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 vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id BE667C433F5 for ; Mon, 21 Mar 2022 14:23:59 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1349185AbiCUOZT (ORCPT ); Mon, 21 Mar 2022 10:25:19 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:34210 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1352279AbiCUOWT (ORCPT ); Mon, 21 Mar 2022 10:22:19 -0400 Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [170.10.133.124]) by lindbergh.monkeyblade.net (Postfix) with ESMTP id BD96E1A6370 for ; Mon, 21 Mar 2022 07:15:40 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1647872050; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: in-reply-to:in-reply-to:references:references; bh=zdZh+PVRiBzCL4O4BEAWERm5HcmHbh2Kl3rjp7JWCdo=; b=fk6YRE1eTaa7doP+QHNzwflDOBmMFZ7CXlOCIrsHDKMy9jjpREDxa6UnmhNNnvbKYUhuIO vfj3OhcBqE07NOOLw1HHvbedWRaybECUvdz9pNiDVpSSjES99co2rNA6mGeuENNe+HTh5N 41zO2NMqfwdBrg8q5WBclyoeCbjEJkU= Received: from mimecast-mx02.redhat.com (mimecast-mx02.redhat.com [66.187.233.88]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id us-mta-60-d1NlD1fuNzyaxa169iA_sw-1; Mon, 21 Mar 2022 10:14:07 -0400 X-MC-Unique: d1NlD1fuNzyaxa169iA_sw-1 Received: from smtp.corp.redhat.com (int-mx09.intmail.prod.int.rdu2.redhat.com [10.11.54.9]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx02.redhat.com (Postfix) with ESMTPS id 422D180352D; Mon, 21 Mar 2022 14:14:06 +0000 (UTC) Received: from warthog.procyon.org.uk (unknown [10.33.36.19]) by smtp.corp.redhat.com (Postfix) with ESMTP id B96CD426353; Mon, 21 Mar 2022 14:14:03 +0000 (UTC) Organization: Red Hat UK Ltd. Registered Address: Red Hat UK Ltd, Amberley Place, 107-111 Peascod Street, Windsor, Berkshire, SI4 1TE, United Kingdom. Registered in England and Wales under Company Registration No. 3798903 From: David Howells In-Reply-To: References: <20220316131723.111553-1-jefflexu@linux.alibaba.com> <20220316131723.111553-4-jefflexu@linux.alibaba.com> To: Matthew Wilcox Cc: dhowells@redhat.com, Jeffle Xu , linux-cachefs@redhat.com, xiang@kernel.org, chao@kernel.org, linux-erofs@lists.ozlabs.org, torvalds@linux-foundation.org, gregkh@linuxfoundation.org, linux-fsdevel@vger.kernel.org, joseph.qi@linux.alibaba.com, bo.liu@linux.alibaba.com, tao.peng@linux.alibaba.com, gerry@linux.alibaba.com, eguan@linux.alibaba.com, linux-kernel@vger.kernel.org, luodaowen.backend@bytedance.com Subject: Re: [PATCH v5 03/22] cachefiles: introduce on-demand read mode MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-ID: <1029981.1647872043.1@warthog.procyon.org.uk> Date: Mon, 21 Mar 2022 14:14:03 +0000 Message-ID: <1029982.1647872043@warthog.procyon.org.uk> X-Scanned-By: MIMEDefang 2.85 on 10.11.54.9 Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Matthew Wilcox wrote: > Why do you have a separate rwlock when the xarray already has its own > spinlock? This is usually a really bad idea. Jeffle wants to hold a lock across the CACHEFILES_DEAD check and the xarray access. However, he tells xarray to do a GFP_KERNEL alloc whilst holding the rwlock:-/ David