unimore/kernel-hacking-2024-linux-steffo
unimore/kernel-hacking-2024-linux-steffo
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mm: introduce page_mapcount_is_type()

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Resolve the awkward "and add one to this opaque constant" test into a
self-documenting inline function.

Link: https://lkml.kernel.org/r/20240821173914.2270383-3-willy@infradead.org
Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Acked-by: David Hildenbrand <david@redhat.com>
Cc: Hyeonggon Yoo <42.hyeyoo@gmail.com>
Cc: Kent Overstreet <kent.overstreet@linux.dev>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
This commit is contained in:
Matthew Wilcox (Oracle) 2024-08-21 18:39:10 +01:00 committed by Andrew Morton
parent e27ad6560e
commit e880034cf7
3 changed files with 11 additions and 7 deletions
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3
fs/proc/internal.h
View file

@ -166,8 +166,7 @@ static inline int folio_precise_page_mapcount(struct folio *folio,
{
int mapcount = atomic_read(&page->_mapcount) + 1;
/* Handle page_has_type() pages */
if (mapcount < PAGE_MAPCOUNT_RESERVE + 1)
if (page_mapcount_is_type(mapcount))
mapcount = 0;
if (folio_test_large(folio))
mapcount += folio_entire_mapcount(folio);

3
include/linux/mm.h
View file

@ -1228,8 +1228,7 @@ static inline int folio_mapcount(const struct folio *folio)
if (likely(!folio_test_large(folio))) {
mapcount = atomic_read(&folio->_mapcount) + 1;
/* Handle page_has_type() pages */
if (mapcount < PAGE_MAPCOUNT_RESERVE + 1)
if (page_mapcount_is_type(mapcount))
mapcount = 0;
return mapcount;
}

12
include/linux/page-flags.h
View file

@ -956,12 +956,18 @@ enum pagetype {
#define folio_test_type(folio, flag) \
((READ_ONCE(folio->page.page_type) & (PAGE_TYPE_BASE | flag)) == PAGE_TYPE_BASE)
static inline int page_type_has_type(unsigned int page_type)
static inline bool page_type_has_type(int page_type)
{
return (int)page_type < PAGE_MAPCOUNT_RESERVE;
return page_type < PAGE_MAPCOUNT_RESERVE;
}
static inline int page_has_type(const struct page *page)
/* This takes a mapcount which is one more than page->_mapcount */
static inline bool page_mapcount_is_type(unsigned int mapcount)
{
return page_type_has_type(mapcount - 1);
}
static inline bool page_has_type(const struct page *page)
{
return page_type_has_type(READ_ONCE(page->page_type));
}