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]) (using TLSv1 with cipher DHE-RSA-AES256-SHA (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id CF8B8C43458 for ; Tue, 7 Jul 2026 13:45:19 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id B428B6B009E; Tue, 7 Jul 2026 09:45:18 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id B1A0A6B009F; Tue, 7 Jul 2026 09:45:18 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id A0BBE6B00A1; Tue, 7 Jul 2026 09:45:18 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0011.hostedemail.com [216.40.44.11]) by kanga.kvack.org (Postfix) with ESMTP id 6F2BA6B009E for ; Tue, 7 Jul 2026 09:45:18 -0400 (EDT) Received: from smtpin10.hostedemail.com (lb01a-stub [10.200.18.249]) by unirelay04.hostedemail.com (Postfix) with ESMTP id 00F3E1A0441 for ; Tue, 7 Jul 2026 13:45:17 +0000 (UTC) X-FDA: 84962102316.10.E8D651D Received: from sea.source.kernel.org (sea.source.kernel.org [172.234.252.31]) by imf14.hostedemail.com (Postfix) with ESMTP id C1CD310000B for ; Tue, 7 Jul 2026 13:45:15 +0000 (UTC) Authentication-Results: imf14.hostedemail.com; dkim=pass header.d=kernel.org header.s=k20260515 header.b=Pu+OUM9r; dmarc=pass (policy=quarantine) header.from=kernel.org; spf=pass (imf14.hostedemail.com: domain of david@kernel.org designates 172.234.252.31 as permitted sender) smtp.mailfrom=david@kernel.org ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1783431915; 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:content-transfer-encoding: in-reply-to:in-reply-to:references:references:dkim-signature; bh=64Zlwh7XthYCB+Y/TXfGoXBgJ2e6mec67Wgib3RpPC8=; b=m94J46QB65HSDXI6GPpFXtIYMz2WuUP5D6ZjYgDQsTywszTJ/a2SwwM+Yujp2N9+QbD1cK 7TUNNFA8mFneeuiO4TLVRoPjXSClSffLneDtY8r1i2dgLcN2cilXUGrynZmedHeLHuV5lF a9JE9DOpdYzyErkWHCxrd4Ul9reQfmA= ARC-Authentication-Results: i=1; imf14.hostedemail.com; dkim=pass header.d=kernel.org header.s=k20260515 header.b=Pu+OUM9r; dmarc=pass (policy=quarantine) header.from=kernel.org; spf=pass (imf14.hostedemail.com: domain of david@kernel.org designates 172.234.252.31 as permitted sender) smtp.mailfrom=david@kernel.org ARC-Seal: i=1; a=rsa-sha256; d=hostedemail.com; s=arc-20220608; cv=none; t=1783431915; b=hiKfEjFW/bHfSr7QyilZyCf2bfujt8/qp5+74A7++YXEHUTRAC6RfR+a6nEbKoAMYj2Nn8 8+yBPj+YUf24q2lufwpOjxzTaEVGh06qlx9OmEe5nIlwHgb2Z2Tb/z73f4MLnmDP4NdrZY Rf5cI6nKBGQcH6qkracN4plKX8PWkjI= Received: from smtp.kernel.org (quasi.space.kernel.org [100.103.45.18]) by sea.source.kernel.org (Postfix) with ESMTP id 80006403F7; Tue, 7 Jul 2026 13:45:14 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 63DDB1F000E9; Tue, 7 Jul 2026 13:45:10 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1783431914; bh=64Zlwh7XthYCB+Y/TXfGoXBgJ2e6mec67Wgib3RpPC8=; h=Date:Subject:To:Cc:References:From:In-Reply-To; b=Pu+OUM9rG5fAkB6Zm9U4wuojbQr9NT3rGIkCZkegq0WhRTpplNn2Ddesc0vV9tVaR