The patch titled
Subject: mm/z3fold.c: limit first_num to the actual range of possible buddy indexes
has been added to the -mm tree. Its filename is
z3fold-limit-first_num-to-the-actual-range-of-possible-buddy-indexes.patch
This patch should soon appear at
http://ozlabs.org/~akpm/mmots/broken-out/z3fold-limit-first_num-to-the-actual-range-of-possible-buddy-indexes.patch
and later at
http://ozlabs.org/~akpm/mmotm/broken-out/z3fold-limit-first_num-to-the-actual-range-of-possible-buddy-indexes.patch
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------------------------------------------------------
From: zhong jiang <zhongjiang@xxxxxxxxxx>
Subject: mm/z3fold.c: limit first_num to the actual range of possible buddy indexes
At present, Tying the first_num size to NCHUNKS_ORDER is confusing. the
number of chunks is completely unrelated to the number of buddies.
The patch limits the first_num to actual range of possible buddy indexes.
and that is more reasonable and obvious without functional change.
Link: http://lkml.kernel.org/r/1476776569-29504-1-git-send-email-zhongjiang@xxxxxxxxxx
Signed-off-by: zhong jiang <zhongjiang@xxxxxxxxxx>
Suggested-by: Dan Streetman <ddstreet@xxxxxxxx>
Acked-by: Dan Streetman <ddstreet@xxxxxxxx>
Acked-by: Vitaly Wool <vitalywool@xxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
mm/z3fold.c | 10 +++++++---
1 file changed, 7 insertions(+), 3 deletions(-)
diff -puN mm/z3fold.c~z3fold-limit-first_num-to-the-actual-range-of-possible-buddy-indexes mm/z3fold.c
--- a/mm/z3fold.c~z3fold-limit-first_num-to-the-actual-range-of-possible-buddy-indexes
+++ a/mm/z3fold.c
@@ -51,7 +51,7 @@
#define ZHDR_SIZE_ALIGNED CHUNK_SIZE
#define NCHUNKS ((PAGE_SIZE - ZHDR_SIZE_ALIGNED) >> CHUNK_SHIFT)
-#define BUDDY_MASK ((1 << NCHUNKS_ORDER) - 1)
+#define BUDDY_MASK (0x3)
struct z3fold_pool;
struct z3fold_ops {
@@ -114,7 +114,7 @@ struct z3fold_header {
unsigned short middle_chunks;
unsigned short last_chunks;
unsigned short start_middle;
- unsigned short first_num:NCHUNKS_ORDER;
+ unsigned short first_num:2;
};
/*
@@ -187,7 +187,11 @@ static struct z3fold_header *handle_to_z
return (struct z3fold_header *)(handle & PAGE_MASK);
}
-/* Returns buddy number */
+/*
+ * (handle & BUDDY_MASK) < zhdr->first_num is possible in encode_handle
+ * but that doesn't matter. because the masking will result in the
+ * correct buddy number.
+ */
static enum buddy handle_to_buddy(unsigned long handle)
{
struct z3fold_header *zhdr = handle_to_z3fold_header(handle);
_
Patches currently in -mm which might be from zhongjiang@xxxxxxxxxx are
z3fold-limit-first_num-to-the-actual-range-of-possible-buddy-indexes.patch
mm-page_owner-align-with-pageblock_nr-pages.patch
mm-walk-the-zone-in-pageblock_nr_pages-steps.patch
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