From: David Hildenbrand <david@redhat.com>
To: linux-kernel@vger.kernel.org
Cc: linux-mm@kvack.org, Andrew Morton <akpm@linux-foundation.org>,
"Matthew Wilcox (Oracle)" <willy@infradead.org>,
Mike Rapoport <rppt@kernel.org>, Minchan Kim <minchan@kernel.org>,
Sergey Senozhatsky <senozhatsky@chromium.org>,
Hyeonggon Yoo <42.hyeyoo@gmail.com>,
wang wei <a929244872@163.com>
Subject: Re: [PATCH v2 2/6] mm: allow reuse of the lower 16 bit of the page type with an actual type
Date: Wed, 29 May 2024 18:00:15 +0200 [thread overview]
Message-ID: <f9b78c91-ae2f-4bb3-bf01-8f157284b2c2@redhat.com> (raw)
In-Reply-To: <20240529111904.2069608-3-david@redhat.com>
>
> diff --git a/include/linux/page-flags.h b/include/linux/page-flags.h
> index d1bdbaaccc964..f060db808102c 100644
> --- a/include/linux/page-flags.h
> +++ b/include/linux/page-flags.h
> @@ -945,15 +945,19 @@ PAGEFLAG_FALSE(HasHWPoisoned, has_hwpoisoned)
> * mistaken for a page type value.
> */
>
> -#define PAGE_TYPE_BASE 0xf0000000
> -/* Reserve 0x0000007f to catch underflows of _mapcount */
> -#define PAGE_MAPCOUNT_RESERVE -128
> -#define PG_buddy 0x00000080
> -#define PG_offline 0x00000100
> -#define PG_table 0x00000200
> -#define PG_guard 0x00000400
> -#define PG_hugetlb 0x00000800
> -#define PG_slab 0x00001000
> +#define PAGE_TYPE_BASE 0x80000000
> +/*
> + * Reserve 0xffff0000 - 0xfffffffe to catch _mapcount underflows and
> + * allow owners that set a type to reuse the lower 16 bit for their own
> + * purposes.
> + */
> +#define PG_buddy 0x40000000
> +#define PG_offline 0x20000000
> +#define PG_table 0x10000000
> +#define PG_guard 0x08000000
> +#define PG_hugetlb 0x04008000
As Wang Wei points out, the 0 and 8 look too similar on my screen ;)
This should be
#define PG_hugetlb 0x04000000
--
Cheers,
David / dhildenb
next prev parent reply other threads:[~2024-05-29 16:00 UTC|newest]
Thread overview: 15+ messages / expand[flat|nested] mbox.gz Atom feed top
2024-05-29 11:18 [PATCH v2 0/6] mm: page_type, zsmalloc and page_mapcount_reset() David Hildenbrand
2024-05-29 11:18 ` [PATCH v2 1/6] mm: update _mapcount and page_type documentation David Hildenbrand
2024-05-29 11:19 ` [PATCH v2 2/6] mm: allow reuse of the lower 16 bit of the page type with an actual type David Hildenbrand
2024-05-29 16:00 ` David Hildenbrand [this message]
2024-05-29 11:19 ` [PATCH v2 3/6] mm/zsmalloc: use a proper page type David Hildenbrand
2024-05-30 5:01 ` Sergey Senozhatsky
2024-05-31 14:27 ` Matthew Wilcox
2024-05-31 14:32 ` David Hildenbrand
2024-06-25 22:33 ` Andrew Morton
2024-06-26 4:41 ` Sergey Senozhatsky
2024-06-26 5:08 ` David Hildenbrand
2024-05-29 11:19 ` [PATCH v2 4/6] mm/page_alloc: clear PageBuddy using __ClearPageBuddy() for bad pages David Hildenbrand
2024-05-29 11:19 ` [PATCH v2 5/6] mm/filemap: reinitialize folio->_mapcount directly David Hildenbrand
2024-05-29 11:19 ` [PATCH v2 6/6] mm/mm_init: initialize page->_mapcount directly in __init_single_page() David Hildenbrand
2024-05-30 5:02 ` [PATCH v2 0/6] mm: page_type, zsmalloc and page_mapcount_reset() Sergey Senozhatsky
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