pMUDmFY2mZBvqOFaoP0/6PqtbZEGYb/lDdPkH2ovov8wQ8EncZtQfXDqxsYw83WOUt UvauRnL0yPG4MM9WK8SwE/J5Bg1YAjZ9kuO7SF4/1DLrPlPsoOFkL931lrKRf5WuZC wFuK+NPZbWoo5bLytlMW1mk/zEUokob+LMybtaJHvRZYlPYWExpVMRtbzfYQ+QcEr+ o7NKW5tL0+zik3VccoJp+icoudiB0IPddMHEIO+P8Lbku02GF0o2EywuzA/hwU1fLf +RKiLOpXzxCbQ== Message-ID: <0e2ba302-254b-432a-b0c6-3e259068ffa9@kernel.org> Date: Tue, 7 Jul 2026 15:45:08 +0200 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v9] mm: fix ASSERT_EXCLUSIVE_BITS by passing memdesc_flags_t by pointer To: Hui Zhu , Andrew Morton , Lorenzo Stoakes , "Liam R. Howlett" , Vlastimil Babka , Mike Rapoport , Suren Baghdasaryan , Michal Hocko , Kairui Song , Qi Zheng , Shakeel Butt , Barry Song , Axel Rasmussen , Yuanchu Xie , Wei Xu , linux-mm@kvack.org, linux-kernel@vger.kernel.org Cc: Hui Zhu References: <20260630070810.470763-1-hui.zhu@linux.dev> From: "David Hildenbrand (Arm)" Content-Language: en-US Autocrypt: addr=david@kernel.org; keydata= xsFNBFXLn5EBEAC+zYvAFJxCBY9Tr1xZgcESmxVNI/0ffzE/ZQOiHJl6mGkmA1R7/uUpiCjJ dBrn+lhhOYjjNefFQou6478faXE6o2AhmebqT4KiQoUQFV4R7y1KMEKoSyy8hQaK1umALTdL QZLQMzNE74ap+GDK0wnacPQFpcG1AE9RMq3aeErY5tujekBS32jfC/7AnH7I0v1v1TbbK3Gp XNeiN4QroO+5qaSr0ID2sz5jtBLRb15RMre27E1ImpaIv2Jw8NJgW0k/D1RyKCwaTsgRdwuK Kx/Y91XuSBdz0uOyU/S8kM1+ag0wvsGlpBVxRR/xw/E8M7TEwuCZQArqqTCmkG6HGcXFT0V9 PXFNNgV5jXMQRwU0O/ztJIQqsE5LsUomE//bLwzj9IVsaQpKDqW6TAPjcdBDPLHvriq7kGjt WhVhdl0qEYB8lkBEU7V2Yb+SYhmhpDrti9Fq1EsmhiHSkxJcGREoMK/63r9WLZYI3+4W2rAc UucZa4OT27U5ZISjNg3Ev0rxU5UH2/pT4wJCfxwocmqaRr6UYmrtZmND89X0KigoFD/XSeVv jwBRNjPAubK9/k5NoRrYqztM9W6sJqrH8+UWZ1Idd/DdmogJh0gNC0+N42Za9yBRURfIdKSb B3JfpUqcWwE7vUaYrHG1nw54pLUoPG6sAA7Mehl3nd4pZUALHwARAQABzS5EYXZpZCBIaWxk ZW5icmFuZCAoQ3VycmVudCkgPGRhdmlkQGtlcm5lbC5vcmc+wsGQBBMBCAA6AhsDBQkmWAik AgsJBBUKCQgCFgICHgUCF4AWIQQb2cqtc1xMOkYN/MpN3hD3AP+DWgUCaYJt/AIZAQAKCRBN 3hD3AP+DWriiD/9BLGEKG+N8L2AXhikJg6YmXom9ytRwPqDgpHpVg2xdhopoWdMRXjzOrIKD g4LSnFaKneQD0hZhoArEeamG5tyo32xoRsPwkbpIzL0OKSZ8G6mVbFGpjmyDLQCAxteXCLXz ZI0VbsuJKelYnKcXWOIndOrNRvE5eoOfTt2XfBnAapxMYY2IsV+qaUXlO63GgfIOg8RBaj7x 3NxkI3rV0SHhI4GU9K6jCvGghxeS1QX6L/XI9mfAYaIwGy5B68kF26piAVYv/QZDEVIpo3t7 /fjSpxKT8plJH6rhhR0epy8dWRHk3qT5tk2P85twasdloWtkMZ7FsCJRKWscm1BLpsDn6EQ4 jeMHECiY9kGKKi8dQpv3FRyo2QApZ49NNDbwcR0ZndK0XFo15iH708H5Qja/8TuXCwnPWAcJ DQoNIDFyaxe26Rx3ZwUkRALa3iPcVjE0//TrQ4KnFf+lMBSrS33xDDBfevW9+Dk6IISmDH1R HFq2jpkN+FX/PE8eVhV68B2DsAPZ5rUwyCKUXPTJ/irrCCmAAb5Jpv11S7hUSpqtM/6oVESC 3z/7CzrVtRODzLtNgV4r5EI+wAv/3PgJLlMwgJM90Fb3CB2IgbxhjvmB1WNdvXACVydx55V7 LPPKodSTF29rlnQAf9HLgCphuuSrrPn5VQDaYZl4N/7zc2wcWM7BTQRVy5+RARAA59fefSDR 9nMGCb9LbMX+TFAoIQo/wgP5XPyzLYakO+94GrgfZjfhdaxPXMsl2+o8jhp/hlIzG56taNdt VZtPp3ih1AgbR8rHgXw1xwOpuAd5lE1qNd54ndHuADO9a9A0vPimIes78Hi1/yy+ZEEvRkHk /kDa6F3AtTc1m4rbbOk2fiKzzsE9YXweFjQvl9p+AMw6qd/iC4lUk9g0+FQXNdRs+o4o6Qvy iOQJfGQ4UcBuOy1IrkJrd8qq5jet1fcM2j4QvsW8CLDWZS1L7kZ5gT5EycMKxUWb8LuRjxzZ 