| Message ID | 20250129115803.2084769-4-david@redhat.com (mailing list archive) |
|---|---|
| State | New |
| Headers | show |
| Series | mm: cleanups for device-exclusive entries (hmm) | expand |
On Wed, Jan 29, 2025 at 12:58:01PM +0100, David Hildenbrand wrote: > Let's pass the folio and the pte to restore_exclusive_pte(), so we > can avoid repeated page_folio() and ptep_get(). To do that, > pass the pte to try_restore_exclusive_pte() and use a folio in there > already. > > While at it, just avoid the "swp_entry_t entry" variable in > try_restore_exclusive_pte() and add a folio-locked check to > restore_exclusive_pte(). Seems reasonable. Reviewed-by: Alistair Popple <apopple@nvidia.com> > Signed-off-by: David Hildenbrand <david@redhat.com> > --- > mm/memory.c | 29 ++++++++++++++--------------- > 1 file changed, 14 insertions(+), 15 deletions(-) > > diff --git a/mm/memory.c b/mm/memory.c > index cd689cd8a7c8..46956994aaff 100644 > --- a/mm/memory.c > +++ b/mm/memory.c > @@ -719,14 +719,13 @@ struct folio *vm_normal_folio_pmd(struct vm_area_struct *vma, > #endif > > static void restore_exclusive_pte(struct vm_area_struct *vma, > - struct page *page, unsigned long address, > - pte_t *ptep) > + struct folio *folio, struct page *page, unsigned long address, > + pte_t *ptep, pte_t orig_pte) > { > - struct folio *folio = page_folio(page); > - pte_t orig_pte; > pte_t pte; > > - orig_pte = ptep_get(ptep); > + VM_WARN_ON_FOLIO(!folio_test_locked(folio), folio); > + > pte = pte_mkold(mk_pte(page, READ_ONCE(vma->vm_page_prot))); > if (pte_swp_soft_dirty(orig_pte)) > pte = pte_mksoft_dirty(pte); > @@ -756,16 +755,15 @@ static void restore_exclusive_pte(struct vm_area_struct *vma, > * Tries to restore an exclusive pte if the page lock can be acquired without > * sleeping. > */ > -static int > -try_restore_exclusive_pte(pte_t *src_pte, struct vm_area_struct *vma, > - unsigned long addr) > +static int try_restore_exclusive_pte(struct vm_area_struct *vma, > + unsigned long addr, pte_t *ptep, pte_t orig_pte) > { > - swp_entry_t entry = pte_to_swp_entry(ptep_get(src_pte)); > - struct page *page = pfn_swap_entry_to_page(entry); > + struct page *page = pfn_swap_entry_to_page(pte_to_swp_entry(orig_pte)); > + struct folio *folio = page_folio(page); > > - if (trylock_page(page)) { > - restore_exclusive_pte(vma, page, addr, src_pte); > - unlock_page(page); > + if (folio_trylock(folio)) { > + restore_exclusive_pte(vma, folio, page, addr, ptep, orig_pte); > + folio_unlock(folio); > return 0; > } > > @@ -871,7 +869,7 @@ copy_nonpresent_pte(struct mm_struct *dst_mm, struct mm_struct *src_mm, > * (ie. COW) mappings. > */ > VM_BUG_ON(!is_cow_mapping(src_vma->vm_flags)); > - if (try_restore_exclusive_pte(src_pte, src_vma, addr)) > + if (try_restore_exclusive_pte(src_vma, addr, src_pte, orig_pte)) > return -EBUSY; > return -ENOENT; > } else if (is_pte_marker_entry(entry)) { > @@ -3979,7 +3977,8 @@ static vm_fault_t remove_device_exclusive_entry(struct vm_fault *vmf) > vmf->pte = pte_offset_map_lock(vma->vm_mm, vmf->pmd, vmf->address, > &vmf->ptl); > if (likely(vmf->pte && pte_same(ptep_get(vmf->pte), vmf->orig_pte))) > - restore_exclusive_pte(vma, vmf->page, vmf->address, vmf->pte); > + restore_exclusive_pte(vma, folio, vmf->page, vmf->address, > + vmf->pte, vmf->orig_pte); > > if (vmf->pte) > pte_unmap_unlock(vmf->pte, vmf->ptl); > -- > 2.48.1 >
