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=-10.3 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI,NICE_REPLY_A, SPF_HELO_NONE,SPF_PASS,USER_AGENT_SANE_1 autolearn=ham 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 E83E5C43461 for ; Tue, 18 May 2021 04:02:30 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id 6FB4761263 for ; Tue, 18 May 2021 04:02:30 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 6FB4761263 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=arm.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=owner-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix) id CFDF48E0009; Tue, 18 May 2021 00:02:29 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id CAE688E0002; Tue, 18 May 2021 00:02:29 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id B9BE98E0009; Tue, 18 May 2021 00:02:29 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0018.hostedemail.com [216.40.44.18]) by kanga.kvack.org (Postfix) with ESMTP id 874EB8E0002 for ; Tue, 18 May 2021 00:02:29 -0400 (EDT) Received: from smtpin36.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay05.hostedemail.com (Postfix) with ESMTP id 16833181AF5FE for ; Tue, 18 May 2021 04:02:29 +0000 (UTC) X-FDA: 78153004818.36.8C51488 Received: from foss.arm.com (foss.arm.com [217.140.110.172]) by imf25.hostedemail.com (Postfix) with ESMTP id DCD546000109 for ; Tue, 18 May 2021 04:02:25 +0000 (UTC) Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.121.207.14]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id 44BF631B; Mon, 17 May 2021 21:02:27 -0700 (PDT) Received: from [10.163.79.24] (unknown [10.163.79.24]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id 75FD33F73D; Mon, 17 May 2021 21:02:24 -0700 (PDT) Subject: Re: linux-next: Tree for May 13 (mm/page_alloc.c, : sizeof(struct page)) To: Matthew Wilcox , Randy Dunlap Cc: Stephen Rothwell , Linux Next Mailing List , Linux Kernel Mailing List , Alexander Duyck , Andrew Morton , Linux MM References: <20210513154418.2946f422@canb.auug.org.au> From: Anshuman Khandual Message-ID: <06c8a6a6-9999-7f03-6bfb-34efb7ced637@arm.com> Date: Tue, 18 May 2021 09:33:09 +0530 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.10.0 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset=utf-8 Content-Language: en-US Authentication-Results: imf25.hostedemail.com; dkim=none; dmarc=pass (policy=none) header.from=arm.com; spf=pass (imf25.hostedemail.com: domain of anshuman.khandual@arm.com designates 217.140.110.172 as permitted sender) smtp.mailfrom=anshuman.khandual@arm.com X-Rspamd-Server: rspam01 X-Rspamd-Queue-Id: DCD546000109 X-Stat-Signature: cbq45ohn9dof8hy3ox7hogpaknom8trd X-HE-Tag: 1621310545-116906 Content-Transfer-Encoding: quoted-printable 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 5/14/21 2:57 AM, Matthew Wilcox wrote: > On Thu, May 13, 2021 at 10:29:49AM -0700, Randy Dunlap wrote: >> On 5/12/21 10:44 PM, Stephen Rothwell wrote: >>> Hi all, >>> >>> Changes since 20210512: >>> >> >> on x86_64: >> >> In function =E2=80=98__mm_zero_struct_page.isra.75=E2=80=99, >> inlined from =E2=80=98__init_single_page.isra.76=E2=80=99 at ../mm= /page_alloc.c:1494:2: >> ./../include/linux/compiler_types.h:328:38: error: call to =E2=80=98__= compiletime_assert_162=E2=80=99 declared with attribute error: BUILD_BUG_= ON failed: sizeof(struct page) > 80 >=20 > Hmm. >=20 > struct { > long unsigned int _pt_pad_1; /* 8 8= */ > pgtable_t pmd_huge_pte; /* 16 8= */ > long unsigned int _pt_pad_2; /* 24 8= */ > union { > struct mm_struct * pt_mm; /* 32 = 8 */ > atomic_t pt_frag_refcount; /* 32 = 4 */ > }; /* 32 8= */ > spinlock_t ptl; /* 40 72= */ > }; /* 8 104= */ >=20 > #if ALLOC_SPLIT_PTLOCKS > spinlock_t *ptl; > #else > spinlock_t ptl; > #endif >=20 > something has disabled ALLOC_SPLIT_PTLOCKS when it ought to be enabled. >=20 > #if USE_SPLIT_PTE_PTLOCKS > #define ALLOC_SPLIT_PTLOCKS (SPINLOCK_SIZE > BITS_PER_LONG/8) > #else > #define ALLOC_SPLIT_PTLOCKS 0 > #endif >=20 > Oh. This is Anshuman's fault. >=20 > commit 9b8a39056e2472592a5e5897987387f43038b8ba > Author: Anshuman Khandual > Date: Tue May 11 15:06:01 2021 +1000 >=20 > mm/thp: make ALLOC_SPLIT_PTLOCKS dependent on USE_SPLIT_PTE_PTLOCKS >=20 >=20 Previously ALLOC_SPLIT_PTLOCKS was evaluated and the spin lock element in struct page was getting created independent of whether split pte locks are being used or not. AFAICS without USE_SPLIT_PTE_PTLOCKS, it does not really matter whether struct page has spinlock_t *ptl or ptl element because that is not going to be used. Should the BUILD_BUG_ON() evaluation be changed when USE_SPLIT_PTE_PTLOCKS is not enabled or we could something like this which drops the ptl element in such cases ? --- a/include/linux/mm_types.h +++ b/include/linux/mm_types.h @@ -152,11 +152,13 @@ struct page { struct mm_struct *pt_mm; /* x86 pgds only= */ atomic_t pt_frag_refcount; /* powerpc */ }; +#if USE_SPLIT_PTE_PTLOCKS #if ALLOC_SPLIT_PTLOCKS spinlock_t *ptl; #else spinlock_t ptl; #endif +#endif }; struct { /* ZONE_DEVICE pages */ /** @pgmap: Points to the hosting device page map= . */