3QY1aQH2kkzn6acigU3HLtgFyV1gBNV44ehjgvJpRY2cC8VhanTx0dZ9mj1YKIky5N+C0f21 zvntBqcxV0+3p8MrxRRcgEtDZNav+xAoT3G0W4SahAaUTWXpsZoOecwtxi74CyneQNPTDjNg azHmvpdBVEfj7k3p4dmJp5i0U66Onmf6mMFpArvBRSMOKU9DlAzMi4IvhiNWjKVaIE2Se9BY FdKVAJaZq85P2y20ZBd08ILnKcj7XKZkLU5FkoA0udEBvQ0f9QLNyyy3DZMCQWcwRuj1m73D sq8DEFBdZ5eEkj1dCyx+t/ga6x2rHyc8Sl86oK1tvAkwBNsfKou3v+jP/l14a7DGBvrmlYjO 59o3t6inu6H7pt7OL6u6BQj7DoMAEQEAAcLBfAQYAQgAJgIbDBYhBBvZyq1zXEw6Rg38yk3e EPcA/4NaBQJonNqrBQkmWAihAAoJEE3eEPcA/4NaKtMQALAJ8PzprBEXbXcEXwDKQu+P/vts IfUb1UNMfMV76BicGa5NCZnJNQASDP/+bFg6O3gx5NbhHHPeaWz/VxlOmYHokHodOvtL0WCC 8A5PEP8tOk6029Z+J+xUcMrJClNVFpzVvOpb1lCbhjwAV465Hy+NUSbbUiRxdzNQtLtgZzOV Zw7jxUCs4UUZLQTCuBpFgb15bBxYZ/BL9MbzxPxvfUQIPbnzQMcqtpUs21CMK2PdfCh5c4gS sDci6D5/ZIBw94UQWmGpM/O1ilGXde2ZzzGYl64glmccD8e87OnEgKnH3FbnJnT4iJchtSvx yJNi1+t0+qDti4m88+/9IuPqCKb6Stl+s2dnLtJNrjXBGJtsQG/sRpqsJz5x1/2nPJSRMsx9 5YfqbdrJSOFXDzZ8/r82HgQEtUvlSXNaXCa95ez0UkOG7+bDm2b3s0XahBQeLVCH0mw3RAQg r7xDAYKIrAwfHHmMTnBQDPJwVqxJjVNr7yBic4yfzVWGCGNE4DnOW0vcIeoyhy9vnIa3w1uZ 3iyY2Nsd7JxfKu1PRhCGwXzRw5TlfEsoRI7V9A8isUCoqE2Dzh3FvYHVeX4Us+bRL/oqareJ CIFqgYMyvHj7Q06kTKmauOe4Nf0l0qEkIuIzfoLJ3qr5UyXc2hLtWyT9Ir+lYlX9efqh7mOY qIws/H2t In-Reply-To: <20260630070810.470763-1-hui.zhu@linux.dev> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit X-Stat-Signature: znuwt8z4ic4fmx8nysc9dhr6mj48c8dm X-Rspamd-Queue-Id: C1CD310000B X-Rspamd-Server: rspam01 X-Rspam-User: X-HE-Tag: 1783431915-598151 X-HE-Meta: U2FsdGVkX19/+awal6h+4GN87JEN1PxExYQmLqaEe4s9APvgx9+XIM32/u3nEG+PRRGKpG1aM9OD338Sw7cNiOlPNY27Sj9pioSzhKKzo+YAGqFIBLd/xswp2UAi+MhYZH4k3RX8uzi66aezvOocQOaVwmS2aQWNAKqVQ2fecLKVcV2nYh2kSlfmqivNMby9rlsEQqnfXq+TI2MVPusnBMzAJctDLWwPwnUf2ZB6Tg14AtWhQAG4T+K4vFfr84iqQ0d3EVtN+orKQEUKjLEWt/9Gc3jwH81EYLb5DYOZwpI6z6/kRuO3TnGr4pA0kKHJZ6pfICs8ilLJn9zTTiiOWHSF0Af56kIVtJi8G323a6v+z/k58p5Q6DzSIAuoehUwo5BI5n0TKOcXks5UDS43lKuMBlReZcHL8+t/P3vbwleISKkZWJ/2Ss8PLAfpxIC1aLqktX5o6f9a3Rhu9LwNuD4Zancm8yCWSbTkgbBo8bCE45wbITXLoWTBwwm8+J4G7lXvLwxEVygMHKPvYW8JALIV0OrEMGWF72GeHLqG4EpOGl1qd6sEkZeeXUNYS7QoF0Z54ZukVl3/RZJ6T2HWdYTzuksqRw4zy3sGx0REeVtEY0R6jI+B3FU36Bx9XpZ7VI/cX5vrREWCP1i4BR9TedDR8vb61gOBI2xSIoeO4TuQN1BVWTrvc3uJsA9uYlEad45LbiaBCl80+T/u29X3Hh4eiXRZuVn3ERjfIcxZTBxfwA2vCGIphbhOWcUV+HCikPCeKSUZVoCsu/3VkniEDmZrUXXkh48iU8OlXXd6gHMa+20yWbK4ONZzP3nErBL517+Oa95bkCx75KErJk7zrpuqomv05ljJTsepEX12CerMEo1bJICJ4HhUEl6je7c+4DA4qVL98iHH93dY2BgnuLbkVep+0oCvEy+W3vWBWQC8nAFRL8WR9KT6apmS9CH42nNcuoeBQd6Y5Dm98Vs AYT0gRDA WIUXLQgkGq7K4aTrAiQRuk1c7RwQuBLEdjX4s2+NKLx7kHmPLhTlEwijkmPgFa8nFrU8hhrhkUdjNqNdm9hqFOWYx7r3P879LFwr58gqDM1QhIFDHwhmYtB8fvuXF12Clga/b9lKpY9rkgmpxnGg98JwooPGKLh07N9FtDUwHiwvY2aZ+ECvyF6YpVxgu3rhKf3nxSmsSv/eXvfJps9c+rA2C3gvbRRXL1TYi4R5PM9D9Q5EdmizGgDc27907je3oQ2kgqn1IT+3zJ27GYYq+xw6d3zpmC/dPtsOWzOQfcFatIURmZZMXOzhs5TqRdz98tK3Z0LVt9M18tWc= Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On 6/30/26 09:08, Hui Zhu wrote: > From: Hui Zhu > > KCSAN reports a data