+ mm-shmem-return-number-of-pages-beeing-freed-in-shmem_free_swap.patch added to mm-unstable branch

[Andrew Morton <akpm@linux-foundation.org>]

The patch titled
     Subject: mm: shmem: return number of pages beeing freed in shmem_free_swap
has been added to the -mm mm-unstable branch.  Its filename is
     mm-shmem-return-number-of-pages-beeing-freed-in-shmem_free_swap.patch

This patch will shortly appear at
     https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches/mm-shmem-return-number-of-pages-beeing-freed-in-shmem_free_swap.patch

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

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------------------------------------------------------
From: Daniel Gomez <da.gomez@samsung.com>
Subject: mm: shmem: return number of pages beeing freed in shmem_free_swap
Date: Tue, 18 Jun 2024 14:54:16 +0800

Both shmem_free_swap callers expect the number of pages being freed.  In
the large folios context, this needs to support larger values other than 0
(used as 1 page being freed) and -ENOENT (used as 0 pages being freed). 
In preparation for large folios adoption, make shmem_free_swap routine
return the number of pages being freed.  So, returning 0 in this context,
means 0 pages being freed.

While we are at it, changing to use free_swap_and_cache_nr() to free large
order swap entry by Baolin Wang.

Link: https://lkml.kernel.org/r/6e567bfbb6bac0bfbdd63e60718bd1aaf8eade6c.1718690645.git.baolin.wang@linux.alibaba.com
Signed-off-by: Daniel Gomez <da.gomez@samsung.com>
Signed-off-by: Baolin Wang <baolin.wang@linux.alibaba.com>
Suggested-by: Matthew Wilcox <willy@infradead.org>
Cc: Barry Song <21cnbao@gmail.com>
Cc: Chris Li <chrisl@kernel.org>
Cc: David Hildenbrand <david@redhat.com>
Cc: "Huang, Ying" <ying.huang@intel.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: Kefeng Wang <wangkefeng.wang@huawei.com>
Cc: Lance Yang <ioworker0@gmail.com>
Cc: Pankaj Raghav <p.raghav@samsung.com>
Cc: Ryan Roberts <ryan.roberts@arm.com>
Cc: Yang Shi <shy828301@gmail.com>
Cc: Zi Yan <ziy@nvidia.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---

 mm/shmem.c |   25 ++++++++++++++++---------
 1 file changed, 16 insertions(+), 9 deletions(-)

--- a/mm/shmem.c~mm-shmem-return-number-of-pages-beeing-freed-in-shmem_free_swap
+++ a/mm/shmem.c
@@ -836,18 +836,22 @@ static void shmem_delete_from_page_cache
 }
 
 /*
- * Remove swap entry from page cache, free the swap and its page cache.
+ * Remove swap entry from page cache, free the swap and its page cache. Returns
+ * the number of pages being freed. 0 means entry not found in XArray (0 pages
+ * being freed).
  */
-static int shmem_free_swap(struct address_space *mapping,
-			   pgoff_t index, void *radswap)
+static long shmem_free_swap(struct address_space *mapping,
+			    pgoff_t index, void *radswap)
 {
+	int order = xa_get_order(&mapping->i_pages, index);
 	void *old;
 
 	old = xa_cmpxchg_irq(&mapping->i_pages, index, radswap, NULL, 0);
 	if (old != radswap)
-		return -ENOENT;
-	free_swap_and_cache(radix_to_swp_entry(radswap));
-	return 0;
+		return 0;
+	free_swap_and_cache_nr(radix_to_swp_entry(radswap), 1 << order);
+
+	return 1 << order;
 }
 
 /*
@@ -999,7 +1003,7 @@ static void shmem_undo_range(struct inod
 			if (xa_is_value(folio)) {
 				if (unfalloc)
 					continue;
-				nr_swaps_freed += !shmem_free_swap(mapping,
+				nr_swaps_freed += shmem_free_swap(mapping,
 							indices[i], folio);
 				continue;
 			}
@@ -1066,14 +1070,17 @@ whole_folios:
 			folio = fbatch.folios[i];
 
 			if (xa_is_value(folio)) {
+				long swaps_freed;
+
 				if (unfalloc)
 					continue;
-				if (shmem_free_swap(mapping, indices[i], folio)) {
+				swaps_freed = shmem_free_swap(mapping, indices[i], folio);
+				if (!swaps_freed) {
 					/* Swap was replaced by page: retry */
 					index = indices[i];
 					break;
 				}
-				nr_swaps_freed++;
+				nr_swaps_freed += swaps_freed;
 				continue;
 			}
 
_

Patches currently in -mm which might be from da.gomez@samsung.com are

mm-shmem-return-number-of-pages-beeing-freed-in-shmem_free_swap.patch