From: Jason Gunthorpe <jgg@nvidia.com>
To: Alistair Popple <apopple@nvidia.com>
Cc: <linux-mm@kvack.org>, <nouveau@lists.freedesktop.org>,
<bskeggs@redhat.com>, <akpm@linux-foundation.org>,
<linux-doc@vger.kernel.org>, <linux-kernel@vger.kernel.org>,
<dri-devel@lists.freedesktop.org>, <jhubbard@nvidia.com>,
<rcampbell@nvidia.com>, <jglisse@redhat.com>, <hch@infradead.org>,
<daniel@ffwll.ch>
Subject: Re: [PATCH v3 5/8] mm: Device exclusive memory access
Date: Mon, 1 Mar 2021 20:05:59 -0400 [thread overview]
Message-ID: <20210302000559.GA763995@nvidia.com> (raw)
In-Reply-To: <20210226071832.31547-6-apopple@nvidia.com>
On Fri, Feb 26, 2021 at 06:18:29PM +1100, Alistair Popple wrote:
> +/**
> + * make_device_exclusive_range() - Mark a range for exclusive use by a device
> + * @mm: mm_struct of assoicated target process
> + * @start: start of the region to mark for exclusive device access
> + * @end: end address of region
> + * @pages: returns the pages which were successfully mark for exclusive acces
> + *
> + * Returns: number of pages successfully marked for exclusive access
> + *
> + * This function finds the ptes mapping page(s) to the given address range and
> + * replaces them with special swap entries preventing userspace CPU access. On
> + * fault these entries are replaced with the original mapping after calling MMU
> + * notifiers.
> + */
> +int make_device_exclusive_range(struct mm_struct *mm, unsigned long start,
> + unsigned long end, struct page **pages)
> +{
> + long npages = (end - start) >> PAGE_SHIFT;
> + long i;
> +
> + npages = get_user_pages_remote(mm, start, npages,
> + FOLL_GET | FOLL_WRITE | FOLL_SPLIT_PMD,
> + pages, NULL, NULL);
> + for (i = 0; i < npages; i++) {
> + if (!trylock_page(pages[i])) {
> + put_page(pages[i]);
> + pages[i] = NULL;
> + continue;
> + }
> +
> + if (!try_to_protect(pages[i])) {
Isn't this racy? get_user_pages returns the ptes at an instant in
time, they could have already been changed to something else?
I would think you'd want to switch to the swap entry atomically under
th PTLs?
Jason
WARNING: multiple messages have this Message-ID (diff)
From: Jason Gunthorpe <jgg@nvidia.com>
To: Alistair Popple <apopple@nvidia.com>
Cc: rcampbell@nvidia.com, linux-doc@vger.kernel.org,
nouveau@lists.freedesktop.org, linux-kernel@vger.kernel.org,
dri-devel@lists.freedesktop.org, hch@infradead.org,
linux-mm@kvack.org, bskeggs@redhat.com, daniel@ffwll.ch,
akpm@linux-foundation.org
Subject: Re: [Nouveau] [PATCH v3 5/8] mm: Device exclusive memory access
Date: Mon, 1 Mar 2021 20:05:59 -0400 [thread overview]
Message-ID: <20210302000559.GA763995@nvidia.com> (raw)
In-Reply-To: <20210226071832.31547-6-apopple@nvidia.com>
On Fri, Feb 26, 2021 at 06:18:29PM +1100, Alistair Popple wrote:
> +/**
> + * make_device_exclusive_range() - Mark a range for exclusive use by a device
> + * @mm: mm_struct of assoicated target process
> + * @start: start of the region to mark for exclusive device access
> + * @end: end address of region
> + * @pages: returns the pages which were successfully mark for exclusive acces
> + *
> + * Returns: number of pages successfully marked for exclusive access
> + *
> + * This function finds the ptes mapping page(s) to the given address range and
> + * replaces them with special swap entries preventing userspace CPU access. On
> + * fault these entries are replaced with the original mapping after calling MMU
> + * notifiers.
> + */
> +int make_device_exclusive_range(struct mm_struct *mm, unsigned long start,
> + unsigned long end, struct page **pages)
> +{
> + long npages = (end - start) >> PAGE_SHIFT;
> + long i;
> +
> + npages = get_user_pages_remote(mm, start, npages,
> + FOLL_GET | FOLL_WRITE | FOLL_SPLIT_PMD,
> + pages, NULL, NULL);
> + for (i = 0; i < npages; i++) {
> + if (!trylock_page(pages[i])) {
> + put_page(pages[i]);
> + pages[i] = NULL;
> + continue;
> + }
> +
> + if (!try_to_protect(pages[i])) {
Isn't this racy? get_user_pages returns the ptes at an instant in
time, they could have already been changed to something else?
