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=-0.8 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 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 02F5AC4338F for ; Tue, 10 Aug 2021 01:07:35 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id D57F860F8F for ; Tue, 10 Aug 2021 01:07:34 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S236732AbhHJBHy (ORCPT ); Mon, 9 Aug 2021 21:07:54 -0400 Received: from mout.gmx.net ([212.227.15.19]:56827 "EHLO mout.gmx.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S233980AbhHJBHx (ORCPT ); Mon, 9 Aug 2021 21:07:53 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=gmx.net; s=badeba3b8450; t=1628557623; bh=xtqclcPFtKgKjC09LgHdgHK6lA9GAA8mf/LdDlqDWKc=; h=X-UI-Sender-Class:Subject:From:To:Cc:Date:In-Reply-To:References; b=a5eJYNxsywhXyve/ZWkD4VSrzwcL8vXcGIf5iip64yfAv1GdsN/vp91kklxJiKWAW lNzG1AUXYBa4wMedSYJvkf8dl2T84qGO5EIii4XiC3ZV3gytRzm/SAQiFVB4CdKiig NbEriagXSll109PBJadXFMxCigKHLSDa/pcueF3E= X-UI-Sender-Class: 01bb95c1-4bf8-414a-932a-4f6e2808ef9c Received: from homer.fritz.box ([185.191.219.22]) by mail.gmx.net (mrgmx005 [212.227.17.190]) with ESMTPSA (Nemesis) id 1N9Mta-1n9NBL2ssO-015KAT; Tue, 10 Aug 2021 03:07:03 +0200 Message-ID: <4fa0e9016f746e070150f6db78202d744a3f9c4c.camel@gmx.de> Subject: Re: [PATCH v4 29/35] mm: slub: Move flush_cpu_slab() invocations __free_slab() invocations out of IRQ context From: Mike Galbraith To: Vlastimil Babka , Qian Cai , Andrew Morton , Christoph Lameter , David Rientjes , Pekka Enberg , Joonsoo Kim Cc: linux-mm@kvack.org, linux-kernel@vger.kernel.org, Sebastian Andrzej Siewior , Thomas Gleixner , Mel Gorman , Jesper Dangaard Brouer , Jann Horn Date: Tue, 10 Aug 2021 03:07:01 +0200 In-Reply-To: <7d9ac614-f18e-de5d-2d47-f92e618d76fc@suse.cz> References: <20210805152000.12817-1-vbabka@suse.cz> <20210805152000.12817-30-vbabka@suse.cz> <0b36128c-3e12-77df-85fe-a153a714569b@quicinc.com> <6e3bb54fdf7208f3f86a5d31e1ef2a576d8e7e37.camel@gmx.de> <7d9ac614-f18e-de5d-2d47-f92e618d76fc@suse.cz> Content-Type: text/plain; charset="UTF-8" User-Agent: Evolution 3.40.3 MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable X-Provags-ID: V03:K1:Niqhnc4JbukI/xu31QlaECKWCPWeGcI1Q31mG5BLCHlc1J2SvEi MRlQUBLMefQTttiMKWz9TGcknwEhTKZeh0KPT3dNMVkSMHXRFNr1uM9Is4z/l31FZeBWO/X kR+K6AaP3IVe25umevTV2DN4mrVoI/nQ1AkUP90i+CsCgKVWbmrHHHtFPObabGvFRT+DxI5 4sB1rg4Xr+P5REMpLnTuA== X-UI-Out-Filterresults: notjunk:1;V03:K0:fEI/fLaXyfc=:UzzMFqSfS1juNk+Pl9Te0r mMlX1LT/0RuAAd7yONKHIuYrvBereSaTJYIzy/VDYlst/7ZHH3ZsmkNQ2ymjuxC+95TNN8dIi jRyOgQAy33T6HPvO3Wn8FT4C3F8hKQzbWJz4EoKW7/Fj0Nm10+VvQUew1cBoMN1N6hmqRSYSO 0/dKxzGd1tZ/JTgdVKvJ+xTls4Pvjw45j00iMHMXvGrNiOYwKcWcFofMmwX5uSUfqEVshR7Aq HK3W7UjC0AmQzPtOXdGkmfB5ypo/WwMWB1qrwJq+t2aQEznv3UWAqQExrwei8iP0jQxOrP/iv WyssiusZYTO+h9dqFLZ9VXoFlVSN2Wc43nTZ4vdkf037gAy6keEc1W+AkXqvqdCWuv27HOr2v 8dO4yEQgfocJe9wMcUUFC8OQHF6YlDZ1065feJyaSYZX0V1p0uqYvYRpzNpyegI6pvizqfhCs cKdj2LXAft40haYpD5mMWI+20enLhuxP35hxmFFpHmIU01sVF2C/Y1j2iHMrHDLGdOIDUR12B sjuFaJoXRMZG7YOBIE37T5Lq6X3rxXRNNtOROYOEFDZTkedQGrl6JzqwZLbaSkrrjMyNZ/pFT FC5Euxu3K6pi9dihO6fA9xkMRZMolebeuQzA+6jd9UpEEwfgg9iOr2H681TIpQjmm5zDXTcTN usICnN42L/oU/rqAshiaRMNLVF+x7uf1Tnh/F9R4lGZoYBYV9JygZILoziRloPmTF/nGEYcPn nYJ7KxGhAUKsjdAbiWQV+CGm53f06OV3bq0FqqOvXcx7C7dhT/MZDDSns1f50is+oVw/5GPmE 4Isxkvj6OcEGA9mjEE53aXDtpwnKZ+QZHo9VPXGjPNNLpRIUlsnS99VvFyi8s+hGbfPq9KmKU xekjOnqSYsTZIehMJrh9ptdFvC6u1BpJBOEeOSJ2io/gFiP9tXcsBFnylHeJB4uN2WRV+ZqqS ZtT1blPWLMOaYNIzClt7N0dS7xoQG99CVbiUR7oR1h5yN84oo5GEvP23CQ2xfz4py7uaC4wN4 C5KCxM/oX7gl3MW0Nkjk5RluWlvZSvoOReUfrQFeAvEusZ3zRgyeFTMkzsYqMEPijymeSSQhH 0JyO54GpAhtog7xClOonsWqECk6y3lL7R0R Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Mon, 2021-08-09 at 22:08 +0200, Vlastimil Babka wrote: > On 8/9/2021 8:44 PM, Mike Galbraith wrote: > > > > > > slab_mutex -> flush_lock > > > > Bugger.=C2=A0 That chain ending with cpu_hotplug_lock makes slub_cpu_d= ead() > > taking slab_mutex a non-starter for cpu hotplug as well.=C2=A0 It's > > established early by kernel_init_freeable()..kmem_cache_destroy() as > > well as by slab_mem_going_offline_callback(). > > I suck at reading the lockdep splats, so I don't see yet how the "existi= ng > reverse order" occurs - I do understand the order in the "lsbug". > What I also wonder is why didn't this occur also in the older RT trees w= ith this > patch. Apparently (oops) nobody got around to hotplug+lockdep testing, RT or otherwise. I know I didn't, goldfish like attention span being used up by explosion testing ;-) -Mike