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 0B069E9E301 for ; Wed, 11 Feb 2026 12:55:24 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id 1B65C6B0005; Wed, 11 Feb 2026 07:55:24 -0500 (EST) Received: by kanga.kvack.org (Postfix, from userid 40) id 164696B0089; Wed, 11 Feb 2026 07:55:24 -0500 (EST) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 046316B008A; Wed, 11 Feb 2026 07:55:24 -0500 (EST) 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 E86196B0005 for ; Wed, 11 Feb 2026 07:55:23 -0500 (EST) Received: from smtpin14.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay03.hostedemail.com (Postfix) with ESMTP id 79FE4B89E4 for ; Wed, 11 Feb 2026 12:55:23 +0000 (UTC) X-FDA: 84432171726.14.9875E8F Received: from out-172.mta0.migadu.com (out-172.mta0.migadu.com [91.218.175.172]) by imf30.hostedemail.com (Postfix) with ESMTP id 933F480007 for ; Wed, 11 Feb 2026 12:55:21 +0000 (UTC) Authentication-Results: imf30.hostedemail.com; dkim=pass header.d=linux.dev header.s=key1 header.b=SWq7b2JH; spf=pass (imf30.hostedemail.com: domain of usama.arif@linux.dev designates 91.218.175.172 as permitted sender) smtp.mailfrom=usama.arif@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=1770814522; 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-transfer-encoding:content-transfer-encoding: in-reply-to:references:dkim-signature; bh=+YanjR3U4weMG4VW1vewWJqflQleiBR1ZTIDoCsnaFE=; b=YSR+uvG0tTkAs2dwUOQj+rxYoYlAWEr5ZjIZoJbnbpgXRQyYFBiVr+4n3IJdWWaHf7CA9c DK6H21mnHGokvEq3JzLkEeME0983vrhP82YRc1YLgVO0r6Ip1vtiuAjNiPhfuXJKuR47Aa 8MPpxyUvPzNRFMJjh3vetz7lgohFzU8= ARC-Authentication-Results: i=1; imf30.hostedemail.com; dkim=pass header.d=linux.dev header.s=key1 header.b=SWq7b2JH; spf=pass (imf30.hostedemail.com: domain of usama.arif@linux.dev designates 91.218.175.172 as permitted sender) smtp.mailfrom=usama.arif@linux.dev; dmarc=pass (policy=none) header.from=linux.dev ARC-Seal: i=1; s=arc-20220608; d=hostedemail.com; t=1770814522; a=rsa-sha256; cv=none; b=FG5ZD+po1fpVPhbSml6kT8FwlzJvrF7nXOl/9aF5isU1IyqUQRiPECZIzWeHkx6jtsntHZ Y63ym6053IEQlmcE+8YS1NFRs3Y+qAp8spOyaIkzDGXZRspeIr8pXFS+8PyNMcCF+Byj/L Dhcs7J8lpNDND+S4cyJg+gjwroRMKmQ= 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=1770814519; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version: content-transfer-encoding:content-transfer-encoding; bh=+YanjR3U4weMG4VW1vewWJqflQleiBR1ZTIDoCsnaFE=; b=SWq7b2JH1CPOwxMheZnHimW9HJpL8AZg6obmI0m2dIL+Pom0a96tDKGXBlm8ruKKKsFrn+ TnH/GuegF2B4bovwZO9eQapE+u5h2PEERC2fOJL4Wx93p3PofpYC/8qjmJhDNI7R61Z2sX OwEvT520XSi/SJcKyf0n2epz/VtjbD0= From: Usama Arif To: Andrew Morton , david@kernel.org, lorenzo.stoakes@oracle.com, willy@infradead.org, linux-mm@kvack.org Cc: fvdl@google.com, hannes@cmpxchg.org, riel@surriel.com, shakeel.butt@linux.dev, kas@kernel.org, baohua@kernel.org, dev.jain@arm.com, baolin.wang@linux.alibaba.com, npache@redhat.com, Liam.Howlett@oracle.com, ryan.roberts@arm.com, vbabka@suse.cz, lance.yang@linux.dev, linux-kernel@vger.kernel.org, kernel-team@meta.com, Usama Arif Subject: [RFC 0/2] mm: thp: split time allocation of page table for THPs Date: Wed, 11 Feb 2026 04:49:44 -0800 Message-ID: <20260211125507.4175026-1-usama.arif@linux.dev> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Migadu-Flow: FLOW_OUT X-Rspamd-Server: rspam11 X-Stat-Signature: 6fnd544whfqe6dyc6pnf1kjyny4dr19z X-Rspam-User: X-Rspamd-Queue-Id: 933F480007 X-HE-Tag: 1770814521-950610 X-HE-Meta: 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 6H+MFe1+ NV83DOIMVMVJKkhNEIBrnBZF0ZC3e95RvYikDrJI1zpHssR2rco9c9QEeYllTbSS9Ppsp4mgPKgfGSfCLNCU5aPHgsnGq1A/UZ9iBupoBSRfyPj8Z5C2M/Qmc5CpnH8O3s5qrZvPCqbnKO15u2dQ5wyQNEH13VQOW14n7ejklH3VW+3U4+hFiUK3Xx4Oxtu3mTdKO0vzZv9W8bdGsEQaN4V14HHw+SG+jUm4h 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: This is an RFC patch to allocate the PTE page table at split time only and not do pre-deposit for THPs as suggested by David [1]. The core patch is the first one. The second one is not needed and its just vmstat counters I used to show that split doesn't fail. Its going to be 0 all the time and won't include it in future revisions. It would have been ideal if all pre-deposit code was removed but its not possible due to PowerPC. The rationale and further details are covered in the commit message of the first patch, including why the patch is safe. [1] https://lore.kernel.org/all/ee5bd77f-87ad-4640-a974-304b488e4c64@kernel.org/ Usama Arif (2): mm: thp: allocate PTE page tables lazily at split time mm: thp: add THP_SPLIT_PMD_PTE_ALLOC_FAILED counter include/linux/huge_mm.h | 4 +- include/linux/vm_event_item.h | 1 + mm/huge_memory.c | 145 ++++++++++++++++++++++++---------- mm/khugepaged.c | 7 +- mm/migrate_device.c | 15 ++-- mm/rmap.c | 42 +++++++++- mm/vmstat.c | 1 + 7 files changed, 162 insertions(+), 53 deletions(-) -- 2.47.3