From: David Hildenbrand Subject: mm/rmap: convert RMAP flags to a proper distinct rmap_t type We want to pass the flags to more than one anon rmap function, getting rid of special "do_page_add_anon_rmap()". So let's pass around a distinct __bitwise type and refine documentation. Link: https://lkml.kernel.org/r/20220329160440.193848-6-david@redhat.com Signed-off-by: David Hildenbrand Acked-by: Vlastimil Babka Cc: Andrea Arcangeli Cc: Christoph Hellwig Cc: David Rientjes Cc: Don Dutile Cc: Hugh Dickins Cc: Jan Kara Cc: Jann Horn Cc: Jason Gunthorpe Cc: John Hubbard Cc: Khalid Aziz Cc: "Kirill A. Shutemov" Cc: Liang Zhang Cc: Matthew Wilcox (Oracle) Cc: Michal Hocko Cc: Mike Kravetz Cc: Mike Rapoport Cc: Nadav Amit Cc: Oded Gabbay Cc: Oleg Nesterov Cc: Pedro Demarchi Gomes Cc: Peter Xu Cc: Rik van Riel Cc: Roman Gushchin Cc: Shakeel Butt Cc: Yang Shi Signed-off-by: Andrew Morton --- include/linux/rmap.h | 22 ++++++++++++++++++---- mm/memory.c | 6 +++--- mm/rmap.c | 7 ++++--- 3 files changed, 25 insertions(+), 10 deletions(-) --- a/include/linux/rmap.h~mm-rmap-convert-rmap-flags-to-a-proper-distinct-rmap_t-type +++ a/include/linux/rmap.h @@ -160,9 +160,23 @@ static inline void anon_vma_merge(struct struct anon_vma *page_get_anon_vma(struct page *page); -/* bitflags for do_page_add_anon_rmap() */ -#define RMAP_EXCLUSIVE 0x01 -#define RMAP_COMPOUND 0x02 +/* RMAP flags, currently only relevant for some anon rmap operations. */ +typedef int __bitwise rmap_t; + +/* + * No special request: if the page is a subpage of a compound page, it is + * mapped via a PTE. The mapped (sub)page is possibly shared between processes. + */ +#define RMAP_NONE ((__force rmap_t)0) + +/* The (sub)page is exclusive to a single process. */ +#define RMAP_EXCLUSIVE ((__force rmap_t)BIT(0)) + +/* + * The compound page is not mapped via PTEs, but instead via a single PMD and + * should be accounted accordingly. + */ +#define RMAP_COMPOUND ((__force rmap_t)BIT(1)) /* * rmap interfaces called when adding or removing pte of page @@ -171,7 +185,7 @@ void page_move_anon_rmap(struct page *, void page_add_anon_rmap(struct page *, struct vm_area_struct *, unsigned long address, bool compound); void do_page_add_anon_rmap(struct page *, struct vm_area_struct *, - unsigned long address, int flags); + unsigned long address, rmap_t flags); void page_add_new_anon_rmap(struct page *, struct vm_area_struct *, unsigned long address, bool compound); void page_add_file_rmap(struct page *, struct vm_area_struct *, --- a/mm/memory.c~mm-rmap-convert-rmap-flags-to-a-proper-distinct-rmap_t-type +++ a/mm/memory.c @@ -3507,10 +3507,10 @@ vm_fault_t do_swap_page(struct vm_fault struct vm_area_struct *vma = vmf->vma; struct page *page = NULL, *swapcache; struct swap_info_struct *si = NULL; + rmap_t rmap_flags = RMAP_NONE; swp_entry_t entry; pte_t pte; int locked; - int exclusive = 0; vm_fault_t ret = 0; void *shadow = NULL; @@ -3685,7 +3685,7 @@ vm_fault_t do_swap_page(struct vm_fault pte = maybe_mkwrite(pte_mkdirty(pte), vma); vmf->flags &= ~FAULT_FLAG_WRITE; ret |= VM_FAULT_WRITE; - exclusive = RMAP_EXCLUSIVE; + rmap_flags |= RMAP_EXCLUSIVE; } flush_icache_page(vma, page); if (pte_swp_soft_dirty(vmf->orig_pte)) @@ -3701,7 +3701,7 @@ vm_fault_t do_swap_page(struct vm_fault page_add_new_anon_rmap(page, vma, vmf->address, false); lru_cache_add_inactive_or_unevictable(page, vma); } else { - do_page_add_anon_rmap(page, vma, vmf->address, exclusive); + do_page_add_anon_rmap(page, vma, vmf->address, rmap_flags); } set_pte_at(vma->vm_mm, vmf->address, vmf->pte, pte); --- a/mm/rmap.c~mm-rmap-convert-rmap-flags-to-a-proper-distinct-rmap_t-type +++ a/mm/rmap.c @@ -1137,7 +1137,8 @@ static void __page_check_anon_rmap(struc void page_add_anon_rmap(struct page *page, struct vm_area_struct *vma, unsigned long address, bool compound) { - do_page_add_anon_rmap(page, vma, address, compound ? RMAP_COMPOUND : 0); + do_page_add_anon_rmap(page, vma, address, + compound ? RMAP_COMPOUND : RMAP_NONE); } /* @@ -1146,7 +1147,7 @@ void page_add_anon_rmap(struct page *pag * Everybody else should continue to use page_add_anon_rmap above. */ void do_page_add_anon_rmap(struct page *page, - struct vm_area_struct *vma, unsigned long address, int flags) + struct vm_area_struct *vma, unsigned long address, rmap_t flags) { bool compound = flags & RMAP_COMPOUND; bool first; @@ -1185,7 +1186,7 @@ void do_page_add_anon_rmap(struct page * /* address might be in next vma when migration races vma_adjust */ else if (first) __page_set_anon_rmap(page, vma, address, - flags & RMAP_EXCLUSIVE); + !!(flags & RMAP_EXCLUSIVE)); else __page_check_anon_rmap(page, vma, address); _