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 3C371ECAAA1 for ; Sat, 10 Sep 2022 03:34:33 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id 19D1E8D0002; Fri, 9 Sep 2022 23:34:33 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 14D406B0072; Fri, 9 Sep 2022 23:34:33 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 0143E8D0002; Fri, 9 Sep 2022 23:34:32 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0012.hostedemail.com [216.40.44.12]) by kanga.kvack.org (Postfix) with ESMTP id E5C676B0071 for ; Fri, 9 Sep 2022 23:34:32 -0400 (EDT) Received: from smtpin01.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay05.hostedemail.com (Postfix) with ESMTP id A94AD40A8F for ; Sat, 10 Sep 2022 03:34:32 +0000 (UTC) X-FDA: 79894758384.01.CEC3E3C Received: from mail-pj1-f50.google.com (mail-pj1-f50.google.com [209.85.216.50]) by imf07.hostedemail.com (Postfix) with ESMTP id 583F540078 for ; Sat, 10 Sep 2022 03:34:32 +0000 (UTC) Received: by mail-pj1-f50.google.com with SMTP id q15-20020a17090a304f00b002002ac83485so3346277pjl.0 for ; Fri, 09 Sep 2022 20:34:32 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20210112; h=in-reply-to:content-disposition:mime-version:references:message-id :subject:cc:to:from:date:from:to:cc:subject:date; bh=p0QNUFOLOI50ZkSvLH1895huJeLBDMNKF4NIGcRoK6g=; b=RnEIyM4+ZpJe9pV9DBbrlTLVFA5AJFJ1C7jixHi9UfJftJpb9X+eYRD9Zyle1XNn0l pCJ04dF/MPbfjGVo1cvjTsFWJKupq1AIPFO4UyilPul6IjFfVtuvh+KeOqJM+qJLMq9S UFcHngPzNk9G3yFqNe5WxoZGSbb3WI6Vp45zYHSEZi4dKulhIJ/JOscybPKjiv5CxB8T CoofL/71z0WyGgisn9jZbDmeqKh1aJHSjgo2BMrqL18lnuzbiIXA0UcxWBMmSIcMJk5/ eZXM+QJNIX0UwynsFO+AMtUgYBDaKBwJ+8jYEASON2RL0LFod11HDP7CfODqKDAXJA/c 5KJg== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=in-reply-to:content-disposition:mime-version:references:message-id :subject:cc:to:from:date:x-gm-message-state:from:to:cc:subject:date; bh=p0QNUFOLOI50ZkSvLH1895huJeLBDMNKF4NIGcRoK6g=; b=Ot5dGQN9QYao35o7yMaJ4+W69Lef6wetOlI8MlY6lfZU9DP2olh1MgfUv7hW0zEkqa Cl4VgAX6TR/fzsCR7xtBU+GZvl1cByG9zx1gdcFCTt9Ypt7vXMDvNsNAKM/sXLXASm1x wOe46eJfCIECvVOa2F9Q99+62mnFz0DqE+B4lK8Op0F+CrTNqrg/YDulXbIgOqeIgcn9 re1/CCUCNegXEsmHiYfChkYTukQD2kvTI72JcquwNZxL041CHru4IrgYabN4ntbHK2QQ HbCY0cdFNuEodJbe5o6TV+ibAxA0W3RWneY8gYW+5FMQcywpNawnD7sia/Q8EgbcsQ9c LD6A== X-Gm-Message-State: ACgBeo1wMn5VFr1u+EdpTLRvm48Fo4ZlzJs2XrDmF3sVrfif0fMA8AVy JNnjxZVe1VZWPpY5YQlUjqM= X-Google-Smtp-Source: AA6agR7ZijQOqgeXzkJsboboOYWWFC2VPnopCsCU0ps1u/dw8O+m6PfNHbPkRxQMd9ajhduQa8Iv5A== X-Received: by 2002:a17:902:da81:b0:178:1d8b:6cb4 with SMTP id j1-20020a170902da8100b001781d8b6cb4mr791687plx.43.1662780871253; Fri, 09 Sep 2022 20:34:31 -0700 (PDT) Received: from hyeyoo ([114.29.91.56]) by smtp.gmail.com with ESMTPSA id p17-20020aa79e91000000b0053639773ad8sm516822pfq.119.2022.09.09.20.34.27 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Fri, 09 Sep 2022 20:34:30 -0700 (PDT) Date: Sat, 10 Sep 2022 12:34:25 +0900 From: Hyeonggon Yoo <42.hyeyoo@gmail.com> To: Vlastimil Babka Cc: kernel test robot , lkp@lists.01.org, lkp@intel.com, Joel Fernandes , linux-mm@kvack.org, rcu@vger.kernel.org, paulmck@kernel.org, Alexey Dobriyan , Matthew Wilcox Subject: Re: [mm/sl[au]b] 3c4cafa313: canonical_address#:#[##] Message-ID: References: <20220906074548.GA72649@inn2.lkp.intel.com> <208c1757-5edd-fd42-67d4-1940cc43b50f@intel.com> <416149c0-1e18-0e00-d116-dd3738957556@suse.cz> <3d178109-5981-f4ee-8fe5-4f1d0c557ed2@suse.cz> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: ARC-Seal: i=1; s=arc-20220608; d=hostedemail.com; t=1662780872; a=rsa-sha256; cv=none; b=GsAWVBDndmFhEln0D6BkmJmGxM1pbXmTd5t0vrWOxhkgQRGYFvflkda3vPO8rvEnrzDkaN o71sP7dfa/Jp5YU360YdSJ2uVAIsC+rieMvA2jzzX7OtwT8e0A4QV7kMXENzQW//xf7S4L