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=-11.5 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS autolearn=unavailable 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 0ACFFC4338F for ; Thu, 12 Aug 2021 11:57:53 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 8873860C3F for ; Thu, 12 Aug 2021 11:57:52 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S237004AbhHLL6Q (ORCPT ); Thu, 12 Aug 2021 07:58:16 -0400 Received: from us-smtp-delivery-124.mimecast.com ([170.10.133.124]:58512 "EHLO us-smtp-delivery-124.mimecast.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S235267AbhHLL6P (ORCPT ); Thu, 12 Aug 2021 07:58:15 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1628769469; 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: content-transfer-encoding:content-transfer-encoding; bh=+MUILZud/IAozexZw2Rp3LH70sCYOJsL7dafaXwyS/4=; b=Kw/gyE/5O/7GYDiZjpUXT4wsTw24mwFXKbfj9/fNxq7ZuCdWm+N5AFsKzG+PyA1ceuupz6 s+Zd/jXmSm33c/oD6UmNLIzaFFw+LZ+WaKiLe0c00zRbNlMpiNBi2ZAznEpRELdG8+pLQU dWitylQyJ59vE60LqIODmXMDTpoKhi4= 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-424-05cOM7r1PKGLzk-WXnMcXA-1; Thu, 12 Aug 2021 07:57:46 -0400 X-MC-Unique: 05cOM7r1PKGLzk-WXnMcXA-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 ADACF1008064; Thu, 12 Aug 2021 11:57:44 +0000 (UTC) Received: from warthog.procyon.org.uk (unknown [10.22.32.7]) by smtp.corp.redhat.com (Postfix) with ESMTP id 4897C60657; Thu, 12 Aug 2021 11:57:42 +0000 (UTC) Subject: [PATCH 0/2] mm: Fix NFS swapfiles and use DIO read for swapfiles From: David Howells To: willy@infradead.org Cc: dhowells@redhat.com, trond.myklebust@primarydata.com, darrick.wong@oracle.com, hch@lst.de, jlayton@kernel.org, sfrench@samba.org, torvalds@linux-foundation.org, linux-nfs@vger.kernel.org, linux-mm@kvack.org, linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org Date: Thu, 12 Aug 2021 12:57:41 +0100 Message-ID: <162876946134.3068428.15475611190876694695.stgit@warthog.procyon.org.uk> User-Agent: StGit/0.23 MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: 7bit X-Scanned-By: MIMEDefang 2.79 on 10.5.11.11 Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hi Willy, Trond, Here's a change to make reads from the swapfile use async DIO rather than readpage(), as requested by Willy. Whilst trying to make this work, I found that NFS's support for swapfiles seems to have been non-functional since Aug 2019 (I think), so the first patch fixes that. Question is: do we actually *want* to keep this functionality, given that it seems that no one's tested it with an upstream kernel in the last couple of years? I tested this using the procedure and program outlined in the first patch. I also encountered occasional instances of the following warning, so I'm wondering if there's a scheduling problem somewhere: BUG: workqueue lockup - pool cpus=0-3 flags=0x5 nice=0 stuck for 34s! Showing busy workqueues and worker pools: workqueue events: flags=0x0 pwq 6: cpus=3 node=0 flags=0x0 nice=0 active=1/256 refcnt=2 in-flight: 1565:fill_page_cache_func workqueue events_highpri: flags=0x10 pwq 3: cpus=1 node=0 flags=0x1 nice=-20 active=1/256 refcnt=2 in-flight: 1547:fill_page_cache_func pwq 1: cpus=0 node=0 flags=0x0 nice=-20 active=1/256 refcnt=2 in-flight: 1811:fill_page_cache_func workqueue events_unbound: flags=0x2 pwq 8: cpus=0-3 flags=0x5 nice=0 active=3/512 refcnt=5 pending: fsnotify_connector_destroy_workfn, fsnotify_mark_destroy_workfn, cleanup_offline_cgwbs_workfn workqueue events_power_efficient: flags=0x82 pwq 8: cpus=0-3 flags=0x5 nice=0 active=4/256 refcnt=6 pending: neigh_periodic_work, neigh_periodic_work, check_lifetime, do_cache_clean workqueue writeback: flags=0x4a pwq 8: cpus=0-3 flags=0x5 nice=0 active=1/256 refcnt=4 in-flight: 433(RESCUER):wb_workfn workqueue rpciod: flags=0xa pwq 8: cpus=0-3 flags=0x5 nice=0 active=38/256 refcnt=40 in-flight: 7:rpc_async_schedule, 1609:rpc_async_schedule, 1610:rpc_async_schedule, 912:rpc_async_schedule, 1613:rpc_async_schedule, 1631:rpc_async_schedule, 34:rpc_async_schedule, 44:rpc_async_schedule pending: rpc_async_schedule, rpc_async_schedule, rpc_async_schedule, rpc_async_schedule, rpc_async_schedule, rpc_async_schedule, rpc_async_schedule, rpc_async_schedule, rpc_async_schedule, rpc_async_schedule, rpc_async_schedule, rpc_async_schedule, rpc_async_schedule, rpc_async_schedule, rpc_async_schedule, rpc_async_schedule, rpc_async_schedule, rpc_async_schedule, rpc_async_schedule, rpc_async_schedule, rpc_async_schedule, rpc_async_schedule, rpc_async_schedule, rpc_async_schedule, rpc_async_schedule, rpc_async_schedule, rpc_async_schedule, rpc_async_schedule, rpc_async_schedule, rpc_async_schedule workqueue ext4-rsv-conversion: flags=0x2000a pool 1: cpus=0 node=0 flags=0x0 nice=-20 hung=59s workers=2 idle: 6 pool 3: cpus=1 node=0 flags=0x1 nice=-20 hung=43s workers=2 manager: 20 pool 6: cpus=3 node=0 flags=0x0 nice=0 hung=0s workers=3 idle: 498 29 pool 8: cpus=0-3 flags=0x5 nice=0 hung=34s workers=9 manager: 1623 pool 9: cpus=0-3 flags=0x5 nice=-20 hung=0s workers=2 manager: 5224 idle: 859 Note that this is due to DIO writes to NFS only, as far as I can tell, and that no reads had happened yet. David --- David Howells (2): nfs: Fix write to swapfile failure due to generic_write_checks() mm: Make swap_readpage() for SWP_FS_OPS use ->direct_IO() not ->readpage() mm/page_io.c | 73 +++++++++++++++++++++++++++++++++++++++++++++++----- 1 file changed, 67 insertions(+), 6 deletions(-)