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 E1801C64E7C for ; Sun, 29 Nov 2020 07:51:34 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 8D46E2078D for ; Sun, 29 Nov 2020 07:51:34 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=gmx.net header.i=@gmx.net header.b="ew/PvgT/" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726477AbgK2HvN (ORCPT ); Sun, 29 Nov 2020 02:51:13 -0500 Received: from mout.gmx.net ([212.227.17.20]:55057 "EHLO mout.gmx.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725468AbgK2HvN (ORCPT ); Sun, 29 Nov 2020 02:51:13 -0500 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=gmx.net; s=badeba3b8450; t=1606636136; bh=nNgEG9W3/dgKx7pGvBI1VNzAAdYXJJj4vN/rQUPGggg=; h=X-UI-Sender-Class:Subject:From:To:Cc:Date:In-Reply-To:References; b=ew/PvgT/S8d7o33a2NMGzGkmsX3A+wG2snNirwEUedpXleVKRMb6AYb1Ts7IDDp1y AKzA0KQeWLgdqrmRzmaBQJaU2ARMN5zxjyiqrAXrVCqxglVnmHLO7KXJGpX3aMWe1D Fv8NUKAxRYCHegz4efA0rAymXbD8Gl6pbGQB5CA4= X-UI-Sender-Class: 01bb95c1-4bf8-414a-932a-4f6e2808ef9c Received: from homer.fritz.box ([185.191.218.83]) by mail.gmx.com (mrgmx104 [212.227.17.168]) with ESMTPSA (Nemesis) id 1MKKYx-1kU6DP1cmV-00Lpna; Sun, 29 Nov 2020 08:48:56 +0100 Message-ID: <79ee43026efe5aaa560953ea8fe29a826ac4e855.camel@gmx.de> Subject: Re: scheduling while atomic in z3fold From: Mike Galbraith To: Oleksandr Natalenko , linux-kernel@vger.kernel.org Cc: linux-mm@kvack.org, Andrew Morton , Sebastian Andrzej Siewior , Steven Rostedt , Thomas Gleixner , linux-rt-users@vger.kernel.org Date: Sun, 29 Nov 2020 08:48:55 +0100 In-Reply-To: <15171df044b167351e7f6a688aabd71bade9ae2a.camel@gmx.de> References: <20201128140523.ovmqon5fjetvpby4@spock.localdomain> <20201128140924.iyqr2h52z2olt6zb@spock.localdomain> <20201128142723.zik6d5skvt3uwu5f@spock.localdomain> <15171df044b167351e7f6a688aabd71bade9ae2a.camel@gmx.de> 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:K1:2s2Ig5gRyWZy9b0M8Nd1i3yTCSuJCmVCkdV7N2Z1b+QZR6GlNCQ gYAi3mUoJbjb3TE9YiiZCziwoCmVnPjsGQFWCIbl9BW0D04w8yYvhwNKN/zDEgWdTXtgutW 10uw5I2Xe76rH+HAyGS53pLOhykN2pql+ZF//2+Yi0KDN8voHlBE8szwq/Oxpa/4giljffj J7J3KsvHPuoJbN/JpE2Sg== X-UI-Out-Filterresults: notjunk:1;V03:K0:9bhgqDbcMzo=:p1nEDMgaPH73Vojta/5ixz oyfuwXPYpqOBa89CLx7Ki3+q4Ev3LsOYA3QFsiduk8+rmcjuoVsC/n37MoJqhhLavZcUgdnpm 09Pb/r9LDlEWqacAqgutumMICTFZfYh0v1M4Vg3AUGnxcwOISXFZxicLzmsXWrpBYnzEay+n1 6gmA3QlE3mSpLEHpjKSvRHpzsPAhTUhRcv+Pv73/T6m8SEp2endrIiZUsa9OpacTc5SDRf9zo 95F2H+o53FY2GwOPQmV4w2WzF5AIGVxpvJ+Q4DHHOF2f3oWI1gvzP1jhns6tKHxPFBYbL+Pwv F9AIbnADBJchPxwU0c6o7zW96plrpbztcDIIJYFIqKA7djcbvtmXSWR+Ev8flxvAyFjpvz580 faEcaksNXzz4s1YtN9tM/LKilBudJKy0vmuZfmCHZtdNvi9Szf2CqMBPuwCEkvdYcP70PPhCS S6cQBMgYcojKCc5ZdxwU4kkFXMZACkki6XZhM+ka0Ww7AOCUB+fj1A09itKShsV3G7Rg6IUPY 5wKOy1QX8bBFXdhN/If1aS1fgl/NggWYvoSv/cKhXbBaKBd6dSJZWc17eZZrQhe1RgbO2gFcd 9LZd8jVXMpT8Db76/Swzc7KSTdFrVoTo9LbK4h+7LqfIQKUuL4GY+cCWOKQ7k+W6KfhSOY+e7 LKl3k2CXLNyUVE/aLtbFqfUQrrcmnfNEa0IVyT5108TQDhBqvF8/CQNeEqBiRtGwm7w1Ukd8M LtD5TO/KVdcp12uERJaOpPdSdey7cwAYYumx/1NAtFu5FzSYzNH5BK5szjqOn2A4RwhZFNKOx