diff options
| author | Matthew Wilcox (Oracle) <willy@infradead.org> | 2024-03-21 14:24:42 +0000 |
|---|---|---|
| committer | Andrew Morton <akpm@linux-foundation.org> | 2024-04-24 19:34:26 -0700 |
| commit | fd1a745ce03e37945674c14833870a9af0882e2d (patch) | |
| tree | c42239c377c8f8e459362f8bbbe4badebf368faf | |
| parent | 12bbaae7635a56049779db3bef6e7140d9aa5f67 (diff) | |
| download | linux-fd1a745ce03e37945674c14833870a9af0882e2d.tar.gz | |
mm: support page_mapcount() on page_has_type() pages
Return 0 for pages which can't be mapped. This matches how page_mapped()
works. It is more convenient for users to not have to filter out these
pages.
Link: https://lkml.kernel.org/r/20240321142448.1645400-5-willy@infradead.org
Fixes: 9c5ccf2db04b ("mm: remove HUGETLB_PAGE_DTOR")
Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Reviewed-by: David Hildenbrand <david@redhat.com>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
Cc: Miaohe Lin <linmiaohe@huawei.com>
Cc: Muchun Song <muchun.song@linux.dev>
Cc: Oscar Salvador <osalvador@suse.de>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
| -rw-r--r-- | fs/proc/page.c | 7 | ||||
| -rw-r--r-- | include/linux/mm.h | 8 | ||||
| -rw-r--r-- | include/linux/page-flags.h | 4 |
3 files changed, 9 insertions, 10 deletions
diff --git a/fs/proc/page.c b/fs/proc/page.c index 195b077c0facbf..9223856c934b40 100644 --- a/fs/proc/page.c +++ b/fs/proc/page.c @@ -67,7 +67,7 @@ static ssize_t kpagecount_read(struct file *file, char __user *buf, */ ppage = pfn_to_online_page(pfn); - if (!ppage || PageSlab(ppage) || page_has_type(ppage)) + if (!ppage) pcount = 0; else pcount = page_mapcount(ppage); @@ -124,11 +124,8 @@ u64 stable_page_flags(struct page *page) /* * pseudo flags for the well known (anonymous) memory mapped pages - * - * Note that page->_mapcount is overloaded in SLAB, so the - * simple test in page_mapped() is not enough. */ - if (!PageSlab(page) && page_mapped(page)) + if (page_mapped(page)) u |= 1 << KPF_MMAP; if (PageAnon(page)) u |= 1 << KPF_ANON; diff --git a/include/linux/mm.h b/include/linux/mm.h index 7b0ee64225de9c..b6bdaa18b9e9d4 100644 --- a/include/linux/mm.h +++ b/include/linux/mm.h @@ -1223,14 +1223,16 @@ static inline void page_mapcount_reset(struct page *page) * a large folio, it includes the number of times this page is mapped * as part of that folio. * - * The result is undefined for pages which cannot be mapped into userspace. - * For example SLAB or special types of pages. See function page_has_type(). - * They use this field in struct page differently. + * Will report 0 for pages which cannot be mapped into userspace, eg + * slab, page tables and similar. */ static inline int page_mapcount(struct page *page) { int mapcount = atomic_read(&page->_mapcount) + 1; + /* Handle page_has_type() pages */ + if (mapcount < 0) + mapcount = 0; if (unlikely(PageCompound(page))) mapcount += folio_entire_mapcount(page_folio(page)); diff --git a/include/linux/page-flags.h b/include/linux/page-flags.h index dc1607f1415ebe..35a0087d091086 100644 --- a/include/linux/page-flags.h +++ b/include/linux/page-flags.h @@ -971,12 +971,12 @@ static inline bool is_page_hwpoison(struct page *page) * page_type may be used. Because it is initialised to -1, we invert the * sense of the bit, so __SetPageFoo *clears* the bit used for PageFoo, and * __ClearPageFoo *sets* the bit used for PageFoo. We reserve a few high and - * low bits so that an underflow or overflow of page_mapcount() won't be + * low bits so that an underflow or overflow of _mapcount won't be * mistaken for a page type value. */ #define PAGE_TYPE_BASE 0xf0000000 -/* Reserve 0x0000007f to catch underflows of page_mapcount */ +/* Reserve 0x0000007f to catch underflows of _mapcount */ #define PAGE_MAPCOUNT_RESERVE -128 #define PG_buddy 0x00000080 #define PG_offline 0x00000100 |