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 E40D4C64E7D for ; Sun, 29 Nov 2020 09:24:06 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id A02E220786 for ; Sun, 29 Nov 2020 09:24:06 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=gmx.net header.i=@gmx.net header.b="eRZqg7hL" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726539AbgK2JXu (ORCPT ); Sun, 29 Nov 2020 04:23:50 -0500 Received: from mout.gmx.net ([212.227.15.19]:40403 "EHLO mout.gmx.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725830AbgK2JXt (ORCPT ); Sun, 29 Nov 2020 04:23:49 -0500 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=gmx.net; s=badeba3b8450; t=1606641695; bh=PMGPeOb1/+9oXMNrHGoQTO0jg3TCyx67VHl7NFtKus0=; h=X-UI-Sender-Class:Subject:From:To:Cc:Date:In-Reply-To:References; b=eRZqg7hLaT1s3VIVbvd972ldV11SR3w7pOQ9lwgpHQLQeRFubYLjBEw4HeWYPHBcF XSM5UJ1RVPhgTLerJlYxeZPVczKAkVkXRNb7YBGU0NL4IRfSjokLfZtAKvjAiLxpiM am7lLQJGchxbJQwllcPJoKWyWa12X+kqVCPeUuCg= X-UI-Sender-Class: 01bb95c1-4bf8-414a-932a-4f6e2808ef9c Received: from homer.fritz.box ([185.191.218.83]) by mail.gmx.com (mrgmx004 [212.227.17.190]) with ESMTPSA (Nemesis) id 1M7Jza-1kr13j1k5s-007l3b; Sun, 29 Nov 2020 10:21:35 +0100 Message-ID: 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 10:21:33 +0100 In-Reply-To: <79ee43026efe5aaa560953ea8fe29a826ac4e855.camel@gmx.de> References: <20201128140523.ovmqon5fjetvpby4@spock.localdomain> <20201128140924.iyqr2h52z2olt6zb@spock.localdomain> <20201128142723.zik6d5skvt3uwu5f@spock.localdomain> <15171df044b167351e7f6a688aabd71bade9ae2a.camel@gmx.de> <79ee43026efe5aaa560953ea8fe29a826ac4e855.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:GmjNT2HpE8rDEjh+40luuj9gtoGfFGc/krPqBwIyo9L7eaDBkFF Ics5SkMg1EIhV5O7dlW/B98VQ7By2dq/APUs8DZbzN5MF2gylQM0hbg7dNnRYYfKfQSLCFW NYtynQp+b4rcBHP1TVlcMQjgwCpekr3TY0sT20hfAwW9XtJkXjRildmYHuxQ3ZRJ7lfa0KX B/SUN/Udfk1HqGpUn7fnw== X-UI-Out-Filterresults: notjunk:1;V03:K0:BWqesIVaxb0=:2frNT0KDmeX30q+FDpL1FF 7chXWWXp180O05kHQ68cuDh1XuLSQXk8+zYg3DA7N0iMXuoGiBuCU7MMx6CH6trfdEE5tBfkn mf45fVgV8EnPV3IXRNStiCggi1s11BBeCs7QJPJMY/pA0dH7avNd1iTROXkjxW1NP0fdq7mJg EbIFEuiNChvdY0ZX/DIpUvrZHK7YK6gJNndCayM1Uy/drmNJ377+5ISQ0NpFQImvkRqlZmNqS G0cQnMfRGP8Yaxx5ZZa0o/UBIRB0xuz3A3BKnueXqSASUy1zmAu8v9Sgwynv11OZ95YaKwb8o nXZJJWM4YU3rU4EqEmMVrjxVz3Xd2TYwcKZn3UBsUEZbJAQe787svrpPEK0dgRJBGD8ghfgwb imfEhScejPGA57SKELh28Du3svhVdIy6zb4gugaUYhHaqoN3nKD3f1exLuwnyeYh1Eayp0k1n