* [patch 053/102] mm: remove SWAP_AGAIN in ttu
@ 2017-05-03 21:54 akpm
0 siblings, 0 replies; only message in thread
From: akpm @ 2017-05-03 21:54 UTC (permalink / raw)
To: akpm, hannes, hillf.zj, khandual, kirill.shutemov, mhocko,
minchan, mm-commits, n-horiguchi, torvalds, vbabka
From: Minchan Kim <minchan@kernel.org>
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@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>
---
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
@@ -1150,8 +1150,6 @@ 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 */
}
_
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2017-05-03 21:54 [patch 053/102] mm: remove SWAP_AGAIN in ttu akpm
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