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 10A43CD4F25 for ; Thu, 14 May 2026 08:00:25 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id 42F926B0088; Thu, 14 May 2026 04:00:24 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 3B9B06B008C; Thu, 14 May 2026 04:00:24 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 259426B0092; Thu, 14 May 2026 04:00:24 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0015.hostedemail.com [216.40.44.15]) by kanga.kvack.org (Postfix) with ESMTP id 0FBA56B0088 for ; Thu, 14 May 2026 04:00:24 -0400 (EDT) Received: from smtpin08.hostedemail.com (lb01a-stub [10.200.18.249]) by unirelay05.hostedemail.com (Postfix) with ESMTP id A369F40522 for ; Thu, 14 May 2026 08:00:23 +0000 (UTC) X-FDA: 84765277926.08.9CB6B98 Received: from smtp-out1.suse.de (smtp-out1.suse.de [195.135.223.130]) by imf19.hostedemail.com (Postfix) with ESMTP id 289B41A0012 for ; Thu, 14 May 2026 08:00:20 +0000 (UTC) Authentication-Results: imf19.hostedemail.com; dkim=pass header.d=suse.de header.s=susede2_rsa header.b=CJLjzcwG; dkim=pass header.d=suse.de header.s=susede2_ed25519 header.b=C4248gcx; dkim=pass header.d=suse.de header.s=susede2_rsa header.b=CJLjzcwG; dkim=pass header.d=suse.de header.s=susede2_ed25519 header.b=C4248gcx; dmarc=pass (policy=none) header.from=suse.de; spf=pass (imf19.hostedemail.com: domain of osalvador@suse.de designates 195.135.223.130 as permitted sender) smtp.mailfrom=osalvador@suse.de ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1778745621; 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=0ApyV1SJgz5wtbwoXbn/VnkSAGGIM5s57P85+2beKro=; b=HWEujhqewAWM539VnlUdmL3RUhyyLNITtXiFX8LTulwJoEQUTGzRKBpYoDWLSA16RvkCQA QZcgm26cAHX0qRckHhHBDEgrHZZfFrLNvizZgARmn8X5O8yt6JEe25TyGSndHXLEV5uVyD BsPgnzzcjPYlqP/1o7wSoySoqLeIdJg= ARC-Seal: i=1; s=arc-20220608; d=hostedemail.com; t=1778745621; a=rsa-sha256; cv=none; b=c8ntTilxt0FKSgd4LJoH9mfmjBYzk0uOr3Mjtu0+p45ZQA4zq0ny5q8GUvjymLQUiROiHe S6EM87DFr5a1/L6ZLUuVnfK583zOBIPxbHwGAskSoij2/XNR8iRTg5jQxebRID2gsKLqKY WoFbyof8jEbLfE4h081yGW/QEU1kJbU= ARC-Authentication-Results: i=1; imf19.hostedemail.com; dkim=pass header.d=suse.de header.s=susede2_rsa header.b=CJLjzcwG; dkim=pass header.d=suse.de header.s=susede2_ed25519 header.b=C4248gcx; dkim=pass header.d=suse.de header.s=susede2_rsa header.b=CJLjzcwG; dkim=pass header.d=suse.de header.s=susede2_ed25519 header.b=C4248gcx; dmarc=pass (policy=none) header.from=suse.de; spf=pass (imf19.hostedemail.com: domain of osalvador@suse.de designates 195.135.223.130 as permitted sender) smtp.mailfrom=osalvador@suse.de Received: from imap1.dmz-prg2.suse.org (unknown [10.150.64.97]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (4096 bits) server-digest SHA256) (No client certificate requested) by smtp-out1.suse.de (Postfix) with ESMTPS id B0A575E0B4; Thu, 14 May 2026 08:00:19 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=suse.de; s=susede2_rsa; t=1778745619; h=from:from:reply-to:date:date:message-id:message-id:to:to:cc:cc: mime-version:mime-version:content-type:content-type: in-reply-to:in-reply-to:references:references; bh=0ApyV1SJgz5wtbwoXbn/VnkSAGGIM5s57P85+2beKro=; b=CJLjzcwGlCsOVB9un6xLW22kKcw6V4Xlum6RMNosJGw32EAzNkqaZ0dXBputXg8joCGJh5 ZC1jpkQXSTxpbM6WBhRM4oeLo+fYzd66yI5ebrozqIG9PAWcPh+1jwQnrrgvtShLJAV6m0 iztuO6FRDH7X+dSyQAMxzhaR+0Yiy8k= DKIM-Signature: v=1; a=ed25519-sha256; c=relaxed/relaxed; d=suse.de; s=susede2_ed25519; t=1778745619; h=from:from:reply-to:date:date:message-id:message-id:to:to:cc:cc: mime-version:mime-version:content-type:content-type: in-reply-to:in-reply-to:references:references; bh=0ApyV1SJgz5wtbwoXbn/VnkSAGGIM5s57P85+2beKro=; b=C4248gcxLcOZ45VZ6Xk2Ku4O2ABnN9dD5IGpb7ZAPZEdfu+e2hfvYKSUMmGYh5vpD4fT12 zLyXzyaJCm0GMMAA== DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=suse.de; s=susede2_rsa; t=1778745619; h=from:from:reply-to:date:date:message-id:message-id:to:to:cc:cc: mime-version:mime-version:content-type:content-type: in-reply-to:in-reply-to:references:references; bh=0ApyV1SJgz5wtbwoXbn/VnkSAGGIM5s57P85+2beKro=; b=CJLjzcwGlCsOVB9un6xLW22kKcw6V4Xlum6RMNosJGw32EAzNkqaZ0dXBputXg8joCGJh5 ZC1jpkQXSTxpbM6WBhRM4oeLo+fYzd66yI5ebrozqIG9PAWcPh+1jwQnrrgvtShLJAV6m0 iztuO6FRDH7X+dSyQAMxzhaR+0Yiy8k= DKIM-Signature: v=1; a=ed25519-sha256; c=relaxed/relaxed; d=suse.de; s=susede2_ed25519; t=1778745619; h=from:from:reply-to:date:date:message-id:message-id:to:to:cc:cc: mime-version:mime-version:content-type:content-type: in-reply-to:in-reply-to:references:references; bh=0ApyV1SJgz5wtbwoXbn/VnkSAGGIM5s57P85+2beKro=; b=C4248gcxLcOZ45VZ6Xk2Ku4O2ABnN9dD5IGpb7ZAPZEdfu+e2hfvYKSUMmGYh5vpD4fT12 zLyXzyaJCm0GMMAA== Received: from imap1.dmz-prg2.suse.org (localhost [127.0.0.1]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (4096 bits) server-digest SHA256) (No client certificate requested) by imap1.dmz-prg2.suse.org (Postfix) with ESMTPS id D86D3593AA; Thu, 14 May 2026 08:00:18 +0000 (UTC) Received: from dovecot-director2.suse.de ([2a07:de40:b281:106:10:150:64:167]) by imap1.dmz-prg2.suse.org with ESMTPSA id 4xHQMhKBBWr/DQAAD6G6ig (envelope-from ); Thu, 14 May 2026 08:00:18 +0000 Date: Thu, 14 May 2026 10:00:17 +0200 From: Oscar Salvador To: Muchun Song Cc: Andrew Morton , David Hildenbrand , Muchun Song , Michael Ellerman , Madhavan Srinivasan , Lorenzo Stoakes , "Liam R . Howlett" , Vlastimil Babka , Mike Rapoport , Suren Baghdasaryan , Michal Hocko , Nicholas Piggin , Christophe Leroy , Ackerley Tng , Frank van der Linden , aneesh.kumar@linux.ibm.com, joao.m.martins@oracle.com, linux-mm@kvack.org, linuxppc-dev@lists.ozlabs.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH v2 03/69] powerpc/mm: Fix wrong addr_pfn tracking in compound vmemmap population Message-ID: References: <20260513130542.35604-1-songmuchun@bytedance.com> <20260513130542.35604-4-songmuchun@bytedance.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20260513130542.35604-4-songmuchun@bytedance.com> X-Rspamd-Server: rspam11 X-Rspamd-Queue-Id: 289B41A0012 X-Stat-Signature: b9p9oerop3qkx1p133j1nzbd9etnhqjp X-Rspam-User: X-HE-Tag: 1778745620-47517 X-HE-Meta: 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 CC/9RrHq wrjwU9xWXTAFc69y8AP5q+b8EsMErodr6/49JE+TdgZOtCSiD3vcOuvCytKTDpz7p3Km2e5u5XwRGZMZE6oIRQKV2zTcT3oLY9pGxCrK9rHyssNoljVszmyaJqsEKNIqzsVGOsB6DHIueJRxzXssQQ4zb5sEFacUHkHW3XzsjjrBbJhIIERsyaFsxWdB8Kd+EmZVC+n2zBeeOGdItwzV5dHpp6qBMzZnO/o8ltiaJcE0xmlqgoWWpG/y8MTxdzxxS3zExLFODwz8OsJYsiX9e0gTrFLdSr8zeAAYODuTdYnHRv2dNr5HYdkKlCBT4CmmxBlklQovSdENt7VE= Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On Wed, May 13, 2026 at 09:04:31PM +0800, Muchun Song wrote: > vmemmap_populate_compound_pages() uses addr_pfn to determine the PFN > offset within a compound page and to decide whether the current > vmemmap slot should be populated as a head page mapping or should reuse > a tail page mapping. > > However, addr_pfn is advanced manually in parallel with addr. The loop > itself progresses in vmemmap address space, so each PAGE_SIZE step in > addr covers PAGE_SIZE / sizeof(struct page) struct page slots. Since > addr_pfn is compared against nr_pages in data-PFN units, it should > advance by the same number of PFNs. The existing manual increments do > not match that and therefore do not reliably track the PFN > corresponding to the current addr. > > As a result, pfn_offset can be computed from the wrong PFN and the code > can make the head/tail decision for the wrong compound-page position. > > Fix this by deriving addr_pfn directly from the current vmemmap address > instead of carrying it as loop state. > > Fixes: f2b79c0d7968 ("powerpc/book3s64/radix: add support for vmemmap optimization for radix") > Signed-off-by: Muchun Song Acked-by: Oscar Salvador -- Oscar Salvador SUSE Labs