SNMgcYqM+gyGX2vagk3Dcns8Mc0juZiZV2tqaKZJhYMEQt+8e8Bp76PwgPj4j86A9S8ciJcBd /QBirQizcrI0XLrUvZq58ROOAxNmeewJQ8uI6jHoDLE4N3KGbqJOoGGKAEDCwvmaGkD2IY3eX NbkzMzicT5V0zsqGMdWV3xDirlIKyuffzhBGCAuGI0Kub3tIFmt9tF6s7/lwHnAofbBTmxaKq RDTb9AOEedgcz+9z4c3EEr40RIdwApQFwKH7+Z4/Wj9QY1rZ8oTJuRk78a1DVyyafKcFjCmLG PHFEO/hZFnCdjPF+HAt2rIZtO9nkCsc8LUpF38hfF5DeFj892Ke31eXlBOqv1P7jZsiImPV+5 Td/5HBzvzC4yqm2Ej9fkvplJfkdsrDJWSJKWwSL2yQ4KAC/jmTz6nK/5rYrJvTjnnJsoyMTjA X2jqkPefddy1J+kdwR4g== Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Sun, 2020-11-29 at 08:48 +0100, Mike Galbraith wrote: > 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 :) Or not, your local_lock+this_cpu_ptr version exploded too. Perhaps there's a bit of non-rt related racy racy going on in zswap thingy that makes swap an even less wonderful idea for RT than usual. crash.rt> bt -s PID: 32399 TASK: ffff8e4528cd8000 CPU: 4 COMMAND: "cc1" #0 [ffff9f0f1228f488] machine_kexec+366 at ffffffff8c05f87e #1 [ffff9f0f1228f4d0] __crash_kexec+210 at ffffffff8c14c052 #2 [ffff9f0f1228f590] crash_kexec+48 at ffffffff8c14d240 #3 [ffff9f0f1228f5a0] oops_end+202 at ffffffff8c02680a #4 [ffff9f0f1228f5c0] exc_general_protection+403 at ffffffff8c8be413 #5 [ffff9f0f1228f650] asm_exc_general_protection+30 at ffffffff8ca00a0e #6 [ffff9f0f1228f6d8] __z3fold_alloc+118 at ffffffff8c2b4ea6 #7 [ffff9f0f1228f760] z3fold_zpool_malloc+115 at ffffffff8c2b56c3 #8 [ffff9f0f1228f7c8] zswap_frontswap_store+789 at ffffffff8c27d335 #9 [ffff9f0f1228f828] __frontswap_store+110 at ffffffff8c27bafe #10 [ffff9f0f1228f858] swap_writepage+55 at ffffffff8c273b17 #11 [ffff9f0f1228f870] shmem_writepage+612 at ffffffff8c232964 #12 [ffff9f0f1228f8a8] pageout+210 at ffffffff8c225f12 #13 [ffff9f0f1228f928] shrink_page_list+2428 at ffffffff8c22744c #14 [ffff9f0f1228f9c0] shrink_inactive_list+534 at ffffffff8c229746 #15 [ffff9f0f1228fa68] shrink_lruvec+927 at ffffffff8c22a35f #16 [ffff9f0f1228fb78] shrink_node+567 at ffffffff8c22a7d7 #17 [ffff9f0f1228fbf8] do_try_to_free_pages+185 at ffffffff8c22ad39 #18 [ffff9f0f1228fc40] try_to_free_pages+201 at ffffffff8c22c239 #19 [ffff9f0f1228fcd0] __alloc_pages_slowpath.constprop.111+1056 at ffffff= ff8c26eb70 #20 [ffff9f0f1228fda8] __alloc_pages_nodemask+786 at ffffffff8c26f7e2 #21 [ffff9f0f1228fe00] alloc_pages_vma+309 at ffffffff8c288f15 #22 [ffff9f0f1228fe40] handle_mm_fault+1687 at ffffffff8c24ee97 #23 [ffff9f0f1228fef8] exc_page_fault+821 at