The patch titled
Subject: mm: add the first tail page to struct folio
has been added to the -mm mm-unstable branch. Its filename is
mm-add-the-first-tail-page-to-struct-folio.patch
This patch will shortly appear at
https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches/mm-add-the-first-tail-page-to-struct-folio.patch
This patch will later appear in the mm-unstable branch at
git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm
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------------------------------------------------------
From: "Matthew Wilcox (Oracle)" <willy@xxxxxxxxxxxxx>
Subject: mm: add the first tail page to struct folio
Date: Fri, 2 Sep 2022 20:45:58 +0100
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.
Link: https://lkml.kernel.org/r/20220902194653.1739778-3-willy@xxxxxxxxxxxxx
Signed-off-by: Matthew Wilcox (Oracle) <willy@xxxxxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
include/linux/mm_types.h | 30 +++++++++++++++++++++++++++++-
1 file changed, 29 insertions(+), 1 deletion(-)
--- a/include/linux/mm_types.h~mm-add-the-first-tail-page-to-struct-folio
+++ a/include/linux/mm_types.h
@@ -246,6 +246,13 @@ 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
@@ -284,9 +291,17 @@ 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);
@@ -301,6 +316,19 @@ 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)
{
_
Patches currently in -mm which might be from willy@xxxxxxxxxxxxx are
tools-fix-compilation-after-gfp_typesh-split.patch
mm-fix-vm_bug_on-in-__delete_from_swap_cache.patch
vmscan-check-folio_test_private-not-folio_get_private.patch
support-highmem-pages-in-vmap_pages_range_noflush.patch
mm-add-vma-iterator.patch
mmap-use-the-vma-iterator-in-count_vma_pages_range.patch
proc-remove-vma-rbtree-use-from-nommu.patch
arm64-remove-mmap-linked-list-from-vdso.patch
parisc-remove-mmap-linked-list-from-cache-handling.patch
powerpc-remove-mmap-linked-list-walks.patch
s390-remove-vma-linked-list-walks.patch
x86-remove-vma-linked-list-walks.patch
xtensa-remove-vma-linked-list-walks.patch
cxl-remove-vma-linked-list-walk.patch
optee-remove-vma-linked-list-walk.patch
um-remove-vma-linked-list-walk.patch
coredump-remove-vma-linked-list-walk.patch
exec-use-vma-iterator-instead-of-linked-list.patch
fs-proc-task_mmu-stop-using-linked-list-and-highest_vm_end.patch
acct-use-vma-iterator-instead-of-linked-list.patch
perf-use-vma-iterator.patch
sched-use-maple-tree-iterator-to-walk-vmas.patch
fork-use-vma-iterator.patch
mm-khugepaged-stop-using-vma-linked-list.patch
mm-ksm-use-vma-iterators-instead-of-vma-linked-list.patch
mm-mlock-use-vma-iterator-and-maple-state-instead-of-vma-linked-list.patch
mm-pagewalk-use-vma_find-instead-of-vma-linked-list.patch
i915-use-the-vma-iterator.patch
nommu-remove-uses-of-vma-linked-list.patch
mm-vmscan-fix-a-lot-of-comments.patch
mm-add-the-first-tail-page-to-struct-folio.patch
mm-reimplement-folio_order-and-folio_nr_pages.patch
mm-add-split_folio.patch
mm-add-folio_add_lru_vma.patch
shmem-convert-shmem_writepage-to-use-a-folio-throughout.patch
shmem-convert-shmem_delete_from_page_cache-to-take-a-folio.patch
shmem-convert-shmem_replace_page-to-use-folios-throughout.patch
mm-swapfile-remove-page_swapcount.patch
mm-swapfile-convert-try_to_free_swap-to-folio_free_swap.patch
mm-swap-convert-__read_swap_cache_async-to-use-a-folio.patch
mm-swap-convert-add_to_swap_cache-to-take-a-folio.patch
mm-swap-convert-put_swap_page-to-put_swap_folio.patch
mm-convert-do_swap_page-to-use-a-folio.patch
mm-convert-do_swap_pages-swapcache-variable-to-a-folio.patch
memcg-convert-mem_cgroup_swapin_charge_page-to-mem_cgroup_swapin_charge_folio.patch
shmem-convert-shmem_mfill_atomic_pte-to-use-a-folio.patch
shmem-convert-shmem_replace_page-to-shmem_replace_folio.patch
swap-add-swap_cache_get_folio.patch
shmem-eliminate-struct-page-from-shmem_swapin_folio.patch
shmem-convert-shmem_getpage_gfp-to-shmem_get_folio_gfp.patch
shmem-convert-shmem_fault-to-use-shmem_get_folio_gfp.patch
shmem-convert-shmem_read_mapping_page_gfp-to-use-shmem_get_folio_gfp.patch
shmem-add-shmem_get_folio.patch
shmem-convert-shmem_get_partial_folio-to-use-shmem_get_folio.patch
shmem-convert-shmem_write_begin-to-use-shmem_get_folio.patch
shmem-convert-shmem_file_read_iter-to-use-shmem_get_folio.patch
shmem-convert-shmem_fallocate-to-use-a-folio.patch
shmem-convert-shmem_symlink-to-use-a-folio.patch
shmem-convert-shmem_get_link-to-use-a-folio.patch
khugepaged-call-shmem_get_folio.patch
userfaultfd-convert-mcontinue_atomic_pte-to-use-a-folio.patch
shmem-remove-shmem_getpage.patch
swapfile-convert-try_to_unuse-to-use-a-folio.patch
swapfile-convert-__try_to_reclaim_swap-to-use-a-folio.patch
swapfile-convert-unuse_pte_range-to-use-a-folio.patch
mm-convert-do_swap_page-to-use-swap_cache_get_folio.patch
mm-remove-lookup_swap_cache.patch
swap_state-convert-free_swap_cache-to-use-a-folio.patch
swap-convert-swap_writepage-to-use-a-folio.patch
mm-convert-do_wp_page-to-use-a-folio.patch
huge_memory-convert-do_huge_pmd_wp_page-to-use-a-folio.patch
madvise-convert-madvise_free_pte_range-to-use-a-folio.patch
uprobes-use-folios-more-widely-in-__replace_page.patch
ksm-use-a-folio-in-replace_page.patch
mm-convert-do_swap_page-to-use-folio_free_swap.patch
memcg-convert-mem_cgroup_swap_full-to-take-a-folio.patch
mm-remove-try_to_free_swap.patch
rmap-convert-page_move_anon_rmap-to-use-a-folio.patch
migrate-convert-__unmap_and_move-to-use-folios.patch
migrate-convert-unmap_and_move_huge_page-to-use-folios.patch
huge_memory-convert-split_huge_page_to_list-to-use-a-folio.patch
huge_memory-convert-unmap_page-to-unmap_folio.patch
mm-convert-page_get_anon_vma-to-folio_get_anon_vma.patch
rmap-remove-page_unlock_anon_vma_read.patch
uprobes-use-new_folio-in-__replace_page.patch
mm-convert-lock_page_or_retry-to-folio_lock_or_retry.patch
