[PATCH v2 11/11] mm, swap: merge zeromap into swap table

Kairui Song via B4 Relay
2026-04-16T18:34:43Z

By reserving one bit for the counting part, we can easily merge the
zeromap into the swap table.

Signed-off-by: Kairui Song <kasong@tencent.com>
---
include/linux/swap.h | 1 -
mm/memory.c | 11 ++------
mm/page_io.c | 58 +++++++++++++++++++++++++++++++------
mm/swap.h | 31 --------------------
mm/swap_state.c | 14 +++++----
mm/swap_table.h | 80 +++++++++++++++++++++++++++++++++++++++++-----------
mm/swapfile.c | 27 ++----------------
7 files changed, 125 insertions(+), 97 deletions(-)

diff --git a/include/linux/swap.h b/include/linux/swap.h
index 57af4647d432..8f0f68e245ba 100644
--- a/include/linux/swap.h
+++ b/include/linux/swap.h
@@ -253,7 +253,6 @@ struct swap_info_struct {
struct plist_node list; /* entry in swap_active_head */
signed char type; /* strange name for an index */
unsigned int max; /* size of this swap device */
- unsigned long *zeromap; /* kvmalloc'ed bitmap to track zero pages */
struct swap_cluster_info *cluster_info; /* cluster info. Only for SSD */
struct list_head free_clusters; /* free clusters list */
struct list_head full_clusters; /* full clusters list */
diff --git a/mm/memory.c b/mm/memory.c
index 404734a5bcff..a45905f8728f 100644
--- a/mm/memory.c
+++ b/mm/memory.c
@@ -4595,13 +4595,11 @@ static vm_fault_t handle_pte_marker(struct vm_fault *vmf)

#ifdef CONFIG_TRANSPARENT_HUGEPAGE
/*
- * Check if the PTEs within a range are contiguous swap entries
- * and have consistent swapcache, zeromap.
+ * Check if the PTEs within a range are contiguous swap entries.
*/
static bool can_swapin_thp(struct vm_fault *vmf, pte_t *ptep, int nr_pages)
{
unsigned long addr;
- softleaf_t entry;
int idx;
pte_t pte;

@@ -4611,18 +4609,13 @@ static bool can_swapin_thp(struct vm_fault *vmf, pte_t *ptep, int nr_pages)

if (!pte_same(pte, pte_move_swp_offset(vmf->orig_pte, -idx)))
return false;
- entry = softleaf_from_pte(pte);
- if (swap_pte_batch(ptep, nr_pages, pte) != nr_pages)
- return false;
-
/*
* swap_read_folio() can't handle the case a large folio is hybridly
* from different backends. And they are likely corner cases. Similar
* things might be added once zswap support large folios.
*/
- if (unlikely(swap_zeromap_batch(entry, nr_pages, NULL) != nr_pages))
+ if (swap_pte_batch(ptep, nr_pages, pte) != nr_pages)
return false;
-
return true;
}

diff --git a/mm/page_io.c b/mm/page_io.c
index 70cea9e24d2f..fffe51bf8543 100644
--- a/mm/page_io.c
+++ b/mm/page_io.c
@@ -26,6 +26,7 @@
#include <linux/delayacct.h>
#include <linux/zswap.h>
#include "swap.h"
+#include "swap_table.h"

static void __end_swap_bio_write(struct bio *bio)
{
@@ -204,15 +205,20 @@ static bool is_folio_zero_filled(struct folio *folio)
static void swap_zeromap_folio_set(struct folio *folio)
{
struct obj_cgroup *objcg = get_obj_cgroup_from_folio(folio);
- struct swap_info_struct *sis = __swap_entry_to_info(folio->swap);
int nr_pages = folio_nr_pages(folio);
+ struct swap_cluster_info *ci;
swp_entry_t entry;
unsigned int i;

