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 954FCC761A6 for ; Tue, 4 Apr 2023 10:41:03 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id 19E376B007B; Tue, 4 Apr 2023 06:41:03 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 128106B007D; Tue, 4 Apr 2023 06:41:03 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id EE2FC6B007E; Tue, 4 Apr 2023 06:41:02 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0017.hostedemail.com [216.40.44.17]) by kanga.kvack.org (Postfix) with ESMTP id DA0946B007B for ; Tue, 4 Apr 2023 06:41:02 -0400 (EDT) Received: from smtpin02.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay07.hostedemail.com (Postfix) with ESMTP id A411C160B40 for ; Tue, 4 Apr 2023 10:41:02 +0000 (UTC) X-FDA: 80643365964.02.8CE3526 Received: from mail-yb1-f176.google.com (mail-yb1-f176.google.com [209.85.219.176]) by imf03.hostedemail.com (Postfix) with ESMTP id D12AD20020 for ; Tue, 4 Apr 2023 10:41:00 +0000 (UTC) Authentication-Results: imf03.hostedemail.com; dkim=pass header.d=google.com header.s=20210112 header.b=SUFUspxs; spf=pass (imf03.hostedemail.com: domain of glider@google.com designates 209.85.219.176 as permitted sender) smtp.mailfrom=glider@google.com; dmarc=pass (policy=reject) header.from=google.com ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1680604860; 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=iwzxcbPB4/3rI7150D2ESWEJjPWEtJtDQ2Zs7FQqEt0=; b=sE0MDpZnyT4cuIqfJ6mVT4lfidFsid0JCW+oc5In7WYRRj/SACMQswzGUu9pCc7u4c25+t n6EAxfNvRji4sweJO66jRFFhmfv7B40wn15tF+Gr+Qs6ZmRHbPcFrLXk5L9GiQtTjsI5pR 1G5HUScDnA1uUGkjTBLgWtzoVAV1Luc= ARC-Authentication-Results: i=1; imf03.hostedemail.com; dkim=pass header.d=google.com header.s=20210112 header.b=SUFUspxs; spf=pass (imf03.hostedemail.com: domain of glider@google.com designates 209.85.219.176 as permitted sender) smtp.mailfrom=glider@google.com; dmarc=pass (policy=reject) header.from=google.com ARC-Seal: i=1; s=arc-20220608; d=hostedemail.com; t=1680604860; a=rsa-sha256; cv=none; b=NO8QZYVGuGzZDM23azujLb5pD/Ssi+xAE/5k3tSxKUjbKFl1WRieXaIzuDswdVRYs7QGe7 MJb16papERgSRl7+tUswz1C+ZdydWk6Ftj6P4drsnqDBcjgMcXZmq7ER53KLTBze53na4C dVnJr/ZPn3Jpl2h21FeTnPW2wtTtHAM= Received: by mail-yb1-f176.google.com with SMTP id z83so38097794ybb.2 for ; Tue, 04 Apr 2023 03:41:00 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20210112; t=1680604860; h=cc:to:subject:message-id:date:from:in-reply-to:references :mime-version:from:to:cc:subject:date:message-id:reply-to; bh=iwzxcbPB4/3rI7150D2ESWEJjPWEtJtDQ2Zs7FQqEt0=; b=SUFUspxs2Cp1C8kUOGZYdY2Zvb4y54hXE/8HnGNxANyC2PDp+d1Q7Hr0T9zeT6oW00 DUi0fT9z66wuS+lE1crsbq4U+qVbo3fgPKBw002TBoyayhmG5rq8XA19PhlnzJ7f2oEJ Vc3ahi76OMDKAU0vLklXduGXmDF+/Nuk8tFF9H/hINrhnYrq5xwJOENWTmAzTBvlFiWT S6DVslWaWnsZE3PCRsPm+R8dAKYQ11JnSbwpVxPnQSIqvpAPsf7b3/u31mBjIoOo6ZEf UfY40lpgwP/g71UOXfoJXMTV2Juu/HgU28QGP3GqR/Na5sSsubESlyHbih+iNT2M10Yz