diff --git a/mm/memory.c b/mm/memory.c index cd689cd8a7c8..46956994aaff 100644 --- a/mm/memory.c +++ b/mm/memory.c @@ -719,14 +719,13 @@ struct folio *vm_normal_folio_pmd(struct vm_area_struct *vma, #endif static void restore_exclusive_pte(struct vm_area_struct *vma, - struct page *page, unsigned long address, - pte_t *ptep) + struct folio *folio, struct page *page, unsigned long address, + pte_t *ptep, pte_t orig_pte) { - struct folio *folio = page_folio(page); - pte_t orig_pte; pte_t pte; - orig_pte = ptep_get(ptep); + VM_WARN_ON_FOLIO(!folio_test_locked(folio), folio); + pte = pte_mkold(mk_pte(page, READ_ONCE(vma->vm_page_prot))); if (pte_swp_soft_dirty(orig_pte)) pte = pte_mksoft_dirty(pte); @@ -756,16 +755,15 @@ static void restore_exclusive_pte(struct vm_area_struct *vma, * Tries to restore an exclusive pte if the page lock can be acquired without * sleeping. */ -static int -try_restore_exclusive_pte(pte_t *src_pte, struct vm_area_struct *vma, - unsigned long addr) +static int try_restore_exclusive_pte(struct vm_area_struct *vma, + unsigned long addr, pte_t *ptep, pte_t orig_pte) { - swp_entry_t entry = pte_to_swp_entry(ptep_get(src_pte)); - struct page *page = pfn_swap_entry_to_page(entry); + struct page *page = pfn_swap_entry_to_page(pte_to_swp_entry(orig_pte)); + struct folio *folio = page_folio(page); - if (trylock_page(page)) { - restore_exclusive_pte(vma, page, addr, src_pte); - unlock_page(page); + if (folio_trylock(folio)) { + restore_exclusive_pte(vma, folio, page, addr, ptep, orig_pte); + folio_unlock(folio); return 0; } @@ -871,7 +869,7 @@ copy_nonpresent_pte(struct mm_struct *dst_mm, struct mm_struct *src_mm, * (ie. COW) mappings. */ VM_BUG_ON(!is_cow_mapping(src_vma->vm_flags)); - if (try_restore_exclusive_pte(src_pte, src_vma, addr)) + if (try_restore_exclusive_pte(src_vma, addr, src_pte, orig_pte)) return -EBUSY; return -ENOENT; } else if (is_pte_marker_entry(entry)) { @@ -3979,7 +3977,8 @@ static vm_fault_t remove_device_exclusive_entry(struct vm_fault *vmf) vmf->pte = pte_offset_map_lock(vma->vm_mm, vmf->pmd, vmf->address, &vmf->ptl); if (likely(vmf->pte && pte_same(ptep_get(vmf->pte), vmf->orig_pte))) - restore_exclusive_pte(vma, vmf->page, vmf->address, vmf->pte); + restore_exclusive_pte(vma, folio, vmf->page, vmf->address, + vmf->pte, vmf->orig_pte); if (vmf->pte) pte_unmap_unlock(vmf->pte, vmf->ptl);
Let's pass the folio and the pte to restore_exclusive_pte(), so we can avoid repeated page_folio() and ptep_get(). To do that, pass the pte to try_restore_exclusive_pte() and use a folio in there already. While at it, just avoid the "swp_entry_t entry" variable in try_restore_exclusive_pte() and add a folio-locked check to restore_exclusive_pte(). Signed-off-by: David Hildenbrand <david@redhat.com> --- mm/memory.c | 29 ++++++++++++++--------------- 1 file changed, 14 insertions(+), 15 deletions(-)