mm/zram: correct ZRAM_ZERO flag bit position

PATCH In review Mahendran Ganesh 4 participants 6 messages Nov 12, 2014 – Nov 13, 2014

Subsystems (3)

Memory management Block layer zram

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Mahendran Ganesh

author

2014-11-12 14:37 UTC #0 lore raw

PATCH 1/1 mm/zram: correct ZRAM_ZERO flag bit position

In struct zram_table_entry, the element *value* contains obj size and obj zram flags. Bit 0 to bit (ZRAM_FLAG_SHIFT - 1) represent obj size, and bit ZRAM_FLAG_SHIFT to the highest bit of unsigned long represent obj zram_flags. So the first zram flag(ZRAM_ZERO) should be from ZRAM_FLAG_SHIFT instead of (ZRAM_FLAG_SHIFT + 1).

This patch fixes this issue.

Also this patch fixes a typo, "page in now accessed" -> "page is now accessed"

Signed-off-by Mahendran Ganesh <[email protected]>

---
 drivers/block/zram/zram_drv.h |    4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

drivers/block/zram/zram_drv.h +2 -2

index c6ee271..b05a816 100644
@@ -66,8 +66,8 @@ static const size_t max_zpage_size = PAGE_SIZE / 4 * 3;
 /* Flags for zram pages (table[page_no].value) */
 enum zram_pageflags {
 	/* Page consists entirely of zeros */
-	ZRAM_ZERO = ZRAM_FLAG_SHIFT + 1,
-	ZRAM_ACCESS,	/* page in now accessed */
+	ZRAM_ZERO = ZRAM_FLAG_SHIFT,
+	ZRAM_ACCESS,	/* page is now accessed */
 
 	__NR_ZRAM_PAGEFLAGS,
 };

Signature · 1 line

1.7.9.5

Minchan Kim

maintainer Acked-by on v1 1/1

2014-11-13 00:02 UTC #1 lore raw

Quoted 11 lines · Mahendran Ganesh

In struct zram_table_entry, the element *value* contains obj size and obj zram flags. Bit 0 to bit (ZRAM_FLAG_SHIFT - 1) represent obj size, and bit ZRAM_FLAG_SHIFT to the highest bit of unsigned long represent obj zram_flags. So the first zram flag(ZRAM_ZERO) should be from ZRAM_FLAG_SHIFT instead of (ZRAM_FLAG_SHIFT + 1).
This patch fixes this issue.
Also this patch fixes a typo, "page in now accessed" -> "page is now accessed"
Signed-off-by Mahendran Ganesh <[email protected]>

Acked-by Minchan Kim <[email protected]>

To be clear about "fixes this issue", it's not a bug but just clean up so it doesn't change any behavior.

Thanks!

Signature · 8 lines

Kind regards,
Minchan Kim

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Weijie Yang

Acked-by

2014-11-13 01:28 UTC #2 lore raw

Quoted 7 lines · Minchan Kim

Quoted 6 lines · Mahendran Ganesh
In struct zram_table_entry, the element *value* contains obj size and obj zram flags. Bit 0 to bit (ZRAM_FLAG_SHIFT - 1) represent obj size, and bit ZRAM_FLAG_SHIFT to the highest bit of unsigned long represent obj zram_flags. So the first zram flag(ZRAM_ZERO) should be from ZRAM_FLAG_SHIFT instead of (ZRAM_FLAG_SHIFT + 1).

Quoted 6 lines

Quoted 5 lines
This patch fixes this issue.
Also this patch fixes a typo, "page in now accessed" -> "page is now accessed"
Signed-off-by Mahendran Ganesh <[email protected]>
Acked-by Minchan Kim <[email protected]>

Acked-by Weijie Yang <[email protected]>

Quoted 13 lines

To be clear about "fixes this issue", it's not a bug but just clean up so it doesn't change any behavior.
Thanks!
--
Kind regards,
Minchan Kim
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Ganesh Mahendran

author

2014-11-13 13:54 UTC #3 lore raw

2014-11-13 9:27 GMT+08:00 Weijie Yang <[email protected]>:

Quoted 8 lines · Minchan Kim

Quoted 7 lines · Mahendran Ganesh
Quoted 6 lines
In struct zram_table_entry, the element *value* contains obj size and obj zram flags. Bit 0 to bit (ZRAM_FLAG_SHIFT - 1) represent obj size, and bit ZRAM_FLAG_SHIFT to the highest bit of unsigned long represent obj zram_flags. So the first zram flag(ZRAM_ZERO) should be from ZRAM_FLAG_SHIFT instead of (ZRAM_FLAG_SHIFT + 1).

