+ mm-swap-add-helper-swap_offset_available.patch added to mm-unstable branch

+ mm-swap-add-helper-swap_offset_available.patch added to mm-unstable branch

[Andrew Morton]

The patch titled
     Subject: mm/swap: add helper swap_offset_available()
has been added to the -mm mm-unstable branch.  Its filename is
     mm-swap-add-helper-swap_offset_available.patch

This patch should soon appear in the mm-unstable branch at
    git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm

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------------------------------------------------------
From: Miaohe Lin <linmiaohe@huawei.com>
Subject: mm/swap: add helper swap_offset_available()

Add helper swap_offset_available() to remove some duplicated codes.  Minor
readability improvement.

Link: https://lkml.kernel.org/r/20220509131416.17553-12-linmiaohe@huawei.com
Signed-off-by: Miaohe Lin <linmiaohe@huawei.com>
Cc: Alistair Popple <apopple@nvidia.com>
Cc: David Hildenbrand <david@redhat.com>
Cc: David Howells <dhowells@redhat.com>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Naoya Horiguchi <naoya.horiguchi@nec.com>
Cc: NeilBrown <neilb@suse.de>
Cc: Peter Xu <peterx@redhat.com>
Cc: Suren Baghdasaryan <surenb@google.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---

 mm/swapfile.c |   33 +++++++++++++++++----------------
 1 file changed, 17 insertions(+), 16 deletions(-)

--- a/mm/swapfile.c~mm-swap-add-helper-swap_offset_available
+++ a/mm/swapfile.c
@@ -775,6 +775,21 @@ static void set_cluster_next(struct swap
 	this_cpu_write(*si->cluster_next_cpu, next);
 }
 
+static inline bool swap_offset_available(struct swap_info_struct *si, unsigned long offset)
+{
+	if (data_race(!si->swap_map[offset])) {
+		spin_lock(&si->lock);
+		return true;
+	}
+
+	if (vm_swap_full() && READ_ONCE(si->swap_map[offset]) == SWAP_HAS_CACHE) {
+		spin_lock(&si->lock);
+		return true;
+	}
+
+	return false;
+}
+
 static int scan_swap_map_slots(struct swap_info_struct *si,
 			       unsigned char usage, int nr,
 			       swp_entry_t slots[])
@@ -952,15 +967,8 @@ done:
 scan:
 	spin_unlock(&si->lock);
 	while (++offset <= READ_ONCE(si->highest_bit)) {
-		if (data_race(!si->swap_map[offset])) {
-			spin_lock(&si->lock);
-			goto checks;
-		}
-		if (vm_swap_full() &&
-		    READ_ONCE(si->swap_map[offset]) == SWAP_HAS_CACHE) {
-			spin_lock(&si->lock);
+		if (swap_offset_available(si, offset))
 			goto checks;
-		}
 		if (unlikely(--latency_ration < 0)) {
 			cond_resched();
 			latency_ration = LATENCY_LIMIT;
@@ -969,15 +977,8 @@ scan:
 	}
 	offset = si->lowest_bit;
 	while (offset < scan_base) {
-		if (data_race(!si->swap_map[offset])) {
-			spin_lock(&si->lock);
+		if (swap_offset_available(si, offset))
 			goto checks;
-		}
-		if (vm_swap_full() &&
-		    READ_ONCE(si->swap_map[offset]) == SWAP_HAS_CACHE) {
-			spin_lock(&si->lock);
-			goto checks;
-		}
 		if (unlikely(--latency_ration < 0)) {
 			cond_resched();
 			latency_ration = LATENCY_LIMIT;
_

Patches currently in -mm which might be from linmiaohe@huawei.com are

mm-swapfile-unuse_pte-can-map-random-data-if-swap-read-fails.patch
mm-swapfile-fix-lost-swap-bits-in-unuse_pte.patch
mm-madvise-free-hwpoison-and-swapin-error-entry-in-madvise_free_pte_range.patch
mm-migration-reduce-the-rcu-lock-duration.patch
mm-migration-remove-unneeded-lock-page-and-pagemovable-check.patch
mm-migration-return-errno-when-isolate_huge_page-failed.patch
mm-migration-fix-potential-pte_unmap-on-an-not-mapped-pte.patch
mm-vmscan-take-min_slab_pages-into-account-when-try-to-call-shrink_node.patch
mm-vmscan-add-a-comment-about-madv_free-pages-check-in-folio_check_dirty_writeback.patch
mm-vmscan-introduce-helper-function-reclaim_page_list.patch
mm-vmscan-take-all-base-pages-of-thp-into-account-when-race-with-speculative-reference.patch
mm-vmscan-remove-obsolete-comment-in-kswapd_run.patch
mm-vmscan-use-helper-folio_is_file_lru.patch
mm-vmscan-use-helper-folio_is_file_lru-fix.patch
mm-z3fold-fix-sheduling-while-atomic.patch
mm-z3fold-fix-possible-null-pointer-dereferencing.patch
mm-z3fold-remove-buggy-use-of-stale-list-for-allocation.patch
mm-z3fold-throw-warning-on-failure-of-trylock_page-in-z3fold_alloc.patch
revert-mm-z3foldc-allow-__gfp_highmem-in-z3fold_alloc.patch
mm-z3fold-put-z3fold-page-back-into-unbuddied-list-when-reclaim-or-migration-fails.patch
mm-z3fold-always-clear-page_claimed-under-z3fold-page-lock.patch
mm-z3fold-fix-z3fold_reclaim_page-races-with-z3fold_free.patch
mm-z3fold-fix-z3fold_page_migrate-races-with-z3fold_map.patch
mm-swap-use-helper-is_swap_pte-in-swap_vma_readahead.patch
mm-swap-use-helper-macro-__attr_rw.patch
mm-swap-fold-__swap_info_get-into-its-sole-caller.patch
mm-swap-remove-unneeded-return-value-of-free_swap_slot.patch
mm-swap-print-bad-swap-offset-entry-in-get_swap_device.patch
mm-swap-remove-buggy-cache-nr-check-in-refill_swap_slots_cache.patch
mm-swap-remove-unneeded-p-=-null-check-in-__swap_duplicate.patch
mm-swap-make-page_swapcount-and-__lru_add_drain_all.patch
mm-swap-avoid-calling-swp_swap_info-when-try-to-check-swp_stable_writes.patch
mm-swap-add-helper-swap_offset_available.patch
mm-swap-fix-the-obsolete-comment-for-swp_type_shift.patch
mm-swap-clean-up-the-comment-of-find_next_to_unuse.patch
mm-swap-fix-the-comment-of-get_kernel_pages.patch
mm-swap-fix-comment-about-swap-extent.patch