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 AC212C433EF for ; Tue, 1 Mar 2022 03:15:36 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id 09EFE8D0002; Mon, 28 Feb 2022 22:15:36 -0500 (EST) Received: by kanga.kvack.org (Postfix, from userid 40) id 04DC88D0001; Mon, 28 Feb 2022 22:15:36 -0500 (EST) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id E7EAD8D0002; Mon, 28 Feb 2022 22:15:35 -0500 (EST) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0194.hostedemail.com [216.40.44.194]) by kanga.kvack.org (Postfix) with ESMTP id D8EED8D0001 for ; Mon, 28 Feb 2022 22:15:35 -0500 (EST) Received: from smtpin18.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay04.hostedemail.com (Postfix) with ESMTP id 86DF397916 for ; Tue, 1 Mar 2022 03:15:35 +0000 (UTC) X-FDA: 79194352230.18.9098AE0 Received: from mail-yb1-f175.google.com (mail-yb1-f175.google.com [209.85.219.175]) by imf14.hostedemail.com (Postfix) with ESMTP id 2B1FC100002 for ; Tue, 1 Mar 2022 03:15:34 +0000 (UTC) Received: by mail-yb1-f175.google.com with SMTP id b35so24549281ybi.13 for ; Mon, 28 Feb 2022 19:15:33 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=bytedance-com.20210112.gappssmtp.com; s=20210112; h=mime-version:references:in-reply-to:from:date:message-id:subject:to :cc; bh=T0AjxvjFrHR6fu2oGFLcKZSFRRlXKq1Dcqtae0GYicM=; b=zI7OFwma/V9whbuWLP6/dekw2Ef4XO1BHT/odjfXiqqBSBN3wNRSaGlW2e5S3DMHh7 6nafsyPBh4XZpyLf2y8+bx1wiOP4m/XVyOhznsE0nDLtBWURJEZWY5eN+FSlXebfO/aq MwUsslVUGDBvCplLbj0DodURsvuHlZKfRKRtG0HI9/Ohu/g8Fmg0lYEl7PCIAzTcnaWE Up6KvQB5PLEdim8+dqyWUZVrTMjwU+YF2tRj6Iur3Wzj7yuugcJee25X7gymnZVLr5Q2 EiswuU88iHSTSH58Nu6p49kDjlzAq1dGIhw6LjEOdmlf7xGuc1AM4V3PFzyIodKR2Uzv nGpw== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=x-gm-message-state:mime-version:references:in-reply-to:from:date :message-id:subject:to:cc; bh=T0AjxvjFrHR6fu2oGFLcKZSFRRlXKq1Dcqtae0GYicM=; b=GtiVd4kDx8XIgPWsdxIHRQ8Oh3TsYnWeuD2zuD8HTFOar+gBdRfkp3Knnxk45DrCId gED1Bck0BUlCXbtY5LI1sPoIxTSEjrzvwAEkz6KMXymUpJdTlqh7L7M1Guf+XADSki2c QWNaxpMemrzf4g5+aRI6DG0irfeZX0LY4+qcmqJEeBrdCKgyNU4MxQ8juiNoJJTiEYT5 M2usGDCSEjKVrR/YP6KsPY7QVkWdEyjy12aKYC8sRvSE0fRh7CC9c1FI8TMeHIHL7S+U jXs5w0w/TNk2Vi2aSppieXdk/iCiTkCoVuykK2V4iPIYAhTDlqgMw7JIV4a5WCRhTACM 9DWw== X-Gm-Message-State: AOAM532RDGUEHbV83HlPa55DRSA38DdKB962XfxEkjqWgHisnm1MZk+u CgMIxLLwO8rUEis+HquvgRcIpC/hrasFcdin99UX5g== X-Google-Smtp-Source: ABdhPJyLlgGIyou+wAfEaWXmEmFOpM1Brk7yD9bDbyrwHm7wvg19Gmdb28Sqk2YKeULEgdNtRu+P34JXz4ZnYeV1Fww= X-Received: by 2002:a25:3d87:0:b0:61e:170c:aa9 with SMTP id k129-20020a253d87000000b0061e170c0aa9mr21333575yba.89.1646104533214; Mon, 28 Feb 2022 19:15:33 -0800 (PST) MIME-Version: 1.0 References: <20220228063536.24911-1-songmuchun@bytedance.com> <20220228063536.24911-5-songmuchun@bytedance.com> <20220228132606.7a9c2bc2d38c70604da98275@linux-foundation.org> In-Reply-To: <20220228132606.7a9c2bc2d38c70604da98275@linux-foundation.org> From: Muchun Song Date: Tue, 1 Mar 2022 11:14:53 +0800 Message-ID: Subject: Re: [PATCH v3 4/6] mm: pvmw: add support for walking devmap pages To: Andrew Morton Cc: Dan Williams , Matthew Wilcox , Jan Kara , Alexander Viro , Alistair Popple , Yang Shi , Ralph Campbell , Hugh Dickins , Xiyu Yang , "Kirill A. Shutemov" , zwisler@kernel.org, Christoph Hellwig , linux-fsdevel , nvdimm@lists.linux.dev, LKML , Linux Memory Management List , Xiongchun