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 bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id B4149C982D2 for ; Thu, 17 Sep 2026 18:12:28 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20210309; h=Sender:List-Subscribe:List-Help :List-Post:List-Archive:List-Unsubscribe:List-Id:Content-Transfer-Encoding: Content-Type:In-Reply-To:From:References:Cc:To:Subject:MIME-Version:Date: Message-ID:Reply-To:Content-ID:Content-Description:Resent-Date:Resent-From: Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Owner; bh=vqyQgMFAJVi2Td/IFUmuzFBF1bi1YpyEHAojG3GW2qw=; b=3f+m7Yi/Aw+G7MeGpg4S6csc9c GOVEMLfiG2TwYpurHTZSb4vd1V1i9BCcvhMxD/tF/cigcmxdoFh8R1upNasVbWWdrw/T1lFzyfBDU YFuvXExCMKHzzt0+Sa7D03OKFXDjYfHs0f+bQWOpjK97b5Jg5IzE4uk2MIN/IYLIjjGDSg7F8JAa2 mueK77kCBe0nYh2oLG5TwWTocy/g+2dZisFNPThgca5M89A3HuGZhGoNMe53A/6oMHxCgU7+yM52l bR2xKyvSRBp64+Ju/9/ZZWaDrbGeJf1I7EHeeJGMufK2xST5rdmJ7l6PTuz2Ndu0egybECTQomN/p qC6pWaKg==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.99.1 #2 (Red Hat Linux)) id 1x7Gar-0000000CBgj-3prY; Thu, 17 Sep 2026 18:12:21 +0000 Received: from foss.arm.com ([217.140.110.172]) by bombadil.infradead.org with esmtp (Exim 4.99.1 #2 (Red Hat Linux)) id 1x7Gao-0000000CBei-3Vp7; Thu, 17 Sep 2026 18:12:20 +0000 Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.121.207.14]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id A6D8D1596; Thu, 17 Sep 2026 11:12:13 -0700 (PDT) Received: from [10.57.7.135] (unknown [10.57.7.135]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id EB6E23F86F; Thu, 17 Sep 2026 11:12:09 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=simple/simple; d=arm.com; s=foss; t=1789668737; bh=JRotaeYUDA8OKw6fWgN1iioU01GNC1YxBAHOCuSkCcg=; h=Date:Subject:To:Cc:References:From:In-Reply-To:From; b=mCMXQQCuXWXGh8CqhS0W7cwhE2pXGdXIab/vrQATUL3/XaFJNt8Xf3XcEukOlMYCK ugh3zQSksUsKim10k1OD4vF/PrNn0SbUDLvpZ5GQyazWmyouKJGKG5+oDmjP89b8Rg 7/ZY9aaQUsSH+CtdxVNQuZgcibuXfkywZeR0hrNM= Message-ID: <19b00695-9f99-4d21-9592-13fad31f85e7@arm.com> Date: Thu, 17 Sep 2026 20:12:07 +0200 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v3 4/6] mm/vmalloc: make set_area_direct_map HUGE_VMAP friendly To: "Mike Rapoport (Microsoft)" , Andrew Morton Cc: =?UTF-8?Q?Adrian_Barna=C5=9B?= , Albert Ou , Alexander Gordeev , Alexandre Ghiti , Andy Lutomirski , Borislav Petkov , Brendan Jackman , 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 References: <20260903-execmem-set-vm-perms-v0-2-v3-0-949b64a9f755@kernel.org> <20260903-execmem-set-vm-perms-v0-2-v3-4-949b64a9f755@kernel.org> From: Kevin Brodsky Content-Language: en-GB In-Reply-To: <20260903-execmem-set-vm-perms-v0-2-v3-4-949b64a9f755@kernel.org> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.9.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20260917_111218_973967_372401DC X-CRM114-Status: GOOD ( 21.35 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org On 03/09/2026 11:28, 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) Reviewed-by: Kevin Brodsky > --- > mm/vmalloc.c | 13 ++++++++----- > 1 file changed, 8 insertions(+), 5 deletions(-) > > diff --git a/mm/vmalloc.c b/mm/vmalloc.c > index 5506b180f5c27..6ed6c160abed7 100644 > --- a/mm/vmalloc.c > +++ b/mm/vmalloc.c > @@ -3367,12 +3367,15 @@ 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); > + } > + } > } > > /* >