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 952AAC433F5 for ; Sat, 19 Mar 2022 01:49:58 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S241734AbiCSBqh (ORCPT ); Fri, 18 Mar 2022 21:46:37 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:59686 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229580AbiCSBqg (ORCPT ); Fri, 18 Mar 2022 21:46:36 -0400 Received: from mail-qv1-xf2c.google.com (mail-qv1-xf2c.google.com [IPv6:2607:f8b0:4864:20::f2c]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 445932DD98C for ; Fri, 18 Mar 2022 18:45:16 -0700 (PDT) Received: by mail-qv1-xf2c.google.com with SMTP id jo24so217948qvb.5 for ; Fri, 18 Mar 2022 18:45:16 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20210112; h=mime-version:references:in-reply-to:from:date:message-id:subject:to :cc; bh=KkQmEP0AU8bSdcTRUOlOUawSBdGr8p6///xsFsEqdbY=; b=SaVw2WOa2mwtdzj3aX1v5v2dOt63VrRXBrdTXp+q/KtFtUxsc8qbHK0bO0QjkSpubT 1y13NGchi3LG6Kf+QSRrtX/IMzlw3yuthJVMRCdU2KQdskJAfSmbMt2Eft08qO/TU9ss IhkKNoKP8U0G2yyzXTA1d0FAg7DKN0YkKVjm81wE70oVAhUFy6wpYx1HoKHwjwSqeCmB wYlU9Mzdzj4A+ThS1bFGDsldoC7b6Qqn9vLTbiKumxoaQV9dBEp9o7M6Ie9BdonxoyUm vHDVZpHEoS+bZRFGvB9qzIIEBRCGodPBzSktO3GR8Df0ursnFrbrDqVQcWFEROjU6Vdo /jEQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=x-gm-message-state:mime-version:references:in-reply-to:from:date :message-id:subject:to:cc; bh=KkQmEP0AU8bSdcTRUOlOUawSBdGr8p6///xsFsEqdbY=; b=MtiICfp7aT+zGk9S5+Kgy2CtzcQ+Lbh/MaIv/jPOOKzoXQDBSa+il106F+gBI0cdog +sbIH40fuK/9gASXwvApR7ZjG2p5lry+heT3QCrdBrfKzsafbZxkcH9SqJT+EUhRRRB2 yOxvxlYBnSpX7vPWxw/JHBrSQVH433AoHx7AOQqXFX7N+Zhy9CJbRKn+EKIAOcbuR9e1 PTSa+uiL9LHacx9c1cfcXXU/EK0tQKPDgGH6n5lX9I1DHbj7un7EehOU8UGskGXakdjk MMQM3kaddcOXS7VrHi8PeJcPojTUyNWqdakrq552+/1bbrmFKsfvp2DwoG08KBIsGOZ2 vtFw== X-Gm-Message-State: AOAM530ZtajpSzFy8FhA3CfFzNVdcyvSZMHmtgoiH7r7+m358Q+Z/5T2 McOX7HCaJhC232B9eShbsZyPAolhVZ0SQmkPCyZiSw== X-Google-Smtp-Source: ABdhPJxmAfiQiJPHxu2Rc7BBfv2iLFQ4QhxKrhO09SuOt9pcK9+vJoTzkXCVzQhxizdkNa/I7WxBvyeXynoJqUFRSXQ= X-Received: by 2002:a05:6214:29e9:b0:439:eedb:dedf with SMTP id jv9-20020a05621429e900b00439eedbdedfmr9213739qvb.15.1647654315245; Fri, 18 Mar 2022 18:45:15 -0700 (PDT) MIME-Version: 1.0 References: <20220319001635.4097742-1-khazhy@google.com> In-Reply-To: From: Khazhy Kumykov Date: Fri, 18 Mar 2022 18:45:04 -0700 Message-ID: Subject: Re: [PATCH RFC] nfsd: avoid recursive locking through fsnotify To: Trond Myklebust Cc: "bfields@fieldses.org" , "chuck.lever@oracle.com" , "linux-mm@kvack.org" , "linux-nfs@vger.kernel.org" , "linux-kernel@vger.kernel.org" Content-Type: multipart/signed; protocol="application/pkcs7-signature"; micalg=sha-256; boundary="00000000000032635b05da886a36" Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org --00000000000032635b05da886a36 Content-Type: text/plain; charset="UTF-8" On Fri, Mar 18, 2022 at 5:36 PM Trond Myklebust wrote: > > Isn't that stack trace showing a slab direct reclaim, and not a > filesystem writeback situation? > > Does memalloc_nofs_save()/restore() really fix this problem? It seems > to me that it cannot, particularly since knfsd is not a filesystem, and > so does not ever handle writeback of dirty pages. Ah you're right. An alternative would be delaying the destroy_mark, which I am noticing now that, on mainline, the shrinker calls nfsd_file_dispose_list_delayed, something missing from the version of 5.4 I was looking at. To my reading 9542e6a643fc6 ("nfsd: Containerise filecache laundrette") should have the effect of fixing this deadlock (and the message does explicitly call out notifier deadlocks) - maybe something to send towards stable? > > > Cc: the linux-mm mailing list in search of answers to the above 2 > questions. > > -- > Trond Myklebust > Linux NFS client maintainer, Hammerspace > trond.myklebust@hammerspace.com > > --00000000000032635b05da886a36 Content-Type: application/pkcs7-signature; name="smime.p7s" Content-Transfer-Encoding: base64 Content-Disposition: attachment; filename="smime.p7s" Content-Description: S/MIME Cryptographic Signature MIIPmwYJKoZIhvcNAQcCoIIPjDCCD4gCAQExDzANBglghkgBZQMEAgEFADALBgkqhkiG9w0BBwGg ggz1MIIEtjCCA56gAwIBAgIQeAMYYHb81ngUVR0WyMTzqzANBgkqhkiG9w0BAQsFADBMMSAwHgYD VQQLExdHbG9iYWxTaWduIFJvb3QgQ0EgLSBSMzETMBEGA1UEChMKR2xvYmFsU2lnbjETMBEGA1UE AxMKR2xvYmFsU2lnbjAeFw0yMDA3MjgwMDAwMDBaFw0yOTAzMTgwMDAwMDBaMFQxCzAJBgNVBAYT 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