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 113ADC5DF6D for ; Wed, 19 Aug 2026 07:01:45 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id 39D2F6B008C; Wed, 19 Aug 2026 03:01:44 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 375386B009D; Wed, 19 Aug 2026 03:01:44 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 2B1C96B00A3; Wed, 19 Aug 2026 03:01:44 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0010.hostedemail.com [216.40.44.10]) by kanga.kvack.org (Postfix) with ESMTP id 0760F6B008C for ; Wed, 19 Aug 2026 03:01:44 -0400 (EDT) Received: from smtpin26.hostedemail.com (lb01a-stub [10.200.18.249]) by unirelay10.hostedemail.com (Postfix) with ESMTP id 807F8C0490 for ; Wed, 19 Aug 2026 07:01:43 +0000 (UTC) X-FDA: 85117123686.26.24518C6 Received: from sea.source.kernel.org (sea.source.kernel.org [172.234.252.31]) by imf29.hostedemail.com (Postfix) with ESMTP id C9BBE120002 for ; Wed, 19 Aug 2026 07:01:41 +0000 (UTC) Authentication-Results: imf29.hostedemail.com; dkim=pass header.d=kernel.org header.s=k20260515 header.b=W218OjmE; spf=pass (imf29.hostedemail.com: domain of rppt@kernel.org designates 172.234.252.31 as permitted sender) smtp.mailfrom=rppt@kernel.org; dmarc=pass (policy=quarantine) header.from=kernel.org ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1787122901; 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: in-reply-to:in-reply-to:references:references:dkim-signature; bh=aMKxJGzD04KmpYdtuo6wR1wjBXa3j2PKTFpPFdjXzYU=; b=2GWCtEqKAksbPpXzQMXa3DQiiDe0ES2VaJKflxtK2dY+wv/+xYRubd9+x5xkgO3/BcQALD 6SxOHc5V+YbXmj/VlzuvJDYrsCRaAqq+3w12P88EySjl9RoBCXmBaJ9RNcTispDxInJryI po8T64D8lZrW7zaBVcpX8MXaLdLs0bk= ARC-Authentication-Results: i=1; imf29.hostedemail.com; dkim=pass header.d=kernel.org header.s=k20260515 header.b=W218OjmE; spf=pass (imf29.hostedemail.com: domain of rppt@kernel.org designates 172.234.252.31 as permitted sender) smtp.mailfrom=rppt@kernel.org; dmarc=pass (policy=quarantine) header.from=kernel.org ARC-Seal: i=1; a=rsa-sha256; d=hostedemail.com; s=arc-20220608; cv=none; t=1787122901; b=YeNB9K7Ek/Pe2FRpPqLXUNBGaWpfxJFbBlCiqg0YC1g7C7W6yJTJ+AuoHXnMhyCiRVWIz+ ss5rK1Q4YDM5M7IvNBBA3fQQaFcdIkyCyOYzUwp2lL8apI9lWJVr45TWdPEFo3J3mL8p0g sc5+wMUSB2n3WfJB1u27MSTyEJymRm4= Received: from smtp.kernel.org (quasi.space.kernel.org [100.103.45.18]) by sea.source.kernel.org (Postfix) with ESMTP id E558B40E0B; Wed, 19 Aug 2026 07:01:40 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id F0E0F1F000E9; Wed, 19 Aug 2026 07:01:28 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1787122900; bh=aMKxJGzD04KmpYdtuo6wR1wjBXa3j2PKTFpPFdjXzYU=; h=Date:From:To:Cc:Subject:References:In-Reply-To; b=W218OjmEyHpxk8/viVdeC99qw0slMQEIeb88kkfoCArZxB5b+ptrrTJCAevq6VxDC vMLWsCTCZofQBaxR8oOPqWS3kHD49USp31sbZl8DRPCFt4KACVCCQrNyM/PgNyaQHR VkV0HOObXqdXGCJvNJhTxaqj9fmO35W5uT1jdRtJNLUOb/HjegZxblTMNGIV/GVRRM flhucOwsPBVMpfnwxRKIG1ToXGaPjBMWqxwbx+olsHHxa7QcV4g0KWxIkN0N9mv8Xz L8AUvX3FOqiw4smqbYXS27a0Eeumx4rnsMmynElmR0J9GQkX0rxY+csbE6hJYTSs4X O/LT5KmkF12xg== Date: Wed, 19 Aug 2026 10:01:25 +0300 From: Mike Rapoport To: Brendan Jackman Cc: Andrew Morton , Adrian =?utf-8?Q?Barna=C5=9B?