The patch titled
Subject: mm: move _refcount out of struct page union
has been added to the -mm tree. Its filename is
mm-move-_refcount-out-of-struct-page-union.patch
This patch should soon appear at
http://ozlabs.org/~akpm/mmots/broken-out/mm-move-_refcount-out-of-struct-page-union.patch
and later at
http://ozlabs.org/~akpm/mmotm/broken-out/mm-move-_refcount-out-of-struct-page-union.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 _refcount out of struct page union
Keeping the refcount in the union only encourages people to put something
else in the union which will overlap with _refcount and eventually explode
messily. pahole reports no fields change location.
Link: http://lkml.kernel.org/r/20180518194519.3820-7-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 | 25 ++++++++++---------------
1 file changed, 10 insertions(+), 15 deletions(-)
diff -puN include/linux/mm_types.h~mm-move-_refcount-out-of-struct-page-union include/linux/mm_types.h
--- a/include/linux/mm_types.h~mm-move-_refcount-out-of-struct-page-union
+++ a/include/linux/mm_types.h
@@ -113,7 +113,13 @@ struct page {
};
};
- union {
+ union { /* This union is 4 bytes in size. */
+ /*
+ * If the page can be mapped to userspace, encodes the number
+ * of times this page is referenced by a page table.
+ */
+ atomic_t _mapcount;
+
/*
* If the page is neither PageSlab nor mappable to userspace,
* the value stored here may help determine what this page
@@ -124,22 +130,11 @@ struct page {
unsigned int active; /* SLAB */
int units; /* SLOB */
-
- struct { /* Page cache */
- /*
- * Count of ptes mapped in mms, to show when
- * page is mapped & limit reverse map searches.
- */
- atomic_t _mapcount;
-
- /*
- * Usage count, *USE WRAPPER FUNCTION* when manual
- * accounting. See page_ref.h
- */
- atomic_t _refcount;
- };
};
+ /* Usage count. *DO NOT USE DIRECTLY*. See page_ref.h */
+ atomic_t _refcount;
+
/*
* WARNING: bit 0 of the first word encode PageTail(). That means
* the rest users of the storage space MUST NOT use the bit to
_
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