+ VM_WARN_ON_ONCE_FOLIO(!folio_test_swapcache(folio), folio);
+ VM_WARN_ON_ONCE_FOLIO(!folio_test_locked(folio), folio);
+
+ ci = swap_cluster_get_and_lock(folio);
for (i = 0; i < folio_nr_pages(folio); i++) {
entry = page_swap_entry(folio_page(folio, i));
- set_bit(swp_offset(entry), sis->zeromap);
+ __swap_table_set_zero(ci, swp_cluster_offset(entry));
}
+ swap_cluster_unlock(ci);

count_vm_events(SWPOUT_ZERO, nr_pages);
if (objcg) {
@@ -223,14 +229,19 @@ static void swap_zeromap_folio_set(struct folio *folio)

static void swap_zeromap_folio_clear(struct folio *folio)
{
- struct swap_info_struct *sis = __swap_entry_to_info(folio->swap);
+ struct swap_cluster_info *ci;
swp_entry_t entry;
unsigned int i;

+ VM_WARN_ON_ONCE_FOLIO(!folio_test_swapcache(folio), folio);
+ VM_WARN_ON_ONCE_FOLIO(!folio_test_locked(folio), folio);
+
+ ci = swap_cluster_get_and_lock(folio);
for (i = 0; i < folio_nr_pages(folio); i++) {
entry = page_swap_entry(folio_page(folio, i));
- clear_bit(swp_offset(entry), sis->zeromap);
+ __swap_table_clear_zero(ci, swp_cluster_offset(entry));
}
+ swap_cluster_unlock(ci);
}

/*
@@ -255,10 +266,9 @@ int swap_writeout(struct folio *folio, struct swap_iocb **swap_plug)
}

/*
- * Use a bitmap (zeromap) to avoid doing IO for zero-filled pages.
- * The bits in zeromap are protected by the locked swapcache folio
- * and atomic updates are used to protect against read-modify-write
- * corruption due to other zero swap entries seeing concurrent updates.
+ * Use the swap table zero mark to avoid doing IO for zero-filled
+ * pages. The zero mark is protected by the cluster lock, which is
+ * acquired internally by swap_zeromap_folio_set/clear.
*/
if (is_folio_zero_filled(folio)) {
swap_zeromap_folio_set(folio);
@@ -509,12 +519,44 @@ static void sio_read_complete(struct kiocb *iocb, long ret)
mempool_free(sio, sio_pool);
}

+/*
+ * Return the count of contiguous swap entries that share the same
+ * zeromap status as the starting entry. If is_zerop is not NULL,
+ * it will return the zeromap status of the starting entry.
+ *
+ * Context: Caller must ensure the cluster containing the entries
+ * that will be checked won't be freed.
+ */
+static int swap_zeromap_batch(swp_entry_t entry, int max_nr,
+ bool *is_zerop)
+{
+ bool is_zero;
+ unsigned long swp_tb;
+ struct swap_cluster_info *ci = __swap_entry_to_cluster(entry);
+ unsigned int ci_start = swp_cluster_offset(entry), ci_off, ci_end;
+
+ ci_off = ci_start;
+ ci_end = ci_off + max_nr;
+ swp_tb = swap_table_get(ci, ci_off);
+ is_zero = __swp_tb_is_zero(swp_tb);
+ if (is_zerop)
+ *is_zerop = is_zero;
+ while (++ci_off < ci_end) {
+ swp_tb = swap_table_get(ci, ci_off);
+ if (is_zero != __swp_tb_is_zero(swp_tb))
+ break;
+ }
+ return ci_off - ci_start;
+}
+
static bool swap_read_folio_zeromap(struct folio *folio)
{
int nr_pages = folio_nr_pages(folio);
struct obj_cgroup *objcg;
bool is_zeromap;

+ VM_WARN_ON_ONCE_FOLIO(!folio_test_locked(folio), folio);
+
/*
* Swapping in a large folio that is partially in the zeromap is not
* currently handled. Return true without marking the folio uptodate so
diff --git a/mm/swap.h b/mm/swap.h
index 319dbe4eb299..68e739923df3 100644
--- a/mm/swap.h
+++ b/mm/swap.h
@@ -315,31 +315,6 @@ static inline unsigned int folio_swap_flags(struct folio *folio)
return __swap_entry_to_info(folio->swap)->flags;
}

