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 52922109B46D for ; Tue, 31 Mar 2026 14:13:47 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id B931C6B0098; Tue, 31 Mar 2026 10:13:46 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id B6A376B0099; Tue, 31 Mar 2026 10:13:46 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id A87116B009B; Tue, 31 Mar 2026 10:13:46 -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 98D6E6B0098 for ; Tue, 31 Mar 2026 10:13:46 -0400 (EDT) Received: from smtpin28.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay01.hostedemail.com (Postfix) with ESMTP id 40F3BE03EC for ; Tue, 31 Mar 2026 14:13:46 +0000 (UTC) X-FDA: 84606551652.28.4C770B8 Received: from sea.source.kernel.org (sea.source.kernel.org [172.234.252.31]) by imf24.hostedemail.com (Postfix) with ESMTP id 64D4C180014 for ; Tue, 31 Mar 2026 14:13:44 +0000 (UTC) Authentication-Results: imf24.hostedemail.com; dkim=pass header.d=kernel.org header.s=k20201202 header.b=CovphkuT; spf=pass (imf24.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; s=arc-20220608; d=hostedemail.com; t=1774966424; a=rsa-sha256; cv=none; b=U7LzZRv/lYI6p20H/DAnkZNluNa3L+s+LJ84Q5zQBMIxufQHoTRwYoAEfIWk8tJCalP6S1 O8ZSVw21CmSIxRHXA7Z+6QG0+67Vyx+AKtRUqg00A476tXPYjYFNHliswG3ceCfMN8N48f yE7ODbCHjXiQtOC2+wSjDM7kq/2TIRg= ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1774966424; 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=JYDw+yPtv+fFP79QWo0MHLGK5KgDpRYehF25TaqMfzI=; b=vh2cmZyHy8AMaTw/lDWWmGUBsT5aKdFOjOZBo8TJxETZINkTLdHorATt82+Fb3DjY3zsbZ eIr0g8V0fix+TRnDialkZ7K0ZJNJO0FJt3w0UGTBswk5K6U0/Adqge0DpcNsXuuY8f9+3t 0Dopn/Iq5rOOTb7Iu7RJOhoyCAMA9ac= ARC-Authentication-Results: i=1; imf24.hostedemail.com; dkim=pass header.d=kernel.org header.s=k20201202 header.b=CovphkuT; spf=pass (imf24.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 Received: from smtp.kernel.org (transwarp.subspace.kernel.org [100.75.92.58]) by sea.source.kernel.org (Postfix) with ESMTP id 576A443856; Tue, 31 Mar 2026 14:13:43 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 383F1C19423; Tue, 31 Mar 2026 14:13:31 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1774966423; bh=GNemy5BN+CGFx1ZwGeM3VFL0of0Cf3xkUkABcfcUz64=; h=Date:Subject:To:Cc:References:From:In-Reply-To:From; b=CovphkuT1CwVRkGB7m0PrEwmP54yl6LImh92u3SL7qbbZPA5+9tBaJYj2qnS00A5g iC+Lu3RXlI7no/6ZK0c+6sQwndKKttgEh3w0EyG8vTIAS0fucIna1Txz9CGyjwdGKK 7qwjxCsYI25TNAHCLpuYenW0kCsUdb8BQCmBxCKM6UDo2xGHdZU7NwZ6Um0banwCbh qVgDMUv3lWPneRvrf3OZapuxILlOypvkUsl85vXr81PogJPRiLEiOPi0EApbqlAl46 yef/uApqF2re7OQzIwBMtBOEfZBpQcVowtJsXLUeSIyCWg5gw8Z6LHjwXRiR8NDljc 3RrdRd0TjYydQ== Message-ID: <0223d45b-e8b4-49a7-882b-477250d0c14d@kernel.org> Date: Tue, 31 Mar 2026 16:13:29 +0200 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH mm-unstable v4 5/5] mm/khugepaged: unify khugepaged and madv_collapse with collapse_single_pmd() To: "Lorenzo Stoakes (Oracle)" , Nico Pache Cc: linux-kernel@vger.kernel.org, linux-mm@kvack.org, aarcange@redhat.com, akpm@linux-foundation.org, anshuman.khandual@arm.com, apopple@nvidia.com, baohua@kernel.org, baolin.wang@linux.alibaba.com, byungchul@sk.com, catalin.marinas@arm.com, cl@gentwo.org, corbet@lwn.net, dave.hansen@linux.intel.com, dev.jain@arm.com, gourry@gourry.net, hannes@cmpxchg.org, hughd@google.com, jackmanb@google.com, jack@suse.cz, jannh@google.com, jglisse@google.com, joshua.hahnjy@gmail.com, kas@kernel.org, lance.yang@linux.dev, Liam.Howlett@oracle.com, lorenzo.stoakes@oracle.com, mathieu.desnoyers@efficios.com, matthew.brost@intel.com, mhiramat@kernel.org