The patch titled
Subject: mm/swapfile.c: replace some #ifdef with IS_ENABLED()
has been added to the -mm tree. Its filename is
mm-swapfilec-replace-some-ifdef-with-is_enabled.patch
This patch should soon appear at
http://ozlabs.org/~akpm/mmots/broken-out/mm-swapfilec-replace-some-ifdef-with-is_enabled.patch
and later at
http://ozlabs.org/~akpm/mmotm/broken-out/mm-swapfilec-replace-some-ifdef-with-is_enabled.patch
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------------------------------------------------------
From: Huang Ying <ying.huang@xxxxxxxxx>
Subject: mm/swapfile.c: replace some #ifdef with IS_ENABLED()
In mm/swapfile.c, THP (Transparent Huge Page) swap specific code is
enclosed by #ifdef CONFIG_THP_SWAP/#endif to avoid code dilating when THP
isn't enabled. But #ifdef/#endif in .c file hurt the code readability, so
Dave suggested to use IS_ENABLED(CONFIG_THP_SWAP) instead and let compiler
to do the dirty job for us. This has potential to remove some duplicated
code too. From output of `size`,
text data bss dec hex filename
THP=y: 26269 2076 340 28685 700d mm/swapfile.o
ifdef/endif: 24115 2028 340 26483 6773 mm/swapfile.o
IS_ENABLED: 24179 2028 340 26547 67b3 mm/swapfile.o
IS_ENABLED() based solution works quite well, almost as good as that of
#ifdef/#endif. And from the diffstat, the removed lines are more than
added lines.
One #ifdef for split_swap_cluster() is kept. Because it is a public
function with a stub implementation for CONFIG_THP_SWAP=n in swap.h.
Link: http://lkml.kernel.org/r/20180720071845.17920-3-ying.huang@xxxxxxxxx
Signed-off-by: "Huang, Ying" <ying.huang@xxxxxxxxx>
Suggested-and-acked-by: Dave Hansen <dave.hansen@xxxxxxxxxxxxxxx>
Reviewed-by: Daniel Jordan <daniel.m.jordan@xxxxxxxxxx>
Reviewed-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
Cc: Michal Hocko <mhocko@xxxxxxxx>
Cc: Johannes Weiner <hannes@xxxxxxxxxxx>
Cc: Shaohua Li <shli@xxxxxxxxxx>
Cc: Hugh Dickins <hughd@xxxxxxxxxx>
Cc: Minchan Kim <minchan@xxxxxxxxxx>
Cc: Rik van Riel <riel@xxxxxxxxxx>
Cc: Dan Williams <dan.j.williams@xxxxxxxxx>
Cc: Matthew Wilcox <willy@xxxxxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
mm/swapfile.c | 60 ++++++++++++++++--------------------------------
1 file changed, 20 insertions(+), 40 deletions(-)
diff -puN mm/swapfile.c~mm-swapfilec-replace-some-ifdef-with-is_enabled mm/swapfile.c
--- a/mm/swapfile.c~mm-swapfilec-replace-some-ifdef-with-is_enabled
+++ a/mm/swapfile.c
@@ -868,7 +868,6 @@ no_page:
return n_ret;
}
-#ifdef CONFIG_THP_SWAP
static int swap_alloc_cluster(struct swap_info_struct *si, swp_entry_t *slot)
{
unsigned long idx;
@@ -876,6 +875,15 @@ static int swap_alloc_cluster(struct swa
unsigned long offset, i;
unsigned char *map;
+ /*
+ * Should not even be attempting cluster allocations when huge
+ * page swap is disabled. Warn and fail the allocation.
