From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-alma10-1.taild15c8.ts.net [100.103.45.18]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id C81025293F2; Tue, 8 Sep 2026 11:12:32 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=100.103.45.18 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1788865961; cv=none; b=dxokDbZLX899OwWCMK+2x+u9TZPXKMTnqodCN75Vy1AurTkbRB9Mk+E1vSyu74wxFWea4jgRmSJlMXtNGNR8RRnBk4X60v95jG8SvdKxBDih/cIt8CVGui4TDQeKFJ9aNPpHIttGQkhUTjzCe5ktuHnq3IuC+4VKX7zBAaNq3QQ= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1788865961; c=relaxed/simple; bh=Lj3DvzIhuhxD3QpxOFRZ9F35EqZo6vnZyodsUrcoUNE=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=p5Lk2B01EbxpbMY0IGkuRfU29gVgeQcZHwZcvVQxosXX7DC+yF7aAqBpN9w4lYbiEyWB7XXfeoNnXLSm9xloPcDU0nrZOn3DVE5IPbBMZL6ORjp06v2ZCiNSApCj5oI8hAf5u8bGirb/xHhzqE/2Bs6m40mudiUc/JdirVgi/jk= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=j0YvJw5X; arc=none smtp.client-ip=100.103.45.18 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="j0YvJw5X" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 5CCEF1F00A3A; Tue, 8 Sep 2026 11:12:16 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1788865947; bh=+8zEZzYXKDWjMscmRriONU7KthgG+ikNsFsSCx8Kl7U=; h=Date:From:To:Cc:Subject:References:In-Reply-To; b=j0YvJw5XRabkDRwY07U/Nr51yNYPwxCyv+z3STNN3DvhiZbQ2LLliKVdQxWj7ppq+ zv9BhrPbhWQJAVescoenFKCBK8dIe4FnLE41q0oGajg4NKGEFMqenvTN8qGcT5KALG fQMcuKC+7NJE6h1JkAWJGjRFe7kuNrWWBJi63S3F7fZ6YaNOkz2UdfAh8vmFC5EXcp bHxMCUACQA7hH4tJIGFFrWqfN8HNtsfKVFr7W/ZxLarzhz8HriGsNqqucFmQRW8PiZ axL0F5cVKdHUSq7uODecJDsNjdMRPzRgNMNU9BLViewX8ONteqjFxwoO/2vXDW+IOk Uivt3hlM1NCZw== Date: Tue, 8 Sep 2026 14:12:12 +0300 From: Mike Rapoport To: "David Hildenbrand (Arm)" Cc: Andrew Morton , Adrian =?utf-8?Q?Barna=C5=9B?= , Albert Ou , Alexander Gordeev , Alexandre Ghiti , Andy Lutomirski , Borislav Petkov , Brendan Jackman , Catalin Marinas , Christian Borntraeger , Dave Hansen , 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 v3 4/6] mm/vmalloc: make set_area_direct_map HUGE_VMAP friendly Message-ID: 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> <2b0f5877-e71a-4824-adeb-5af2dd8b0269@kernel.org> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <2b0f5877-e71a-4824-adeb-5af2dd8b0269@kernel.org> On Tue, Sep 08, 2026 at 12:41:48PM +0200, David Hildenbrand (Arm) wrote: > On 9/3/26 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) > > --- > > 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); > > Do we really expect some pages to have a directmap and others not? Every page in the area can be allocated separately and __vmalloc_area_node() has if (!(gfp_mask & (GFP_DMA | GFP_DMA32))) gfp_mask |= __GFP_HIGHMEM; so generally speaking yes :) > -- > Cheers, > > David -- Sincerely yours, Mike.