, mhocko@suse.com, peterx@redhat.com, pfalcato@suse.de, rakie.kim@sk.com, raquini@redhat.com, rdunlap@infradead.org, richard.weiyang@gmail.com, rientjes@google.com, rostedt@goodmis.org, rppt@kernel.org, ryan.roberts@arm.com, shivankg@amd.com, sunnanyong@huawei.com, surenb@google.com, thomas.hellstrom@linux.intel.com, tiwai@suse.de, usamaarif642@gmail.com, vbabka@suse.cz, vishal.moola@gmail.com, wangkefeng.wang@huawei.com, will@kernel.org, willy@infradead.org, yang@os.amperecomputing.com, ying.huang@linux.alibaba.com, ziy@nvidia.com, zokeefe@google.com References: <20260325114022.444081-1-npache@redhat.com> <20260325114022.444081-6-npache@redhat.com> <7760c811-e100-4d40-9217-0813c28314be@lucifer.local> 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: <7760c811-e100-4d40-9217-0813c28314be@lucifer.local> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit X-Rspam-User: X-Rspamd-Server: rspam11 X-Rspamd-Queue-Id: 64D4C180014 X-Stat-Signature: a43tod3akez1u6xd1t3t6g8fmnwh1ww7 X-HE-Tag: 1774966424-78137 X-HE-Meta: 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 lB9PSXnN Uezraqg7398eN4j3FwvZxolZHhZA+J19TCbfzu1C+JZSamjpbExNX5M5nbiCvIbZ8G0rW0cRZc7UAz0kOlC2A6hQii1j72wZPw3YxYNOnKa84PvhqvL4Sskzk80+atWKyEU6y/F9AEsPgAUAW1fP+LQqle6n1zjSq9wcSYEgfsQGKq+ZY1nzVLLO+pBy+1xy1zIF/Lsarq976t+AmCDy0PRQ3ZG2GN9pPqeIz9yEflJACOAcAxtUzqnxa+mAnAb+4lrvNK2YTxRmrV0fqEE6HXeYw+XprFzB5ToW4OzgFdqBmFXInQl5U3dBL07MsWSyJ0Sa6GRIFW8NXxMz4xh6NTz9HPVszdXZmF7GlDU/QUOwHXohfVVB20+AMAtT1Po9M5hgH7P6uJN7nqD7OeN6oWBhDgQ== Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: >> + if (*lock_dropped) { >> cond_resched(); >> mmap_read_lock(mm); >> - mmap_locked = true; >> + *lock_dropped = false; > > So this is the bug. 'lock_dropped' needs to record if the lock was _ever_ > dropped, not if it is _currently_ dropped. Ah, well spotted. I thought we discussed that at some point during review ... Thanks for tackling this! [...] > > ----8<---- > From a4dfc7718a15035449f344a0bc7f58e449366405 Mon Sep 17 00:00:00 2001 > From: "Lorenzo Stoakes (Oracle)" > Date: Tue, 31 Mar 2026 13:11:18 +0100 > Subject: [PATCH] mm/khugepaged: fix issue with tracking lock > > We are incorrectly treating lock_dropped to track both whether the lock is > currently held and whether or not the lock was ever dropped. > > Update this change to account for this. > > Signed-off-by: Lorenzo Stoakes (Oracle) > --- > mm/khugepaged.c | 12 ++++++++---- > 1 file changed, 8 insertions(+), 4 deletions(-) > > diff --git a/mm/khugepaged.c b/mm/khugepaged.c > index d21348b85a59..b8452dbdb043 100644 > --- a/mm/khugepaged.c > +++ b/mm/khugepaged.c > @@ -2828,6 +2828,7 @@ int madvise_collapse(struct vm_area_struct *vma, unsigned long start, > unsigned long hstart, hend, addr; > enum scan_result last_fail = SCAN_FAIL; > int thps = 0; > + bool mmap_unlocked = false; > > BUG_ON(vma->vm_start > start); > BUG_ON(vma->vm_end < end); > @@ -2850,10 +2851,11 @@ int madvise_collapse(struct vm_area_struct *vma, unsigned long start, > for (addr = hstart; addr < hend; addr += HPAGE_PMD_SIZE) { > enum scan_result result = SCAN_FAIL; > > - if (*lock_dropped) { > + if (mmap_unlocked) { > cond_resched(); > mmap_read_lock(mm); > - *lock_dropped = false; > + mmap_unlocked = false; > + *lock_dropped = true; > result = hugepage_vma_revalidate(mm, addr, false, &vma, > cc); > if (result != SCAN_SUCCEED) { > @@ -2864,7 +2866,7 @@ int madvise_collapse(struct vm_area_struct *vma, unsigned long start, (in hurry so I might be wrong) Do we have to handle when collapse_single_pmd() dropped the lock as well? -- Cheers, David