oVjw== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; t=1680604860; h=cc:to:subject:message-id:date:from:in-reply-to:references :mime-version:x-gm-message-state:from:to:cc:subject:date:message-id :reply-to; bh=iwzxcbPB4/3rI7150D2ESWEJjPWEtJtDQ2Zs7FQqEt0=; b=c1gt/X7GvQBrVGSOhNNhpLzknxMZLVimTvQgpJgreQzrs9oeRd60HGxnXVwnwPLv25 EUKRqzRLKAUK6/KjDbUgNaAyHJXHBRS96EFnkVLz5m8s3JeI+DD2g83EEmJejhuFiRP6 7dqyANy8KiI0t0WVAsA4jXFDr8Ri80JAM+Tx3zqZ5aj6f3jD1JnL+T7NrC78IiYLnUcX CsGjQEvDslHkAVIAOw9JzNlRjaq9sT9x8WiMUU7O7RQ1pz1XHroQrwqO3y7tjWyO7SIL yEue/VHalcRCOtCl2EqP59gRCdpz1qNQf140zO2n0u5IcYQlMyZSQUCCazc18NT2glT6 jXAw== X-Gm-Message-State: AAQBX9cHgVKOJ+stv6bzEtGeU8jl7h4qxzaSspN1nD2ZB43sITdKr09g An+fAolkuORhonBlbLYZzRmQ4ZASPi20hTRV3psktg== X-Google-Smtp-Source: AKy350bZ9UZGq0HiTB71Lay4t1LWQkCqgaAqqLPnMGi8vARxIVQ4/GlwkNrGcd5OS9PIrjqQ2KdjmOcuOat5Z7oaiwc= X-Received: by 2002:a25:d0e:0:b0:990:b53f:933a with SMTP id 14-20020a250d0e000000b00990b53f933amr2425696ybn.60.1680604859787; Tue, 04 Apr 2023 03:40:59 -0700 (PDT) MIME-Version: 1.0 References: <20230403122738.6006-1-zhangpeng.00@bytedance.com> In-Reply-To: From: Alexander Potapenko Date: Tue, 4 Apr 2023 12:40:23 +0200 Message-ID: Subject: Re: [PATCH v2] mm: kfence: Improve the performance of __kfence_alloc() and __kfence_free() To: Peng Zhang Cc: elver@google.com, dvyukov@google.com, akpm@linux-foundation.org, kasan-dev@googlegroups.com, linux-mm@kvack.org, linux-kernel@vger.kernel.org Content-Type: text/plain; charset="UTF-8" X-Rspamd-Server: rspam05 X-Rspamd-Queue-Id: D12AD20020 X-Stat-Signature: kksmgutnbok3jqz8ianpwq7gqhxabue4 X-Rspam-User: X-HE-Tag: 1680604860-984142 X-HE-Meta: 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 a70hIUGM yTHPNBM4ASY9JbHpDKbVbkXAPNcR1/AyXM36oh368RqWXLZY8nfSusM7LyqcFk+X19K5fxFUOzHlUPtHJ6aAI9iJBIJDjyhE4vSoTGdysH635tTwFsEVYZtpYXdJzt/dcSEc8TJdb8QQFPTcBFT+ycHB/HuaWjbfgVKLeLKdKKsxgKMMNkI6ibybfnlo8Rj+3N2g4Q4DPm18Yj2GgUqvmvgPpBWRF5XPhryX3ybZ3oW2TlSuToXhgHBq3KIOaGsPsRgRlQXlHriTdMCX+PW5jSERfRzIaHB7C3VFo X-Bogosity: Ham, tests=bogofilter, spamicity=0.069717, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: > > > > /* Apply to left of object. */ > > - for (addr = pageaddr; addr < meta->addr; addr++) { > > - if (!fn((u8 *)addr)) > > + for (; meta->addr - addr >= sizeof(u64); addr += sizeof(u64)) { > > + if (unlikely(*((u64 *)addr) != KFENCE_CANARY_PATTERN_U64)) > > break; > > } > I am confused. Right now this loop either runs from pageaddr to > meta_addr if there's no corruption, or breaks at the first corrupted > byte. > Regardless of that, we are applying check_canary_byte() to every byte > of that range in the following loop. > Shouldn't the two be nested, like in the case of the canary bytes to > the right of the object? > Please disregard my comment. This loop is fine, it just speeds up finding the first corrupted byte.