From: Jason Gunthorpe <jgg@nvidia.com>
To: Alistair Popple <apopple@nvidia.com>
Cc: rcampbell@nvidia.com, willy@infradead.org,
linux-doc@vger.kernel.org, nouveau@lists.freedesktop.org,
dri-devel@lists.freedesktop.org, linux-kernel@vger.kernel.org,
kvm-ppc@vger.kernel.org, hch@infradead.org, linux-mm@kvack.org,
bskeggs@redhat.com, daniel@ffwll.ch, akpm@linux-foundation.org,
Christoph Hellwig <hch@lst.de>
Subject: Re: [Nouveau] [PATCH v7 5/8] mm: Device exclusive memory access
Date: Tue, 30 Mar 2021 16:32:34 -0300 [thread overview]
Message-ID: <20210330193234.GA2356281@nvidia.com> (raw)
In-Reply-To: <20210326000805.2518-6-apopple@nvidia.com>
On Fri, Mar 26, 2021 at 11:08:02AM +1100, Alistair Popple wrote:
> diff --git a/mm/memory.c b/mm/memory.c
> index 3a5705cfc891..33d11527ef77 100644
> +++ b/mm/memory.c
> @@ -781,6 +781,27 @@ copy_nonpresent_pte(struct mm_struct *dst_mm, struct mm_struct *src_mm,
> pte = pte_swp_mkuffd_wp(pte);
> set_pte_at(src_mm, addr, src_pte, pte);
> }
> + } else if (is_device_exclusive_entry(entry)) {
> + page = pfn_swap_entry_to_page(entry);
> +
> + get_page(page);
> + rss[mm_counter(page)]++;
> +
> + if (is_writable_device_exclusive_entry(entry) &&
> + is_cow_mapping(vm_flags)) {
> + /*
> + * COW mappings require pages in both
> + * parent and child to be set to read.
> + */
> + entry = make_readable_device_exclusive_entry(
> + swp_offset(entry));
> + pte = swp_entry_to_pte(entry);
> + if (pte_swp_soft_dirty(*src_pte))
> + pte = pte_swp_mksoft_dirty(pte);
> + if (pte_swp_uffd_wp(*src_pte))
> + pte = pte_swp_mkuffd_wp(pte);
> + set_pte_at(src_mm, addr, src_pte, pte);
> + }
This needs to have the same logic as we now have in
copy_present_page(). The page *is* present and we can't copy the PTE
value hidden in a swap entry if we can't copy the PTE normally.
The code should be shared because nobody is going to remember about
this corner case.
Jason
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next prev parent reply other threads:[~2021-03-30 19:32 UTC|newest]
Thread overview: 31+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-03-26 0:07 [Nouveau] [PATCH v7 0/8] Add support for SVM atomics in Nouveau Alistair Popple
2021-03-26 0:07 ` [Nouveau] [PATCH v7 1/8] mm: Remove special swap entry functions Alistair Popple
2021-03-30 18:38 ` Jason Gunthorpe
2021-03-26 0:07 ` [Nouveau] [PATCH v7 2/8] mm/swapops: Rework swap entry manipulation code Alistair Popple
2021-03-26 0:08 ` [Nouveau] [PATCH v7 3/8] mm/rmap: Split try_to_munlock from try_to_unmap Alistair Popple
2021-03-30 18:49 ` Jason Gunthorpe
2021-03-30 22:09 ` Alistair Popple
2021-03-30 22:16 ` Alistair Popple
2021-03-30 22:24 ` Jason Gunthorpe
2021-03-30 22:43 ` John Hubbard
2021-03-30 22:56 ` Alistair Popple
2021-03-31 3:56 ` John Hubbard
2021-03-31 4:09 ` John Hubbard
2021-03-31 4:15 ` Alistair Popple
2021-03-31 11:57 ` Jason Gunthorpe
2021-04-01 4:36 ` Alistair Popple
2021-04-01 19:21 ` Shakeel Butt
2021-03-26 0:08 ` [Nouveau] [PATCH v7 4/8] mm/rmap: Split migration into its own function Alistair Popple
2021-03-26 0:08 ` [Nouveau] [PATCH v7 5/8] mm: Device exclusive memory access Alistair Popple
2021-03-30 19:32 ` Jason Gunthorpe [this message]
2021-03-31 12:59 ` Alistair Popple
2021-03-31 13:18 ` Jason Gunthorpe
2021-03-31 13:27 ` Alistair Popple
2021-03-31 13:46 ` Jason Gunthorpe
2021-04-01 0:45 ` Alistair Popple
2021-04-01 0:48 ` Jason Gunthorpe
2021-04-01 2:20 ` Alistair Popple
2021-04-01 11:55 ` Jason Gunthorpe
2021-03-26 0:08 ` [Nouveau] [PATCH v7 6/8] mm: Selftests for exclusive device memory Alistair Popple
2021-03-26 0:08 ` [Nouveau] [PATCH v7 7/8] nouveau/svm: Refactor nouveau_range_fault Alistair Popple
2021-03-26 0:08 ` [Nouveau] [PATCH v7 8/8] nouveau/svm: Implement atomic SVM access Alistair Popple
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