race between page_to_nid()/folio_pgdat() reading > page->flags and folio_trylock()/folio_lock() concurrently doing > test_and_set_bit_lock(PG_locked, ...) on the same word, e.g.: > > BUG: KCSAN: data-race in __lruvec_stat_mod_folio / shmem_get_folio_gfp > > The race is benign: nid/zone bits are set once at page init and never > overlap with PG_locked. However, ASSERT_EXCLUSIVE_BITS() inside > memdesc_nid/zonenum() was checking a by-value copy of the flags word, > not the live page->flags, so it failed to annotate the real access. > > Change memdesc_nid(), memdesc_zonenum(), memdesc_section(), and > memdesc_is_zone_device() to take a const memdesc_flags_t * and update > all callers to pass &page->flags / &folio->flags, so > ASSERT_EXCLUSIVE_BITS() operates on the actual shared word. > > Guard the ASSERT_EXCLUSIVE_BITS() calls in memdesc_zonenum() and > memdesc_section() under ZONES_WIDTH != 0 / SECTIONS_WIDTH != 0 to avoid > a zero-mask check on configs where the corresponding field is absent. > Under CONFIG_NUMA=n, stub out page_to_nid() and folio_nid() as plain > "return 0" instead of reading page->flags when NODES_MASK is 0 and the > check can never fire. > > Signed-off-by: Hui Zhu > > Co-developed-by: David Hildenbrand (Arm) > Signed-off-by: David Hildenbrand (Arm) > Signed-off-by: Hui Zhu > --- > Changelog: > v9: > Add the SECTIONS_WIDTH check to memdesc_section. > v8: > According to the comments of Andrew, include kcsan-checks.h in mm.h. > Incorporate David's patch that switch memdesc_nid(), memdesc_zonenum(), > memdesc_section() and memdesc_is_zone_device() to take a const > memdesc_flags_t * instead of using a per-accessor macro/call-site hack. > Update all callers accordingly and extend the same exclusive-bits check > to memdesc_section() and memdesc_is_zone_device(), guarded by > SECTIONS_WIDTH != 0 / reusing ZONES_WIDTH != 0 to avoid zero-mask checks > on configs without the corresponding field. > v7: > According to the comments of Sashiko, restrict the memdesc_nid() macro > to CONFIG_NUMA, keeping a plain "return 0" static inline stub otherwise, > and re-add a local page pointer in page_to_nid() to avoid evaluating > PF_POISONED_CHECK(page) twice. > v6: > According to the comments of David, turn memdesc_nid() from a static > inline function into a macro so ASSERT_EXCLUSIVE_BITS() can check the > caller's page->flags/folio->flags directly. > v5: > According to the comments of Sashiko, guard the ASSERT_EXCLUSIVE_BITS() > calls with #ifndef NODE_NOT_IN_PAGE_FLAGS (for nid) and #if > ZONES_WIDTH != 0 (for zonenum). > According to the comments of David, avoid calling > PF_POISONED_CHECK(page) twice in page_to_nid(). > According to the warning of lkp, switch the CONFIG_NUMA=n > page_to_nid()/folio_nid() stubs from macros to static inline functions. > v4: > According to the comments of Andrew and Sashiko, set > page_to_nid()/folio_nid() as static inline stubs returning 0 > under CONFIG_NUMA=n. > v3: > According to the comments of Andrew and Sashiko, move > ASSERT_EXCLUSIVE_BITS out of memdesc_nid()/memdesc_zonenum() > into the page/folio call sites. > v2: > According to the comments of David, remove useless comments and use > ASSERT_EXCLUSIVE_BITS() in memdesc_nid() instead of data_race() in > page_to_nid(). > > include/asm-generic/memory_model.h | 2 +- > include/linux/mm.h | 42 ++++++++++++++++++++++++------ > include/linux/mm_inline.h | 4 +-- > include/linux/mmzone.h | 26 +++++++++--------- > mm/page_alloc.c | 6 ++--- > mm/slab.h | 2 +- > mm/sparse.c | 2 +- > 7 files changed, 56 insertions(+), 28 deletions(-) > > diff --git a/include/asm-generic/memory_model.h b/include/asm-generic/memory_model.h > index efa6610acbc7..f8404bc7773c 100644 > --- a/include/asm-generic/memory_model.h > +++ b/include/asm-generic/memory_model.h > @@ -53,7 +53,7 @@ static inline int pfn_valid(unsigned long pfn) > */ > #define __page_to_pfn(pg) \ > ({ const struct page *__pg = (pg); \ > - int __sec = memdesc_section(__pg->flags); \ > + int __sec = memdesc_section(&__pg->flags); \ > (unsigned long)(__pg - __section_mem_map_addr(__nr_to_section(__sec))); \ > }) > > diff --git a/include/linux/mm.h b/include/linux/mm.h > index 485df9c2dbdd..60722c42a622 100644 > --- a/include/linux/mm.h > +++ b/include/linux/mm.h > @@ -37,6 +37,7 @@ > #include > #include > #include > +#include > > struct mempolicy; > struct anon_vma; > @@ -2286,23 +2287,45 @@ static inline int page_zone_id(struct page *page) > } > > #ifdef NODE_NOT_IN_PAGE_FLAGS > -int memdesc_nid(memdesc_flags_t mdf); > +int memdesc_nid(const memdesc_flags_t *mdf); > #else > -static inline int memdesc_nid(memdesc_flags_t mdf) > +#ifdef CONFIG_NUMA > +static inline int memdesc_nid(const memdesc_flags_t *mdf) > { > - return (mdf.f >> NODES_PGSHIFT) & NODES_MASK; > + ASSERT_EXCLUSIVE_BITS(mdf->f, NODES_MASK << NODES_PGSHIFT); > + return (mdf->f >> NODES_PGSHIFT) & NODES_MASK; > +} > +#else > +static inline int memdesc_nid(const memdesc_flags_t *mdf) > +{ > + return 0; > } > #endif > +#endif > + > +#ifdef CONFIG_NUMA > +static inline int page_to_nid(const struct page *page) > +{ > + const struct page *p = PF_POISONED_CHECK(page); > > + return memdesc_nid(&p->flags); > +} > + > +static inline int folio_nid(const struct folio *folio) > +{ > + return memdesc_nid(&folio->flags); > +} > +#else > static inline int page_to_nid(const struct page *page) > { > - return memdesc_nid(PF_POISONED_CHECK(page)->flags); > + return 0; > } > > static inline int folio_nid(const struct folio *folio) > { > - return memdesc_nid(folio->flags); > + return 0; > } Why do we need two sets of helpers here as well? Shouldn't memdesc_nid() take care of that already? > +#endif > > #ifdef CONFIG_NUMA_BALANCING > /* page access time bits needs to hold