From nobody Wed Dec 24 05:06:05 2025 Received: from mail-pf1-f172.google.com (mail-pf1-f172.google.com [209.85.210.172]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id EC3A93F9CD for ; Mon, 29 Jan 2024 17:55:06 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=209.85.210.172 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1706550908; cv=none; b=W/rrf3taxBwnOVVA4LQZhw4IDulip//E1R7Qbnt7AAolS7vEGGZ0EZSplW7R/OdYZnpKZv/6i2RS2agpz2Ned7vK627C7Zpama0GfDf9hbkAt6ZI7S79uSKTI+uniqigCNA3EIJtUpFAd0igXXo8GwtahsqCebOWBmgrReR2Ykk= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1706550908; c=relaxed/simple; bh=kRJzgUNYG78tqYjV4uFsGxS1v+z5PuURjbt6RULZG/Q=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=HkkApGvZTO0GBFNgF1WIBtgS4S+Ab0/y/2JalaNL0AaQTvtcp7pg1sLnP10n24hNeEeiLitDO9rYUBFJISzkE3wvlbdDE7Ras1VFSWbYEHdWwFFnBfDLG1TSU/xHCSWi73/Eza8S9pble8sQYggIqr6Ge5WOavGBIZRj7yHYgy4= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=gmail.com; spf=pass smtp.mailfrom=gmail.com; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b=VENJkoIN; arc=none smtp.client-ip=209.85.210.172 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=gmail.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=gmail.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b="VENJkoIN" Received: by mail-pf1-f172.google.com with SMTP id d2e1a72fcca58-6dde65d585bso1390592b3a.0 for ; Mon, 29 Jan 2024 09:55:06 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20230601; t=1706550906; x=1707155706; 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=NOwwXIxywhgTYH3p3yq4nMufS2IRUoqO/tf1yKZ7qLU=; b=VENJkoIN49Q9ZKzdOX1XAvMgkE4nH6XNNqlBagT+sJpXW/qoohUJJVUjxCSwiWoZpy fcWPJYdPYPwRnP150KPhSRbNdnyv7BIWT1fWWG7NUVM2JJ2tb2xbaK29tO4Ae0g7IRl0 m7TRpBxUJfLhJMqQsqj0iJxrHiuPZ8ao5wZ0nWF+NcSwSCeKJGMTQGjl6wsmoIySMFWM jgghHCMON330FO9+wjfRTyaoXBdMwqcfVn72l0sE3LdGLVHRaKO89xSjoDB7SVTLUvBL efBJtgurkzsdKncHKwpsUpBwTDXdSpxDwq2s4znuy7VK4OCt6fwbrX5iIoPhlNpXb64G f7+A== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1706550906; x=1707155706; 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=NOwwXIxywhgTYH3p3yq4nMufS2IRUoqO/tf1yKZ7qLU=; b=irjQFyLc63pSBSvx71SuAUBhCQqOPssvYE6CTS64kyHqiYt34nwk3pS5fDOBNbpeY0 guaMCwQDLbMVaDmqv02R9z/Z1RkM+XeJetAwlcj10tD6WTjbE50DlyQWyvxwTvchFVao yS76uN8/CgXept8e1Fxp9sedznpnQsHWQUlZTT3lG6bPkHKSrvWkekDPXOUGeNL0/s4/ MOcIMNGJygk6hvh5foCn9aQxYI69Y1yOl5zzrARMBCI1I4QBCCaxGrl59T4MCTsSEhif G6zsxjgfurUrPvEoZg23/i/uKy3MIGAZr5vmp+xEWy7vSI2Y7lCesLUrErP9Ta3E3Oc4 LoKQ== X-Gm-Message-State: AOJu0YwShPOS5nEmng3rjppmkdjhIXkzLIZDT1acsT/nqTBIBj7bGkM7 kmHz9rXXq6mp0JVeCOcEGiaqmqkFl47y2uePkML7NL1aU3vU6NXD X-Google-Smtp-Source: AGHT+IHcsxUcn8preTc9iTpcswRaxjzdS4S22LBey4Xk5lFq3gP76HzVu0IIMkVly7esBhMrp+Y1Kw== X-Received: by 2002:aa7:8a13:0:b0:6db:e14f:3956 with SMTP id m19-20020aa78a13000000b006dbe14f3956mr2218904pfa.20.1706550906055; Mon, 29 Jan 2024 09:55:06 -0800 (PST) Received: from KASONG-MB2.tencent.com ([1.203.117.98]) by smtp.gmail.com with ESMTPSA id h8-20020aa79f48000000b006ddcadb1e2csm6116676pfr.29.2024.01.29.09.55.02 (version=TLS1_3 cipher=TLS_CHACHA20_POLY1305_SHA256 bits=256/256); Mon, 29 Jan 2024 09:55:05 -0800 (PST) From: Kairui Song To: linux-mm@kvack.org Cc: Andrew Morton , Chris Li , "Huang, Ying" , Hugh Dickins , Johannes Weiner , Matthew Wilcox , Michal Hocko , Yosry Ahmed , David Hildenbrand , linux-kernel@vger.kernel.org, Kairui Song Subject: [PATCH v3 1/7] mm/swapfile.c: add back some comment Date: Tue, 30 Jan 2024 01:54:16 +0800 Message-ID: <20240129175423.1987-2-ryncsn@gmail.com> X-Mailer: git-send-email 2.43.0 In-Reply-To: <20240129175423.1987-1-ryncsn@gmail.com> References: <20240129175423.1987-1-ryncsn@gmail.com> Reply-To: Kairui Song Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable 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 0008cd39af42..606d95b56304 100644 --- a/mm/swapfile.c +++ b/mm/swapfile.c @@ -1881,6 +1881,17 @@ 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 2.43.0