[PATCH -v2 1/2] mm, swap: Use kvzalloc to allocate some swap data structure

["Huang, Ying" <ying.huang@intel.com>]

From: Huang Ying <ying.huang@intel.com>

Now vzalloc() is used in swap code to allocate various data
structures, such as swap cache, swap slots cache, cluster info, etc.
Because the size may be too large on some system, so that normal
kzalloc() may fail.  But using kzalloc() has some advantages, for
example, less memory fragmentation, less TLB pressure, etc.  So change
the data structure allocation in swap code to use kvzalloc() which
will try kzalloc() firstly, and fallback to vzalloc() if kzalloc()
failed.

The allocation for swap_map[] in struct swap_info_struct is not
changed, because that is usually quite large and vmalloc_to_page() is
used for it.  That makes it a little harder to change.

Signed-off-by: Huang Ying <ying.huang@intel.com>
Acked-by: Tim Chen <tim.c.chen@intel.com>
---
 mm/swap_slots.c | 19 +++++++++++--------
 mm/swap_state.c |  2 +-
 mm/swapfile.c   | 10 ++++++----
 3 files changed, 18 insertions(+), 13 deletions(-)

diff --git a/mm/swap_slots.c b/mm/swap_slots.c
index 9b5bc86f96ad..7376d2ffb2db 100644
--- a/mm/swap_slots.c
+++ b/mm/swap_slots.c
@@ -31,6 +31,7 @@
 #include <linux/cpumask.h>
 #include <linux/vmalloc.h>
 #include <linux/mutex.h>
+#include <linux/mm.h>
 
 #ifdef CONFIG_SWAP
 
@@ -119,16 +120,18 @@ static int alloc_swap_slot_cache(unsigned int cpu)
 
 	/*
 	 * Do allocation outside swap_slots_cache_mutex
-	 * as vzalloc could trigger reclaim and get_swap_page,
+	 * as kvzalloc could trigger reclaim and get_swap_page,
 	 * which can lock swap_slots_cache_mutex.
 	 */
-	slots = vzalloc(sizeof(swp_entry_t) * SWAP_SLOTS_CACHE_SIZE);
+	slots = kvzalloc(sizeof(swp_entry_t) * SWAP_SLOTS_CACHE_SIZE,
+			 GFP_KERNEL);
 	if (!slots)
 		return -ENOMEM;
 
-	slots_ret = vzalloc(sizeof(swp_entry_t) * SWAP_SLOTS_CACHE_SIZE);
+	slots_ret = kvzalloc(sizeof(swp_entry_t) * SWAP_SLOTS_CACHE_SIZE,
+			     GFP_KERNEL);
 	if (!slots_ret) {
-		vfree(slots);
+		kvfree(slots);
 		return -ENOMEM;
 	}
 
@@ -152,9 +155,9 @@ static int alloc_swap_slot_cache(unsigned int cpu)
 out:
 	mutex_unlock(&swap_slots_cache_mutex);
 	if (slots)
-		vfree(slots);
+		kvfree(slots);
 	if (slots_ret)
-		vfree(slots_ret);
+		kvfree(slots_ret);
 	return 0;
 }
 
@@ -171,7 +174,7 @@ static void drain_slots_cache_cpu(unsigned int cpu, unsigned int type,
 		cache->cur = 0;
 		cache->nr = 0;
 		if (free_slots && cache->slots) {
-			vfree(cache->slots);
+			kvfree(cache->slots);
 			cache->slots = NULL;
 		}
 		mutex_unlock(&cache->alloc_lock);
@@ -186,7 +189,7 @@ static void drain_slots_cache_cpu(unsigned int cpu, unsigned int type,
 		}
 		spin_unlock_irq(&cache->free_lock);
 		if (slots)
-			vfree(slots);
+			kvfree(slots);
 	}
 }
 
diff --git a/mm/swap_state.c b/mm/swap_state.c
index 7bfb9bd1ca21..539b8885e3d1 100644
--- a/mm/swap_state.c
+++ b/mm/swap_state.c
@@ -523,7 +523,7 @@ int init_swap_address_space(unsigned int type, unsigned long nr_pages)
 	unsigned int i, nr;
 
 	nr = DIV_ROUND_UP(nr_pages, SWAP_ADDRESS_SPACE_PAGES);
-	spaces = vzalloc(sizeof(struct address_space) * nr);
+	spaces = kvzalloc(sizeof(struct address_space) * nr, GFP_KERNEL);
 	if (!spaces)
 		return -ENOMEM;
 	for (i = 0; i < nr; i++) {
diff --git a/mm/swapfile.c b/mm/swapfile.c
index 53b5881ee0d6..90054f3c2cdc 100644
--- a/mm/swapfile.c
+++ b/mm/swapfile.c
@@ -2272,8 +2272,8 @@ SYSCALL_DEFINE1(swapoff, const char __user *, specialfile)
 	free_percpu(p->percpu_cluster);
 	p->percpu_cluster = NULL;
 	vfree(swap_map);
-	vfree(cluster_info);
-	vfree(frontswap_map);
+	kvfree(cluster_info);
+	kvfree(frontswap_map);
 	/* Destroy swap account information */
 	swap_cgroup_swapoff(p->type);
 	exit_swap_address_space(p->type);
@@ -2796,7 +2796,8 @@ SYSCALL_DEFINE2(swapon, const char __user *, specialfile, int, swap_flags)
 		p->cluster_next = 1 + (prandom_u32() % p->highest_bit);
 		nr_cluster = DIV_ROUND_UP(maxpages, SWAPFILE_CLUSTER);
 
-		cluster_info = vzalloc(nr_cluster * sizeof(*cluster_info));
+		cluster_info = kvzalloc(nr_cluster * sizeof(*cluster_info),
+					GFP_KERNEL);
 		if (!cluster_info) {
 			error = -ENOMEM;
 			goto bad_swap;
@@ -2829,7 +2830,8 @@ SYSCALL_DEFINE2(swapon, const char __user *, specialfile, int, swap_flags)
 	}
 	/* frontswap enabled? set up bit-per-page map for frontswap */
 	if (IS_ENABLED(CONFIG_FRONTSWAP))
-		frontswap_map = vzalloc(BITS_TO_LONGS(maxpages) * sizeof(long));
+		frontswap_map = kvzalloc(BITS_TO_LONGS(maxpages) * sizeof(long),
+					 GFP_KERNEL);
 
 	if (p->bdev &&(swap_flags & SWAP_FLAG_DISCARD) && swap_discardable(p)) {
 		/*
-- 
2.11.0