From: Alistair Popple <apopple@nvidia.com>
To: Christoph Hellwig <hch@infradead.org>
Cc: rcampbell@nvidia.com, daniel@ffwll.ch, linux-doc@vger.kernel.org,
nouveau@lists.freedesktop.org, linux-kernel@vger.kernel.org,
dri-devel@lists.freedesktop.org, linux-mm@kvack.org,
bskeggs@redhat.com, jgg@nvidia.com, akpm@linux-foundation.org
Subject: Re: [Nouveau] [PATCH v3 1/8] mm: Remove special swap entry functions
Date: Tue, 2 Mar 2021 19:52:53 +1100 [thread overview]
Message-ID: <2110609.1zlQqR5hOE@nvdebian> (raw)
In-Reply-To: <20210226155909.GA2907711@infradead.org>
On Saturday, 27 February 2021 2:59:09 AM AEDT Christoph Hellwig wrote:
> > - struct page *page = migration_entry_to_page(entry);
> > + struct page *page = pfn_to_page(swp_offset(entry));
>
> I wonder if keeping a single special_entry_to_page() helper would still
> me a useful. But I'm not entirely sure. There are also two more open
> coded copies of this in the THP migration code.
I think it might be if only to clearly document where these entries are used.
Will add it for the next version to see what it looks like.
> > -#define free_swap_and_cache(e) ({(is_migration_entry(e) ||
is_device_private_entry(e));})
> > -#define swapcache_prepare(e) ({(is_migration_entry(e) ||
is_device_private_entry(e));})
> > +#define free_swap_and_cache(e) is_special_entry(e)
> > +#define swapcache_prepare(e) is_special_entry(e)
>
> Staring at this I'm really, really confused at what this is doing.
>
> Looking a little closer these are the !CONFIG_SWAP stubs, but it could
> probably use a comment or two.
Will do, thanks.
- Alistair
> > } else if (is_migration_entry(entry)) {
> > - page = migration_entry_to_page(entry);
> > + page = pfn_to_page(swp_offset(entry));
> >
> > rss[mm_counter(page)]++;
> >
> > @@ -737,7 +737,7 @@ copy_nonpresent_pte(struct mm_struct *dst_mm, struct
mm_struct *src_mm,
> > set_pte_at(src_mm, addr, src_pte, pte);
> > }
> > } else if (is_device_private_entry(entry)) {
> > - page = device_private_entry_to_page(entry);
> > + page = pfn_to_page(swp_offset(entry));
> >
> > /*
> > * Update rss count even for unaddressable pages, as
> > @@ -1274,7 +1274,7 @@ static unsigned long zap_pte_range(struct mmu_gather
*tlb,
> >
> > entry = pte_to_swp_entry(ptent);
> > if (is_device_private_entry(entry)) {
> > - struct page *page = device_private_entry_to_page(entry);
> > + struct page *page = pfn_to_page(swp_offset(entry));
> >
> > if (unlikely(details && details->check_mapping)) {
> > /*
> > @@ -1303,7 +1303,7 @@ static unsigned long zap_pte_range(struct mmu_gather
*tlb,
> > else if (is_migration_entry(entry)) {
> > struct page *page;
> >
> > - page = migration_entry_to_page(entry);
> > + page = pfn_to_page(swp_offset(entry));
> > rss[mm_counter(page)]--;
> > }
> > if (unlikely(!free_swap_and_cache(entry)))
> > @@ -3271,7 +3271,7 @@ vm_fault_t do_swap_page(struct vm_fault *vmf)
> > migration_entry_wait(vma->vm_mm, vmf->pmd,
> > vmf->address);
> > } else if (is_device_private_entry(entry)) {
> > - vmf->page = device_private_entry_to_page(entry);
> > + vmf->page = pfn_to_page(swp_offset(entry));
> > ret = vmf->page->pgmap->ops->migrate_to_ram(vmf);
> > } else if (is_hwpoison_entry(entry)) {
> > ret = VM_FAULT_HWPOISON;
> > diff --git a/mm/migrate.c b/mm/migrate.c
> > index 20ca887ea769..72adcc3d8f5b 100644
> > --- a/mm/migrate.c
> > +++ b/mm/migrate.c
> > @@ -321,7 +321,7 @@ void __migration_entry_wait(struct mm_struct *mm,
pte_t *ptep,
> > if (!is_migration_entry(entry))
> > goto out;
> >
> > - page = migration_entry_to_page(entry);
> > + page = pfn_to_page(swp_offset(entry));
> >
> > /*
> > * Once page cache replacement of page migration started, page_count
> > @@ -361,7 +361,7 @@ void pmd_migration_entry_wait(struct mm_struct *mm,
