrdkcx8dIHSSa DQ0RoMYLhigpSvwDTto6btWVqAQu5aF1DNESgT9vPsnP+70h2E4pdZH0CJgkBE2M0WN3 ovdRVzX20sXBeKJd/zgJ95aZbOXKf2ETuzlYrNyIW1Znf8BM2T4mMSNsKpDSNDDEy874 cUNjRuizQH3mwx4GLTgWf9TgFuWRJ2BNrTTKx1W/WgTWarnrKQ0/x//JHMqXhf1eqjeb X7BHIz/pejB41bTRlSi9uKHxb+Xr95lsA9x7pvN8eYOXUqJ04jlO8a5+BEsoMzxqdtq4 itSw== X-Gm-Message-State: AOJu0YzS44t4sk1xM3JMDaCRHfjvwppsUbVPIeIer9h9MyGrUF+pRknw eq7Qc1mj36D36QQzv3rlvv0= X-Google-Smtp-Source: AGHT+IE1y2y3wIZaEr+VeLd45/7RB5OVC0un5QZpdb1Dva1zs1cgZibYuz6x5YXuFZ86VBTCpW+iXw== X-Received: by 2002:a81:4841:0:b0:5be:94a6:d919 with SMTP id v62-20020a814841000000b005be94a6d919mr6198288ywa.25.1700423288412; Sun, 19 Nov 2023 11:48:08 -0800 (PST) Received: from KASONG-MB2.tencent.com ([115.171.40.79]) by smtp.gmail.com with ESMTPSA id a6-20020aa78646000000b006cb7feae74fsm1237140pfo.164.2023.11.19.11.48.05 (version=TLS1_3 cipher=TLS_CHACHA20_POLY1305_SHA256 bits=256/256); Sun, 19 Nov 2023 11:48:07 -0800 (PST) From: Kairui Song To: linux-mm@kvack.org Cc: Andrew Morton , "Huang, Ying" , David Hildenbrand , Hugh Dickins , Johannes Weiner , Matthew Wilcox , Michal Hocko , linux-kernel@vger.kernel.org, Kairui Song Subject: [PATCH 02/24] mm/swapfile.c: add back some comment Date: Mon, 20 Nov 2023 03:47:18 +0800 Message-ID: <20231119194740.94101-3-ryncsn@gmail.com> X-Mailer: git-send-email 2.42.0 In-Reply-To: <20231119194740.94101-1-ryncsn@gmail.com> References: <20231119194740.94101-1-ryncsn@gmail.com> Reply-To: Kairui Song MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Type: text/plain; charset="utf-8" From: Kairui Song Some useful comments were dropped in commit b56a2d8af914 ('mm: rid swapoff of quadratic complexity'), add them back. Signed-off-by: Kairui Song --- mm/swapfile.c | 11 +++++++++++ 1 file changed, 11 insertions(+) diff --git a/mm/swapfile.c b/mm/swapfile.c index 4bc70f459164..756104ebd585 100644 --- a/mm/swapfile.c +++ b/mm/swapfile.c @@ -1879,6 +1879,17 @@ static int unuse_pte_range(struct vm_area_struct *vm= a, pmd_t *pmd, folio =3D page_folio(page); } if (!folio) { + /* + * The entry could have been freed, and will not + * be reused since swapoff() already disabled + * allocation from here, or alloc_page() failed. + * + * We don't hold lock here, so the swap entry could be + * SWAP_MAP_BAD (when the cluster is discarding). + * Instead of fail out, We can just skip the swap + * entry because swapoff will wait for discarding + * finish anyway. + */ swp_count =3D READ_ONCE(si->swap_map[offset]); if (swp_count =3D=3D 0 || swp_count =3D=3D SWAP_MAP_BAD) continue; --=20 2.42.0