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 23267C982D4 for ; Fri, 16 Jan 2026 16:07:16 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id 558FF6B0098; Fri, 16 Jan 2026 11:07:15 -0500 (EST) Received: by kanga.kvack.org (Postfix, from userid 40) id 4F3BC6B0099; Fri, 16 Jan 2026 11:07:15 -0500 (EST) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 3B3BF6B009D; Fri, 16 Jan 2026 11:07:15 -0500 (EST) 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 284466B0098 for ; Fri, 16 Jan 2026 11:07:15 -0500 (EST) Received: from smtpin20.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay10.hostedemail.com (Postfix) with ESMTP id C1CDEC0A65 for ; Fri, 16 Jan 2026 16:07:14 +0000 (UTC) X-FDA: 84338306388.20.08959F7 Received: from smtp-out2.suse.de (smtp-out2.suse.de [195.135.223.131]) by imf14.hostedemail.com (Postfix) with ESMTP id 59A4E100018 for ; Fri, 16 Jan 2026 16:07:12 +0000 (UTC) Authentication-Results: imf14.hostedemail.com; spf=pass (imf14.hostedemail.com: domain of vbabka@suse.cz designates 195.135.223.131 as permitted sender) smtp.mailfrom=vbabka@suse.cz ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1768579632; 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; bh=c7Vh2c/n2mDZGXXGDz0nxbDwSrlvvd34frJi0zzgXSw=; b=XVSmIjJeuHJTKqhezKX9svEImY3i/pm//QWwV5gTDr9cJE1Ad5hoJUh7oih+BErOW17KNV Np5UmW8EfXfDNPg9juIDRBK+LQLggGWBeWajkg8Eir/j7oMu2cZvpqDRv3VJN5z3Q+rjIZ wJORD6czzwH8k180Q8rXisvvFWocHnw= ARC-Authentication-Results: i=1; imf14.hostedemail.com; dkim=none; spf=pass (imf14.hostedemail.com: domain of vbabka@suse.cz designates 195.135.223.131 as permitted sender) smtp.mailfrom=vbabka@suse.cz; dmarc=none ARC-Seal: i=1; s=arc-20220608; d=hostedemail.com; t=1768579632; a=rsa-sha256; cv=none; b=gb2/7HMsao3I35DbW1Af8D7ebampXCSLHRZQwVK0WIrRbeBzkQjQD1GrMrENL6djNuvuVJ b8Rp8YDPOO6/P3/eOLQ2fFgBhNhmdFlT0Nr0ssklZ7Z2z7wUNXXowyynas64B4oO8oEqvg im3wqv3LUNYDUd1PP43kH86i6bjfjL0= Received: from imap1.dmz-prg2.suse.org (imap1.dmz-prg2.suse.org [IPv6:2a07:de40:b281:104:10:150:64:97]) (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-out2.suse.de (Postfix) with ESMTPS id B10535BE17; Fri, 16 Jan 2026 16:07:10 +0000 (UTC) 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 53CDC3EA63; Fri, 16 Jan 2026 16:07:10 +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 ympjEi5iamn6TgAAD6G6ig (envelope-from ); Fri, 16 Jan 2026 16:07:10 +0000 Message-ID: Date: Fri, 16 Jan 2026 17:07:09 +0100 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v6 1/5] mm/zone_device: Reinitialize large zone device private folios Content-Language: en-US To: Francois Dugast , intel-xe@lists.freedesktop.org Cc: dri-devel@lists.freedesktop.org, Matthew Brost , Zi Yan , Alistair Popple , adhavan Srinivasan , Nicholas Piggin , Michael Ellerman , "Christophe Leroy (CS GROUP)" , Felix Kuehling , Alex Deucher , =?UTF-8?Q?Christian_K=C3=B6nig?