+ */
+ if (!IS_ENABLED(CONFIG_THP_SWAP)) {
+ VM_WARN_ON_ONCE(1);
+ return 0;
+ }
+
if (cluster_list_empty(&si->free_clusters))
return 0;
@@ -906,13 +914,6 @@ static void swap_free_cluster(struct swa
unlock_cluster(ci);
swap_range_free(si, offset, SWAPFILE_CLUSTER);
}
-#else
-static int swap_alloc_cluster(struct swap_info_struct *si, swp_entry_t *slot)
-{
- VM_WARN_ON_ONCE(1);
- return 0;
-}
-#endif /* CONFIG_THP_SWAP */
static unsigned long scan_swap_map(struct swap_info_struct *si,
unsigned char usage)
@@ -1200,7 +1201,6 @@ static void swapcache_free(swp_entry_t e
}
}
-#ifdef CONFIG_THP_SWAP
static void swapcache_free_cluster(swp_entry_t entry)
{
unsigned long offset = swp_offset(entry);
@@ -1211,6 +1211,9 @@ static void swapcache_free_cluster(swp_e
unsigned int i, free_entries = 0;
unsigned char val;
+ if (!IS_ENABLED(CONFIG_THP_SWAP))
+ return;
+
si = _swap_info_get(entry);
if (!si)
return;
@@ -1246,6 +1249,7 @@ static void swapcache_free_cluster(swp_e
}
}
+#ifdef CONFIG_THP_SWAP
int split_swap_cluster(swp_entry_t entry)
{
struct swap_info_struct *si;
@@ -1260,11 +1264,7 @@ int split_swap_cluster(swp_entry_t entry
unlock_cluster(ci);
return 0;
}
-#else
-static inline void swapcache_free_cluster(swp_entry_t entry)
-{
-}
-#endif /* CONFIG_THP_SWAP */
+#endif
void put_swap_page(struct page *page, swp_entry_t entry)
{
@@ -1414,7 +1414,6 @@ out:
return count;
}
-#ifdef CONFIG_THP_SWAP
static bool swap_page_trans_huge_swapped(struct swap_info_struct *si,
swp_entry_t entry)
{
@@ -1425,6 +1424,9 @@ static bool swap_page_trans_huge_swapped
int i;
bool ret = false;
+ if (!IS_ENABLED(CONFIG_THP_SWAP))
+ return swap_swapcount(si, entry) != 0;
+
ci = lock_cluster_or_swap_info(si, offset);
if (!ci || !cluster_is_huge(ci)) {
if (map[roffset] != SWAP_HAS_CACHE)
@@ -1447,7 +1449,7 @@ static bool page_swapped(struct page *pa
swp_entry_t entry;
struct swap_info_struct *si;
- if (likely(!PageTransCompound(page)))
+ if (!IS_ENABLED(CONFIG_THP_SWAP) || likely(!PageTransCompound(page)))
return page_swapcount(page) != 0;
page = compound_head(page);
@@ -1471,10 +1473,8 @@ static int page_trans_huge_map_swapcount
/* hugetlbfs shouldn't call it */
VM_BUG_ON_PAGE(PageHuge(page), page);
- if (likely(!PageTransCompound(page))) {
- mapcount = atomic_read(&page->_mapcount) + 1;
- if (total_mapcount)
- *total_mapcount = mapcount;
+ if (!IS_ENABLED(CONFIG_THP_SWAP) || likely(!PageTransCompound(page))) {
+ mapcount = page_trans_huge_mapcount(page, total_mapcount);
if (PageSwapCache(page))
swapcount = page_swapcount(page);
if (total_swapcount)
@@ -1521,26 +1521,6 @@ static int page_trans_huge_map_swapcount
return map_swapcount;
}
-#else
-#define swap_page_trans_huge_swapped(si, entry) swap_swapcount(si, entry)
-#define page_swapped(page) (page_swapcount(page) != 0)
-
-static int page_trans_huge_map_swapcount(struct page *page, int *total_mapcount,
- int *total_swapcount)
-{
- int mapcount, swapcount = 0;
-
- /* hugetlbfs shouldn't call it */
- VM_BUG_ON_PAGE(PageHuge(page), page);
-
- mapcount = page_trans_huge_mapcount(page, total_mapcount);
- if (PageSwapCache(page))
- swapcount = page_swapcount(page);
- if (total_swapcount)
- *total_swapcount = swapcount;
- return mapcount + swapcount;
-}
-#endif
/*
* We can write to an anon page without COW if there are no other references
_
Patches currently in -mm which might be from ying.huang@xxxxxxxxx are
mm-clear_huge_page-move-order-algorithm-into-a-separate-function.patch
mm-huge-page-copy-target-sub-page-last-when-copy-huge-page.patch
mm-hugetlbfs-rename-address-to-haddr-in-hugetlb_cow.patch
mm-hugetlbfs-pass-fault-address-to-cow-handler.patch
mm-swap-make-config_thp_swap-depends-on-config_swap.patch
swap-add-comments-to-lock_cluster_or_swap_info.patch
mm-swapfilec-replace-some-ifdef-with-is_enabled.patch
swap-use-swap_count-in-swap_page_trans_huge_swapped.patch
swap-unify-normal-huge-code-path-in-swap_page_trans_huge_swapped.patch
swap-unify-normal-huge-code-path-in-put_swap_page.patch
swap-get_swap_pages-use-entry_size-instead-of-cluster-in-parameter.patch
swap-add-__swap_entry_free_locked.patch
swap-put_swap_page-share-more-between-huge-normal-code-path.patch
mm-swap-fix-race-between-swapoff-and-some-swap-operations.patch
mm-swap-fix-race-between-swapoff-and-some-swap-operations-v6.patch
mm-fix-race-between-swapoff-and-mincore.patch
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