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 kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by smtp.lore.kernel.org (Postfix) with ESMTP id 4A4BCC5478C for ; Tue, 27 Feb 2024 07:52:18 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id A510E4401FD; Tue, 27 Feb 2024 02:52:17 -0500 (EST) Received: by kanga.kvack.org (Postfix, from userid 40) id A01364401FB; Tue, 27 Feb 2024 02:52:17 -0500 (EST) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 8C8A94401FD; Tue, 27 Feb 2024 02:52:17 -0500 (EST) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0014.hostedemail.com [216.40.44.14]) by kanga.kvack.org (Postfix) with ESMTP id 7B1CF4401FB for ; Tue, 27 Feb 2024 02:52:17 -0500 (EST) Received: from smtpin02.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay05.hostedemail.com (Postfix) with ESMTP id 42D7340A9C for ; Tue, 27 Feb 2024 07:52:17 +0000 (UTC) X-FDA: 81836815914.02.8A148D0 Received: from mail-pl1-f169.google.com (mail-pl1-f169.google.com [209.85.214.169]) by imf16.hostedemail.com (Postfix) with ESMTP id 65553180002 for ; Tue, 27 Feb 2024 07:52:15 +0000 (UTC) Authentication-Results: imf16.hostedemail.com; dkim=pass header.d=chromium.org header.s=google header.b=KuAY4pB6; spf=pass (imf16.hostedemail.com: domain of senozhatsky@chromium.org designates 209.85.214.169 as permitted sender) smtp.mailfrom=senozhatsky@chromium.org; dmarc=pass (policy=none) header.from=chromium.org ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1709020335; h=from:from:sender:reply-to:subject:subject:date:date: message-id:message-id:to:to:cc:cc:mime-version:mime-version: content-type:content-type:content-transfer-encoding: in-reply-to:in-reply-to:references:references:dkim-signature; bh=ENJj/6O9DH4cxRE/TQEbtaKBpIfwOdtzioRhc7Nl6I8=; b=aYfM7vT5Is5KKLSgXUxsvIf5eRhOe9A8yLqtYzD2l5ROS+aTGDi0/xF5ttt8jxlSCewoWs XrnI8irWT71JunvQ+h6bruUs7muvL0Tsr+/6DtbJfgzmBGFKSxYJAoERe224633XfWCCje QGNEGEZBKtoOb6J9ICZ0lCKgJ6XChYA= ARC-Seal: i=1; s=arc-20220608; d=hostedemail.com; t=1709020335; a=rsa-sha256; cv=none; b=2C2sCpiCVul2r9GKh3LB+cZRXuYtqEbT7vOAQqoDxmqDDOEKgv3Mt6CqutZnxtY2496IX2 ggNwGfmZmEXZBLamjWLtk9xlyuISi9Hv4B6jiatmMNYFVXZwtSoL4UDlC1/t0G5/GrKInk MXERmBilPFXdmDOrrmwBb2j/x/uEvTA= ARC-Authentication-Results: i=1; imf16.hostedemail.com; dkim=pass header.d=chromium.org header.s=google header.b=KuAY4pB6; spf=pass (imf16.hostedemail.com: domain of senozhatsky@chromium.org designates 209.85.214.169 as permitted sender) smtp.mailfrom=senozhatsky@chromium.org; dmarc=pass (policy=none) header.from=chromium.org Received: by mail-pl1-f169.google.com with SMTP id d9443c01a7336-1d911c2103aso21679545ad.0 for ; Mon, 26 Feb 2024 23:52:15 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=chromium.org; s=google; t=1709020334; x=1709625134; darn=kvack.org; h=in-reply-to:content-disposition:mime-version:references:message-id :subject:cc:to:from:date:from:to:cc:subject:date:message-id:reply-to; bh=ENJj/6O9DH4cxRE/TQEbtaKBpIfwOdtzioRhc7Nl6I8=; b=KuAY4pB6tASzX+J6F5rxU99eosiTgOeYVvlm/HrfUIXoZfZ+P9YUBO1W+bhsmOlbbb DX9cda03gH1xlVOLRAb2pPv/GebXZ9i/LSYjK1Uh4ItTnn+zWwWbTl2tRTxPZoeDbx0Z vyhTMGDZNWGfusf5bJq5Yl/dlbbuyGHBNUDSQ= X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1709020334; x=1709625134; h=in-reply-to:content-disposition:mime-version:references:message-id :subject:cc:to:from:date:x-gm-message-state:from:to:cc:subject:date :message-id:reply-to; bh=ENJj/6O9DH4cxRE/TQEbtaKBpIfwOdtzioRhc7Nl6I8=; b=WgJFRBzBtjd+BT6StIfizGieKNtknuBzVrMV5khSEUCQTJZ9SfvMKqQ6qPvHbIMFSs vFhbfK6wCjpFFrnrGfgTFbT/ErzlyvCarufxGdKEoWDa9h7AmB9EvsH00QeMER/uIIPJ TVCZ4vK/PgBTcGZA+GumEIY2OeDeRhWfojCkbG++E2lkkLowfFSbWjkJXq+dGsnlJ2CQ QHKiY0OXVao2Tk4/Aao/mpon71Nt2WMy4mepOlyfIWWpjuNDLUx6Ht2KJ+bkvy5NOziF 8A+diAgLnKw4JgCK+qbR382VltCUioQTbdxxHBtVMgkcDBVsao486FSaRzXVTeqkl5y1 hPGw== X-Forwarded-Encrypted: i=1; AJvYcCXrouHasps0i5pgXu3VPJ5HICmQoJNsW32pSNv57TKjoaS8nGlMo8L0r/zH0kN6M+0DZWbC/hnC6woPfaxSvRRZyNg= X-Gm-Message-State: AOJu0YxdhTh2KMsHuNrAnWknd5AU+QQrm8flelaW3osJsan9cBoJ4ex4 66m0Foq7rFIz0IijAAReRNTZp1N1Kwcu3Yk5sVoI7sMfqJXYBPhbUiOg+mMlpBbK7ZrE7kYBumy EEQ== X-Google-Smtp-Source: AGHT+IHoSiz3A+hlmxfNO+hdIrVvlJj1VC+1EonpCetHm1MwdjZTWc/oUEw7NbQj6yQqC4qDRXxp0A== X-Received: by 2002:a17:902:d4c3:b0:1dc:b6ef:e233 with SMTP id o3-20020a170902d4c300b001dcb6efe233mr1675638plg.50.1709020334115; Mon, 26 Feb 2024 23:52:14 -0800 (PST) Received: from google.com ([2401:fa00:8f:203:f4f0:fb4d:aa01:9068]) by smtp.gmail.com with ESMTPSA id i8-20020a17090332c800b001da2f9d04b0sm901544plr.15.2024.02.26.23.52.11 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 26 Feb 2024 23:52:13 -0800 (PST) Date: Tue, 27 Feb 2024 16:52:09 +0900 From: Sergey Senozhatsky To: chengming.zhou@linux.dev Cc: minchan@kernel.org, senozhatsky@chromium.org, akpm@linux-foundation.org, hannes@cmpxchg.org, nphamcs@gmail.com, yosryahmed@google.com, linux-mm@kvack.org, linux-kernel@vger.kernel.org, Chengming Zhou Subject: Re: [PATCH] mm/zsmalloc: don't need to save tag bit in handle Message-ID: <20240227075209.GA11972@google.com> References: <20240227030045.3443702-1-chengming.zhou@linux.dev> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20240227030045.3443702-1-chengming.zhou@linux.dev> X-Stat-Signature: jsdotrmbjjdj9r6kpgzyo3hjsck65kxf X-Rspamd-Server: rspam10 X-Rspamd-Queue-Id: 65553180002 X-Rspam-User: X-HE-Tag: 1709020335-727426 X-HE-Meta: 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 cEjdr16j J+zPm8LwDn+gO2L8z94i53ALCD34cIsCqLLsO2vFicOfA7rC/czQlvtDGlKiOup4JluNTZq/37imEuEFBQoKQMSiVt7Sah5rMTVA/kG3WoTHw7cZyJc5xDOgs1jpn/EO3dq1nBIzbB17LLgoxKe5kUmUKaVGzjqhVYVVuXSK9XwpiBPUEiuyECxh9NxWiwrFl07W85UXLTgPBpreHH046FBSA6qR9GIdZ/xheL7vLkz9uKDP31+CTmDgnmYj1znWP9dW7x9lQkEt1dVdP31WxMKOvSCdshjvgxkBfvVIiOIY808s55v/qEQbdag7HuGmMRkS5vNywNpfKqupluti3c7KUCceY/BQAUHGnJPHOmhxy8wKKx/EHDswWOXykNenUYlgMvcqUg8ULQ6w= X-Bogosity: Ham, tests=bogofilter, spamicity=0.008096, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On (24/02/27 03:00), chengming.zhou@linux.dev wrote: > > We only need to save the position (pfn + obj_idx) in the handle, don't > need to save tag bit in handle. So one more bit can be used as obj_idx. [..] > mm/zsmalloc: don't need to save tag bit in handle Does this mean "don't need to reserve LSB for tag"? We still save allocated tag in the handle, that's what handle |= OBJ_ALLOCATED_TAG; does. > Actually, the tag bit is only useful in zspage's memory space, to tell > if an object is allocated or not. I'm not completely sure if I follow this sentence.