zlPCr9jTridCrnw59252CFQSrn05sMh+sGnHQO9lsAqbJdtTseFGbanAldjWTY4oh6A1cA3ZH qxLzqMjHnIIOPeUMhLQw== Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Sun, 2020-11-29 at 07:41 +0100, Mike Galbraith wrote: > On Sat, 2020-11-28 at 15:27 +0100, Oleksandr Natalenko wrote: > > > > > > Shouldn't the list manipulation be protected with > > > > local_lock+this_cpu_ptr instead of get_cpu_ptr+spin_lock? > > > > Totally untested: > > Hrm, the thing doesn't seem to care deeply about preemption being > disabled, so adding another lock may be overkill. It looks like you > could get the job done via migrate_disable()+this_cpu_ptr(). There is however an ever so tiny chance that I'm wrong about that :) crash.rt> bt -s PID: 6699 TASK: ffff913c464b5640 CPU: 0 COMMAND: "oom01" #0 [ffffb6b94adff6f0] machine_kexec+366 at ffffffffbd05f87e #1 [ffffb6b94adff738] __crash_kexec+210 at ffffffffbd14c052 #2 [ffffb6b94adff7f8] crash_kexec+48 at ffffffffbd14d240 #3 [ffffb6b94adff808] oops_end+202 at ffffffffbd02680a #4 [ffffb6b94adff828] no_context+333 at ffffffffbd06d7ed #5 [ffffb6b94adff888] exc_page_fault+696 at ffffffffbd8c0b68 #6 [ffffb6b94adff8e0] asm_exc_page_fault+30 at ffffffffbda00ace #7 [ffffb6b94adff968] mark_wakeup_next_waiter+81 at ffffffffbd0ea1e1 #8 [ffffb6b94adff9c8] rt_mutex_futex_unlock+79 at ffffffffbd8cc3cf #9 [ffffb6b94adffa08] z3fold_zpool_free+1319 at ffffffffbd2b6b17 #10 [ffffb6b94adffa68] zswap_free_entry+67 at ffffffffbd27c6f3 #11 [ffffb6b94adffa78] zswap_frontswap_invalidate_page+138 at ffffffffbd27= c7fa #12 [ffffb6b94adffaa0] __frontswap_invalidate_page+72 at ffffffffbd27bee8 #13 [ffffb6b94adffac8] swapcache_free_entries+494 at ffffffffbd276e1e #14 [ffffb6b94adffb10] free_swap_slot+173 at ffffffffbd27b7dd #15 [ffffb6b94adffb30] __swap_entry_free+112 at ffffffffbd2768d0 #16 [ffffb6b94adffb58] free_swap_and_cache+57 at ffffffffbd278939 #17 [ffffb6b94adffb80] unmap_page_range+1485 at ffffffffbd24c52d #18 [ffffb6b94adffc40] __oom_reap_task_mm+178 at ffffffffbd218f02 #19 [ffffb6b94adffd10] exit_mmap+339 at ffffffffbd257da3 #20 [ffffb6b94adffdb0] mmput+78 at ffffffffbd07fe7e #21 [ffffb6b94adffdc0] do_exit+822 at ffffffffbd089bc6 #22 [ffffb6b94adffe28] do_group_exit+71 at ffffffffbd08a547 #23 [ffffb6b94adffe50] get_signal+319 at ffffffffbd0979ff #24 [ffffb6b94adffe98] arch_do_signal+30 at ffffffffbd022cbe #25 [ffffb6b94adfff28] exit_to_user_mode_prepare+293 at ffffffffbd1223e5 #26 [ffffb6b94adfff48] irqentry_exit_to_user_mode+5 at ffffffffbd8c1675 #27 [ffffb6b94adfff50] asm_exc_page_fault+30 at ffffffffbda00ace RIP: 0000000000414300 RSP: 00007f5ddf065ec0 RFLAGS: 00010206 RAX: 0000000000001000 RBX: 00000000c0000000 RCX: 00000000adf28000 RDX: 00007f5d0bf8d000 RSI: 00000000c0000000 RDI: 0000000000000000 RBP: 00007f5c5e065000 R8: ffffffffffffffff R9: 0000000000000000 R10: 0000000000000022 R11: 0000000000000246 R12: 0000000000001000 R13: 0000000000000001 R14: 0000000000000001 R15: 00007ffc953ebcd0 ORIG_RAX: ffffffffffffffff CS: 0033 SS: 002b crash.rt>