[05/59] mm: Add the first tail page to struct folio

Message ID	20220808193430.3378317-6-willy@infradead.org (mailing list archive)
State	New
Headers	show Return-Path: <owner-linux-mm@kvack.org> From: "Matthew Wilcox (Oracle)" <willy@infradead.org> To: linux-mm@kvack.org Cc: "Matthew Wilcox (Oracle)" <willy@infradead.org>, hughd@google.com Subject: [PATCH 05/59] mm: Add the first tail page to struct folio Date: Mon, 8 Aug 2022 20:33:33 +0100 Message-Id: <20220808193430.3378317-6-willy@infradead.org> In-Reply-To: <20220808193430.3378317-1-willy@infradead.org> References: <20220808193430.3378317-1-willy@infradead.org> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Sender: owner-linux-mm@kvack.org Precedence: bulk
Series	MM folio changes for 6.1 \| expand [00/59] MM folio changes for 6.1 [01/59] mm: Fix VM_BUG_ON in __delete_from_swap_cache() [02/59] shmem: Update folio if shmem_replace_page() updates the page [03/59] vmscan: Check folio_test_private(), not folio_get_private() [04/59] mm/vmscan: Fix a lot of comments [05/59] mm: Add the first tail page to struct folio [06/59] mm: Reimplement folio_order() and folio_nr_pages() [07/59] mm: Add split_folio() [08/59] mm: Add folio_add_lru_vma() [09/59] shmem: Convert shmem_writepage() to use a folio throughout [10/59] shmem: Convert shmem_delete_from_page_cache() to take a folio [11/59] shmem: Convert shmem_replace_page() to use folios throughout [12/59] mm/swapfile: Remove page_swapcount() [13/59] mm/swapfile: Convert try_to_free_swap() to folio_free_swap() [14/59] mm/swap: Convert __read_swap_cache_async() to use a folio [15/59] mm/swap: Convert add_to_swap_cache() to take a folio [16/59] mm/swap: Convert put_swap_page() to put_swap_folio() [17/59] mm: Convert do_swap_page() to use a folio [18/59] mm: Convert do_swap_page()'s swapcache variable to a folio [19/59] memcg: Convert mem_cgroup_swapin_charge_page() to mem_cgroup_swapin_charge_folio() [20/59] shmem: Convert shmem_mfill_atomic_pte() to use a folio [21/59] shmem: Convert shmem_replace_page() to shmem_replace_folio() [22/59] swap: Add swap_cache_get_folio() [23/59] shmem: Eliminate struct page from shmem_swapin_folio() [24/59] shmem: Convert shmem_getpage_gfp() to shmem_get_folio_gfp() [25/59] shmem: Convert shmem_fault() to use shmem_get_folio_gfp() [26/59] shmem: Convert shmem_read_mapping_page_gfp() to use shmem_get_folio_gfp() [27/59] shmem: Add shmem_get_folio() [28/59] shmem: Convert shmem_get_partial_folio() to use shmem_get_folio() [29/59] shmem: Convert shmem_write_begin() to use shmem_get_folio() [30/59] shmem: Convert shmem_file_read_iter() to use shmem_get_folio() [31/59] shmem: Convert shmem_fallocate() to use a folio [32/59] shmem: Convert shmem_symlink() to use a folio [33/59] shmem: Convert shmem_get_link() to use a folio [34/59] khugepaged: Call shmem_get_folio() [35/59] userfaultfd: Convert mcontinue_atomic_pte() to use a folio [36/59] shmem: Remove shmem_getpage() [37/59] swapfile: Convert try_to_unuse() to use a folio [38/59] swapfile: Convert __try_to_reclaim_swap() to use a folio [39/59] swapfile: Convert unuse_pte_range() to use a folio [40/59] mm: Convert do_swap_page() to use swap_cache_get_folio() [41/59] mm: Remove lookup_swap_cache() [42/59] swap_state: Convert free_swap_cache() to use a folio [43/59] swap: Convert swap_writepage() to use a folio [44/59] mm: Convert do_wp_page() to use a folio [45/59] huge_memory: Convert do_huge_pmd_wp_page() to use a folio [46/59] madvise: Convert madvise_free_pte_range() to use a folio [47/59] uprobes: Use folios more widely in __replace_page() [48/59] ksm: Use a folio in replace_page() [49/59] mm: Convert do_swap_page() to use folio_free_swap() [50/59] memcg: Convert mem_cgroup_swap_full() to take a folio [51/59] mm: Remove try_to_free_swap() [52/59] rmap: Convert page_move_anon_rmap() to use a folio [53/59] migrate: Convert __unmap_and_move() to use folios [54/59] migrate: Convert unmap_and_move_huge_page() to use folios [55/59] huge_memory: Convert split_huge_page_to_list() to use a folio [56/59] huge_memory: Convert unmap_page() to unmap_folio() [57/59] mm: Convert page_get_anon_vma() to folio_get_anon_vma() [58/59] rmap: Remove page_unlock_anon_vma_read() [59/59] uprobes: Use new_folio in __replace_page()

