diff options
| -rw-r--r-- | include/linux/frontswap.h | 2 | ||||
| -rw-r--r-- | mm/Kconfig | 16 | ||||
| -rw-r--r-- | mm/frontswap.c | 10 | ||||
| -rw-r--r-- | mm/zswap.c | 28 |
4 files changed, 45 insertions, 11 deletions
diff --git a/include/linux/frontswap.h b/include/linux/frontswap.h index a631bac12220..eaa0ac5f9003 100644 --- a/include/linux/frontswap.h +++ b/include/linux/frontswap.h @@ -10,7 +10,7 @@ struct frontswap_ops { void (*init)(unsigned); /* this swap type was just swapon'ed */ int (*store)(unsigned, pgoff_t, struct page *); /* store a page */ - int (*load)(unsigned, pgoff_t, struct page *); /* load a page */ + int (*load)(unsigned, pgoff_t, struct page *, bool *); /* load a page */ void (*invalidate_page)(unsigned, pgoff_t); /* page no longer needed */ void (*invalidate_area)(unsigned); /* swap type just swapoff'ed */ }; diff --git a/mm/Kconfig b/mm/Kconfig index 7672a22647b4..12f32f8d26bf 100644 --- a/mm/Kconfig +++ b/mm/Kconfig @@ -46,6 +46,22 @@ config ZSWAP_DEFAULT_ON The selection made here can be overridden by using the kernel command line 'zswap.enabled=' option. +config ZSWAP_EXCLUSIVE_LOADS_DEFAULT_ON + bool "Invalidate zswap entries when pages are loaded" + depends on ZSWAP + help + If selected, exclusive loads for zswap will be enabled at boot, + otherwise it will be disabled. + + If exclusive loads are enabled, when a page is loaded from zswap, + the zswap entry is invalidated at once, as opposed to leaving it + in zswap until the swap entry is freed. + + This avoids having two copies of the same page in memory + (compressed and uncompressed) after faulting in a page from zswap. + The cost is that if the page was never dirtied and needs to be + swapped out again, it will be re-compressed. + choice prompt "Default compressor" depends on ZSWAP diff --git a/mm/frontswap.c b/mm/frontswap.c index 279e55b4ed87..2fb5df3384b8 100644 --- a/mm/frontswap.c +++ b/mm/frontswap.c @@ -206,6 +206,7 @@ int __frontswap_load(struct page *page) int type = swp_type(entry); struct swap_info_struct *sis = swap_info[type]; pgoff_t offset = swp_offset(entry); + bool exclusive = false; VM_BUG_ON(!frontswap_ops); VM_BUG_ON(!PageLocked(page)); @@ -215,9 +216,14 @@ int __frontswap_load(struct page *page) return -1; /* Try loading from each implementation, until one succeeds. */ - ret = frontswap_ops->load(type, offset, page); - if (ret == 0) + ret = frontswap_ops->load(type, offset, page, &exclusive); + if (ret == 0) { inc_frontswap_loads(); + if (exclusive) { + SetPageDirty(page); + __frontswap_clear(sis, offset); + } + } return ret; } diff --git a/mm/zswap.c b/mm/zswap.c index bcb82e09eb64..9fa86265f6dd 100644 --- a/mm/zswap.c +++ b/mm/zswap.c @@ -138,6 +138,10 @@ static bool zswap_non_same_filled_pages_enabled = true; module_param_named(non_same_filled_pages_enabled, zswap_non_same_filled_pages_enabled, bool, 0644); +static bool zswap_exclusive_loads_enabled = IS_ENABLED( + CONFIG_ZSWAP_EXCLUSIVE_LOADS_DEFAULT_ON); +module_param_named(exclusive_loads, zswap_exclusive_loads_enabled, bool, 0644); + /********************************* * data structures **********************************/ @@ -1340,12 +1344,22 @@ shrink: goto reject; } +static void zswap_invalidate_entry(struct zswap_tree *tree, + struct zswap_entry *entry) +{ + /* remove from rbtree */ + zswap_rb_erase(&tree->rbroot, entry); + + /* drop the initial reference from entry creation */ + zswap_entry_put(tree, entry); +} + /* * returns 0 if the page was successfully decompressed * return -1 on entry not found or error */ static int zswap_frontswap_load(unsigned type, pgoff_t offset, - struct page *page) + struct page *page, bool *exclusive) { struct zswap_tree *tree = zswap_trees[type]; struct zswap_entry *entry; @@ -1415,6 +1429,10 @@ stats: freeentry: spin_lock(&tree->lock); zswap_entry_put(tree, entry); + if (!ret && zswap_exclusive_loads_enabled) { + zswap_invalidate_entry(tree, entry); + *exclusive = true; + } spin_unlock(&tree->lock); return ret; @@ -1434,13 +1452,7 @@ static void zswap_frontswap_invalidate_page(unsigned type, pgoff_t offset) spin_unlock(&tree->lock); return; } - - /* remove from rbtree */ - zswap_rb_erase(&tree->rbroot, entry); - - /* drop the initial reference from entry creation */ - zswap_entry_put(tree, entry); - + zswap_invalidate_entry(tree, entry); spin_unlock(&tree->lock); } |