ffffffff8c8c1be5 #24 [ffff9f0f1228ff50] asm_exc_page_fault+30 at ffffffff8ca00ace RIP: 00000000010fea3b RSP: 00007ffc88ad5a50 RFLAGS: 00010206 RAX: 00007f4a548d1638 RBX: 00007f4a5c0c5000 RCX: 0000000000000000 RDX: 0000000000020000 RSI: 000000000000000f RDI: 0000000000018001 RBP: 00007f4a5547a000 R8: 0000000000018000 R9: 0000000000240000 R10: 00007f4a5523a000 R11: 0000000000098628 R12: 00007f4a548d1638 R13: 00007f4a54ab1478 R14: 000000005002ac29 R15: 0000000000000000 ORIG_RAX: ffffffffffffffff CS: 0033 SS: 002b crash.rt> 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 2E7E8C3E8C5 for ; 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Sun, 29 Nov 2020 10:21:35 +0100 Message-ID: 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 10:21:33 +0100 In-Reply-To: <79ee43026efe5aaa560953ea8fe29a826ac4e855.camel@gmx.de> References: <20201128140523.ovmqon5fjetvpby4@spock.localdomain> <20201128140924.iyqr2h52z2olt6zb@spock.localdomain> <20201128142723.zik6d5skvt3uwu5f@spock.localdomain> <15171df044b167351e7f6a688aabd71bade9ae2a.camel@gmx.de> <79ee43026efe5aaa560953ea8fe29a826ac4e855.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:GmjNT2HpE8rDEjh+40luuj9gtoGfFGc/krPqBwIyo9L7eaDBkFF Ics5SkMg1EIhV5O7dlW/B98VQ7By2dq/APUs8DZbzN5MF2gylQM0hbg7dNnRYYfKfQSLCFW NYtynQp+b4rcBHP1TVlcMQjgwCpekr3TY0sT20hfAwW9XtJkXjRildmYHuxQ3ZRJ7lfa0KX B/SUN/Udfk1HqGpUn7fnw== X-UI-Out-Filterresults: notjunk:1;V03:K0:BWqesIVaxb0=:2frNT0KDmeX30q+FDpL1FF 7chXWWXp180O05kHQ68cuDh1XuLSQXk8+zYg3DA7N0iMXuoGiBuCU7MMx6CH6trfdEE5tBfkn mf45fVgV8EnPV3IXRNStiCggi1s11BBeCs7QJPJMY/pA0dH7avNd1iTROXkjxW1NP0fdq7mJg EbIFEuiNChvdY0ZX/DIpUvrZHK7YK6gJNndCayM1Uy/drmNJ377+5ISQ0NpFQImvkRqlZmNqS G0cQnMfRGP8Yaxx5ZZa0o/UBIRB0xuz3A3BKnueXqSASUy1zmAu8v9Sgwynv11OZ95YaKwb8o nXZJJWM4YU3rU4EqEmMVrjxVz3Xd2TYwcKZn3UBsUEZbJAQe787svrpPEK0dgRJBGD8ghfgwb imfEhScejPGA57SKELh28Du3svhVdIy6zb4gugaUYhHaqoN3nKD3f1exLuwnyeYh1Eayp0k1n SNMgcYqM+gyGX2vagk3Dcns8Mc0juZiZV2tqaKZJhYMEQt+8e8Bp76PwgPj4j86A9S8ciJcBd /QBirQizcrI0XLrUvZq58ROOAxNmeewJQ8uI6jHoDLE4N3KGbqJOoGGKAEDCwvmaGkD2IY3eX NbkzMzicT5V0zsqGMdWV3xDirlIKyuffzhBGCAuGI0Kub3tIFmt9tF6s7/lwHnAofbBTmxaKq RDTb9AOEedgcz+9z4c3EEr40RIdwApQFwKH7+Z4/Wj9QY1rZ8oTJuRk78a1DVyyafKcFjCmLG PHFEO/hZFnCdjPF+HAt2rIZtO9nkCsc8LUpF38hfF5DeFj892Ke31eXlBOqv1P7jZsiImPV+5 Td/5HBzvzC4yqm2Ej9fkvplJfkdsrDJWSJKWwSL2yQ4KAC/jmTz6nK/5rYrJvTjnnJsoyMTjA X2jqkPefddy1J+kdwR4g== 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 Sun, 2020-11-29 