diff options
Diffstat (limited to 'mm/rmap.c')
| -rw-r--r-- | mm/rmap.c | 25 |
1 files changed, 16 insertions, 9 deletions
diff --git a/mm/rmap.c b/mm/rmap.c index 69cbd7ac2a5c..c0c99f91ade1 100644 --- a/mm/rmap.c +++ b/mm/rmap.c @@ -1401,30 +1401,35 @@ void folio_add_anon_rmap_pmd(struct folio *folio, struct page *page, * @folio: The folio to add the mapping to. * @vma: the vm area in which the mapping is added * @address: the user virtual address mapped + * @flags: The rmap flags * * Like folio_add_anon_rmap_*() but must only be called on *new* folios. * This means the inc-and-test can be bypassed. - * The folio does not have to be locked. + * The folio doesn't necessarily need to be locked while it's exclusive + * unless two threads map it concurrently. However, the folio must be + * locked if it's shared. * - * If the folio is pmd-mappable, it is accounted as a THP. As the folio - * is new, it's assumed to be mapped exclusively by a single process. + * If the folio is pmd-mappable, it is accounted as a THP. */ void folio_add_new_anon_rmap(struct folio *folio, struct vm_area_struct *vma, - unsigned long address) + unsigned long address, rmap_t flags) { - int nr = folio_nr_pages(folio); + const int nr = folio_nr_pages(folio); + const bool exclusive = flags & RMAP_EXCLUSIVE; int nr_pmdmapped = 0; VM_WARN_ON_FOLIO(folio_test_hugetlb(folio), folio); + VM_WARN_ON_FOLIO(!exclusive && !folio_test_locked(folio), folio); VM_BUG_ON_VMA(address < vma->vm_start || address + (nr << PAGE_SHIFT) > vma->vm_end, vma); __folio_set_swapbacked(folio); - __folio_set_anon(folio, vma, address, true); + __folio_set_anon(folio, vma, address, exclusive); if (likely(!folio_test_large(folio))) { /* increment count (starts at -1) */ atomic_set(&folio->_mapcount, 0); - SetPageAnonExclusive(&folio->page); + if (exclusive) + SetPageAnonExclusive(&folio->page); } else if (!folio_test_pmd_mappable(folio)) { int i; @@ -1433,7 +1438,8 @@ void folio_add_new_anon_rmap(struct folio *folio, struct vm_area_struct *vma, /* increment count (starts at -1) */ atomic_set(&page->_mapcount, 0); - SetPageAnonExclusive(page); + if (exclusive) + SetPageAnonExclusive(page); } /* increment count (starts at -1) */ @@ -1445,7 +1451,8 @@ void folio_add_new_anon_rmap(struct folio *folio, struct vm_area_struct *vma, /* increment count (starts at -1) */ atomic_set(&folio->_large_mapcount, 0); atomic_set(&folio->_nr_pages_mapped, ENTIRELY_MAPPED); - SetPageAnonExclusive(&folio->page); + if (exclusive) + SetPageAnonExclusive(&folio->page); nr_pmdmapped = nr; } |