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 0514BCD8CB2 for ; Wed, 10 Jun 2026 11:34:07 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id 23FFE6B0005; Wed, 10 Jun 2026 07:34:06 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 2179B6B0088; Wed, 10 Jun 2026 07:34:06 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 154586B008A; Wed, 10 Jun 2026 07:34:06 -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 04E266B0005 for ; Wed, 10 Jun 2026 07:34:06 -0400 (EDT) Received: from smtpin01.hostedemail.com (lb01a-stub [10.200.18.249]) by unirelay04.hostedemail.com (Postfix) with ESMTP id 891191A0969 for ; Wed, 10 Jun 2026 11:34:05 +0000 (UTC) X-FDA: 84863794050.01.E626F8F Received: from out-171.mta0.migadu.com (out-171.mta0.migadu.com [91.218.175.171]) by imf09.hostedemail.com (Postfix) with ESMTP id 5DE1C140011 for ; Wed, 10 Jun 2026 11:34:03 +0000 (UTC) Authentication-Results: imf09.hostedemail.com; dkim=pass header.d=linux.dev header.s=key1 header.b=nMgRuPUs; dmarc=pass (policy=none) header.from=linux.dev; spf=pass (imf09.hostedemail.com: domain of lance.yang@linux.dev designates 91.218.175.171 as permitted sender) smtp.mailfrom=lance.yang@linux.dev ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1781091244; 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=XkPIYc6BxTC1Yyureze7Jc2IGyRH65P2wbDPNEliW2Q=; b=qjcFydgt3cu8oI7Zu4yHjYWZFrGgU4hA7MBgRbBXl5oLvEIJ2zosKQV32crwUfKrIt89iu +yxAH54bKquZxn4gIGsd+x3Q3mHlLV3Eq2DjiYyQeDuFiAUB+0VxLGRO21EOLcwkqXprIB MPbRfpGwOUKWXSDS3eCaNK7ZJ0q7hDs= ARC-Authentication-Results: i=1; imf09.hostedemail.com; dkim=pass header.d=linux.dev header.s=key1 header.b=nMgRuPUs; dmarc=pass (policy=none) header.from=linux.dev; spf=pass (imf09.hostedemail.com: domain of lance.yang@linux.dev designates 91.218.175.171 as permitted sender) smtp.mailfrom=lance.yang@linux.dev ARC-Seal: i=1; a=rsa-sha256; d=hostedemail.com; s=arc-20220608; cv=none; t=1781091244; b=C8eTRgcBvVkQjSCsgTdH96Rk9G8HArij3aHK3Q2P6H8vdkZ5C/7+udtXTO7piWRGttPFf0 pjO2RPnqpmq0wruNLL7mzwsziaSEYQLvQCAHdgJGo2f+BTMY+cetLaqsmm51ewba2vRaS6 sUmJyXNfGiRYIrXf9vTEER/m2igAETE= X-Report-Abuse: Please report any abuse attempt to abuse@migadu.com and include these headers. DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linux.dev; s=key1; t=1781091241; 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=XkPIYc6BxTC1Yyureze7Jc2IGyRH65P2wbDPNEliW2Q=; b=nMgRuPUsEF8gQiESTcWPWxWWBTGfXbuGadgVqAI4pbIRJufF1wFEEr2lZqs/7Nyb2C0vL+ A9avhuVNiCQ1fylOgqDEFHvbXwWvJoZD5BykXWoB21ypEEzJ1tcQT7AW/yw6ZfIZ4mC2fW /hr0stp5on41u8nUGq09svg8KurEuaE= From: Lance Yang To: baolin.wang@linux.alibaba.com Cc: akpm@linux-foundation.org, david@kernel.org, ljs@kernel.org, hughd@google.com, willy@infradead.org, ziy@nvidia.com, liam@infradead.org, npache@redhat.com, ryan.roberts@arm.com, dev.jain@arm.com, baohua@kernel.org, lance.yang@linux.dev, linux-mm@kvack.org, linux-kselftest@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: [RFC PATCH v2 06/11] mm: khugepaged: allow khugepaged to check all shmem mTHP-sized orders Date: Wed, 10 Jun 2026 19:33:52 +0800 Message-Id: <20260610113352.25352-1-lance.yang@linux.dev> In-Reply-To: References: MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit X-Migadu-Flow: FLOW_OUT X-Rspamd-Server: rspam07 X-Rspam-User: X-Stat-Signature: 58qqnn3s8f1x8q6q5skj9xsdufg78rq7 X-Rspamd-Queue-Id: 5DE1C140011 X-HE-Tag: 1781091243-685500 X-HE-Meta: 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 IpfNowXq 2lQfy0nQc+/Z/N1hA4Aa0JT8lDJcvmO6O1J6rN9B0Yndz2l9/ynOBwLgjs6VI0TeXocXmKRoOYqqzKkDYngYJ/jjBwV3V+72JqL9YmZgWkT/tbwHsWJ09tE66WkJom4pUTg1KjPcsHksHJ3fLvjvCzhTsjQOoyupC8EE2rw5b4oIP3BmJdSdDRSIE1IDSbWa0zzrHrBeu/HGwPO0GHGQPf1IVtIA70y5u+R7Hj82WQT4HaD8= Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On Wed, Jun 10, 2026 at 06:29:14PM +0800, Baolin Wang wrote: >We are now ready to enable shmem mTHP collapse, allowing >thp_vma_allowable_orders() to check all permissible shmem large orders. > >Signed-off-by: Baolin Wang >--- > mm/khugepaged.c | 7 ++++++- > 1 file changed, 6 insertions(+), 1 deletion(-) > >diff --git a/mm/khugepaged.c b/mm/khugepaged.c >index 75b18ec4a6c3..a87918b7e18c 100644 >--- a/mm/khugepaged.c >+++ b/mm/khugepaged.c >@@ -578,9 +578,14 @@ static unsigned long collapse_possible_orders(struct vm_area_struct *vma, > { > unsigned long orders; > >- /* If khugepaged is scanning an anonymous vma, allow mTHP collapse */ >+ /* >+ * If khugepaged is scanning an anonymous or shmem vma, >+ * allow mTHP collapse. >+ */ > if ((tva_flags == TVA_KHUGEPAGED) && vma_is_anonymous(vma)) > orders = THP_ORDERS_ALL_ANON; >+ else if ((tva_flags == TVA_KHUGEPAGED) && vma_is_shmem(vma)) >+ orders = THP_ORDERS_ALL_FILE_DEFAULT; Hmm... for shmem, is the lower bound in mthp_collapse() expected? #define KHUGEPAGED_MIN_MTHP_ORDER 2 #define THP_ORDERS_ALL_FILE_DEFAULT \ ((BIT(MAX_PAGECACHE_ORDER + 1) - 1) & ~BIT(0)) KHUGEPAGED_MIN_MTHP_ORDER is 2, which was introduced for anon collapse. For shmem, though, we're feeding mthp_collapse() orders from THP_ORDERS_ALL_FILE_DEFAULT, and that only filter out order-0 ... if (order > KHUGEPAGED_MIN_MTHP_ORDER && (enabled_orders & GENMASK(order - 1, 0))) { order--; continue; } So order-1 never gets a chance. The walker stops at order-2 and never tries it, right? > else > orders = BIT(HPAGE_PMD_ORDER); > >-- >2.47.3 > >