= , David Airlie , Simona Vetter , Maarten Lankhorst , Maxime Ripard , Thomas Zimmermann , Lyude Paul , Danilo Krummrich , David Hildenbrand , Oscar Salvador , Andrew Morton , Jason Gunthorpe , Leon Romanovsky , Lorenzo Stoakes , "Liam R . Howlett" , Mike Rapoport , Suren Baghdasaryan , Michal Hocko , Balbir Singh , linuxppc-dev@lists.ozlabs.org, kvm@vger.kernel.org, linux-kernel@vger.kernel.org, amd-gfx@lists.freedesktop.org, nouveau@lists.freedesktop.org, linux-mm@kvack.org, linux-cxl@vger.kernel.org References: <20260116111325.1736137-1-francois.dugast@intel.com> <20260116111325.1736137-2-francois.dugast@intel.com> From: Vlastimil Babka Autocrypt: addr=vbabka@suse.cz; keydata= xsFNBFZdmxYBEADsw/SiUSjB0dM+vSh95UkgcHjzEVBlby/Fg+g42O7LAEkCYXi/vvq31JTB KxRWDHX0R2tgpFDXHnzZcQywawu8eSq0LxzxFNYMvtB7sV1pxYwej2qx9B75qW2plBs+7+YB 87tMFA+u+L4Z5xAzIimfLD5EKC56kJ1CsXlM8S/LHcmdD9Ctkn3trYDNnat0eoAcfPIP2OZ+ 9oe9IF/R28zmh0ifLXyJQQz5ofdj4bPf8ecEW0rhcqHfTD8k4yK0xxt3xW+6Exqp9n9bydiy tcSAw/TahjW6yrA+6JhSBv1v2tIm+itQc073zjSX8OFL51qQVzRFr7H2UQG33lw2QrvHRXqD Ot7ViKam7v0Ho9wEWiQOOZlHItOOXFphWb2yq3nzrKe45oWoSgkxKb97MVsQ+q2SYjJRBBH4 8qKhphADYxkIP6yut/eaj9ImvRUZZRi0DTc8xfnvHGTjKbJzC2xpFcY0DQbZzuwsIZ8OPJCc LM4S7mT25NE5kUTG/TKQCk922vRdGVMoLA7dIQrgXnRXtyT61sg8PG4wcfOnuWf8577aXP1x 6mzw3/jh3F+oSBHb/GcLC7mvWreJifUL2gEdssGfXhGWBo6zLS3qhgtwjay0Jl+kza1lo+Cv BB2T79D4WGdDuVa4eOrQ02TxqGN7G0Biz5ZLRSFzQSQwLn8fbwARAQABzSBWbGFzdGltaWwg QmFia2EgPHZiYWJrYUBzdXNlLmN6PsLBlAQTAQoAPgIbAwULCQgHAwUVCgkICwUWAgMBAAIe AQIXgBYhBKlA1DSZLC6OmRA9UCJPp+fMgqZkBQJnyBr8BQka0IFQAAoJECJPp+fMgqZkqmMQ AIbGN95ptUMUvo6aAdhxaOCHXp1DfIBuIOK/zpx8ylY4pOwu3GRe4dQ8u4XS9gaZ96Gj4bC+ jwWcSmn+TjtKW3rH1dRKopvC07tSJIGGVyw7ieV/5cbFffA8NL0ILowzVg8w1ipnz1VTkWDr 2zcfslxJsJ6vhXw5/npcY0ldeC1E8f6UUoa4eyoskd70vO0wOAoGd02ZkJoox3F5ODM0kjHu Y97VLOa3GG66lh+ZEelVZEujHfKceCw9G3PMvEzyLFbXvSOigZQMdKzQ8D/OChwqig8wFBmV QCPS4yDdmZP3oeDHRjJ9jvMUKoYODiNKsl2F+xXwyRM2qoKRqFlhCn4usVd1+wmv9iLV8nPs 2Db1ZIa49fJet3Sk3PN4bV1rAPuWvtbuTBN39Q/6MgkLTYHb84HyFKw14Rqe5YorrBLbF3rl M51Dpf6Egu1yTJDHCTEwePWug4XI11FT8lK0LNnHNpbhTCYRjX73iWOnFraJNcURld1jL1nV r/LRD+/e2gNtSTPK0Qkon6HcOBZnxRoqtazTU6YQRmGlT0v+rukj/cn5sToYibWLn+RoV1CE Qj6tApOiHBkpEsCzHGu+iDQ1WT0Idtdynst738f/uCeCMkdRu4WMZjteQaqvARFwCy3P/jpK uvzMtves5HvZw33ZwOtMCgbpce00DaET4y/UzsBNBFsZNTUBCACfQfpSsWJZyi+SHoRdVyX5 J6rI7okc4+b571a7RXD5UhS9dlVRVVAtrU9ANSLqPTQKGVxHrqD39XSw8hxK61pw8p90pg4G /N3iuWEvyt+t0SxDDkClnGsDyRhlUyEWYFEoBrrCizbmahOUwqkJbNMfzj5Y7n7OIJOxNRkB IBOjPdF26dMP69BwePQao1M8Acrrex9sAHYjQGyVmReRjVEtv9iG4DoTsnIR3amKVk6si4Ea X/mrapJqSCcBUVYUFH8M7bsm4CSxier5ofy8jTEa/CfvkqpKThTMCQPNZKY7hke5qEq1CBk2 wxhX48ZrJEFf1v3NuV3OimgsF2odzieNABEBAAHCwXwEGAEKACYCGwwWIQSpQNQ0mSwujpkQ PVAiT6fnzIKmZAUCZ8gcVAUJFhTonwAKCRAiT6fnzIKmZLY8D/9uo3Ut9yi2YCuASWxr7QQZ lJCViArjymbxYB5NdOeC50/0gnhK4pgdHlE2MdwF6o34x7TPFGpjNFvycZqccSQPJ/gibwNA zx3q9vJT4Vw+YbiyS53iSBLXMweeVV1Jd9IjAoL+EqB0cbxoFXvnjkvP1foiiF5r73jCd4PR rD+GoX5BZ7AZmFYmuJYBm28STM2NA6LhT0X+2su16f/HtummENKcMwom0hNu3MBNPUOrujtW khQrWcJNAAsy4yMoJ2Lw51T/5X5Hc7jQ9da9fyqu+phqlVtn70qpPvgWy4HRhr25fCAEXZDp xG4RNmTm+pqorHOqhBkI7wA7P/nyPo7ZEc3L+ZkQ37u0nlOyrjbNUniPGxPxv1imVq8IyycG AN5FaFxtiELK22gvudghLJaDiRBhn8/AhXc642/Z/yIpizE2xG4KU4AXzb6C+o7LX/WmmsWP Ly6jamSg6tvrdo4/e87lUedEqCtrp2o1xpn5zongf6cQkaLZKQcBQnPmgHO5OG8+50u88D9I