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=-0.7 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,FREEMAIL_FORGED_FROMDOMAIN,FREEMAIL_FROM, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS, URIBL_BLOCKED autolearn=no 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 D3E19C4361B for ; Sat, 19 Dec 2020 10:29:08 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 9FC7423BDE for ; Sat, 19 Dec 2020 10:29:08 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726483AbgLSK2w (ORCPT ); Sat, 19 Dec 2020 05:28:52 -0500 Received: from mout.gmx.net ([212.227.17.20]:46007 "EHLO mout.gmx.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726439AbgLSK2w (ORCPT ); Sat, 19 Dec 2020 05:28:52 -0500 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=gmx.net; s=badeba3b8450; t=1608373622; bh=Uup18DtdpxUG00UIwFBlOlG16e821LeWTjq7JYouQ0U=; h=X-UI-Sender-Class:Subject:From:To:Cc:Date:In-Reply-To:References; b=XGI0ANM6WR6I821FwRSA+h3NYTbXQHEax6Q9cDbjN4T3N4UiWbw2wDb6f9gEyUE7e VjEA9EIsYGluSifzqTYVyiZvirxO0DEe8mFFGP78ITS55uf8v52EDSdsBWx+/5+mXC wDJhR4RpMiv5KqwqImAHqLMlv7tgVirFdLjdDMqQ= X-UI-Sender-Class: 01bb95c1-4bf8-414a-932a-4f6e2808ef9c Received: from homer.fritz.box ([185.221.150.14]) by mail.gmx.com (mrgmx105 [212.227.17.168]) with ESMTPSA (Nemesis) id 1MYNNy-1kds6m0q6k-00VQED; Sat, 19 Dec 2020 11:27:02 +0100 Message-ID: <6946d6e798866276f0d635f219cdd4ad05156351.camel@gmx.de> Subject: Re: [patch] zswap: fix zswap_frontswap_load() vs zsmalloc::map/unmap() might_sleep() splat From: Mike Galbraith To: Vitaly Wool Cc: LKML , linux-mm , Barry Song , Sebastian Andrzej Siewior Date: Sat, 19 Dec 2020 11:27:00 +0100 In-Reply-To: References: Content-Type: text/plain; charset="ISO-8859-15" User-Agent: Evolution 3.34.4 MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable X-Provags-ID: V03:K1:j0AiefRXZcSVfA5RaK4B6RVZ3hsyTiR/pq1/qisinIm89qxRA6f ozeYbohZaEne2CMg3bzBMta6UL08iHoLaro8yQQ9DzHxJeekckFHJ5yNN6bIOVuVjCKv093 x1fAPRB0mX8IrEbntvft5gwHK40h2dHpwWndU/bdOhXOQfeUNEDShFMUDidEJmHFrfQBdOS 852nTxpStHw479ISvvsyg== X-UI-Out-Filterresults: notjunk:1;V03:K0:3Bzr+CNfzpI=:BUvt7sW0s8jkhE2IABLZCm lR3jrnlA2VCjw58KKPJNrGkgzfGYCUeSY+K0/nU7+MpFlm/Fwrqw2ZPMVjbpHxQXZzPeF1CyB hs6VYBJK3BmPubt+iE0CYb+2Z/rhGc9vdBeWZU/CFpTHwzV437FkkOec4M/w6hQdO5w3M63G5 alJGbso0vAumRIbZuva/8PSPwNJWgDnJGkU4duV/FCkhM/CQOmLgEFKg7EfwXO73SkIwduU+l eu7S6iSNEehd67N+meHSGE/LmfKAkhBYfXDwDX8OI/5Ot+IbXrpK6WWnUn8u/6ARPSCIA7f87 TJIoSCY28Ucan9Pmuua9WG+lr7+vaMlNlq6whhuQfi3OK08mNfAyoTgsyHyf7FTsx+MopZNw+ 9LESQzcB1K3rdrei5ygd2yLXVpYgjwhDmmtrMITQtH/nEcD0jb+wCkZAf6C2qwMCH+Dp43utx EMi4VQQFNy9TKsPeQhAJJiwscTsZ/htwqteDZS556gnrkvsOkL3CbQoGidnM6fDEpX/rv+KKg wmu4LMU4Licb1gmig0PSYSVs0P57kDH9ySfeiZ0tfNAQH49+N19PA7kTvDLAEviVxb0GJ7d87 N2o9lCMgEnUlTtXhFhPlAmssOpYKWA2sIC8HAVE7DVNL0tv8U1WSvqbed3DcUrojr+ThztRpe vahmyKzceEMKG4CZ6sR4BTYRewQI5yQVOWrp3BtkGjaJSweexR+Q1iqRZ66wNMMtGbnMYolrK EtvBlxcJh4bHre6gYWXxx6fEHjlQQBEPoL5YXS6btfjaGd2StkL2TjlSJIUirmuVWk29cxi7H +fT+YYulT4CQSZ+sFkbB7ACT4UlH9oBPPSNNL+dR5ZRA2GLxz3FZ559/6yO9HLPY26oGWPgbU w5zVodvWWoLJoCQbsdvQ== Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Sat, 2020-12-19 at 11:20 +0100, Vitaly Wool wrote: > Hi Mike, > > On Sat, Dec 19, 2020 at 11:12 AM Mike Galbraith wrote: > > > > (mailer partially munged formatting? resend) > > > > mm/zswap: fix zswap_frontswap_load() vs zsmalloc::map/unmap() might_sl= eep() splat > > > > zsmalloc map/unmap methods use preemption disabling bit spinlocks. Ta= ke the > > mutex outside of pool map/unmap methods in zswap_frontswap_load() as i= s done > > in zswap_frontswap_store(). > > oh wait... So is zsmalloc taking a spin lock in its map callback and > releasing it only in unmap? In this case, I would rather keep zswap as > is, mark zsmalloc as RT unsafe and have zsmalloc maintainer fix it. The kernel that generated that splat was NOT an RT kernel, it was plain master.today with a PREEMPT config. -Mike 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=-0.7 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,FREEMAIL_FORGED_FROMDOMAIN,FREEMAIL_FROM, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS, URIBL_BLOCKED autolearn=no 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 227E7C4361B for ; Sat, 19 Dec 2020 10:27:13 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id 9FBF723BEE for ; Sat, 19 Dec 2020 10:27:12 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 9FBF723BEE Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=gmx.de Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=owner-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix) id F0C706B0068; Sat, 19 Dec 2020 05:27:11 -0500 (EST) Received: by kanga.kvack.org (Postfix, from userid 40) id EBCBD6B006C; Sat, 19 Dec 2020 05:27:11 -0500 (EST) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id DD4786B006E; Sat, 19 Dec 2020 05:27:11 -0500 (EST) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0062.hostedemail.com [216.40.44.62]) by kanga.kvack.org (Postfix) with ESMTP id C86ED6B0068 for ; Sat, 19 Dec 2020 05:27:11 -0500 (EST) Received: from smtpin19.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay02.hostedemail.com (Postfix) with ESMTP id 91EF21DF8 for ; Sat, 19 Dec 2020 10:27:11 +0000 (UTC) X-FDA: 77609654262.19.flame16_5c0e9af27445 Received: from filter.hostedemail.com (10.5.16.251.rfc1918.com [10.5.16.251]) by smtpin19.hostedemail.com (Postfix) with ESMTP id 790841ACEA2 for ; Sat, 19 Dec 2020 10:27:11 +0000 (UTC) X-HE-Tag: flame16_5c0e9af27445 X-Filterd-Recvd-Size: 3834 Received: from mout.gmx.net (mout.gmx.net [212.227.17.20]) by imf38.hostedemail.com (Postfix) with ESMTP for ; Sat, 19 Dec 2020 10:27:10 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=gmx.net; s=badeba3b8450; t=1608373622; bh=Uup18DtdpxUG00UIwFBlOlG16e821LeWTjq7JYouQ0U=; h=X-UI-Sender-Class:Subject:From:To:Cc:Date:In-Reply-To:References; b=XGI0ANM6WR6I821FwRSA+h3NYTbXQHEax6Q9cDbjN4T3N4UiWbw2wDb6f9gEyUE7e