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 41932CA600B for ; Thu, 8 Oct 2026 11:53:09 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id DCE476B008A; Thu, 8 Oct 2026 07:53:07 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id D7F326B008C; Thu, 8 Oct 2026 07:53:07 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id C463E6B0092; Thu, 8 Oct 2026 07:53:07 -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 9FF216B008A for ; Thu, 8 Oct 2026 07:53:07 -0400 (EDT) Received: from smtpin09.hostedemail.com (lb01a-stub [10.200.18.249]) by unirelay03.hostedemail.com (Postfix) with ESMTP id 30A67A0111 for ; Thu, 8 Oct 2026 11:53:07 +0000 (UTC) X-FDA: 85299298014.09.7472FDD Received: from mta1.migadu.com (out-166.mta1.migadu.com [95.215.58.166]) by imf28.hostedemail.com (Postfix) with ESMTP id A18C1C0006 for ; Thu, 8 Oct 2026 11:53:03 +0000 (UTC) Authentication-Results: imf28.hostedemail.com; dkim=pass header.d=linux.dev header.s=key1 header.b=duuf7Jai; spf=pass (imf28.hostedemail.com: domain of zenghui.yu@linux.dev designates 95.215.58.166 as permitted sender) smtp.mailfrom=zenghui.yu@linux.dev; dmarc=pass (policy=none) header.from=linux.dev ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1791460384; 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=d9k9xlGFI1uVXvB7M3niJjgNuYSwmZd2EOoeeLUBHyc=; b=wxIXm9qj9+AtqF2/YdHn+tKlAjFlU+G5aasZuYyGsO8crsnpJ6QIKcNzwCLFhS2XyG1cb4 ZP60mNivYP2+H+jrYqa0XjvK6ZxHajXuRsx3AdbKGnAChwIb/n3WpTKp3+eSvCad3yxMFp N1LaG6KziQFhiQAvrYuIFRlwaezgoYA= ARC-Seal: i=1; a=rsa-sha256; d=hostedemail.com; s=arc-20220608; cv=none; t=1791460384; b=DOG4MqS2VcfuhQBnjVMul2+tGpz2vuMZzMDll5XTit5oBj3CILEpPPQYePvnHScK3JJPQY pqCQjonPYp9quMvrhj0ZNv7NruBrtenztd3t6F8NPL14iEFJgs3d4cCnK/keh72GTUDzmN jkXQE0YLia1whAMyGroCCjN9DYRTcSY= ARC-Authentication-Results: i=1; imf28.hostedemail.com; dkim=pass header.d=linux.dev header.s=key1 header.b=duuf7Jai; spf=pass (imf28.hostedemail.com: domain of zenghui.yu@linux.dev designates 95.215.58.166 as permitted sender) smtp.mailfrom=zenghui.yu@linux.dev; dmarc=pass (policy=none) header.from=linux.dev X-Envelope-To: linux-mm@kvack.org DKIM-Signature: a=rsa-sha256; bh=gMqeE0xl8Ovcpe/2DG1ldO6wSB1ZHK72dsybg+woYM4=; c=simple/simple; d=linux.dev; h=from:to:subject:date:message-id:mime-version:content-type; s=key1; t=1791460379; v=1; x=1792065179; b=duuf7Jaiw14bXnB2HwUVRL74r0/WvC48gV25qNvPEiOO2rqi1cDXdTb0Hcj/YguOu2JTntjv 5noCEKsS13uwVTvxRwDLeBgvw5L+pJ07ap+I7w3pvotIZQdJxu57YCMhUoJLpCmFzg+W3oB+cu5 M8AsySSD6eo2VW3BFvvnkPyA= X-Envelope-To: linux-mm@kvack.org Received: by smtp.migadu.com with ESMTPS id 51f5bb7d1a53d99c; Thu, 08 Oct 2026 11:52:58 +0000 X-Mizu-Trace-ID: 51f5bb7d1a53d99c X-Migadu-Flow: FLOW_OUT Message-ID: <5862cddb-a78f-419f-a5a1-15e16a422bf5@linux.dev> Date: Thu, 8 Oct 2026 19:52:18 +0800 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v6 02/19] selftests/mm: skip collapse_compound_extreme() where the PMD is too large To: Kiryl Shutsemau Cc: Andrew Morton , "David Hildenbrand (Arm)" , "Lorenzo Stoakes (ARM)" , Mike Rapoport , Baolin Wang , "Kiryl Shutsemau (Meta)" , linux-mm@kvack.org, linux-kselftest@vger.kernel.org, linux-kernel@vger.kernel.org, Muhammad Usama Anjum , Usama Arif , "Nico Pache (Red Hat)" , Zi Yan , Barry Song , Dev Jain , Hugh Dickins , Lance Yang , "Liam R. Howlett" , Michal Hocko , Ryan Roberts , Shuah Khan , Suren Baghdasaryan , "Vlastimil Babka (SUSE)" , Alexander Gordeev , Jason Gunthorpe , Leon Romanovsky , kernel-team@meta.com References: <20260919002451.496763-1-kirill@shutemov.name> <20260919002451.496763-3-kirill@shutemov.name> Content-Language: en-US From: Zenghui Yu In-Reply-To: <20260919002451.496763-3-kirill@shutemov.name> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit X-Rspamd-Queue-Id: A18C1C0006 X-Rspam-User: X-Rspamd-Server: rspam05 X-Stat-Signature: 67a87tgd8p6bzpqgc5csabdgjzauostj X-HE-Tag: 1791460383-8681 X-HE-Meta: U2FsdGVkX1+NFiTmKIEVI4yWXFmjWru6WbsgZu5i0sKqAHUB3SWNKRd+Efx3U2+6LJwyhymHNuqWzeSMxBJdQdvBiv1+VT7qgiXw4m6YWNrZR/d5bCsrJUwIA8tH5PJK5HGEgzeaVJkFGxgeZF7QP9/erPYkH1j4EtCvwAz72Rw7lyhG83Aso6RNaRGj5lTVRtSNC/LVpvRtDlN43AIPNbWCL3ku+FjVRerqhJ29D7585ULNoXRG4U3LMPpLvaPY4amdV8LZaoEX1iFyaH/tZFOy8n6iwqFq2S0ykZ49oFiFHyaIClSVRpgYvQDzHw44XdUHxXgOgwpPjP/b03pktzOHQRfhM7gq2ws0vywH+4zuxlkzSfyDRz+8aTIafmpirigxvEhEPEF0qQ02pEKEIP9JlUz8u0vymD8tD0qRaKYdVTVi3zk5xlqGYFY5bUugNPxquOngJrnlqCFE2K33gRM68RnRXt5pKg4VeqmKYtXOgO0u482fOOKR7tjM7ye49LxgYxZaLT236d8xn5vJJ00BTKvHHzdOOwcZxv3f6LihijIS/ofRD2+f0VfGgaDrGxZnFbfQGnix+WrIX0+TShICMNbF/aZtxqCpA3TdBLAkai24LZ33IAS5qrKS/uCMf3x3Tre7OzD8oBLLoya/Rity5+/PIPTRf183dXyE6cPwcL4pAY0Fq2RpR9+nY7kNDoXLJ+o9XU+YtkExng2ELPCXArQYHBjDZjYeISN9gJLZiChtgbxsf90rFGT8QktwaTbFMRy89oqWezJrs0m5rUrjqtLLTYHsSFu6Qrcu/0fMVSCO+mONJcs0M5ql9dQAeuSk4YT3OsX61s0FTie1BW4+9wCAmLVnE3V7IdX4uC1eQ5GID7F0YTONJSP5E5TF3hPWVecMX7BbznsMt2GvRR19FGLIm/MKKxlm13PlWmaFmMu7eue9cIl+06EDv+GTvoYlv08o5euRXPX9AMx XG9zP+B2 5OHUsN2aqe2tWpDR7Dmm8CjHInbTZ6JTbmI4zfl5BmhcASASHzCoKb141ZCMrt1RMBMu1LH3XnwAXi86dKB0vxGgPxghgTGJ8q3jAZsK2Vn6mnH1+lCgV3MGTiFXbzpInt94o4jRs3JZhpdZfUl7RVnENAZAL3C69T8R03IdXDmuxKjo08jBAhelRqE1teUFRCHWkk1XyjxTh7K8xznNSfA4sxFx0C5boNOisPFDrs+8SMEbU9iaRm+Q1u7+HmGAxTfT4vE6dd3F5CsSXlfAHPp33m75bukgS0MnxqpHJxY6JdHqDF2NSTbp+VP3TWiDmfx47Q6JGWf2Ih/z93A6U5syQ6Q== Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: Hi Kiryl, On 9/19/26 8:24 AM, Kiryl Shutsemau wrote: > From: "Kiryl Shutsemau (Meta)" > > collapse_compound_extreme() builds a PTE table full of distinct PTE-mapped > compound pages by cycling hpage_pmd_nr fault-time THPs through mremap. It > therefore needs hpage_pmd_nr PMD-order allocations in a row. That is fine > at a 2M PMD (4K base pages) or a 32M one (16K). A 512M PMD -- arm64 with > 64K base pages -- makes each of those an order-13 allocation, which the > allocator cannot reliably hand out even once, let alone 8192 times. > > The failure is not a quiet one: the case calls ksft_exit_fail_msg(), so the > whole binary stops and every case after it is lost. > > Skip the case where the PMD is larger than 32M. The MADV_COLLAPSE cases > still cover PMD-order collapse on those configurations, and 4K and 16K > PMDs are unaffected. collapse_compound_extreme() failed on an arm64 virtual machines with 16k pages. The VM has 8GB of memory. Not sure if this is the same issue that this patch attempts to address. [root@localhost mm]# ./khugepaged [ snipped ] # # Run test: collapse_full_of_compound (madvise:anon) # Allocate huge page... OK # Split huge page leaving single PTE page table full of compound pages... OK # Collapse PTE table full of compound pages... OK ok 76 collapse_full_of_compound # # Run test: collapse_compound_extreme (khugepaged:anon) # Construct PTE page table full of different PTE-mapped compound pages Bail out! Failed to allocate huge page # 1 skipped test(s) detected. Consider enabling relevant config options to improve coverage. # Planned tests != run tests (91 != 76) # Totals: pass:75 fail:0 xfail:0 xpass:0 skip:1 error:0 Thanks, Zenghui