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 11E67CAC5BB for ; Sat, 4 Oct 2025 05:24:45 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id 089BF8E0008; Sat, 4 Oct 2025 01:24:45 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id F24A48E0002; Sat, 4 Oct 2025 01:24:44 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id E13748E0008; Sat, 4 Oct 2025 01:24:44 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0011.hostedemail.com [216.40.44.11]) by kanga.kvack.org (Postfix) with ESMTP id CC0768E0002 for ; Sat, 4 Oct 2025 01:24:44 -0400 (EDT) Received: from smtpin22.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay09.hostedemail.com (Postfix) with ESMTP id 2B65C8827E for ; Sat, 4 Oct 2025 05:24:44 +0000 (UTC) X-FDA: 83959292088.22.3D8334C Received: from out-183.mta0.migadu.com (out-183.mta0.migadu.com [91.218.175.183]) by imf25.hostedemail.com (Postfix) with ESMTP id 31243A0007 for ; Sat, 4 Oct 2025 05:24:41 +0000 (UTC) Authentication-Results: imf25.hostedemail.com; dkim=pass header.d=linux.dev header.s=key1 header.b=tznUARli; spf=pass (imf25.hostedemail.com: domain of lance.yang@linux.dev designates 91.218.175.183 as permitted sender) smtp.mailfrom=lance.yang@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=1759555482; 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=krAO9cVScKxnq0tyI21OqQImIBgM9hOhnJCkOerMbok=; b=ohrHSB0gijBtgPBLaYRORC/goN0YL0A1x1kVOq/GyTtAGKaNTHlqHxUAxC8q23yJJ26q0I sVOpOfQQ288LjdbYqzr/Oji4Fs7qgIpp6fd3068ps/z00LON7nFNedC+gLEqut7s8ezYIy vFTlVvzRWarX4QLq0tSNlnyu5aBokt8= ARC-Seal: i=1; s=arc-20220608; d=hostedemail.com; t=1759555482; a=rsa-sha256; cv=none; b=YB/LYxq+Qd1l1lC1GjgAVNy+il/Tom0xpIdselB1NY51KiUDScizr6zwkQu3Tydh4l5Df7 wuyJd81ZySCNopyvqwz9eiBFvtu15WqUzDdQ7YPDlSzkxnoTSC3RVMUj3uGOJEDtFoS+oI XOkvafQMlLUmcQbeWqPNF+inJiXEOis= ARC-Authentication-Results: i=1; imf25.hostedemail.com; dkim=pass header.d=linux.dev header.s=key1 header.b=tznUARli; spf=pass (imf25.hostedemail.com: domain of lance.yang@linux.dev designates 91.218.175.183 as permitted sender) smtp.mailfrom=lance.yang@linux.dev; dmarc=pass (policy=none) header.from=linux.dev Message-ID: <44d529b6-a538-4131-a00c-76c73ae49d81@linux.dev> DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linux.dev; s=key1; t=1759555479; h=from:from: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; bh=krAO9cVScKxnq0tyI21OqQImIBgM9hOhnJCkOerMbok=; b=tznUARlix33V/Dh3vG3SYEpL/6iSYMloakXilkcJK1RXFcZIt7XmtZmPg7g5vaZJ5JIGmq WVK0w2XjqPTyPZXmj0Z21rALpyCwCONyy3Iw38WXM59xn6dr7/qJNZ+v6ms0nXq6PFTKhY KrMKMWysn1CU2uBhQVS0ZP87yDHGPeg= Date: Sat, 4 Oct 2025 13:24:27 +0800 MIME-Version: 1.0 Subject: Re: [PATCH mm-new 2/2] mm/khugepaged: merge PTE scanning logic into a new helper Content-Language: en-US To: Dev Jain Cc: ziy@nvidia.com, baolin.wang@linux.alibaba.com, Liam.Howlett@oracle.com, npache@redhat.com, ryan.roberts@arm.com, baohua@kernel.org, ioworker0@gmail.com, david@redhat.com, richard.weiyang@gmail.com, linux-kernel@vger.kernel.org, lorenzo.stoakes@oracle.com, linux-mm@kvack.org, akpm@linux-foundation.org