VjEA9EIsYGluSifzqTYVyiZvirxO0DEe8mFFGP78ITS55uf8v52EDSdsBWx+/5+mXC wDJhR4RpMiv5KqwqImAHqLMlv7tgVirFdLjdDMqQ= X-UI-Sender-Class: 01bb95c1-4bf8-414a-932a-4f6e2808ef9c Received: from homer.fritz.box ([185.221.150.14]) by mail.gmx.com (mrgmx105 [212.227.17.168]) with ESMTPSA (Nemesis) id 1MYNNy-1kds6m0q6k-00VQED; Sat, 19 Dec 2020 11:27:02 +0100 Message-ID: <6946d6e798866276f0d635f219cdd4ad05156351.camel@gmx.de> Subject: Re: [patch] zswap: fix zswap_frontswap_load() vs zsmalloc::map/unmap() might_sleep() splat From: Mike Galbraith To: Vitaly Wool Cc: LKML , linux-mm , Barry Song , Sebastian Andrzej Siewior Date: Sat, 19 Dec 2020 11:27:00 +0100 In-Reply-To: References: Content-Type: text/plain; charset="ISO-8859-15" User-Agent: Evolution 3.34.4 MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable X-Provags-ID: V03:K1:j0AiefRXZcSVfA5RaK4B6RVZ3hsyTiR/pq1/qisinIm89qxRA6f ozeYbohZaEne2CMg3bzBMta6UL08iHoLaro8yQQ9DzHxJeekckFHJ5yNN6bIOVuVjCKv093 x1fAPRB0mX8IrEbntvft5gwHK40h2dHpwWndU/bdOhXOQfeUNEDShFMUDidEJmHFrfQBdOS 852nTxpStHw479ISvvsyg== X-UI-Out-Filterresults: notjunk:1;V03:K0:3Bzr+CNfzpI=:BUvt7sW0s8jkhE2IABLZCm lR3jrnlA2VCjw58KKPJNrGkgzfGYCUeSY+K0/nU7+MpFlm/Fwrqw2ZPMVjbpHxQXZzPeF1CyB hs6VYBJK3BmPubt+iE0CYb+2Z/rhGc9vdBeWZU/CFpTHwzV437FkkOec4M/w6hQdO5w3M63G5 alJGbso0vAumRIbZuva/8PSPwNJWgDnJGkU4duV/FCkhM/CQOmLgEFKg7EfwXO73SkIwduU+l eu7S6iSNEehd67N+meHSGE/LmfKAkhBYfXDwDX8OI/5Ot+IbXrpK6WWnUn8u/6ARPSCIA7f87 TJIoSCY28Ucan9Pmuua9WG+lr7+vaMlNlq6whhuQfi3OK08mNfAyoTgsyHyf7FTsx+MopZNw+ 9LESQzcB1K3rdrei5ygd2yLXVpYgjwhDmmtrMITQtH/nEcD0jb+wCkZAf6C2qwMCH+Dp43utx EMi4VQQFNy9TKsPeQhAJJiwscTsZ/htwqteDZS556gnrkvsOkL3CbQoGidnM6fDEpX/rv+KKg wmu4LMU4Licb1gmig0PSYSVs0P57kDH9ySfeiZ0tfNAQH49+N19PA7kTvDLAEviVxb0GJ7d87 N2o9lCMgEnUlTtXhFhPlAmssOpYKWA2sIC8HAVE7DVNL0tv8U1WSvqbed3DcUrojr+ThztRpe vahmyKzceEMKG4CZ6sR4BTYRewQI5yQVOWrp3BtkGjaJSweexR+Q1iqRZ66wNMMtGbnMYolrK EtvBlxcJh4bHre6gYWXxx6fEHjlQQBEPoL5YXS6btfjaGd2StkL2TjlSJIUirmuVWk29cxi7H +fT+YYulT4CQSZ+sFkbB7ACT4UlH9oBPPSNNL+dR5ZRA2GLxz3FZ559/6yO9HLPY26oGWPgbU w5zVodvWWoLJoCQbsdvQ== 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: On Sat, 2020-12-19 at 11:20 +0100, Vitaly Wool wrote: > Hi Mike, > > On Sat, Dec 19, 2020 at 11:12 AM Mike Galbraith wrote: > > > > (mailer partially munged formatting? resend) > > > > mm/zswap: fix zswap_frontswap_load() vs zsmalloc::map/unmap() might_sl= eep() splat > > > > zsmalloc map/unmap methods use preemption disabling bit spinlocks. Ta= ke the > > mutex outside of pool map/unmap methods in zswap_frontswap_load() as i= s done > > in zswap_frontswap_store(). > > oh wait... So is zsmalloc taking a spin lock in its map callback and > releasing it only in unmap? In this case, I would rather keep zswap as > is, mark zsmalloc as RT unsafe and have zsmalloc maintainer fix it. The kernel that generated that splat was NOT an RT kernel, it was plain master.today with a PREEMPT config. -Mike