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 7BBF0C43458 for ; Fri, 10 Jul 2026 14:45:41 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id 5F0036B00A6; Fri, 10 Jul 2026 10:45:40 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 5A0B46B00A7; Fri, 10 Jul 2026 10:45:40 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 4916E6B00A9; Fri, 10 Jul 2026 10:45:40 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0012.hostedemail.com [216.40.44.12]) by kanga.kvack.org (Postfix) with ESMTP id 0FE096B00A6 for ; Fri, 10 Jul 2026 10:45:40 -0400 (EDT) Received: from smtpin19.hostedemail.com (lb01a-stub [10.200.18.249]) by unirelay03.hostedemail.com (Postfix) with ESMTP id 8F62DA047F for ; Fri, 10 Jul 2026 14:45:39 +0000 (UTC) X-FDA: 84973140798.19.EAF5AE5 Received: from sea.source.kernel.org (sea.source.kernel.org [172.234.252.31]) by imf07.hostedemail.com (Postfix) with ESMTP id BFAF740014 for ; Fri, 10 Jul 2026 14:45:37 +0000 (UTC) Authentication-Results: imf07.hostedemail.com; dkim=pass header.d=kernel.org header.s=k20260515 header.b=ZfJIw52t; spf=pass (imf07.hostedemail.com: domain of david@kernel.org designates 172.234.252.31 as permitted sender) smtp.mailfrom=david@kernel.org; dmarc=pass (policy=quarantine) header.from=kernel.org ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1783694737; 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=MUJmReX//1mrcIJ16GPEOQBodF0W4wFoWOp7JURewLU=; b=Z+vpijwOKkNzLwIFP51iOYOpupu/ptB3tyc6dfbsy4LuPnGPG4p9Je7VHgZTA85yj9tyvC CzO+xuLZbFSE1B1RzxHE2a/Y5s2WqmvSYKfCmksoP89jex4xTvGjITksGYcIK1TnhcyL70 RsGQDEnNr5aV1cc4NnuNER82THahOGY= ARC-Authentication-Results: i=1; imf07.hostedemail.com; dkim=pass header.d=kernel.org header.s=k20260515 header.b=ZfJIw52t; spf=pass (imf07.hostedemail.com: domain of david@kernel.org designates 172.234.252.31 as permitted sender) smtp.mailfrom=david@kernel.org; dmarc=pass (policy=quarantine) header.from=kernel.org ARC-Seal: i=1; a=rsa-sha256; d=hostedemail.com; s=arc-20220608; cv=none; t=1783694737; b=LeohAWcvqdNKOPO6ueIGE6jH+zgXmMfX/tuYcqx+jb8DxbXBTJnpoMbcmkP5/dSy9Zotvh xq7MZD7wlOSJ/T6PbkVkh/7M1HMzJMDxKkvnuFlgXQmC36O8QPnbdoG9F3dkG4c5caLya5 sQ1blSy44spHX14kmOLtbpbTg0CglZA= Received: from smtp.kernel.org (quasi.space.kernel.org [100.103.45.18]) by sea.source.kernel.org (Postfix) with ESMTP id AF56C43CF4; Fri, 10 Jul 2026 14:45:36 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 52F861F000E9; Fri, 10 Jul 2026 14:45:33 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1783694736; bh=MUJmReX//1mrcIJ16GPEOQBodF0W4wFoWOp7JURewLU=; h=Date:Subject:To:Cc:References:From:In-Reply-To; b=ZfJIw52t0KXkXY5nQiQeJDMPiHsL8aO0tbO+K2a5PaiTIYOJIGawQwSus9MWR+8mo zcyoSr54fcF8jv4K25j4hGXzgzmbKnB1Xa46w220/9AcvjrnYfZ2VPHm3ah9Zj716r 7Cq9KsvPMa/sXXzzGJ8UFLY9eWCwy0c0Yofke7snybalqA0a+qa0K/hMIkWEv9U/Vn rceJVoqsjvM5KF+ipsVzMx1VW2LbhY6m+mI99T8UeKD+6vFBifiIOXN5kgnlfcZ+e+ HdpeFTOB1QqjzJR/SpKi/YRTneJ7akJ1fcTMtxLDa65G6n8pmmFrBJaNJSrN8XWEfg CeRwUPZOw/Yug== Message-ID: <9210ef86-3131-464b-93e7-336420d894d9@kernel.org> Date: Fri, 10 Jul 2026 16:45:31 +0200 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH] mm/page_alloc: free allocated PFNs if the range does not match To: Zi Yan , "Vlastimil Babka (SUSE)" , Andrew Morton , Suren Baghdasaryan , Michal Hocko , Brendan Jackman , Johannes Weiner , Lorenzo Stoakes , "Liam R. Howlett" , Mike Rapoport , Yu Zhao Cc: linux-mm@kvack.org, linux-kernel@vger.kernel.org, stable@vger.kernel.org References: <20260629-free-pfn-on-alloc-contig-range-error-path-v1-1-496ff9ca22db@nvidia.com> <4549ad0e-abb1-4156-95c6-5e3c1319dffe@kernel.org> 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: Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit X-Rspam-User: X-Rspamd-Server: rspam08 X-Rspamd-Queue-Id: BFAF740014 X-Stat-Signature: yn1irf4faxwiop4h56wzshgg8x9zsa84 X-HE-Tag: 1783694737-857330 X-HE-Meta: U2FsdGVkX18lWyqCQfErzJkmVR9QYCDlg6ZeRhldgqpX+G+WBsFaqDKaFfvDdmvxvJd/gsNlN132VFRI/4TvTiY37srHc32t5NSTvf5icD3C7ppLnvboY6kCrQXRldtRF40yJmi89PBbsvaPDH6YZUXcTS4WCdJ/ZD7CYfRBfsehdo+iVknGJvRZxI4HyQ7LkVz7RjKyy6G0ueSetZ+b6pQiTPfS1zOotreKhQ0M4QrBu1q6wsvygWhi4RtIv3ZzOjpx8gNKm8bjf8lSRm4t0AGiNCGAw82u4QLctughci2Y7lW0ZisGKl9s57MPrHbIuLDJ+vemEb78we30uAUITP6ItLX4UwOVsECK4fg/gzYjJQRKY+4ahUq+rflIDyXHDtgetGSOAAX6XD+R7FrEqFxNhDfWynbRQiJJf2k2YFH6etDfjRrprhafftLnKdgVRy05KPvu/a0zIufQ/9JTLNy8mPHEDp+v5xjrpeuNjzAGOXRSePNW7wp6jhkmaZ1e7XD7u7MZgS+aXqMsmdr3Tav0VQgsVtZsjM0Y5NAY7K4stOpjK6iFMotgjrAM8ceT5wO8+Fa6nNYrp+3Ys0nrvUpVMM44MCn/rujZUvAv8df4SCtH51Cl6JWHjR3+KvnnNBOK+SzeEwOjvlmKKt1Sa8eP9UWfZmJKRL3Ni/TVnW9j97e2pTAtgkwQg0gVDvbfqFtNJBF9k3r1jTmeXPntfZn2OOeuJxqiZCayzwY/woibZi/CFzW/fgEazffq20aTRGuzLt20tWIHHNq+JqGY1gAynmr+DQJgKOEXnMreOk37y41yhGQmws+uvYnB0cEpwX8sIkiqQNYXuu/gwQIcGoE/6gTZmFlBect3q/v5B8ovHaym+ELp6aAGBB+qWtnH7w2H81soAg2mSDFEwzhJOaEcy+JViNlum9NjqOCt7GWk85YXJbOPJx6d75h8tmY+iIuSyHWy3XpDEd/tkp6 kkrjmg0l KVj4Qk+ysdxyMYiFTsPIeEdiMOqKvvZqgmJt4Vr6sr7o4HI/Sxj4fX8ICQsOZbRJh+wxOGH87NS0eTg0pq/cqmgE+ipudvloHhA0UvYHOj7UGyzIsBmMVvW6nW/9KkWeErkXGXOF3lQ/8B1HpFjB/1+sXx/0I4iE6K6/lc98vEmzQG3XnrY8xHJKKeetkEKLchILAY7Hy2jK41jUhd593at9FmXMslWMi18vWR/vECsYGgVmncdxlby7Noj0cZvGEVZDR681i+NmzAt9aHlLeOXv0WcJo6FzXZDo1javxGZ8bQ/UGU7b4pHHM9xhk0zy9HlIV83w08JB/5WM= Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On 6/30/26 17:06, Zi Yan wrote: > On Tue Jun 30, 2026 at 9:39 AM EDT, David Hildenbrand (Arm) wrote: >> On 6/30/26 09:44, Vlastimil Babka (SUSE) wrote: >>> >>> So this? >>> Reported-by: Sashiko >>> >>> >>> Hm well, it's a path that warns, can only happen due to a development error? >>> Not sure we care about stable then. Anyway. >>> >> >> If someone would run into the WARN we would already be in Fixes: territory. >> >> it's a path that should never be executed. If it does, the real issue must be fixed. >> >> So (a) I don't think this is stable material (b) I am skeptical that this is >> even a Fixes and (c) I am wondering whether we should touch this *at all*. >> >> :) > > I looked at the code again and agree with you that the code is not > reachable and the fix should not be in the WARN path. Theoretically, if > order = ilog2(end - start) is smaller than MAX_PAGE_ORDER, > find_large_buddy() can return an outer_start smaller than start, leading > to this WARN path. But currently alloc_contig_frozen_range() with > __GFP_COMP is used by gigantic hugetlb, thus that is not possible. > > How about > 1. making sure order is bigger or equal to MAX_PAGE_ORDER, Makes sense. As you say, hugetlb doesn't need something smaller. > 2. adding a comment in the WARN path to prevent someone else trying to > fix WARN path if Sashiko reports this again Agreed. -- Cheers, David