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 mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 83E2BC433F5 for ; Tue, 5 Oct 2021 13:15:48 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 6AF36615E3 for ; Tue, 5 Oct 2021 13:15:48 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S234983AbhJENRh (ORCPT ); Tue, 5 Oct 2021 09:17:37 -0400 Received: from us-smtp-delivery-124.mimecast.com ([170.10.133.124]:58680 "EHLO us-smtp-delivery-124.mimecast.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S234978AbhJENRh (ORCPT ); Tue, 5 Oct 2021 09:17:37 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1633439746; 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=aVKc5yd2u429wV/BLHqqmA9iOdQQcgUkmy1ws4LmTWQ=; b=Bt7g0KVo+ZRHCMS0m70fUrK4dWm4pmJY7pnyG82wl9wpg6wkc534H4YgM+GkSnrGNdF5Fo QSKyW8XqUUHqDoHCEgTDOKG8MFQBA0Ih4dK899gZiqnf7O+Pb1vV/9rzS6iZx90oFXBSVd n8k4Puukv13kN1b/ba3AJp226bkQ+WQ= Received: from mimecast-mx01.redhat.com (mimecast-mx01.redhat.com [209.132.183.4]) (Using TLS) by relay.mimecast.com with ESMTP id us-mta-52-dKSukSxeNrmdtMHa7dOL2g-1; Tue, 05 Oct 2021 09:15:45 -0400 X-MC-Unique: dKSukSxeNrmdtMHa7dOL2g-1 Received: from smtp.corp.redhat.com (int-mx01.intmail.prod.int.phx2.redhat.com [10.5.11.11]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id 196B6100C624; Tue, 5 Oct 2021 13:15:43 +0000 (UTC) Received: from warthog.procyon.org.uk (unknown [10.33.36.44]) by smtp.corp.redhat.com (Postfix) with ESMTP id 758A853E08; Tue, 5 Oct 2021 13:15:41 +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: <23033528036059af4633f60b8325e48eab95ac36.camel@hammerspace.com> References: <23033528036059af4633f60b8325e48eab95ac36.camel@hammerspace.com> <97eb17f51c8fd9a89f10d9dd0bf35f1075f6b236.camel@hammerspace.com> <163189104510.2509237.10805032055807259087.stgit@warthog.procyon.org.uk> <163189108292.2509237.12615909591150927232.stgit@warthog.procyon.org.uk> <81120.1633099916@warthog.procyon.org.uk> To: Trond Myklebust Cc: dhowells@redhat.com, "linux-cachefs@redhat.com" , "linux-mm@kvack.org" , "linux-nfs@vger.kernel.org" , "willy@infradead.org" , "anna.schumaker@netapp.com" , "dwysocha@redhat.com" Subject: Re: Can the GFP flags to releasepage() be trusted? -- was Re: [PATCH v2 3/8] nfs: Move to using the alternate fallback fscache I/O API MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-ID: <1080873.1633439740.1@warthog.procyon.org.uk> Date: Tue, 05 Oct 2021 14:15:40 +0100 Message-ID: <1080874.1633439740@warthog.procyon.org.uk> X-Scanned-By: MIMEDefang 2.79 on 10.5.11.11 Precedence: bulk List-ID: X-Mailing-List: linux-nfs@vger.kernel.org Trond Myklebust wrote: > To elaborate a bit: we used to have code here that would check whether > the page had been cleaned but was unstable, and if an argument of > GFP_KERNEL or above was set, we'd try to call COMMIT to ensure the page > was synched to disk on the server (and we'd wait for that call to > complete). > > That code would end up deadlocking in all sorts of horrible ways, so we > ended up having to pull it. I don't think that a deadlock should be possible with this. PG_fscache is now only being used to indicate that a DIO write to the cache is in progress on the page. It will complete and remove the mark at some point. David