Message ID

20220808193430.3378317-6-willy@infradead.org (mailing list archive)

State

New

Headers

From: "Matthew Wilcox (Oracle)" <willy@infradead.org>
To: linux-mm@kvack.org
Cc: "Matthew Wilcox (Oracle)" <willy@infradead.org>,
	hughd@google.com
Subject: [PATCH 05/59] mm: Add the first tail page to struct folio
Date: Mon,  8 Aug 2022 20:33:33 +0100
Message-Id: <20220808193430.3378317-6-willy@infradead.org>
In-Reply-To: <20220808193430.3378317-1-willy@infradead.org>
References: <20220808193430.3378317-1-willy@infradead.org>
MIME-Version: 1.0
Content-Transfer-Encoding: 8bit
Sender: owner-linux-mm@kvack.org
Precedence: bulk

Series

MM folio changes for 6.1 | expand

Commit Message

Matthew Wilcox Aug. 8, 2022, 7:33 p.m. UTC

Some of the static checkers get confused by extracting the page from
the folio and referring to fields in the first tail page.  Adding these
fields to struct folio lets us avoid doing that.  It has the risk that
people will refer to those fields without checking that the folio is
actually a large folio, so prefix them with underscores and document
the preferred function to use instead.

Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
---
 include/linux/mm_types.h | 30 +++++++++++++++++++++++++++++-
 1 file changed, 29 insertions(+), 1 deletion(-)

diff --git a/include/linux/mm_types.h b/include/linux/mm_types.h
index cf97f3884fda..8a9ee9d24973 100644
--- a/include/linux/mm_types.h
+++ b/include/linux/mm_types.h
@@ -244,6 +244,13 @@  struct page {
  * @_refcount: Do not access this member directly.  Use folio_ref_count()
  *    to find how many references there are to this folio.
  * @memcg_data: Memory Control Group data.
+ * @_flags_1: For large folios, additional page flags.
+ * @__head: Points to the folio.  Do not use.
+ * @_folio_dtor: Which destructor to use for this folio.
+ * @_folio_order: Do not use directly, call folio_order().
+ * @_total_mapcount: Do not use directly, call folio_entire_mapcount().
+ * @_pincount: Do not use directly, call folio_maybe_dma_pinned().
+ * @_folio_nr_pages: Do not use directly, call folio_nr_pages().
  *
  * A folio is a physically, virtually and logically contiguous set
  * of bytes.  It is a power-of-two in size, and it is aligned to that
@@ -282,9 +289,17 @@  struct folio {
 		};
 		struct page page;
 	};
+	unsigned long _flags_1;
+	unsigned long __head;
+	unsigned char _folio_dtor;
+	unsigned char _folio_order;
+	atomic_t _total_mapcount;
+	atomic_t _pincount;
+#ifdef CONFIG_64BIT
+	unsigned int _folio_nr_pages;
+#endif
 };
 
-static_assert(sizeof(struct page) == sizeof(struct folio));
 #define FOLIO_MATCH(pg, fl)						\
 	static_assert(offsetof(struct page, pg) == offsetof(struct folio, fl))
 FOLIO_MATCH(flags, flags);
@@ -299,6 +314,19 @@  FOLIO_MATCH(_refcount, _refcount);
 FOLIO_MATCH(memcg_data, memcg_data);
 #endif
 #undef FOLIO_MATCH
+#define FOLIO_MATCH(pg, fl)						\
+	static_assert(offsetof(struct folio, fl) ==			\
+			offsetof(struct page, pg) + sizeof(struct page))
+FOLIO_MATCH(flags, _flags_1);
+FOLIO_MATCH(compound_head, __head);
+FOLIO_MATCH(compound_dtor, _folio_dtor);
+FOLIO_MATCH(compound_order, _folio_order);
+FOLIO_MATCH(compound_mapcount, _total_mapcount);
+FOLIO_MATCH(compound_pincount, _pincount);
+#ifdef CONFIG_64BIT
+FOLIO_MATCH(compound_nr, _folio_nr_pages);
+#endif
+#undef FOLIO_MATCH
 
 static inline atomic_t *folio_mapcount_ptr(struct folio *folio)
 {

[05/59] mm: Add the first tail page to struct folio

Commit Message

Patch