The patch titled
Subject: mm: combine first three unions in struct page
has been added to the -mm tree. Its filename is
mm-combine-first-three-unions-in-struct-page.patch
This patch should soon appear at
http://ozlabs.org/~akpm/mmots/broken-out/mm-combine-first-three-unions-in-struct-page.patch
and later at
http://ozlabs.org/~akpm/mmotm/broken-out/mm-combine-first-three-unions-in-struct-page.patch
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*** Remember to use Documentation/process/submit-checklist.rst when testing your code ***
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------------------------------------------------------
From: Matthew Wilcox <mawilcox@xxxxxxxxxxxxx>
Subject: mm: combine first three unions in struct page
By combining these three one-word unions into one three-word union, we
make it easier for users to add their own multi-word fields to struct
page, as well as making it obvious that SLUB needs to keep its double-word
alignment for its freelist & counters.
No field moves position; verified with pahole.
Link: http://lkml.kernel.org/r/20180518194519.3820-8-willy@xxxxxxxxxxxxx
Signed-off-by: Matthew Wilcox <mawilcox@xxxxxxxxxxxxx>
Acked-by: Kirill A. Shutemov <kirill.shutemov@xxxxxxxxxxxxxxx>
Acked-by: Vlastimil Babka <vbabka@xxxxxxx>
Cc: Christoph Lameter <cl@xxxxxxxxx>
Cc: Dave Hansen <dave.hansen@xxxxxxxxxxxxxxx>
Cc: Jérôme Glisse <jglisse@xxxxxxxxxx>
Cc: Lai Jiangshan <jiangshanlai@xxxxxxxxx>
Cc: Martin Schwidefsky <schwidefsky@xxxxxxxxxx>
Cc: Pekka Enberg <penberg@xxxxxxxxxx>
Cc: Randy Dunlap <rdunlap@xxxxxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
include/linux/mm_types.h | 66 ++++++++++++++++++-------------------
1 file changed, 33 insertions(+), 33 deletions(-)
diff -puN include/linux/mm_types.h~mm-combine-first-three-unions-in-struct-page include/linux/mm_types.h
--- a/include/linux/mm_types.h~mm-combine-first-three-unions-in-struct-page
+++ a/include/linux/mm_types.h
@@ -70,46 +70,46 @@ struct hmm;
#endif
struct page {
- /* First double word block */
unsigned long flags; /* Atomic flags, some possibly
* updated asynchronously */
+ /* Three words (12/24 bytes) are available in this union. */
union {
- /* See page-flags.h for the definition of PAGE_MAPPING_FLAGS */
- struct address_space *mapping;
-
- struct kmem_cache *slab_cache; /* SL[AU]B: Pointer to slab */
+ struct { /* Page cache and anonymous pages */
+ /* See page-flags.h for PAGE_MAPPING_FLAGS */
+ struct address_space *mapping;
+ pgoff_t index; /* Our offset within mapping. */
+ /**
+ * @private: Mapping-private opaque data.
+ * Usually used for buffer_heads if PagePrivate.
+ * Used for swp_entry_t if PageSwapCache.
+ * Indicates order in the buddy system if PageBuddy.
+ */
+ unsigned long private;
+ };
+ struct { /* slab, slob and slub */
+ struct kmem_cache *slab_cache; /* not slob */
+ /* Double-word boundary */
+ void *freelist; /* first free object */
+ union {
+ void *s_mem; /* slab: first object */
+ unsigned long counters; /* SLUB */
+ struct { /* SLUB */
+ unsigned inuse:16;
+ unsigned objects:15;
+ unsigned frozen:1;
+ };
+ };
+ };
atomic_t compound_mapcount; /* first tail page */
- /* page_deferred_list().next -- second tail page */
- };
-
- /* Second double word */
- union {
- pgoff_t index; /* Our offset within mapping. */
- void *freelist; /* sl[aou]b first free object */
- /* page_deferred_list().prev -- second tail page */
- };
-
- union {
- /*
- * Mapping-private opaque data:
- * Usually used for buffer_heads if PagePrivate
- * Used for swp_entry_t if PageSwapCache
- * Indicates order in the buddy system if PageBuddy
- */
- unsigned long private;
-#if USE_SPLIT_PTE_PTLOCKS
+ struct list_head deferred_list; /* second tail page */
+ struct { /* Page table pages */
+ unsigned long _pt_pad_2; /* mapping */
+ unsigned long _pt_pad_3;
#if ALLOC_SPLIT_PTLOCKS
- spinlock_t *ptl;
+ spinlock_t *ptl;
#else
- spinlock_t ptl;
-#endif
+ spinlock_t ptl;
#endif
- void *s_mem; /* slab first object */
- unsigned long counters; /* SLUB */
- struct { /* SLUB */
- unsigned inuse:16;
- unsigned objects:15;
- unsigned frozen:1;
};
};
_
Patches currently in -mm which might be from mawilcox@xxxxxxxxxxxxx are
lib-test_bitmapc-fix-bitmap-optimisation-tests-to-report-errors-correctly.patch
slab-__gfp_zero-is-incompatible-with-a-constructor.patch
s390-use-_refcount-for-pgtables.patch
mm-split-page_type-out-from-_mapcount.patch
mm-mark-pages-in-use-for-page-tables.patch
mm-switch-s_mem-and-slab_cache-in-struct-page.patch
mm-move-private-union-within-struct-page.patch
mm-move-_refcount-out-of-struct-page-union.patch
mm-combine-first-three-unions-in-struct-page.patch
mm-use-page-deferred_list.patch
mm-move-lru-union-within-struct-page.patch
mm-combine-lru-and-main-union-in-struct-page.patch
mm-improve-struct-page-documentation.patch
mm-add-pt_mm-to-struct-page.patch
mm-add-hmm_data-to-struct-page.patch
slabslub-remove-rcu_head-size-checks.patch
slub-remove-kmem_cache-reserved.patch
slub-remove-reserved-file-from-sysfs.patch
mm-distinguish-vmalloc-pages.patch
ida-remove-simple_ida_lock.patch
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