T5yaZDdJgk2oCBGLoCmQyxqd7T21Zr4= ARC-Authentication-Results: i=1; imf07.hostedemail.com; dkim=pass header.d=gmail.com header.s=20210112 header.b=RnEIyM4+; spf=pass (imf07.hostedemail.com: domain of 42.hyeyoo@gmail.com designates 209.85.216.50 as permitted sender) smtp.mailfrom=42.hyeyoo@gmail.com; dmarc=pass (policy=none) header.from=gmail.com ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1662780872; h=from:from:sender:reply-to:subject:subject:date:date: message-id:message-id:to:to:cc:cc:mime-version:mime-version: content-type:content-type:content-transfer-encoding: in-reply-to:in-reply-to:references:references:dkim-signature; bh=p0QNUFOLOI50ZkSvLH1895huJeLBDMNKF4NIGcRoK6g=; b=ooYJ+3FgqPhC9nEzrQSIfPwf/W+dcPQFxbZVnWnTWu940Lmc9lwZjbj1FoA/6mX0Bqs+7c qAD8cgFLXcQHvg/D0DRiTyMYDseeZ71wrJrgtH9+4Vn46M+5udeoxEh93GCod8ZrClCWkw mXMFyLc3ZK1FZVsNhMh84ZD1jRlr70M= Authentication-Results: imf07.hostedemail.com; dkim=pass header.d=gmail.com header.s=20210112 header.b=RnEIyM4+; spf=pass (imf07.hostedemail.com: domain of 42.hyeyoo@gmail.com designates 209.85.216.50 as permitted sender) smtp.mailfrom=42.hyeyoo@gmail.com; dmarc=pass (policy=none) header.from=gmail.com X-Rspam-User: X-Stat-Signature: ijp9yc8cmn3mb47o645kxfrdjyue5dyd X-Rspamd-Queue-Id: 583F540078 X-Rspamd-Server: rspam08 X-HE-Tag: 1662780872-688440 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 Fri, Sep 09, 2022 at 11:16:51PM +0200, Vlastimil Babka wrote: > On 9/9/22 16:32, Hyeonggon Yoo wrote: > > On Fri, Sep 09, 2022 at 03:44:19PM +0200, Vlastimil Babka wrote: > >> On 9/9/22 13:05, Hyeonggon Yoo wrote: > >> >> ----8<---- > >> >> From d6f9fbb33b908eb8162cc1f6ce7f7c970d0f285f Mon Sep 17 00:00:00 2001 > >> >> From: Vlastimil Babka > >> >> Date: Fri, 9 Sep 2022 12:03:10 +0200 > >> >> Subject: [PATCH 2/3] mm/migrate: make isolate_movable_page() skip slab pages > >> >> > >> >> In the next commit we want to rearrange struct slab fields to allow a > >> >> larger rcu_head. Afterwards, the page->mapping field will overlap > >> >> with SLUB's "struct list_head slab_list", where the value of prev > >> >> pointer can become LIST_POISON2, which is 0x122 + POISON_POINTER_DELTA. > >> >> Unfortunately the bit 1 being set can confuse PageMovable() to be a > >> >> false positive and cause a GPF as reported by lkp [1]. > >> >> > >> >> To fix this, make isolate_movable_page() skip pages with the PageSlab > >> >> flag set. This is a bit tricky as we need to add memory barriers to SLAB > >> >> and SLUB's page allocation and freeing, and their counterparts to > >> >> isolate_movable_page(). > >> > > >> > Hello, I just took a quick grasp, > >> > Is this approach okay with folio_test_anon()? > >> > >> Not if used on a completely random page as compaction scanners can, but > >> relies on those being first tested for PageLRU or coming from a page table > >> lookup etc. > >> Not ideal huh. Well I could improve also by switching 'next' and 'slabs' > >> field and relying on the fact that the value of LIST_POISON2 doesn't include > >> 0x1, just 0x2. > > > > What about swapping counters and freelist? > > freelist should be always aligned. > > Great suggestion, thanks! > > Had to deal with SLAB too as there was list_head.prev also aliasing > page->mapping. Wanted to use freelist as well, but turns out it's not > aligned, so had to use s_mem instead. > > The patch that isolate_movable_page() skip slab pages was thus dropped. The > result is in slab.git below and if nothing blows up, will restore it to -next > > https://git.kernel.org/pub/scm/linux/kernel/git/vbabka/slab.git/log/?h=for-6.1/fit_rcu_head Looks fine to me, Thanks! > > > > > -- Thanks, Hyeonggon