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authorMinchan Kim <minchan@kernel.org>2017-05-03 14:54:17 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2017-05-03 15:52:10 -0700
commit33fc80e2574737e6e21eecc4c1d7942370a2c752 (patch)
treeee10306d5b2bf35138563377b7f77d89e689855f /mm
parentad6b67041a45497261617d7a28b15159b202cb5a (diff)
downloadlinux-33fc80e2574737e6e21eecc4c1d7942370a2c752.tar.bz2
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@kernel.org Signed-off-by: Minchan Kim <minchan@kernel.org> Cc: Anshuman Khandual <khandual@linux.vnet.ibm.com> Cc: Hillf Danton <hillf.zj@alibaba-inc.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Kirill A. Shutemov <kirill.shutemov@linux.intel.com> Cc: Michal Hocko <mhocko@suse.com> Cc: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com> Cc: Vlastimil Babka <vbabka@suse.cz> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'mm')
-rw-r--r--mm/rmap.c11
-rw-r--r--mm/vmscan.c2
2 files changed, 3 insertions, 10 deletions
diff --git a/mm/rmap.c b/mm/rmap.c
index 45f41d4fa670..a3645d029400 100644
--- a/mm/rmap.c
+++ b/mm/rmap.c
@@ -1504,13 +1504,10 @@ static int page_mapcount_is_zero(struct page *page)
* 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 ttu_flags flags)
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 --git a/mm/vmscan.c b/mm/vmscan.c
index cfd2651966a8..f80a54da5f7f 100644
--- a/mm/vmscan.c
+++ b/mm/vmscan.c
@@ -1150,8 +1150,6 @@ static unsigned long shrink_page_list(struct list_head *page_list,
case SWAP_FAIL:
nr_unmap_fail++;
goto activate_locked;
- case SWAP_AGAIN:
- goto keep_locked;
case SWAP_SUCCESS:
; /* try to free the page below */
}