pmd_t *pmd)
> > ptl = pmd_lock(mm, pmd);
> > if (!is_pmd_migration_entry(*pmd))
> > goto unlock;
> > - page = migration_entry_to_page(pmd_to_swp_entry(*pmd));
> > + page = pfn_to_page(swp_offset(pmd_to_swp_entry(*pmd)));
> > if (!get_page_unless_zero(page))
> > goto unlock;
> > spin_unlock(ptl);
> > @@ -2437,7 +2437,7 @@ static int migrate_vma_collect_pmd(pmd_t *pmdp,
> > if (!is_device_private_entry(entry))
> > goto next;
> >
> > - page = device_private_entry_to_page(entry);
> > + page = pfn_to_page(swp_offset(entry));
> > if (!(migrate->flags &
> > MIGRATE_VMA_SELECT_DEVICE_PRIVATE) ||
> > page->pgmap->owner != migrate->pgmap_owner)
> > diff --git a/mm/page_vma_mapped.c b/mm/page_vma_mapped.c
> > index 86e3a3688d59..34230d08556a 100644
> > --- a/mm/page_vma_mapped.c
> > +++ b/mm/page_vma_mapped.c
> > @@ -96,7 +96,7 @@ static bool check_pte(struct page_vma_mapped_walk *pvmw)
> > if (!is_migration_entry(entry))
> > return false;
> >
> > - pfn = migration_entry_to_pfn(entry);
> > + pfn = swp_offset(entry);
> > } else if (is_swap_pte(*pvmw->pte)) {
> > swp_entry_t entry;
> >
> > @@ -105,7 +105,7 @@ static bool check_pte(struct page_vma_mapped_walk
*pvmw)
> > if (!is_device_private_entry(entry))
> > return false;
> >
> > - pfn = device_private_entry_to_pfn(entry);
> > + pfn = swp_offset(entry);
> > } else {
> > if (!pte_present(*pvmw->pte))
> > return false;
> > @@ -200,7 +200,7 @@ bool page_vma_mapped_walk(struct page_vma_mapped_walk
*pvmw)
> > if (is_migration_entry(pmd_to_swp_entry(*pvmw->pmd))) {
> > swp_entry_t entry = pmd_to_swp_entry(*pvmw->pmd);
> >
> > - if (migration_entry_to_page(entry) != page)
> > + if (pfn_to_page(swp_offset(entry)) != page)
> > return not_found(pvmw);
> > return true;
> > }
> ---end quoted text---
>
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next prev parent reply other threads:[~2021-03-02 8:53 UTC|newest]
Thread overview: 32+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-02-26 7:18 [Nouveau] [PATCH v3 0/8] Add support for SVM atomics in Nouveau Alistair Popple
2021-02-26 7:18 ` [Nouveau] [PATCH v3 1/8] mm: Remove special swap entry functions Alistair Popple
2021-02-26 15:59 ` Christoph Hellwig
2021-03-02 8:52 ` Alistair Popple [this message]
2021-03-02 12:02 ` Alistair Popple
2021-03-01 17:46 ` Jason Gunthorpe
2021-03-02 0:21 ` Alistair Popple
2021-02-26 7:18 ` [Nouveau] [PATCH v3 2/8] mm/swapops: Rework swap entry manipulation code Alistair Popple
2021-02-26 16:00 ` Christoph Hellwig
2021-03-01 17:47 ` Jason Gunthorpe
2021-02-26 7:18 ` [Nouveau] [PATCH v3 3/8] mm/rmap: Split try_to_munlock from try_to_unmap Alistair Popple
2021-02-26 16:01 ` Christoph Hellwig
2021-03-01 16:10 ` Jason Gunthorpe
2021-03-04 4:27 ` Alistair Popple
2021-02-26 7:18 ` [Nouveau] [PATCH v3 4/8] mm/rmap: Split migration into its own function Alistair Popple
2021-02-26 16:03 ` Christoph Hellwig
2021-03-02 22:08 ` Zi Yan
2021-03-04 23:54 ` Alistair Popple
2021-02-26 7:18 ` [Nouveau] [PATCH v3 5/8] mm: Device exclusive memory access Alistair Popple
2021-03-01 17:54 ` Jason Gunthorpe
2021-03-01 22:55 ` Ralph Campbell
2021-03-02 0:05 ` Jason Gunthorpe
2021-03-02 8:57 ` Alistair Popple
2021-03-02 12:41 ` Jason Gunthorpe
2021-03-04 5:20 ` Alistair Popple
2021-02-26 7:18 ` [Nouveau] [PATCH v3 6/8] mm: Selftests for exclusive device memory Alistair Popple
2021-03-01 17:55 ` Jason Gunthorpe
2021-03-01 18:07 ` Ralph Campbell
2021-03-01 23:14 ` Ralph Campbell
2021-03-02 9:12 ` Alistair Popple
2021-02-26 7:18 ` [Nouveau] [PATCH v3 7/8] nouveau/svm: Refactor nouveau_range_fault Alistair Popple
2021-02-26 7:18 ` [Nouveau] [PATCH v3 8/8] nouveau/svm: Implement atomic SVM access Alistair Popple
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