I would think you'd want to switch to the swap entry atomically under
th PTLs?
Jason
_______________________________________________
Nouveau mailing list
Nouveau@lists.freedesktop.org
https://lists.freedesktop.org/mailman/listinfo/nouveau
WARNING: multiple messages have this Message-ID (diff)
From: Jason Gunthorpe <jgg@nvidia.com>
To: Alistair Popple <apopple@nvidia.com>
Cc: rcampbell@nvidia.com, linux-doc@vger.kernel.org,
nouveau@lists.freedesktop.org, linux-kernel@vger.kernel.org,
dri-devel@lists.freedesktop.org, hch@infradead.org,
linux-mm@kvack.org, jglisse@redhat.com, bskeggs@redhat.com,
jhubbard@nvidia.com, akpm@linux-foundation.org
Subject: Re: [PATCH v3 5/8] mm: Device exclusive memory access
Date: Mon, 1 Mar 2021 20:05:59 -0400 [thread overview]
Message-ID: <20210302000559.GA763995@nvidia.com> (raw)
In-Reply-To: <20210226071832.31547-6-apopple@nvidia.com>
On Fri, Feb 26, 2021 at 06:18:29PM +1100, Alistair Popple wrote:
> +/**
> + * make_device_exclusive_range() - Mark a range for exclusive use by a device
> + * @mm: mm_struct of assoicated target process
> + * @start: start of the region to mark for exclusive device access
> + * @end: end address of region
> + * @pages: returns the pages which were successfully mark for exclusive acces
> + *
> + * Returns: number of pages successfully marked for exclusive access
> + *
> + * This function finds the ptes mapping page(s) to the given address range and
> + * replaces them with special swap entries preventing userspace CPU access. On
> + * fault these entries are replaced with the original mapping after calling MMU
> + * notifiers.
> + */
> +int make_device_exclusive_range(struct mm_struct *mm, unsigned long start,
> + unsigned long end, struct page **pages)
> +{
> + long npages = (end - start) >> PAGE_SHIFT;
> + long i;
> +
> + npages = get_user_pages_remote(mm, start, npages,
> + FOLL_GET | FOLL_WRITE | FOLL_SPLIT_PMD,
> + pages, NULL, NULL);
> + for (i = 0; i < npages; i++) {
> + if (!trylock_page(pages[i])) {
> + put_page(pages[i]);
> + pages[i] = NULL;
> + continue;
> + }
> +
> + if (!try_to_protect(pages[i])) {
Isn't this racy? get_user_pages returns the ptes at an instant in
time, they could have already been changed to something else?
I would think you'd want to switch to the swap entry atomically under
th PTLs?
Jason
_______________________________________________
dri-devel mailing list
dri-devel@lists.freedesktop.org
https://lists.freedesktop.org/mailman/listinfo/dri-devel
next prev parent reply other threads:[~2021-03-02 7:44 UTC|newest]
Thread overview: 92+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-02-26 7:18 [PATCH v3 0/8] Add support for SVM atomics in Nouveau Alistair Popple
2021-02-26 7:18 ` Alistair Popple
2021-02-26 7:18 ` [Nouveau] " Alistair Popple
2021-02-26 7:18 ` [PATCH v3 1/8] mm: Remove special swap entry functions Alistair Popple
2021-02-26 7:18 ` Alistair Popple
2021-02-26 7:18 ` [Nouveau] " Alistair Popple
2021-02-26 15:59 ` Christoph Hellwig
2021-02-26 15:59 ` [Nouveau] " Christoph Hellwig
2021-03-02 8:52 ` Alistair Popple
2021-03-02 8:52 ` Alistair Popple
2021-03-02 8:52 ` [Nouveau] " Alistair Popple
2021-03-02 12:02 ` Alistair Popple
2021-03-02 12:02 ` Alistair Popple
2021-03-02 12:02 ` [Nouveau] " Alistair Popple
2021-03-01 17:46 ` Jason Gunthorpe
2021-03-01 17:46 ` Jason Gunthorpe
2021-03-01 17:46 ` [Nouveau] " Jason Gunthorpe
