The patch titled
Subject: mm: move 'private' union within struct page
has been added to the -mm tree. Its filename is
mm-move-private-union-within-struct-page.patch
This patch should soon appear at
http://ozlabs.org/~akpm/mmots/broken-out/mm-move-private-union-within-struct-page.patch
and later at
http://ozlabs.org/~akpm/mmotm/broken-out/mm-move-private-union-within-struct-page.patch
Before you just go and hit "reply", please:
a) Consider who else should be cc'ed
b) Prefer to cc a suitable mailing list as well
c) Ideally: find the original patch on the mailing list and do a
reply-to-all to that, adding suitable additional cc's
*** Remember to use Documentation/process/submit-checklist.rst when testing your code ***
The -mm tree is included into linux-next and is updated
there every 3-4 working days
------------------------------------------------------
From: Matthew Wilcox <mawilcox@xxxxxxxxxxxxx>
Subject: mm: move 'private' union within struct page
By moving page->private to the fourth word of struct page, we can put the
SLUB counters in the same word as SLAB's s_mem and still do the
cmpxchg_double trick. Now the SLUB counters no longer overlap with the
mapcount or refcount so we can drop the call to page_mapcount_reset() and
simplify set_page_slub_counters() to a single line.
Link: http://lkml.kernel.org/r/20180518194519.3820-6-willy@xxxxxxxxxxxxx
Signed-off-by: Matthew Wilcox <mawilcox@xxxxxxxxxxxxx>
Acked-by: Vlastimil Babka <vbabka@xxxxxxx>
Acked-by: Kirill A. Shutemov <kirill.shutemov@xxxxxxxxxxxxxxx>
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 | 56 ++++++++++++++++---------------------
mm/slub.c | 20 +------------
2 files changed, 27 insertions(+), 49 deletions(-)
diff -puN include/linux/mm_types.h~mm-move-private-union-within-struct-page include/linux/mm_types.h
--- a/include/linux/mm_types.h~mm-move-private-union-within-struct-page
+++ a/include/linux/mm_types.h
@@ -65,15 +65,9 @@ struct hmm;
*/
#ifdef CONFIG_HAVE_ALIGNED_STRUCT_PAGE
#define _struct_page_alignment __aligned(2 * sizeof(unsigned long))
-#if defined(CONFIG_HAVE_CMPXCHG_DOUBLE)
-#define _slub_counter_t unsigned long
#else
-#define _slub_counter_t unsigned int
-#endif
-#else /* !CONFIG_HAVE_ALIGNED_STRUCT_PAGE */
#define _struct_page_alignment
-#define _slub_counter_t unsigned int
-#endif /* !CONFIG_HAVE_ALIGNED_STRUCT_PAGE */
+#endif
struct page {
/* First double word block */
@@ -97,6 +91,30 @@ struct 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
+#if ALLOC_SPLIT_PTLOCKS
+ spinlock_t *ptl;
+#else
+ spinlock_t ptl;
+#endif
+#endif
+ void *s_mem; /* slab first object */
+ unsigned long counters; /* SLUB */
+ struct { /* SLUB */
+ unsigned inuse:16;
+ unsigned objects:15;
+ unsigned frozen:1;
+ };
+ };
+
+ union {
+ /*
* If the page is neither PageSlab nor mappable to userspace,
* the value stored here may help determine what this page
* is used for. See page-flags.h for a list of page types
@@ -104,13 +122,7 @@ struct page {
*/
unsigned int page_type;
- _slub_counter_t counters;
unsigned int active; /* SLAB */
- struct { /* SLUB */
- unsigned inuse:16;
- unsigned objects:15;
- unsigned frozen:1;
- };
int units; /* SLOB */
struct { /* Page cache */
@@ -179,24 +191,6 @@ struct page {
#endif
};
- 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
-#if ALLOC_SPLIT_PTLOCKS
- spinlock_t *ptl;
-#else
- spinlock_t ptl;
-#endif
-#endif
- void *s_mem; /* slab first object */
- };
-
#ifdef CONFIG_MEMCG
struct mem_cgroup *mem_cgroup;
#endif
diff -puN mm/slub.c~mm-move-private-union-within-struct-page mm/slub.c
--- a/mm/slub.c~mm-move-private-union-within-struct-page
+++ a/mm/slub.c
@@ -356,21 +356,6 @@ static __always_inline void slab_unlock(
__bit_spin_unlock(PG_locked, &page->flags);
}
-static inline void set_page_slub_counters(struct page *page, unsigned long counters_new)
-{
- struct page tmp;
- tmp.counters = counters_new;
- /*
- * page->counters can cover frozen/inuse/objects as well
- * as page->_refcount. If we assign to ->counters directly
- * we run the risk of losing updates to page->_refcount, so
- * be careful and only assign to the fields we need.
- */
- page->frozen = tmp.frozen;
- page->inuse = tmp.inuse;
- page->objects = tmp.objects;
-}
-
/* Interrupts must be disabled (for the fallback code to work right) */
static inline bool __cmpxchg_double_slab(struct kmem_cache *s, struct page *page,
void *freelist_old, unsigned long counters_old,
@@ -392,7 +377,7 @@ static inline bool __cmpxchg_double_slab
if (page->freelist == freelist_old &&
page->counters == counters_old) {
page->freelist = freelist_new;
- set_page_slub_counters(page, counters_new);
+ page->counters = counters_new;
slab_unlock(page);
return true;
}
@@ -431,7 +416,7 @@ static inline bool cmpxchg_double_slab(s
if (page->freelist == freelist_old &&
page->counters == counters_old) {
page->freelist = freelist_new;
- set_page_slub_counters(page, counters_new);
+ page->counters = counters_new;
slab_unlock(page);
local_irq_restore(flags);
return true;
@@ -1694,7 +1679,6 @@ static void __free_slab(struct kmem_cach
__ClearPageSlabPfmemalloc(page);
__ClearPageSlab(page);
- page_mapcount_reset(page);
page->mapping = NULL;
if (current->reclaim_state)
current->reclaim_state->reclaimed_slab += pages;
_
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
--
To unsubscribe from this list: send the line "unsubscribe mm-commits" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
