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 X-Spam-Level: X-Spam-Status: No, score=-15.7 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER, INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_NONE,URIBL_BLOCKED autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 43EEFC433B4 for ; Fri, 30 Apr 2021 05:57:31 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 21F676147E for ; Fri, 30 Apr 2021 05:57:31 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S230253AbhD3F6S (ORCPT ); Fri, 30 Apr 2021 01:58:18 -0400 Received: from mail.kernel.org ([198.145.29.99]:51414 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229591AbhD3F6R (ORCPT ); Fri, 30 Apr 2021 01:58:17 -0400 Received: by mail.kernel.org (Postfix) with ESMTPSA id A560761459; Fri, 30 Apr 2021 05:57:29 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linux-foundation.org; s=korg; t=1619762250; bh=PnjKEMulhbpNzVpYdM2JoKkNwRM9fiwIe5Ywl4i76Y0=; h=Date:From:To:Subject:In-Reply-To:From; b=BVySyO5Wd34xu4M0DV+whJKGgO7YvbDNZgD/DiLSh6PjdZ9f8vsbgMuhZ7GwpturM +mStMBP0P0WSighAAWKiFuJieouwfcF4ol7HZRwlc1MDhErMMTNsS1IIrIxKZB5n8o WLZnndyO+yEfONq/3qVHzlSbmPESX1BLHGq1vhJk= Date: Thu, 29 Apr 2021 22:57:29 -0700 From: Andrew Morton To: akpm@linux-foundation.org, chris@chris-wilson.co.uk, daniel.vetter@ffwll.ch, hch@lst.de, jani.nikula@linux.intel.com, joonas.lahtinen@linux.intel.com, linux-mm@kvack.org, mm-commits@vger.kernel.org, peterz@infradead.org, rodrigo.vivi@intel.com, torvalds@linux-foundation.org Subject: [patch 084/178] mm: add remap_pfn_range_notrack Message-ID: <20210430055729.ttwZAEx64%akpm@linux-foundation.org> In-Reply-To: <20210429225251.02b6386d21b69255b4f6c163@linux-foundation.org> User-Agent: s-nail v14.8.16 Precedence: bulk Reply-To: linux-kernel@vger.kernel.org List-ID: X-Mailing-List: mm-commits@vger.kernel.org From: Christoph Hellwig Subject: mm: add remap_pfn_range_notrack Patch series "add remap_pfn_range_notrack instead of reinventing it in i915", v2. i915 has some reason to want to avoid the track_pfn_remap overhead in remap_pfn_range. Add a function to the core VM to do just that rather than reinventing the functionality poorly in the driver. Note that the remap_io_sg path does get exercises when using Xorg on my Thinkpad X1, so this should be considered lightly tested, I've not managed to hit the remap_io_mapping path at all. This patch (of 4): Add a version of remap_pfn_range that does not call track_pfn_range. This will be used to fix horrible abuses of VM internals in the i915 driver. Link: https://lkml.kernel.org/r/20210326055505.1424432-1-hch@lst.de Link: https://lkml.kernel.org/r/20210326055505.1424432-2-hch@lst.de Signed-off-by: Christoph Hellwig Acked-by: Daniel Vetter Cc: Jani Nikula Cc: Joonas Lahtinen Cc: Rodrigo Vivi Cc: Chris Wilson Cc: Peter Zijlstra Signed-off-by: Andrew Morton --- include/linux/mm.h | 2 + mm/memory.c | 51 ++++++++++++++++++++++++++----------------- 2 files changed, 33 insertions(+), 20 deletions(-) --- a/include/linux/mm.h~mm-add-remap_pfn_range_notrack +++ a/include/linux/mm.h @@ -2732,6 +2732,8 @@ unsigned long change_prot_numa(struct vm struct vm_area_struct *find_extend_vma(struct mm_struct *, unsigned long addr); int remap_pfn_range(struct vm_area_struct *, unsigned long addr, unsigned long pfn, unsigned long size, pgprot_t); +int remap_pfn_range_notrack(struct vm_area_struct *vma, unsigned long addr, + unsigned long pfn, unsigned long size, pgprot_t prot); int vm_insert_page(struct vm_area_struct *, unsigned long addr, struct page *); int vm_insert_pages(struct vm_area_struct *vma, unsigned long addr, struct page **pages, unsigned long *num); --- a/mm/memory.c~mm-add-remap_pfn_range_notrack +++ a/mm/memory.c @@ -2260,26 +2260,17 @@ static inline int remap_p4d_range(struct return 0; } -/** - * remap_pfn_range - remap kernel memory to userspace - * @vma: user vma to map to - * @addr: target page aligned user address to start at - * @pfn: page frame number of kernel physical memory address - * @size: size of mapping area - * @prot: page protection flags for this mapping - * - * Note: this is only safe if the mm semaphore is held when called. - * - * Return: %0 on success, negative error code otherwise. +/* + * Variant of remap_pfn_range that does not call track_pfn_remap. The caller + * must have pre-validated the caching bits of the pgprot_t. */ -int remap_pfn_range(struct vm_area_struct *vma, unsigned long addr, - unsigned long pfn, unsigned long size, pgprot_t prot) +int remap_pfn_range_notrack(struct vm_area_struct *vma, unsigned long addr, + unsigned long pfn, unsigned long size, pgprot_t prot) { pgd_t *pgd; unsigned long next; unsigned long end = addr + PAGE_ALIGN(size); struct mm_struct *mm = vma->vm_mm; - unsigned long remap_pfn = pfn; int err; if (WARN_ON_ONCE(!PAGE_ALIGNED(addr))) @@ -2309,10 +2300,6 @@ int remap_pfn_range(struct vm_area_struc vma->vm_pgoff = pfn; } - err = track_pfn_remap(vma, &prot, remap_pfn, addr, PAGE_ALIGN(size)); - if (err) - return -EINVAL; - vma->vm_flags |= VM_IO | VM_PFNMAP | VM_DONTEXPAND | VM_DONTDUMP; BUG_ON(addr >= end); @@ -2324,12 +2311,36 @@ int remap_pfn_range(struct vm_area_struc err = remap_p4d_range(mm, pgd, addr, next, pfn + (addr >> PAGE_SHIFT), prot); if (err) - break; + return err; } while (pgd++, addr = next, addr != end); + return 0; +} + +/** + * remap_pfn_range - remap kernel memory to userspace + * @vma: user vma to map to + * @addr: target page aligned user address to start at + * @pfn: page frame number of kernel physical memory address + * @size: size of mapping area + * @prot: page protection flags for this mapping + * + * Note: this is only safe if the mm semaphore is held when called. + * + * Return: %0 on success, negative error code otherwise. + */ +int remap_pfn_range(struct vm_area_struct *vma, unsigned long addr, + unsigned long pfn, unsigned long size, pgprot_t prot) +{ + int err; + + err = track_pfn_remap(vma, &prot, pfn, addr, PAGE_ALIGN(size)); if (err) - untrack_pfn(vma, remap_pfn, PAGE_ALIGN(size)); + return -EINVAL; + err = remap_pfn_range_notrack(vma, addr, pfn, size, prot); + if (err) + untrack_pfn(vma, pfn, PAGE_ALIGN(size)); return err; } EXPORT_SYMBOL(remap_pfn_range); _