From a448f2d07f891ac65cc48017f17735ec73086bf0 Mon Sep 17 00:00:00 2001 From: Huang Ying Date: Tue, 21 Aug 2018 21:52:17 -0700 Subject: mm/swapfile.c: unify normal/huge code path in put_swap_page() In this patch, the normal/huge code path in put_swap_page() and several helper functions are unified to avoid duplicated code, bugs, etc. and make it easier to review the code. The removed lines are more than added lines. And the binary size is kept exactly same when CONFIG_TRANSPARENT_HUGEPAGE=n. Link: http://lkml.kernel.org/r/20180720071845.17920-6-ying.huang@intel.com Signed-off-by: "Huang, Ying" Suggested-by: Dave Hansen Acked-by: Dave Hansen Reviewed-by: Daniel Jordan Cc: Michal Hocko Cc: Johannes Weiner Cc: Shaohua Li Cc: Hugh Dickins Cc: Minchan Kim Cc: Rik van Riel Cc: Dan Williams Cc: Matthew Wilcox Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- mm/swapfile.c | 83 ++++++++++++++++++++++++++--------------------------------- 1 file changed, 37 insertions(+), 46 deletions(-) (limited to 'mm') diff --git a/mm/swapfile.c b/mm/swapfile.c index 3c1172b53436..043645e7f0b5 100644 --- a/mm/swapfile.c +++ b/mm/swapfile.c @@ -204,8 +204,16 @@ static void discard_swap_cluster(struct swap_info_struct *si, #ifdef CONFIG_THP_SWAP #define SWAPFILE_CLUSTER HPAGE_PMD_NR + +#define swap_entry_size(size) (size) #else #define SWAPFILE_CLUSTER 256 + +/* + * Define swap_entry_size() as constant to let compiler to optimize + * out some code if !CONFIG_THP_SWAP + */ +#define swap_entry_size(size) 1 #endif #define LATENCY_LIMIT 256 @@ -1192,18 +1200,7 @@ void swap_free(swp_entry_t entry) /* * Called after dropping swapcache to decrease refcnt to swap entries. */ -static void swapcache_free(swp_entry_t entry) -{ - struct swap_info_struct *p; - - p = _swap_info_get(entry); - if (p) { - if (!__swap_entry_free(p, entry, SWAP_HAS_CACHE)) - free_swap_slot(entry); - } -} - -static void swapcache_free_cluster(swp_entry_t entry) +void put_swap_page(struct page *page, swp_entry_t entry) { unsigned long offset = swp_offset(entry); unsigned long idx = offset / SWAPFILE_CLUSTER; @@ -1212,39 +1209,41 @@ static void swapcache_free_cluster(swp_entry_t entry) unsigned char *map; unsigned int i, free_entries = 0; unsigned char val; - - if (!IS_ENABLED(CONFIG_THP_SWAP)) - return; + int size = swap_entry_size(hpage_nr_pages(page)); si = _swap_info_get(entry); if (!si) return; - ci = lock_cluster(si, offset); - VM_BUG_ON(!cluster_is_huge(ci)); - map = si->swap_map + offset; - for (i = 0; i < SWAPFILE_CLUSTER; i++) { - val = map[i]; - VM_BUG_ON(!(val & SWAP_HAS_CACHE)); - if (val == SWAP_HAS_CACHE) - free_entries++; - } - if (!free_entries) { - for (i = 0; i < SWAPFILE_CLUSTER; i++) - map[i] &= ~SWAP_HAS_CACHE; - } - cluster_clear_huge(ci); - unlock_cluster(ci); - if (free_entries == SWAPFILE_CLUSTER) { - spin_lock(&si->lock); + if (size == SWAPFILE_CLUSTER) { ci = lock_cluster(si, offset); - memset(map, 0, SWAPFILE_CLUSTER); + VM_BUG_ON(!cluster_is_huge(ci)); + map = si->swap_map + offset; + for (i = 0; i < SWAPFILE_CLUSTER; i++) { + val = map[i]; + VM_BUG_ON(!(val & SWAP_HAS_CACHE)); + if (val == SWAP_HAS_CACHE) + free_entries++; + } + if (!free_entries) { + for (i = 0; i < SWAPFILE_CLUSTER; i++) + map[i] &= ~SWAP_HAS_CACHE; + } + cluster_clear_huge(ci); unlock_cluster(ci); - mem_cgroup_uncharge_swap(entry, SWAPFILE_CLUSTER); - swap_free_cluster(si, idx); - spin_unlock(&si->lock); - } else if (free_entries) { - for (i = 0; i < SWAPFILE_CLUSTER; i++, entry.val++) { + if (free_entries == SWAPFILE_CLUSTER) { + spin_lock(&si->lock); + ci = lock_cluster(si, offset); + memset(map, 0, SWAPFILE_CLUSTER); + unlock_cluster(ci); + mem_cgroup_uncharge_swap(entry, SWAPFILE_CLUSTER); + swap_free_cluster(si, idx); + spin_unlock(&si->lock); + return; + } + } + if (size == 1 || free_entries) { + for (i = 0; i < size; i++, entry.val++) { if (!__swap_entry_free(si, entry, SWAP_HAS_CACHE)) free_swap_slot(entry); } @@ -1268,14 +1267,6 @@ int split_swap_cluster(swp_entry_t entry) } #endif -void put_swap_page(struct page *page, swp_entry_t entry) -{ - if (!PageTransHuge(page)) - swapcache_free(entry); - else - swapcache_free_cluster(entry); -} - static int swp_entry_cmp(const void *ent1, const void *ent2) { const swp_entry_t *e1 = ent1, *e2 = ent2; -- cgit v1.2.3