From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from foss.arm.com (foss.arm.com [217.140.110.172]) by smtp.subspace.kernel.org (Postfix) with ESMTP id 2016D547071; Thu, 17 Sep 2026 18:12:17 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=217.140.110.172 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1789668740; cv=none; b=VVgQ46/uIdvyWbtvOFS8xApO7sQlifJ8tj6LK6Cv/fNETTn7WFrtzYqUSWqHs7kBdV06CYe9EQLnCTift2d5MyZgcKHr82+JRKK3kEuAlzgOyNj7UYc/fkh01yKqrWgY++PweibwiNUMMrGpcBG/9yroJ/epwpFcr9bTWU61P8A= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1789668740; c=relaxed/simple; bh=JRotaeYUDA8OKw6fWgN1iioU01GNC1YxBAHOCuSkCcg=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=A+WiMdyH09KRiQQK8rbppLwHH3B0RkDemfNQq32+JBRJUyTrpCtrOjhay/mMk2mDeHUdSPJIDnls0FE0EQ+s0MXc+8Jk64CaVM5AEPw2JdlcJElsbQLa6J8ii7Kxqo2eB08WhdqOEcOmPAPhesKrvdsyaJx+2a0x2bPdLbDh43E= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=arm.com; spf=pass smtp.mailfrom=arm.com; dkim=pass (1024-bit key) header.d=arm.com header.i=@arm.com header.b=mCMXQQCu; arc=none smtp.client-ip=217.140.110.172 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=arm.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=arm.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=arm.com header.i=@arm.com header.b="mCMXQQCu" 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 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: 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 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); > + } > + } > } > > /* >