Commit 932961c4 authored by David Hildenbrand's avatar David Hildenbrand Committed by Andrew Morton
Browse files

mm/rmap: abstract large mapcount operations for large folios (!hugetlb) 

Let's abstract the operations so we can extend these operations easily.

Link: https://lkml.kernel.org/r/20250303163014.1128035-10-david@redhat.com


Signed-off-by: default avatarDavid Hildenbrand <david@redhat.com>
Cc: Andy Lutomirks^H^Hski <luto@kernel.org>
Cc: Borislav Betkov <bp@alien8.de>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Jann Horn <jannh@google.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: Lance Yang <ioworker0@gmail.com>
Cc: Liam Howlett <liam.howlett@oracle.com>
Cc: Lorenzo Stoakes <lorenzo.stoakes@oracle.com>
Cc: Matthew Wilcow (Oracle) <willy@infradead.org>
Cc: Michal Koutn <mkoutny@suse.com>
Cc: Muchun Song <muchun.song@linux.dev>
Cc: tejun heo <tj@kernel.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Zefan Li <lizefan.x@bytedance.com>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
parent 1862a4af

include/linux/rmap.h

+28 −4
Original line number Diff line number Diff line
@@ -173,6 +173,30 @@ static inline void anon_vma_merge(struct vm_area_struct *vma, 


struct anon_vma *folio_get_anon_vma(const struct folio *folio);



static inline void folio_set_large_mapcount(struct folio *folio, int mapcount,

		struct vm_area_struct *vma)

{

	/* Note: mapcounts start at -1. */

	atomic_set(&folio->_large_mapcount, mapcount - 1);

}



static inline void folio_add_large_mapcount(struct folio *folio,

		int diff, struct vm_area_struct *vma)

{

	atomic_add(diff, &folio->_large_mapcount);

}



static inline void folio_sub_large_mapcount(struct folio *folio,

		int diff, struct vm_area_struct *vma)

{

	atomic_sub(diff, &folio->_large_mapcount);

}



#define folio_inc_large_mapcount(folio, vma) \

	folio_add_large_mapcount(folio, 1, vma)

#define folio_dec_large_mapcount(folio, vma) \

	folio_sub_large_mapcount(folio, 1, vma)



/* RMAP flags, currently only relevant for some anon rmap operations. */

typedef int __bitwise rmap_t;
@@ -352,12 +376,12 @@ static __always_inline void __folio_dup_file_rmap(struct folio *folio, 
		do {

			atomic_inc(&page->_mapcount);

		} while (page++, --nr_pages > 0);

		atomic_add(orig_nr_pages, &folio->_large_mapcount);

		folio_add_large_mapcount(folio, orig_nr_pages, dst_vma);

		break;

	case RMAP_LEVEL_PMD:

	case RMAP_LEVEL_PUD:

		atomic_inc(&folio->_entire_mapcount);

		atomic_inc(&folio->_large_mapcount);

		folio_inc_large_mapcount(folio, dst_vma);

		break;

	}

}
@@ -451,7 +475,7 @@ static __always_inline int __folio_try_dup_anon_rmap(struct folio *folio, 
				ClearPageAnonExclusive(page);

			atomic_inc(&page->_mapcount);

		} while (page++, --nr_pages > 0);

		atomic_add(orig_nr_pages, &folio->_large_mapcount);

		folio_add_large_mapcount(folio, orig_nr_pages, dst_vma);

		break;

	case RMAP_LEVEL_PMD:

	case RMAP_LEVEL_PUD:
@@ -461,7 +485,7 @@ static __always_inline int __folio_try_dup_anon_rmap(struct folio *folio, 
			ClearPageAnonExclusive(page);

		}

		atomic_inc(&folio->_entire_mapcount);

		atomic_inc(&folio->_large_mapcount);

		folio_inc_large_mapcount(folio, dst_vma);

		break;

	}

	return 0;

mm/rmap.c

+6 −8
Original line number Diff line number Diff line
@@ -1266,7 +1266,7 @@ static __always_inline unsigned int __folio_add_rmap(struct folio *folio, 
		    atomic_add_return_relaxed(first, mapped) < ENTIRELY_MAPPED)

			nr = first;



		atomic_add(orig_nr_pages, &folio->_large_mapcount);

		folio_add_large_mapcount(folio, orig_nr_pages, vma);

		break;

	case RMAP_LEVEL_PMD:

	case RMAP_LEVEL_PUD:
@@ -1290,7 +1290,7 @@ static __always_inline unsigned int __folio_add_rmap(struct folio *folio, 
				nr = 0;

			}

		}

		atomic_inc(&folio->_large_mapcount);

		folio_inc_large_mapcount(folio, vma);

		break;

	}

	return nr;
@@ -1556,14 +1556,12 @@ void folio_add_new_anon_rmap(struct folio *folio, struct vm_area_struct *vma, 
				SetPageAnonExclusive(page);

		}



		/* increment count (starts at -1) */

		atomic_set(&folio->_large_mapcount, nr - 1);

		folio_set_large_mapcount(folio, nr, vma);

		atomic_set(&folio->_nr_pages_mapped, nr);

	} else {

		/* increment count (starts at -1) */

		atomic_set(&folio->_entire_mapcount, 0);

		/* increment count (starts at -1) */

		atomic_set(&folio->_large_mapcount, 0);

		folio_set_large_mapcount(folio, 1, vma);

		atomic_set(&folio->_nr_pages_mapped, ENTIRELY_MAPPED);

		if (exclusive)

			SetPageAnonExclusive(&folio->page);
@@ -1665,7 +1663,7 @@ static __always_inline void __folio_remove_rmap(struct folio *folio, 
			break;

		}



		atomic_sub(nr_pages, &folio->_large_mapcount);

		folio_sub_large_mapcount(folio, nr_pages, vma);

		do {

			last += atomic_add_negative(-1, &page->_mapcount);

		} while (page++, --nr_pages > 0);
@@ -1678,7 +1676,7 @@ static __always_inline void __folio_remove_rmap(struct folio *folio, 
		break;

	case RMAP_LEVEL_PMD:

	case RMAP_LEVEL_PUD:

		atomic_dec(&folio->_large_mapcount);

		folio_dec_large_mapcount(folio, vma);

		last = atomic_add_negative(-1, &folio->_entire_mapcount);

		if (last) {

			nr = atomic_sub_return_relaxed(ENTIRELY_MAPPED, mapped);