swp_entry_t swp = folio->swap;
pgoff_t offset = swp_offset(swp);
struct page *page = &folio->page;
+ bool swapcache = folio_test_swapcache(folio);
struct zswap_tree *tree = swap_zswap_tree(swp);
struct zswap_entry *entry;
u8 *dst;
spin_unlock(&tree->lock);
return false;
}
- zswap_rb_erase(&tree->rbroot, entry);
+ /*
+ * When reading into the swapcache, invalidate our entry. The
+ * swapcache can be the authoritative owner of the page and
+ * its mappings, and the pressure that results from having two
+ * in-memory copies outweighs any benefits of caching the
+ * compression work.
+ *
+ * (Most swapins go through the swapcache. The notable
+ * exception is the singleton fault on SWP_SYNCHRONOUS_IO
+ * files, which reads into a private page and may free it if
+ * the fault fails. We remain the primary owner of the entry.)
+ */
+ if (swapcache)
+ zswap_rb_erase(&tree->rbroot, entry);
spin_unlock(&tree->lock);
if (entry->length)
if (entry->objcg)
count_objcg_event(entry->objcg, ZSWPIN);
- zswap_entry_free(entry);
-
- folio_mark_dirty(folio);
+ if (swapcache) {
+ zswap_entry_free(entry);
+ folio_mark_dirty(folio);
+ }
return true;
}