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 kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by smtp.lore.kernel.org (Postfix) with ESMTP id E3C2FC433EF for ; Sat, 19 Mar 2022 01:45:17 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id F1EF88D0001; Fri, 18 Mar 2022 21:45:16 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id ECCEC6B0072; Fri, 18 Mar 2022 21:45:16 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id D94AE8D0001; Fri, 18 Mar 2022 21:45:16 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (relay.hostedemail.com [64.99.140.26]) by kanga.kvack.org (Postfix) with ESMTP id C9F766B0071 for ; Fri, 18 Mar 2022 21:45:16 -0400 (EDT) Received: from smtpin11.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay09.hostedemail.com (Postfix) with ESMTP id 8234524E19 for ; Sat, 19 Mar 2022 01:45:16 +0000 (UTC) X-FDA: 79259443032.11.0D0E977 Received: from mail-qv1-f41.google.com (mail-qv1-f41.google.com [209.85.219.41]) by imf12.hostedemail.com (Postfix) with ESMTP id 0A9A540032 for ; Sat, 19 Mar 2022 01:45:15 +0000 (UTC) Received: by mail-qv1-f41.google.com with SMTP id k7so2222029qvc.4 for ; Fri, 18 Mar 2022 18:45:15 -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=J119OWgtBMzSwLXkRPZXlrNvFDTfHCojM6eVPdYPNXs=; b=d1DLWAinHLkQMU+kzFkuDQzx9Y3eB9v1syOKx20kwTOyrJpXkLkzqT+5KX8rIjznim 9DmZQdMimLB1D+kIxCRUBPGSXH3k2YVtXMnteu04LW/dulWs4zV/mJunH3y3HI1IcVmt I5ox568MKN9r5SmwHdfVJgTt5adZGGSD22KbXtg5ojdYMIf8J3/p6myisGZRcpCdIbj6 aB7GTWOVIhnPMbCCHQqaYM3f0U67mMAc8HuwP7aXBvdQ8KMIwOBiUjN2kopKM8FN4D75 NyolCVraOxm/YYbN/N3o4T15eAqopG6g/Xf3bgJMBovp6Tu7zhJHu4zafApHlgFNt0NM mURg== 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=J119OWgtBMzSwLXkRPZXlrNvFDTfHCojM6eVPdYPNXs=; b=HKvV7D4uqM1pEwSUmhXPpYsXCwKJbdFtYCvE11ZPsnq+fOfZy/f/WVmWmqQKFlJMfZ POEplGPIrrw/g9nVF845Z6fLxEUPzhkyw74iQDya3r7GFs7vWGzNzOce1DRzI7wOc0Rg a2zQzCbwXfDeRQXu1OQKb8N3S40+eZvcxcpDbP8fOW8+Yru2m4y3rqErhBi3ODsC5P57 Jz/L3OyPjRHxKTwDv8bCmubaRMHIScJMIDIGoRqBlYXnTbwJTexxp5s/bqX0tJY7u0NV GZkpxFtZzOApv2wSnFm+FYZunUkgVqg02fbgwuSIeWHHsBvnlRFTv/FP0SWApSK3EJWM Lsuw== X-Gm-Message-State: AOAM533Aj53TW1beHvbHmkpPML2GmEUZ+Qms/LdfvKl30o9EZUScgbfG n6AbaOQBiToDFPmJQtutpmS2HabQsZmreHtLlJ3ZZA== 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="00000000000032702b05da886a40" X-Rspam-User: X-Rspamd-Server: rspam10 X-Rspamd-Queue-Id: 0A9A540032 X-Stat-Signature: 9x7daajpfur6a8cci5p13ujxn1z4trr6 Authentication-Results: imf12.hostedemail.com; dkim=pass header.d=google.com header.s=20210112 header.b=d1DLWAin; dmarc=pass (policy=reject) header.from=google.com; spf=pass (imf12.hostedemail.com: domain of khazhy@google.com designates 209.85.219.41 as permitted sender) smtp.mailfrom=khazhy@google.com X-HE-Tag: 1647654315-844227 X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: --00000000000032702b05da886a40 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 > > --00000000000032702b05da886a40 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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