The patch titled
Subject: mm: remove SWAP_AGAIN in ttu
has been added to the -mm tree. Its filename is
mm-remove-swap_again-in-ttu.patch
This patch should soon appear at
http://ozlabs.org/~akpm/mmots/broken-out/mm-remove-swap_again-in-ttu.patch
and later at
http://ozlabs.org/~akpm/mmotm/broken-out/mm-remove-swap_again-in-ttu.patch
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------------------------------------------------------
From: Minchan Kim <minchan@xxxxxxxxxx>
Subject: mm: remove SWAP_AGAIN in ttu
In 2002, [1] introduced SWAP_AGAIN. At that time, try_to_unmap_one used
spin_trylock(&mm->page_table_lock) so it's really easy to contend and fail
to hold a lock so SWAP_AGAIN to keep LRU status makes sense.
However, now we changed it to mutex-based lock and be able to block
without skip pte so there is few of small window to return SWAP_AGAIN so
remove SWAP_AGAIN and just return SWAP_FAIL.
[1] c48c43e, minimal rmap
Link: http://lkml.kernel.org/r/1489555493-14659-7-git-send-email-minchan@xxxxxxxxxx
Signed-off-by: Minchan Kim <minchan@xxxxxxxxxx>
Cc: Anshuman Khandual <khandual@xxxxxxxxxxxxxxxxxx>
Cc: Hillf Danton <hillf.zj@xxxxxxxxxxxxxxx>
Cc: Johannes Weiner <hannes@xxxxxxxxxxx>
Cc: Kirill A. Shutemov <kirill.shutemov@xxxxxxxxxxxxxxx>
Cc: Michal Hocko <mhocko@xxxxxxxx>
Cc: Naoya Horiguchi <n-horiguchi@xxxxxxxxxxxxx>
Cc: Vlastimil Babka <vbabka@xxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
mm/rmap.c | 11 +++--------
mm/vmscan.c | 2 --
2 files changed, 3 insertions(+), 10 deletions(-)
diff -puN mm/rmap.c~mm-remove-swap_again-in-ttu mm/rmap.c
--- a/mm/rmap.c~mm-remove-swap_again-in-ttu
+++ a/mm/rmap.c
@@ -1504,13 +1504,10 @@ static int page_mapcount_is_zero(struct
* Return values are:
*
* SWAP_SUCCESS - we succeeded in removing all mappings
- * SWAP_AGAIN - we missed a mapping, try again later
* SWAP_FAIL - the page is unswappable
*/
int try_to_unmap(struct page *page, enum ttu_flags flags)
{
- int ret;
-
struct rmap_walk_control rwc = {
.rmap_one = try_to_unmap_one,
.arg = (void *)flags,
@@ -1530,13 +1527,11 @@ int try_to_unmap(struct page *page, enum
rwc.invalid_vma = invalid_migration_vma;
if (flags & TTU_RMAP_LOCKED)
- ret = rmap_walk_locked(page, &rwc);
+ rmap_walk_locked(page, &rwc);
else
- ret = rmap_walk(page, &rwc);
+ rmap_walk(page, &rwc);
- if (!page_mapcount(page))
- ret = SWAP_SUCCESS;
- return ret;
+ return !page_mapcount(page) ? SWAP_SUCCESS : SWAP_FAIL;
}
static int page_not_mapped(struct page *page)
diff -puN mm/vmscan.c~mm-remove-swap_again-in-ttu mm/vmscan.c
--- a/mm/vmscan.c~mm-remove-swap_again-in-ttu
+++ a/mm/vmscan.c
@@ -1148,8 +1148,6 @@ static unsigned long shrink_page_list(st
case SWAP_FAIL:
nr_unmap_fail++;
goto activate_locked;
- case SWAP_AGAIN:
- goto keep_locked;
case SWAP_SUCCESS:
; /* try to free the page below */
}
_
Patches currently in -mm which might be from minchan@xxxxxxxxxx are
mm-reclaim-madv_free-pages-fix.patch
mm-fix-lazyfree-bug-on-check-in-try_to_unmap_one.patch
mm-fix-lazyfree-bug-on-check-in-try_to_unmap_one-fix.patch
mm-do-not-use-double-negation-for-testing-page-flags.patch
mm-remove-unncessary-ret-in-page_referenced.patch
mm-remove-swap_dirty-in-ttu.patch
mm-remove-swap_mlock-check-for-swap_success-in-ttu.patch
mm-make-the-try_to_munlock-void-function.patch
mm-remove-swap_mlock-in-ttu.patch
mm-remove-swap_again-in-ttu.patch
mm-make-ttus-return-boolean.patch
mm-make-rmap_walk-void-function.patch
mm-make-rmap_one-boolean-function.patch
mm-remove-swap_.patch
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