2021-03-02 0:21 ` Alistair Popple
2021-03-02 0:21 ` Alistair Popple
2021-03-02 0:21 ` [Nouveau] " Alistair Popple
2021-02-26 7:18 ` [PATCH v3 2/8] mm/swapops: Rework swap entry manipulation code Alistair Popple
2021-02-26 7:18 ` Alistair Popple
2021-02-26 7:18 ` [Nouveau] " Alistair Popple
2021-02-26 16:00 ` Christoph Hellwig
2021-02-26 16:00 ` [Nouveau] " Christoph Hellwig
2021-03-01 17:47 ` Jason Gunthorpe
2021-03-01 17:47 ` Jason Gunthorpe
2021-03-01 17:47 ` [Nouveau] " Jason Gunthorpe
2021-02-26 7:18 ` [PATCH v3 3/8] mm/rmap: Split try_to_munlock from try_to_unmap Alistair Popple
2021-02-26 7:18 ` Alistair Popple
2021-02-26 7:18 ` [Nouveau] " Alistair Popple
2021-02-26 16:01 ` Christoph Hellwig
2021-02-26 16:01 ` [Nouveau] " Christoph Hellwig
2021-03-01 16:10 ` Jason Gunthorpe
2021-03-01 16:10 ` Jason Gunthorpe
2021-03-01 16:10 ` [Nouveau] " Jason Gunthorpe
2021-03-04 4:27 ` Alistair Popple
2021-03-04 4:27 ` Alistair Popple
2021-03-04 4:27 ` [Nouveau] " Alistair Popple
2021-02-26 7:18 ` [PATCH v3 4/8] mm/rmap: Split migration into its own function Alistair Popple
2021-02-26 7:18 ` Alistair Popple
2021-02-26 7:18 ` [Nouveau] " Alistair Popple
2021-02-26 16:03 ` Christoph Hellwig
2021-02-26 16:03 ` [Nouveau] " Christoph Hellwig
2021-03-02 22:08 ` Zi Yan
2021-03-02 22:08 ` Zi Yan
2021-03-02 22:08 ` [Nouveau] " Zi Yan
2021-03-04 23:54 ` Alistair Popple
2021-03-04 23:54 ` Alistair Popple
2021-03-04 23:54 ` [Nouveau] " Alistair Popple
2021-02-26 7:18 ` [PATCH v3 5/8] mm: Device exclusive memory access Alistair Popple
2021-02-26 7:18 ` Alistair Popple
2021-02-26 7:18 ` [Nouveau] " Alistair Popple
2021-03-01 17:54 ` Jason Gunthorpe
2021-03-01 17:54 ` Jason Gunthorpe
2021-03-01 17:54 ` [Nouveau] " Jason Gunthorpe
2021-03-01 22:55 ` Ralph Campbell
2021-03-01 22:55 ` Ralph Campbell
2021-03-01 22:55 ` [Nouveau] " Ralph Campbell
2021-03-02 0:05 ` Jason Gunthorpe [this message]
2021-03-02 0:05 ` Jason Gunthorpe
2021-03-02 0:05 ` [Nouveau] " Jason Gunthorpe
2021-03-02 8:57 ` Alistair Popple
2021-03-02 8:57 ` Alistair Popple
2021-03-02 8:57 ` [Nouveau] " Alistair Popple
2021-03-02 12:41 ` Jason Gunthorpe
2021-03-02 12:41 ` Jason Gunthorpe
2021-03-02 12:41 ` [Nouveau] " Jason Gunthorpe
2021-03-04 5:20 ` Alistair Popple
2021-03-04 5:20 ` Alistair Popple
2021-03-04 5:20 ` [Nouveau] " Alistair Popple
2021-02-26 7:18 ` [PATCH v3 6/8] mm: Selftests for exclusive device memory Alistair Popple
2021-02-26 7:18 ` Alistair Popple
2021-02-26 7:18 ` [Nouveau] " Alistair Popple
2021-03-01 17:55 ` Jason Gunthorpe
2021-03-01 17:55 ` Jason Gunthorpe
2021-03-01 17:55 ` [Nouveau] " Jason Gunthorpe
2021-03-01 18:07 ` Ralph Campbell
2021-03-01 18:07 ` Ralph Campbell
2021-03-01 18:07 ` [Nouveau] " Ralph Campbell
2021-03-01 23:14 ` Ralph Campbell
2021-03-01 23:14 ` Ralph Campbell
2021-03-01 23:14 ` [Nouveau] " Ralph Campbell
2021-03-02 9:12 ` Alistair Popple
2021-03-02 9:12 ` Alistair Popple
2021-03-02 9:12 ` [Nouveau] " Alistair Popple
2021-02-26 7:18 ` [PATCH v3 7/8] nouveau/svm: Refactor nouveau_range_fault Alistair Popple
2021-02-26 7:18 ` Alistair Popple
2021-02-26 7:18 ` [Nouveau] " Alistair Popple
2021-02-26 7:18 ` [PATCH v3 8/8] nouveau/svm: Implement atomic SVM access Alistair Popple
2021-02-26 7:18 ` Alistair Popple
2021-02-26 7:18 ` [Nouveau] " Alistair Popple
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