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imf13.hostedemail.com; dkim=pass header.d=kernel.org header.s=k20201202 header.b=Fu2UCV+t; spf=pass (imf13.hostedemail.com: domain of david@kernel.org designates 172.105.4.254 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=1770925902; a=rsa-sha256; cv=none; b=bLqQUnrS0GhqTPJtq5xD+IHsBW2WuJSQzmsTZduoOF1zVaFgz5PclXvtdMLhqDOQizjJA1 z+gaeCwpqBwSEd+HuuubaC3kbZWANqAXHwYOlwaVbNkxAgkk1/2KlsOcDcy5xfi3q4zvqS J5AI/swp2UXLgR68XsXDnDNnIXllgo4= Received: from smtp.kernel.org (transwarp.subspace.kernel.org [100.75.92.58]) by tor.source.kernel.org (Postfix) with ESMTP id 87EC06132E; Thu, 12 Feb 2026 19:51:41 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id A1138C19424; Thu, 12 Feb 2026 19:51:28 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1770925901; bh=ZGlUyowuJ/4IhUY0sQZKkJjYbYXoo0csOOP4hmRvPAg=; h=Date:Subject:To:Cc:References:From:In-Reply-To:From; b=Fu2UCV+tTzXaMHiosOBdTGAwWf2IhsIEijmp8dmTq06u07heLkC9cO9U4SLPg+L41 5kDBzKJRACdJrJk4emsWT5IeM6TShLLPOm/Srk3fcqFkxkitXoU1GffsUHFMDhiHZL F/a7DN5FHcza8ctSzBqf+Ji9HhDrbl81F06giV0kJVvZ7S7M+KfrtbJqB4KIUpve4z 5jiGNy+QLZ7Sco/XLsM5Hp2NvrBjLF1BK1c9ZtDui7bTxRg3Mp11to3rJpGs6eB7U5 roiBruCj9Gqo916l8+Py+01JWQqwzafZ2CrHnE/QddfSoHuH+MogfRK0LtDfACY2k6 rAU3BhXv/6j9w== Message-ID: <493d7898-c959-42ee-ad09-35ffc631ec21@kernel.org> Date: Thu, 12 Feb 2026 20:51:26 +0100 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH mm-unstable v1 3/5] mm/khugepaged: define COLLAPSE_MAX_PTES_LIMIT as HPAGE_PMD_NR - 1 To: Nico Pache , linux-kernel@vger.kernel.org, linux-mm@kvack.org Cc: 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: <20260212021835.17755-1-npache@redhat.com> <20260212021835.17755-4-npache@redhat.com> 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: <20260212021835.17755-4-npache@redhat.com> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit X-Rspam-User: X-Rspamd-Queue-Id: B37CC20005 X-Rspamd-Server: rspam07 X-Stat-Signature: ycza6f9p8zonnf57te6an4zkqyfy5akd X-HE-Tag: 1770925902-780971 X-HE-Meta: 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 /4I7THot g1QYXZ5qkUOxsdCb/i1/v/nvan+EkgJutY8WsVNUYHHX9uXcHy7buqZCLlRnWLYw55mf4d/pNKqNz8meLXsY9QjJH4E9FWb9T4Blfp+SE3BRJzVoCFRe6cP23N66UF3kW1wHLQpEPpZRzz70kkGtDzHYZtOTVV5qtk5nVPyL+oJCBh7a/097BsTXvAouPM/QOG3aAhPrZQmak9lGeoaRD6Q5QxpBGpPS2RWp27NqCVg13H1Q582fcBGwOquG5lC2rGTGpslIfOOoElU5rTskxCvWotLl7FP8jvRUddU+t/m1pLMCZDLdJAW24FHLT4QcMvTz5VVFdatzNsgY1qoEGFvOKV7+T2Wz6f+5F0H2oPmH6OazdKe+rUAxg674Q9y+gS2Ue7X/rgFmzB2s= 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 2/12/26 03:18, Nico Pache wrote: > The value (HPAGE_PMD_NR - 1) is used often in the khugepaged code to > signify the limit of the max_ptes_* values. Add a define for this to > increase code readability and reuse. > > Signed-off-by: Nico Pache > --- > mm/khugepaged.c | 15 ++++++++------- > 1 file changed, 8 insertions(+), 7 deletions(-) > > diff --git a/mm/khugepaged.c b/mm/khugepaged.c > index c362b3b2e08a..3dcce6018f20 100644 > --- a/mm/khugepaged.c > +++ b/mm/khugepaged.c > @@ -85,6 +85,7 @@ static DECLARE_WAIT_QUEUE_HEAD(khugepaged_wait); > * > * Note that these