References: <20251002073255.14867-1-lance.yang@linux.dev> <20251002073255.14867-3-lance.yang@linux.dev> <0d55d763-81ff-4b99-bb13-3dbb9af53cdc@arm.com> X-Report-Abuse: Please report any abuse attempt to abuse@migadu.com and include these headers. From: Lance Yang In-Reply-To: Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit X-Migadu-Flow: FLOW_OUT X-Rspamd-Server: rspam12 X-Rspamd-Queue-Id: 31243A0007 X-Stat-Signature: 5e7kxp73947aeue41eoac4nesp8t9pfm X-Rspam-User: X-HE-Tag: 1759555481-433849 X-HE-Meta: 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 gvV5ttRf AFAS84CXaBgVR650kjHGePQ60i1Te63JRh/L8jahXD9rK06WB4HyTJZqYJ3EVL1SwTGjL8HtF6isjFC+Oot2k5QsFe95onMGP5kxNxHouf3sorJhCIrn3QiLyj+F7HOUKgLlgIOXk/EPIqLvaYjCnbHCd//OUGNGrsGuB+9Una1aymGQPRkayuYYVj91ptjVg30t2kwel+ACG+cqi4e7kKCFnYFHzTiFwJ0yyecYyLj0WGogQtPjp1x6YFu6WxaGPOmixcWU9axPpf2rLzJwzHZf0TLz5sL97mA4ZwDHjvKHi6id51haIX+ofbWV2fRyrnOTDzVOTHcjv40o= 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 2025/10/4 12:42, Dev Jain wrote: > > On 04/10/25 8:33 am, Lance Yang wrote: >> >> >> On 2025/10/4 01:05, Dev Jain wrote: >>> >>> On 02/10/25 1:02 pm, Lance Yang wrote: >>>> From: Lance Yang >>>> >>>> As David suggested, the PTE scanning logic in hpage_collapse_scan_pmd() >>>> and __collapse_huge_page_isolate() was almost duplicated. >>>> >>>> This patch cleans things up by moving all the common PTE checking logic >>>> into a new shared helper, thp_collapse_check_pte(). >>>> >>>> Suggested-by: David Hildenbrand >>>> Signed-off-by: Lance Yang >>>> --- >>> >>> In hpage_collapse_scan_pmd(), we enter with mmap lock held, so for >>> an anonymous vma, is it even possible to hit if (! >>> folio_test_anon(folio))? >> >> Ah, indeed :) >> >>> In which case we can replace this with VM_BUG_ON_FOLIO and abstract away >>> till the folio_maybe_mapped_shared() block? >> >> So you meant something like this: >> >> diff --git a/mm/khugepaged.c b/mm/khugepaged.c >> index 2a897cfb1d03..ef87d7fe3d50 100644 >> --- a/mm/khugepaged.c >> +++ b/mm/khugepaged.c >> @@ -1374,11 +1374,7 @@ static int hpage_collapse_scan_pmd(struct >> mm_struct *mm, >>                         goto out_unmap; >>                 } >>                 folio = page_folio(page); >> - >> -               if (!folio_test_anon(folio)) { >> -                       result = SCAN_PAGE_ANON; >> -                       goto out_unmap; >> -               } >> +               VM_BUG_ON_FOLIO(!folio_test_anon(folio), folio); > > Yes, I would suggest a different patch making this change, then in the > > last patch you can abstract away till the shared statistics line since that > > much code will become common between scan_pmd and _isolate. Nice. Makes sense to me! I'll rework the series into three patches then: 1) The if-else-if-else-if optimization 2) Convert the !folio_test_anon() check to a VM_BUG_ON_FOLIO() 3) The final merge of the scanning logic into a new helper Thanks, Lance > > >> >>                 /* >>                  * We treat a single page as shared if any part of the >> THP >> >>