= , Albert Ou , Alexander Gordeev , Alexandre Ghiti , Andy Lutomirski , Borislav Petkov , Catalin Marinas , Christian Borntraeger , Dave Hansen , David Hildenbrand , Gerald Schaefer , Heiko Carstens , Huacai Chen , Ingo Molnar , Len Brown , Palmer Dabbelt , Paul Walmsley , Pavel Machek , Peter Zijlstra , "H. Peter Anvin" , "Rafael J. Wysocki" , Ryan Roberts , Sven Schnelle , Thomas Gleixner , Uladzislau Rezki , Vasily Gorbik , WANG Xuerui , Will Deacon , x86@kernel.org, linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, linux-mm@kvack.org, linux-pm@vger.kernel.org, linux-riscv@lists.infradead.org, linux-s390@vger.kernel.org, loongarch@lists.linux.dev Subject: Re: [PATCH 4/6] mm/vmalloc: make set_area_direct_map HUGE_VMAP friendly Message-ID: References: <20260816-execmem-set-vm-perms-v0-2-v1-0-90944a3ad43f@kernel.org> <20260816-execmem-set-vm-perms-v0-2-v1-4-90944a3ad43f@kernel.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: X-Stat-Signature: c14gtt6rbt6t7r9inweesd5nq5xqwq4o X-Rspamd-Queue-Id: C9BBE120002 X-Rspam-User: X-Rspamd-Server: rspam12 X-HE-Tag: 1787122901-378900 X-HE-Meta: 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 62PNWNI6 J1Lnur/uIQnIn3RCrg3PPck1gjz16wXOIdqjcIcH52lsXPVAPuZn+OjQOWMHa2n0shWNS0nhxFK6WBnV9Tp3AninGaQh3MdTYUFdDSJR71fOhH2PlCucfFc6cFiECT85SMpPNsEIpxmA0E4QzWrEnrK70jzPfyjCUlhmtYYxC2qhrNSNpDvF8otcFnhQKC9V9k3PPteg90PAS2AuO7w8rqT76FY6KTibGrBjbQXCHWSl/7bgKkDAKSM++EBkpYJttzKzt1FnytxG8SwzlXqR+O2gbAmQIKVbxb2lsumb006q8IwIQt4pzVKfyV452d69jVZTZhbEoONyD99E= Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On Mon, Aug 17, 2026 at 02:21:41PM +0200, Brendan Jackman wrote: > On Sun Aug 16, 2026 at 12:59 PM CEST, Mike Rapoport (Microsoft) wrote: > > set_area_direct_map() always updates direct map alias permissions in > > single page increments. > > > > For HUGE_VMAP areas it's suboptimal. Not only the loop in > > set_area_direct_map() needlessly has more iterations (e.g times 512 on > > x86), but it also causes fragmentation of the direct map that could be > > avoided for the HUGE_VMAP areas populated with large pages. > > > > All pages in an area are always of the same order: either same-order > > large pages when VM_ALLOW_HUGE_VMAP is set and all huge pages were > > successfully allocated, or order-0 page when VM_ALLOW_HUGE_VMAP is > > cleared or when huge pages allocation fails and fallback path is taken. > > > > Instead of updating the direct map permissions for every order-0 page in > > an area, use the area's page_order as the loop increment and update the > > large pages in one call to set_direct_map_{invalid,default}_noflush(). > > > > Signed-off-by: Mike Rapoport (Microsoft) > > --- > > mm/vmalloc.c | 13 ++++++++----- > > 1 file changed, 8 insertions(+), 5 deletions(-) > > > > diff --git a/mm/vmalloc.c b/mm/vmalloc.c > > index fc7993db4152..11170d1ee5be 100644 > > --- a/mm/vmalloc.c > > +++ b/mm/vmalloc.c > > @@ -3361,12 +3361,15 @@ static inline void set_area_direct_map(const struct vm_struct *area, > > int (*set_direct_map)(struct page *page, > > unsigned int nr)) > > { > > - unsigned long i; > > + unsigned int nr = (1U << vm_area_page_order(area)); > > + > > + for (unsigned long i = 0; i < area->nr_pages; i += nr) { > > + if (page_address(area->pages[i])) { > > + int err = set_direct_map(area->pages[i], nr); > > > > - /* HUGE_VMALLOC passes small pages to set_direct_map */ > > - for (i = 0; i < area->nr_pages; i++) > > - if (page_address(area->pages[i])) > > - set_direct_map(area->pages[i], 1); > > + WARN_ON_ONCE(err); > > Nit: Maybe worth a comment on why this is expected to always succeed? > I.e. I think we are assuming the only failure mode is allocation but > because we know vm_area_page_order() there shouldn't be any allocation? The assumption we relying on is more involved, but yeah, I can add a comment. -- Sincerely yours, Mike.