duan , Muchun Song Content-Type: text/plain; charset="UTF-8" X-Rspam-User: X-Rspamd-Server: rspam04 X-Rspamd-Queue-Id: 2B1FC100002 X-Stat-Signature: chdpreasobaxqu9ankfo55p4it14pauu Authentication-Results: imf14.hostedemail.com; dkim=pass header.d=bytedance-com.20210112.gappssmtp.com header.s=20210112 header.b=zI7OFwma; spf=pass (imf14.hostedemail.com: domain of songmuchun@bytedance.com designates 209.85.219.175 as permitted sender) smtp.mailfrom=songmuchun@bytedance.com; dmarc=pass (policy=none) header.from=bytedance.com X-HE-Tag: 1646104534-232955 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 Tue, Mar 1, 2022 at 5:26 AM Andrew Morton wrote: > > On Mon, 28 Feb 2022 14:35:34 +0800 Muchun Song wrote: > > > The devmap pages can not use page_vma_mapped_walk() to check if a huge > > devmap page is mapped into a vma. Add support for walking huge devmap > > pages so that DAX can use it in the next patch. > > > > x86_64 allnoconfig: > > In file included from : > In function 'check_pmd', > inlined from 'page_vma_mapped_walk' at mm/page_vma_mapped.c:219:10: > ././include/linux/compiler_types.h:347:45: error: call to '__compiletime_assert_232' declared with attribute error: BUILD_BUG failed > 347 | _compiletime_assert(condition, msg, __compiletime_assert_, __COUNTER__) > | ^ > ././include/linux/compiler_types.h:328:25: note: in definition of macro '__compiletime_assert' > 328 | prefix ## suffix(); \ > | ^~~~~~ > ././include/linux/compiler_types.h:347:9: note: in expansion of macro '_compiletime_assert' > 347 | _compiletime_assert(condition, msg, __compiletime_assert_, __COUNTER__) > | ^~~~~~~~~~~~~~~~~~~ > ./include/linux/build_bug.h:39:37: note: in expansion of macro 'compiletime_assert' > 39 | #define BUILD_BUG_ON_MSG(cond, msg) compiletime_assert(!(cond), msg) > | ^~~~~~~~~~~~~~~~~~ > ./include/linux/build_bug.h:59:21: note: in expansion of macro 'BUILD_BUG_ON_MSG' > 59 | #define BUILD_BUG() BUILD_BUG_ON_MSG(1, "BUILD_BUG failed") > | ^~~~~~~~~~~~~~~~ > ./include/linux/huge_mm.h:307:28: note: in expansion of macro 'BUILD_BUG' > 307 | #define HPAGE_PMD_SHIFT ({ BUILD_BUG(); 0; }) > | ^~~~~~~~~ > ./include/linux/huge_mm.h:104:26: note: in expansion of macro 'HPAGE_PMD_SHIFT' > 104 | #define HPAGE_PMD_ORDER (HPAGE_PMD_SHIFT-PAGE_SHIFT) > | ^~~~~~~~~~~~~~~ > ./include/linux/huge_mm.h:105:26: note: in expansion of macro 'HPAGE_PMD_ORDER' > 105 | #define HPAGE_PMD_NR (1< | ^~~~~~~~~~~~~~~ > mm/page_vma_mapped.c:113:20: note: in expansion of macro 'HPAGE_PMD_NR' > 113 | if ((pfn + HPAGE_PMD_NR - 1) < pvmw->pfn) > | ^~~~~~~~~~~~ > make[1]: *** [scripts/Makefile.build:288: mm/page_vma_mapped.o] Error 1 > make: *** [Makefile:1971: mm] Error 2 > > > because check_pmd() uses HPAGE_PMD_NR and > > #else /* CONFIG_TRANSPARENT_HUGEPAGE */ > #define HPAGE_PMD_SHIFT ({ BUILD_BUG(); 0; }) > > I don't immediately see why this patch triggers it... Maybe the reason is as follows. The first check_pmd() is wrapped inside `if (pmd_trans_huge(pmde))` block, since pmd_trans_huge() just returns 0, check_pmd() will be optimized out. There is a `if (!thp_migration_supported()) return;` block before the second check_pmd(), however, thp_migration_supported() returns 0 on riscv. So the second check_pmd() can be optimized out as well. I think I should replace `pmd_leaf` with `pmd_trans_huge() || pmd_devmap()` to fix it. Thanks.