The patch titled
Subject: zram: revive swap_slot_free_notify
has been added to the -mm tree. Its filename is
zram-revive-swap_slot_free_notify.patch
This patch should soon appear at
http://ozlabs.org/~akpm/mmots/broken-out/zram-revive-swap_slot_free_notify.patch
and later at
http://ozlabs.org/~akpm/mmotm/broken-out/zram-revive-swap_slot_free_notify.patch
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------------------------------------------------------
From: Minchan Kim <minchan@xxxxxxxxxx>
Subject: zram: revive swap_slot_free_notify
b430e9d1c6d4 ("remove compressed copy from zram in-memory") applied
swap_slot_free_notify call in *end_swap_bio_read* to remove duplicated
memory between zram and memory.
However, with the introduction of rw_page in zram: 8c7f01025f7b ("zram:
implement rw_page operation of zram"), it became void because rw_page
doesn't need bio.
This patch restores the function for rw_page.
Signed-off-by: Minchan Kim <minchan@xxxxxxxxxx>
Cc: Sergey Senozhatsky <sergey.senozhatsky@xxxxxxxxx>
Cc: karam.lee <karam.lee@xxxxxxx>
Cc: <sangseok.lee@xxxxxxx>
Cc: Chan Jeong <chan.jeong@xxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
mm/page_io.c | 93 ++++++++++++++++++++++++++-----------------------
1 file changed, 50 insertions(+), 43 deletions(-)
diff -puN mm/page_io.c~zram-revive-swap_slot_free_notify mm/page_io.c
--- a/mm/page_io.c~zram-revive-swap_slot_free_notify
+++ a/mm/page_io.c
@@ -66,6 +66,54 @@ void end_swap_bio_write(struct bio *bio)
bio_put(bio);
}
+static void swap_slot_free_notify(struct page *page)
+{
+ struct swap_info_struct *sis;
+ struct gendisk *disk;
+
+ /*
+ * There is no guarantee that the page is in swap cache - the software
+ * suspend code (at least) uses end_swap_bio_read() against a non-
+ * swapcache page. So we must check PG_swapcache before proceeding with
+ * this optimization.
+ */
+ if (unlikely(!PageSwapCache(page)))
+ return;
+
+ sis = page_swap_info(page);
+ if (!(sis->flags & SWP_BLKDEV))
+ return;
+
+ /*
+ * The swap subsystem performs lazy swap slot freeing,
+ * expecting that the page will be swapped out again.
+ * So we can avoid an unnecessary write if the page
+ * isn't redirtied.
+ * This is good for real swap storage because we can
+ * reduce unnecessary I/O and enhance wear-leveling
+ * if an SSD is used as the as swap device.
+ * But if in-memory swap device (eg zram) is used,
+ * this causes a duplicated copy between uncompressed
+ * data in VM-owned memory and compressed data in
+ * zram-owned memory. So let's free zram-owned memory
+ * and make the VM-owned decompressed page *dirty*,
+ * so the page should be swapped out somewhere again if
+ * we again wish to reclaim it.
+ */
+ disk = sis->bdev->bd_disk;
+ if (disk->fops->swap_slot_free_notify) {
+ swp_entry_t entry;
+ unsigned long offset;
+
+ entry.val = page_private(page);
+ offset = swp_offset(entry);
+
+ SetPageDirty(page);
+ disk->fops->swap_slot_free_notify(sis->bdev,
+ offset);
+ }
+}
+
static void end_swap_bio_read(struct bio *bio)
{
struct page *page = bio->bi_io_vec[0].bv_page;
@@ -81,49 +129,7 @@ static void end_swap_bio_read(struct bio
}
SetPageUptodate(page);
-
- /*
- * There is no guarantee that the page is in swap cache - the software
- * suspend code (at least) uses end_swap_bio_read() against a non-
- * swapcache page. So we must check PG_swapcache before proceeding with
- * this optimization.
- */
- if (likely(PageSwapCache(page))) {
- struct swap_info_struct *sis;
-
- sis = page_swap_info(page);
- if (sis->flags & SWP_BLKDEV) {
- /*
- * The swap subsystem performs lazy swap slot freeing,
- * expecting that the page will be swapped out again.
- * So we can avoid an unnecessary write if the page
- * isn't redirtied.
- * This is good for real swap storage because we can
- * reduce unnecessary I/O and enhance wear-leveling
- * if an SSD is used as the as swap device.
- * But if in-memory swap device (eg zram) is used,
- * this causes a duplicated copy between uncompressed
- * data in VM-owned memory and compressed data in
- * zram-owned memory. So let's free zram-owned memory
- * and make the VM-owned decompressed page *dirty*,
- * so the page should be swapped out somewhere again if
- * we again wish to reclaim it.
- */
- struct gendisk *disk = sis->bdev->bd_disk;
- if (disk->fops->swap_slot_free_notify) {
- swp_entry_t entry;
- unsigned long offset;
-
- entry.val = page_private(page);
- offset = swp_offset(entry);
-
- SetPageDirty(page);
- disk->fops->swap_slot_free_notify(sis->bdev,
- offset);
- }
- }
- }
-
+ swap_slot_free_notify(page);
out:
unlock_page(page);
bio_put(bio);
@@ -347,6 +353,7 @@ int swap_readpage(struct page *page)
ret = bdev_read_page(sis->bdev, swap_page_sector(page), page);
if (!ret) {
+ swap_slot_free_notify(page);
count_vm_event(PSWPIN);
return 0;
}
_
Patches currently in -mm which might be from minchan@xxxxxxxxxx are
zram-revive-swap_slot_free_notify.patch
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