Quoted 8 lines

Quoted 6 lines
Quoted 5 lines
This patch fixes this issue.
Also this patch fixes a typo, "page in now accessed" -> "page is now accessed"
Signed-off-by Mahendran Ganesh <[email protected]>
Acked-by Minchan Kim <[email protected]>
Acked-by Weijie Yang <[email protected]>

Thanks

Quoted 6 lines

Quoted 6 lines
To be clear about "fixes this issue", it's not a bug but just clean up so it doesn't change any behavior.
Thanks!

Quoted 10 lines

Quoted 8 lines
--
Kind regards,
Minchan Kim
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Ganesh Mahendran

author

2014-11-13 13:54 UTC #4 lore raw

In reply to Minchan Kim

2014-11-13 8:02 GMT+08:00 Minchan Kim <[email protected]>:

Quoted 7 lines · Mahendran Ganesh

Quoted 6 lines
In struct zram_table_entry, the element *value* contains obj size and obj zram flags. Bit 0 to bit (ZRAM_FLAG_SHIFT - 1) represent obj size, and bit ZRAM_FLAG_SHIFT to the highest bit of unsigned long represent obj zram_flags. So the first zram flag(ZRAM_ZERO) should be from ZRAM_FLAG_SHIFT instead of (ZRAM_FLAG_SHIFT + 1).

Quoted 6 lines

Quoted 5 lines
This patch fixes this issue.
Also this patch fixes a typo, "page in now accessed" -> "page is now accessed"
Signed-off-by Mahendran Ganesh <[email protected]>
Acked-by Minchan Kim <[email protected]>

Thanks!

Quoted 9 lines

To be clear about "fixes this issue", it's not a bug but just clean up so it doesn't change any behavior.
Thanks!
--
Kind regards,
Minchan Kim

Sergey Senozhatsky

Acked-by on v1 1/1

2014-11-13 14:55 UTC #5 lore raw

In reply to Mahendran Ganesh

Quoted 7 lines · Mahendran Ganesh

In struct zram_table_entry, the element *value* contains obj size and obj zram flags. Bit 0 to bit (ZRAM_FLAG_SHIFT - 1) represent obj size, and bit ZRAM_FLAG_SHIFT to the highest bit of unsigned long represent obj zram_flags. So the first zram flag(ZRAM_ZERO) should be from ZRAM_FLAG_SHIFT instead of (ZRAM_FLAG_SHIFT + 1).
This patch fixes this issue.

well, I wouldn't say this is an issue; but still.

Acked-by Sergey Senozhatsky <[email protected]>

-ss

Quoted 25 lines

Also this patch fixes a typo, "page in now accessed" -> "page is now accessed"

Signed-off-by Mahendran Ganesh <[email protected]>

---
 drivers/block/zram/zram_drv.h |    4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

drivers/block/zram/zram_drv.h +2 -2

index c6ee271..b05a816 100644
@@ -66,8 +66,8 @@ static const size_t max_zpage_size = PAGE_SIZE / 4 * 3;
 /* Flags for zram pages (table[page_no].value) */
 enum zram_pageflags {
 	/* Page consists entirely of zeros */
-	ZRAM_ZERO = ZRAM_FLAG_SHIFT + 1,
-	ZRAM_ACCESS,	/* page in now accessed */
+	ZRAM_ZERO = ZRAM_FLAG_SHIFT,
+	ZRAM_ACCESS,	/* page is now accessed */
 
 	__NR_ZRAM_PAGEFLAGS,
 };

Signature · 1 line

1.7.9.5