rywqgzTUhHFKKF6/9L/lYtrNcHU8Z6Y4Ju/MLUiNYkmtrGIMnkjKCiRqlRrZE/v5YFHbayRD dJKXobXTtCBYpLJM4ZYRpGZXne/FAtWNe4KbNJJqxMvrTOrnIatPj8NhBVI0RSJRsbilh6TE m6M14QORSWTLRg== In-Reply-To: <20260116111325.1736137-2-francois.dugast@intel.com> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit X-Rspamd-Pre-Result: action=no action; module=replies; Message is reply to one we originated X-Rspamd-Pre-Result: action=no action; module=replies; Message is reply to one we originated X-Rspamd-Action: no action X-Rspam-User: X-Rspamd-Server: rspam07 X-Rspamd-Queue-Id: 59A4E100018 X-Stat-Signature: wjyoc9fm6o8jfbn13rboug8ipujbk3yj X-HE-Tag: 1768579632-408432 X-HE-Meta: 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 BwOO5eFv ZfR/EhesijQ1kq/9JucLIwWYcTxJI/XM0hQN1nXRXQRho+vX9QD5ApAE2cTC+GYkqjaE9gOVsWOWldqSs1ez4MCFD9votI0ouIwn1hc/KOvZ7j0QdUvBxrED6Y4mRhQvOh+lh1GnPRguO8vkmKuS+eS38PpkymiodbcMLhKlsyI/r+md6KbJ1AfwkiSgIW+gy4RaU 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: List-Subscribe: List-Unsubscribe: On 1/16/26 12:10, Francois Dugast wrote: > From: Matthew Brost > diff --git a/mm/memremap.c b/mm/memremap.c > index 63c6ab4fdf08..ac7be07e3361 100644 > --- a/mm/memremap.c > +++ b/mm/memremap.c > @@ -477,10 +477,43 @@ void free_zone_device_folio(struct folio *folio) > } > } > > -void zone_device_page_init(struct page *page, unsigned int order) > +void zone_device_page_init(struct page *page, struct dev_pagemap *pgmap, > + unsigned int order) > { > + struct page *new_page = page; > + unsigned int i; > + > VM_WARN_ON_ONCE(order > MAX_ORDER_NR_PAGES); > > + for (i = 0; i < (1UL << order); ++i, ++new_page) { > + struct folio *new_folio = (struct folio *)new_page; > + > + /* > + * new_page could have been part of previous higher order folio > + * which encodes the order, in page + 1, in the flags bits. We > + * blindly clear bits which could have set my order field here, > + * including page head. > + */ > + new_page->flags.f &= ~0xffUL; /* Clear possible order, page head */ > + > +#ifdef NR_PAGES_IN_LARGE_FOLIO > + /* > + * This pointer math looks odd, but new_page could have been > + * part of a previous higher order folio, which sets _nr_pages > + * in page + 1 (new_page). Therefore, we use pointer casting to > + * correctly locate the _nr_pages bits within new_page which > + * could have modified by previous higher order folio. > + */ > + ((struct folio *)(new_page - 1))->_nr_pages = 0; > +#endif > + > + new_folio->mapping = NULL; > + new_folio->pgmap = pgmap; /* Also clear compound head */ > + new_folio->share = 0; /* fsdax only, unused for device private */ > + VM_WARN_ON_FOLIO(folio_ref_count(new_folio), new_folio); > + VM_WARN_ON_FOLIO(!folio_is_zone_device(new_folio), new_folio); > + } > + > /* > * Drivers shouldn't be allocating pages after calling > * memunmap_pages(). Can't say I'm a fan of this. It probably works now (so I'm not nacking) but seems rather fragile. It seems likely to me somebody will try to change some implementation detail in the page allocator and not notice it breaks this, for example. I hope we can eventually get to something more robust.