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 X-Spam-Level: X-Spam-Status: No, score=-2.7 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,FREEMAIL_FORGED_FROMDOMAIN,FREEMAIL_FROM, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS, URIBL_BLOCKED autolearn=no autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 1F67BC432BE for ; Fri, 20 Aug 2021 01:49:11 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id F0BE560F9F for ; Fri, 20 Aug 2021 01:49:10 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S236386AbhHTBtq (ORCPT ); Thu, 19 Aug 2021 21:49:46 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:59002 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S234909AbhHTBto (ORCPT ); Thu, 19 Aug 2021 21:49:44 -0400 Received: from mail-yb1-xb2b.google.com (mail-yb1-xb2b.google.com [IPv6:2607:f8b0:4864:20::b2b]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 1A4CBC061575 for ; Thu, 19 Aug 2021 18:49:07 -0700 (PDT) Received: by mail-yb1-xb2b.google.com with SMTP id p4so15940642yba.3 for ; Thu, 19 Aug 2021 18:49:07 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=mime-version:references:in-reply-to:from:date:message-id:subject:to :cc; bh=cfA42dYUBZY6kxKenPYN1PDY1E3ZRSIEN7D/AlYpFrE=; b=cuViM2TUQIsTEtgf9kRqZyKiDbpZFnU+scXYX5sxzQymd23QuAMJQP+YDwZb0YqGUo BXEwztG0qbBX9IXZokrLgXD5ayOgRBxC8c60FZDoTayrn+FTBq+WVKHZEbbC9zO3QVlZ sNIv1Qkr11WRifxzg97obqjeTuN4aeDZezpwaQYtC7hIAy0w6mm94GFbOsFDpYGAkSnL ilNwr97j9+CkEo1QSp4YmUqtj/vMx4WUJGYKTVqAdggkzaNRvt07LA9uE4ulmUgy1sLV 1KYUCrbucoX8GX6yUmOO9AJen85v9eS3B/CoO+eRuBKHHRSAFTsYCd0VcB30tC41f6D2 S6UA== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:mime-version:references:in-reply-to:from:date :message-id:subject:to:cc; bh=cfA42dYUBZY6kxKenPYN1PDY1E3ZRSIEN7D/AlYpFrE=; b=gxYiqmVOCkYOjBU7u8mOANchDxUHD96Rav2GLHE7CxhEwbZKbHPIWlUUGs+lSvvxBI rfzJ8V6fduX/A8iBPH7TytDoPqQ8prOUPoRR8a7a53JyVy3aqONKr/86cc41qCiyqUf/ s8pSjNBYnp6ZfdAz7JSFGsoauAmfwUukMNWDdd+ycG2YIkr3gf81QzQ8Ep/1ghFYEkXb YjLWNKHY+SEfbEZTA2xNZ7VpRuYmF0mhtQUpHK/e6hSIqlX3DO9Qs604FOgp8Qup86sL cwchU6/6DUPLUFmvJAOdrj4tHeDazAZ/lHykhY1jtYwqmKa5Ps9ncN2r5gr6YRqkGU/r 7FpA== X-Gm-Message-State: AOAM532tlFIwG+XShOAWFH6F5TIrh9Lu4dAnvt8zYJogOHHWWMb+pIg/ wFrOmeEHeRhR75arybKUbuc/BnZMAkv+73CKe9B5u3fjoa8= X-Google-Smtp-Source: ABdhPJwEgUaLGLBXDnG+J06MbaLtrnsU1e/xUAHzg39aFbWIEdGKM5k5OkOIFw3txmAYe8ZngH+DYboH0+BJCG3jeLY= X-Received: by 2002:a25:49c3:: with SMTP id w186mr582252yba.383.1629424146438; Thu, 19 Aug 2021 18:49:06 -0700 (PDT) MIME-Version: 1.0 References: In-Reply-To: From: Hao Peng Date: Fri, 20 Aug 2021 09:48:42 +0800 Message-ID: Subject: Re: [PATCH] fuse: Use kmap_local_page() To: Miklos Szeredi Cc: linux-fsdevel@vger.kernel.org Content-Type: text/plain; charset="UTF-8" Precedence: bulk List-ID: X-Mailing-List: linux-fsdevel@vger.kernel.org >On Tue, Aug 17, 2021 at 11:42 PM Miklos Szeredi wrote: > > On Tue, 17 Aug 2021 at 05:17, Hao Peng wrote: > > > > kmap_local_page() is enough. > > This explanation is not enough for me to understand the patch. Please > describe in more detail. > Due to the introduction of kmap_local_*, the storage of slots used for short-term mapping has changed from per-CPU to per-thread. kmap_atomic() disable preemption, while kmap_local_*() only disable migration. There is no need to disable preemption in several kamp_atomic places used in fuse. The detailed introduction of kmap_local_*d can be found here: https://lwn.net/Articles/836144/ Thanks. > Thanks, > Miklos