at least 4 seconds */ > @@ -2541,12 +2564,15 @@ static inline void set_page_section(struct page *page, unsigned long section) > page->flags.f |= (section & SECTIONS_MASK) << SECTIONS_PGSHIFT; > } > > -static inline unsigned long memdesc_section(memdesc_flags_t mdf) > +static inline unsigned long memdesc_section(const memdesc_flags_t *mdf) > { > - return (mdf.f >> SECTIONS_PGSHIFT) & SECTIONS_MASK; > +#if SECTIONS_WIDTH != 0 How can we have SECTION_IN_PAGE_FLAGS but !SECTIONS_WIDTH? We have #if defined(CONFIG_SPARSEMEM) && !defined(CONFIG_SPARSEMEM_VMEMMAP) #define SECTION_IN_PAGE_FLAGS #endif And #if defined(CONFIG_SPARSEMEM) && !defined(CONFIG_SPARSEMEM_VMEMMAP) #define SECTIONS_WIDTH SECTIONS_SHIFT #else ... > + ASSERT_EXCLUSIVE_BITS(mdf->f, SECTIONS_MASK << SECTIONS_PGSHIFT); > +#endif > + return (mdf->f >> SECTIONS_PGSHIFT) & SECTIONS_MASK; > } > #else /* !SECTION_IN_PAGE_FLAGS */ > -static inline unsigned long memdesc_section(memdesc_flags_t mdf) > +static inline unsigned long memdesc_section(const memdesc_flags_t *mdf) > { > return 0; > } > diff --git a/include/linux/mm_inline.h b/include/linux/mm_inline.h > index a8430a7ae054..efcddb9925ad 100644 > --- a/include/linux/mm_inline.h > +++ b/include/linux/mm_inline.h > @@ -650,7 +650,7 @@ static inline bool vma_has_recency(const struct vm_area_struct *vma) > static inline size_t num_pages_contiguous(struct page **pages, size_t nr_pages) > { > struct page *cur_page = pages[0]; > - unsigned long section = memdesc_section(cur_page->flags); > + unsigned long section = memdesc_section(&cur_page->flags); > size_t i; > > for (i = 1; i < nr_pages; i++) { > @@ -660,7 +660,7 @@ static inline size_t num_pages_contiguous(struct page **pages, size_t nr_pages) > * In unproblematic kernel configs, page_to_section() == 0 and > * the whole check will get optimized out. > */ > - if (memdesc_section(cur_page->flags) != section) > + if (memdesc_section(&cur_page->flags) != section) > break; > } > > diff --git a/include/linux/mmzone.h b/include/linux/mmzone.h > index ca2712187147..e60dad546ca6 100644 > --- a/include/linux/mmzone.h > +++ b/include/linux/mmzone.h > @@ -1272,31 +1272,33 @@ static inline bool zone_is_empty(const struct zone *zone) > #define KASAN_TAG_MASK ((1UL << KASAN_TAG_WIDTH) - 1) > #define ZONEID_MASK ((1UL << ZONEID_SHIFT) - 1) > > -static inline enum zone_type memdesc_zonenum(memdesc_flags_t flags) > +static inline enum zone_type memdesc_zonenum(const memdesc_flags_t *flags) > { > - ASSERT_EXCLUSIVE_BITS(flags.f, ZONES_MASK << ZONES_PGSHIFT); > - return (flags.f >> ZONES_PGSHIFT) & ZONES_MASK; > +#if ZONES_WIDTH != 0 > + ASSERT_EXCLUSIVE_BITS(flags->f, ZONES_MASK << ZONES_PGSHIFT); > +#endif > + return (flags->f >> ZONES_PGSHIFT) & ZONES_MASK; > } Okay, ZONES_WIDTH can be 0 with "MAX_NR_ZONES < 2", and we'll always return 0. Nothing else jumped at me. -- Cheers, David