From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp-out2.suse.de (smtp-out2.suse.de [195.135.223.131]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id DF83E272E66 for ; Thu, 5 Jun 2025 13:54:44 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=195.135.223.131 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1749131686; cv=none; b=JzhvDd/HCHncmmm4G2EE7n8V1kU7glJI7jh5yEoVGRSnchcBwPxdq+7yBIk0pSdPS3n9byNcmw6wCHAg74DNw28az+wg7pC3/pI1jjztCQIk7D9BXvgOztizb8ry46omlvP5sjYkkuf7cDOMT4STtJ/UQl2BalJdvuDN1Hl7rdk= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1749131686; c=relaxed/simple; bh=szHUMyEagTRSGn6iHlytR5FiftCyOKdjnleqz8t9Yp4=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=tzIH8RISdPDtIjArahdJd7kMd0uhiXH+4D4QYNcI+BpOUWN9EJqb+8zl+BTL0lDBf8k6A1BuSGsUetTwIzcMgDyvT7YVoHnsLIVJFt3WkRSAHqwE2NAmWV7JSYOW0VJn6fb2t9vKZVrvdiFF8RcW1ZUlcFZJz7Yj8q84WlttwzA= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=suse.cz; spf=pass smtp.mailfrom=suse.cz; dkim=pass (1024-bit key) header.d=suse.cz header.i=@suse.cz header.b=jOw6czks; dkim=permerror (0-bit key) header.d=suse.cz header.i=@suse.cz header.b=0izkGtDf; dkim=pass (1024-bit key) header.d=suse.cz header.i=@suse.cz header.b=jOw6czks; dkim=permerror (0-bit key) header.d=suse.cz header.i=@suse.cz header.b=0izkGtDf; arc=none smtp.client-ip=195.135.223.131 Authentication-Results: smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=suse.cz Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=suse.cz Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=suse.cz header.i=@suse.cz header.b="jOw6czks"; dkim=permerror (0-bit key) header.d=suse.cz header.i=@suse.cz header.b="0izkGtDf"; dkim=pass (1024-bit key) header.d=suse.cz header.i=@suse.cz header.b="jOw6czks"; dkim=permerror (0-bit key) header.d=suse.cz header.i=@suse.cz header.b="0izkGtDf" 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 EA8801F78B; Thu, 5 Jun 2025 13:54:42 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=suse.cz; s=susede2_rsa; t=1749131683; h=from:from:reply-to: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:autocrypt:autocrypt; bh=8WI5cFL3G+D5a9ubaoXvIdIGlDQaUzuqFzuHKUXzaHI=; b=jOw6czksgFuuGqJI0hIeJM/FAECX2zcHRr6BxL2juTtlqhAVDnDmLIQuPA/HI8NNred1Kr AGYuegq4dfKko541WdMUt1ThrmJBr+Hd5R6iufuJDV8dJkoDQsK+qELljCAvo5Z0nE/con ltURVobC3u7vkrRahNuk7gF3+PCQ6No= DKIM-Signature: v=1; a=ed25519-sha256; c=relaxed/relaxed; d=suse.cz; s=susede2_ed25519; t=1749131683; h=from:from:reply-to: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:autocrypt:autocrypt; bh=8WI5cFL3G+D5a9ubaoXvIdIGlDQaUzuqFzuHKUXzaHI=; b=0izkGtDfYJAvv5In8NgQEGVwrUFX/Jjgga5bjO0cNNhYDKJAY4icVAPsO+7vwGM6VYipAr kzSni6VQHcTtepBw== Authentication-Results: smtp-out2.suse.de; dkim=pass header.d=suse.cz header.s=susede2_rsa header.b=jOw6czks; dkim=pass header.d=suse.cz header.s=susede2_ed25519 header.b=0izkGtDf DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=suse.cz; s=susede2_rsa; t=1749131683; h=from:from:reply-to: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:autocrypt:autocrypt; bh=8WI5cFL3G+D5a9ubaoXvIdIGlDQaUzuqFzuHKUXzaHI=; b=jOw6czksgFuuGqJI0hIeJM/FAECX2zcHRr6BxL2juTtlqhAVDnDmLIQuPA/HI8NNred1Kr AGYuegq4dfKko541WdMUt1ThrmJBr+Hd5R6iufuJDV8dJkoDQsK+qELljCAvo5Z0nE/con ltURVobC3u7vkrRahNuk7gF3+PCQ6No= DKIM-Signature: v=1; a=ed25519-sha256; c=relaxed/relaxed; d=suse.cz; s=susede2_ed25519; t=1749131683; h=from:from:reply-to: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:autocrypt:autocrypt; bh=8WI5cFL3G+D5a9ubaoXvIdIGlDQaUzuqFzuHKUXzaHI=; b=0izkGtDfYJAvv5In8NgQEGVwrUFX/Jjgga5bjO0cNNhYDKJAY4icVAPsO+7vwGM6VYipAr kzSni6VQHcTtepBw== 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 C214F137FE; Thu, 5 Jun 2025 13:54:42 +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 ni3WLqKhQWixOwAAD6G6ig (envelope-from ); Thu, 05 Jun 2025 13:54:42 +0000 Message-ID: <31d04f63-5595-48c6-adf1-675648a0c130@suse.cz> Date: Thu, 5 Jun 2025 15:54:42 +0200 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v3] mm/pagewalk: split walk_page_range_novma() into kernel/user parts Content-Language: en-US To: Lorenzo Stoakes , Andrew Morton Cc: Barry Song , David Hildenbrand , "Liam R . Howlett" , Mike Rapoport , Suren Baghdasaryan , Michal Hocko , Muchun Song , Oscar Salvador , Huacai Chen , WANG Xuerui , Jonas Bonn , Stefan Kristiansson , Stafford Horne , Paul Walmsley , Palmer Dabbelt , Albert Ou , Alexandre Ghiti , Jann Horn , loongarch@lists.linux.dev, linux-kernel@vger.kernel.org, linux-openrisc@vger.kernel.org, linux-riscv@lists.infradead.org, linux-mm@kvack.org References: <20250605135104.90720-1-lorenzo.stoakes@oracle.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: <20250605135104.90720-1-lorenzo.stoakes@oracle.com> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit X-Rspamd-Server: rspamd2.dmz-prg2.suse.org X-Rspamd-Queue-Id: EA8801F78B X-Rspamd-Action: no action X-Spam-Flag: NO X-Spamd-Result: default: False [-4.51 / 50.00]; BAYES_HAM(-3.00)[100.00%]; NEURAL_HAM_LONG(-1.00)[-1.000]; R_DKIM_ALLOW(-0.20)[suse.cz:s=susede2_rsa,suse.cz:s=susede2_ed25519]; NEURAL_HAM_SHORT(-0.20)[-1.000]; MIME_GOOD(-0.10)[text/plain]; MX_GOOD(-0.01)[]; RCVD_VIA_SMTP_AUTH(0.00)[]; RCPT_COUNT_TWELVE(0.00)[25]; MIME_TRACE(0.00)[0:+]; RCVD_TLS_ALL(0.00)[]; MID_RHS_MATCH_FROM(0.00)[]; ARC_NA(0.00)[]; FUZZY_BLOCKED(0.00)[rspamd.com]; FREEMAIL_ENVRCPT(0.00)[gmail.com]; DKIM_SIGNED(0.00)[suse.cz:s=susede2_rsa,suse.cz:s=susede2_ed25519]; FROM_EQ_ENVFROM(0.00)[]; FROM_HAS_DN(0.00)[]; FREEMAIL_CC(0.00)[kernel.org,redhat.com,oracle.com,google.com,suse.com,linux.dev,suse.de,xen0n.name,southpole.se,saunalahti.fi,gmail.com,sifive.com,dabbelt.com,eecs.berkeley.edu,ghiti.fr,lists.linux.dev,vger.kernel.org,lists.infradead.org,kvack.org]; TO_DN_SOME(0.00)[]; RCVD_COUNT_TWO(0.00)[2]; TO_MATCH_ENVRCPT_ALL(0.00)[]; DBL_BLOCKED_OPENRESOLVER(0.00)[imap1.dmz-prg2.suse.org:rdns,imap1.dmz-prg2.suse.org:helo,suse.cz:mid,suse.cz:dkim,suse.cz:email,suse.de:email]; SPAMHAUS_XBL(0.00)[2a07:de40:b281:104:10:150:64:97:from]; DKIM_TRACE(0.00)[suse.cz:+] X-Spam-Score: -4.51 X-Spam-Level: On 6/5/25 15:51, Lorenzo Stoakes wrote: > The walk_page_range_novma() function is rather confusing - it supports two > modes, one used often, the other used only for debugging. > > The first mode is the common case of traversal of kernel page tables, which > is what nearly all callers use this for. > > Secondly it provides an unusual debugging interface that allows for the > traversal of page tables in a userland range of memory even for that memory > which is not described by a VMA. > > It is far from certain that such page tables should even exist, but perhaps > this is precisely why it is useful as a debugging mechanism. > > As a result, this is utilised by ptdump only. Historically, things were > reversed - ptdump was the only user, and other parts of the kernel evolved > to use the kernel page table walking here. > > Since we have some complicated and confusing locking rules for the novma > case, it makes sense to separate the two usages into their own functions. > > Doing this also provide self-documentation as to the intent of the caller - > are they doing something rather unusual or are they simply doing a standard > kernel page table walk? > > We therefore establish two separate functions - walk_page_range_debug() for > this single usage, and walk_kernel_page_table_range() for general kernel > page table walking. > > The walk_page_range_debug() function is currently used to traverse both > userland and kernel mappings, so we maintain this and in the case of kernel > mappings being traversed, we have walk_page_range_debug() invoke > walk_kernel_page_table_range() internally. > > We additionally make walk_page_range_debug() internal to mm. > > Signed-off-by: Lorenzo Stoakes > Acked-by: Mike Rapoport (Microsoft) > Acked-by: Qi Zheng > Reviewed-by: Oscar Salvador > Reviewed-by: Suren Baghdasaryan Reviewed-by: Vlastimil Babka Thanks!