at 08:48 +0100, Mike Galbraith wrote: > 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 :) Or not, your local_lock+this_cpu_ptr version exploded too. Perhaps there's a bit of non-rt related racy racy going on in zswap thingy that makes swap an even less wonderful idea for RT than usual. crash.rt> bt -s PID: 32399 TASK: ffff8e4528cd8000 CPU: 4 COMMAND: "cc1" #0 [ffff9f0f1228f488] machine_kexec+366 at ffffffff8c05f87e #1 [ffff9f0f1228f4d0] __crash_kexec+210 at ffffffff8c14c052 #2 [ffff9f0f1228f590] crash_kexec+48 at ffffffff8c14d240 #3 [ffff9f0f1228f5a0] oops_end+202 at ffffffff8c02680a #4 [ffff9f0f1228f5c0] exc_general_protection+403 at ffffffff8c8be413 #5 [ffff9f0f1228f650] asm_exc_general_protection+30 at ffffffff8ca00a0e #6 [ffff9f0f1228f6d8] __z3fold_alloc+118 at ffffffff8c2b4ea6 #7 [ffff9f0f1228f760] z3fold_zpool_malloc+115 at ffffffff8c2b56c3 #8 [ffff9f0f1228f7c8] zswap_frontswap_store+789 at ffffffff8c27d335 #9 [ffff9f0f1228f828] __frontswap_store+110 at ffffffff8c27bafe #10 [ffff9f0f1228f858] swap_writepage+55 at ffffffff8c273b17 #11 [ffff9f0f1228f870] shmem_writepage+612 at ffffffff8c232964 #12 [ffff9f0f1228f8a8] pageout+210 at ffffffff8c225f12 #13 [ffff9f0f1228f928] shrink_page_list+2428 at ffffffff8c22744c #14 [ffff9f0f1228f9c0] shrink_inactive_list+534 at ffffffff8c229746 #15 [ffff9f0f1228fa68] shrink_lruvec+927 at ffffffff8c22a35f #16 [ffff9f0f1228fb78] shrink_node+567 at ffffffff8c22a7d7 #17 [ffff9f0f1228fbf8] do_try_to_free_pages+185 at ffffffff8c22ad39 #18 [ffff9f0f1228fc40] try_to_free_pages+201 at ffffffff8c22c239 #19 [ffff9f0f1228fcd0] __alloc_pages_slowpath.constprop.111+1056 at ffffff= ff8c26eb70 #20 [ffff9f0f1228fda8] __alloc_pages_nodemask+786 at ffffffff8c26f7e2 #21 [ffff9f0f1228fe00] alloc_pages_vma+309 at ffffffff8c288f15 #22 [ffff9f0f1228fe40] handle_mm_fault+1687 at ffffffff8c24ee97 #23 [ffff9f0f1228fef8] exc_page_fault+821 at ffffffff8c8c1be5 #24 [ffff9f0f1228ff50] asm_exc_page_fault+30 at ffffffff8ca00ace RIP: 00000000010fea3b RSP: 00007ffc88ad5a50 RFLAGS: 00010206 RAX: 00007f4a548d1638 RBX: 00007f4a5c0c5000 RCX: 0000000000000000 RDX: 0000000000020000 RSI: 000000000000000f RDI: 0000000000018001 RBP: 00007f4a5547a000 R8: 0000000000018000 R9: 0000000000240000 R10: 00007f4a5523a000 R11: 0000000000098628 R12: 00007f4a548d1638 R13: 00007f4a54ab1478 R14: 000000005002ac29 R15: 0000000000000000 ORIG_RAX: ffffffffffffffff CS: 0033 SS: 002b crash.rt>