are only respected if collapse was initiated by khugepaged. > */ > +#define COLLAPSE_MAX_PTES_LIMIT (HPAGE_PMD_NR - 1) > unsigned int khugepaged_max_ptes_none __read_mostly; > static unsigned int khugepaged_max_ptes_swap __read_mostly; > static unsigned int khugepaged_max_ptes_shared __read_mostly; > @@ -252,7 +253,7 @@ static ssize_t max_ptes_none_store(struct kobject *kobj, > unsigned long max_ptes_none; > > err = kstrtoul(buf, 10, &max_ptes_none); > - if (err || max_ptes_none > HPAGE_PMD_NR - 1) > + if (err || max_ptes_none > COLLAPSE_MAX_PTES_LIMIT) > return -EINVAL; > > khugepaged_max_ptes_none = max_ptes_none; > @@ -277,7 +278,7 @@ static ssize_t max_ptes_swap_store(struct kobject *kobj, > unsigned long max_ptes_swap; > > err = kstrtoul(buf, 10, &max_ptes_swap); > - if (err || max_ptes_swap > HPAGE_PMD_NR - 1) > + if (err || max_ptes_swap > COLLAPSE_MAX_PTES_LIMIT) > return -EINVAL; > > khugepaged_max_ptes_swap = max_ptes_swap; > @@ -303,7 +304,7 @@ static ssize_t max_ptes_shared_store(struct kobject *kobj, > unsigned long max_ptes_shared; > > err = kstrtoul(buf, 10, &max_ptes_shared); > - if (err || max_ptes_shared > HPAGE_PMD_NR - 1) > + if (err || max_ptes_shared > COLLAPSE_MAX_PTES_LIMIT) > return -EINVAL; > > khugepaged_max_ptes_shared = max_ptes_shared; > @@ -384,7 +385,7 @@ int __init khugepaged_init(void) > return -ENOMEM; > > khugepaged_pages_to_scan = HPAGE_PMD_NR * 8; > - khugepaged_max_ptes_none = HPAGE_PMD_NR - 1; > + khugepaged_max_ptes_none = COLLAPSE_MAX_PTES_LIMIT; > khugepaged_max_ptes_swap = HPAGE_PMD_NR / 8; > khugepaged_max_ptes_shared = HPAGE_PMD_NR / 2; Changing these is ok. I don't like the name either. It should be clear that they all belong to the "khugepaged_max_ptes" * values. (see below) > > @@ -1869,7 +1870,7 @@ static enum scan_result collapse_file(struct mm_struct *mm, unsigned long addr, > bool is_shmem = shmem_file(file); > > VM_BUG_ON(!IS_ENABLED(CONFIG_READ_ONLY_THP_FOR_FS) && !is_shmem); > - VM_BUG_ON(start & (HPAGE_PMD_NR - 1)); > + VM_BUG_ON(start & (COLLAPSE_MAX_PTES_LIMIT)); > > result = alloc_charge_folio(&new_folio, mm, cc); > if (result != SCAN_SUCCEED) > @@ -2209,7 +2210,7 @@ static enum scan_result collapse_file(struct mm_struct *mm, unsigned long addr, > * unwritten page. > */ > folio_mark_uptodate(new_folio); > - folio_ref_add(new_folio, HPAGE_PMD_NR - 1); > + folio_ref_add(new_folio, COLLAPSE_MAX_PTES_LIMIT); > > if (is_shmem) > folio_mark_dirty(new_folio); > @@ -2303,7 +2304,7 @@ static enum scan_result hpage_collapse_scan_file(struct mm_struct *mm, unsigned > memset(cc->node_load, 0, sizeof(cc->node_load)); > nodes_clear(cc->alloc_nmask); > rcu_read_lock(); > - xas_for_each(&xas, folio, start + HPAGE_PMD_NR - 1) { > + xas_for_each(&xas, folio, start + COLLAPSE_MAX_PTES_LIMIT) { > if (xas_retry(&xas, folio)) > continue; > Changing these is not. They are semantically something different. E.g., folio_ref_add() adds "HPAGE_PMD_NR - 1" because we already obtained a reference, and we need one per page -- HPAGE_PMD_NR. So it's something different than when messing with the magical khugepaged_max_ptes_none values. -- Cheers, David