-/*
- * Return the count of contiguous swap entries that share the same
- * zeromap status as the starting entry. If is_zeromap is not NULL,
- * it will return the zeromap status of the starting entry.
- */
-static inline int swap_zeromap_batch(swp_entry_t entry, int max_nr,
- bool *is_zeromap)
-{
- struct swap_info_struct *sis = __swap_entry_to_info(entry);
- unsigned long start = swp_offset(entry);
- unsigned long end = start + max_nr;
- bool first_bit;
-
- first_bit = test_bit(start, sis->zeromap);
- if (is_zeromap)
- *is_zeromap = first_bit;
-
- if (max_nr <= 1)
- return max_nr;
- if (first_bit)
- return find_next_zero_bit(sis->zeromap, end, start) - start;
- else
- return find_next_bit(sis->zeromap, end, start) - start;
-}
-
#else /* CONFIG_SWAP */
struct swap_iocb;
static inline struct swap_cluster_info *swap_cluster_lock(
@@ -477,11 +452,5 @@ static inline unsigned int folio_swap_flags(struct folio *folio)
{
return 0;
}
-
-static inline int swap_zeromap_batch(swp_entry_t entry, int max_nr,
- bool *has_zeromap)
-{
- return 0;
-}
#endif /* CONFIG_SWAP */
#endif /* _MM_SWAP_H */
diff --git a/mm/swap_state.c b/mm/swap_state.c
index c3d19c9fc594..b842fb65ae7e 100644
--- a/mm/swap_state.c
+++ b/mm/swap_state.c
@@ -159,6 +159,7 @@ static int __swap_cache_add_check(struct swap_cluster_info *ci,
{
unsigned int ci_off, ci_end;
unsigned long old_tb;
+ bool is_zero;

/*
* If the target slot is not swapped out, return
@@ -181,12 +182,14 @@ static int __swap_cache_add_check(struct swap_cluster_info *ci,
if (nr == 1)
return 0;

+ is_zero = __swp_tb_is_zero(old_tb);
ci_off = round_down(ci_off, nr);
ci_end = ci_off + nr;
do {
old_tb = __swap_table_get(ci, ci_off);
if (unlikely(swp_tb_is_folio(old_tb) ||
!__swp_tb_get_count(old_tb) ||
+ is_zero != __swp_tb_is_zero(old_tb) ||
(memcg_id && *memcg_id != __swap_cgroup_get(ci, ci_off))))
return -EBUSY;
} while (++ci_off < ci_end);
@@ -210,7 +213,7 @@ static void __swap_cache_do_add_folio(struct swap_cluster_info *ci,
do {
old_tb = __swap_table_get(ci, ci_off);
VM_WARN_ON_ONCE(swp_tb_is_folio(old_tb));
- __swap_table_set(ci, ci_off, pfn_to_swp_tb(pfn, __swp_tb_get_count(old_tb)));
+ __swap_table_set(ci, ci_off, pfn_to_swp_tb(pfn, __swp_tb_get_flags(old_tb)));
} while (++ci_off < ci_end);

folio_ref_add(folio, nr_pages);
@@ -246,7 +249,6 @@ static void __swap_cache_do_del_folio(struct swap_cluster_info *ci,
struct folio *folio,
swp_entry_t entry, void *shadow)
{
- int count;
unsigned long old_tb;
struct swap_info_struct *si;
unsigned int ci_start, ci_off, ci_end;
@@ -266,13 +268,13 @@ static void __swap_cache_do_del_folio(struct swap_cluster_info *ci,
old_tb = __swap_table_get(ci, ci_off);
WARN_ON_ONCE(!swp_tb_is_folio(old_tb) ||
swp_tb_to_folio(old_tb) != folio);
- count = __swp_tb_get_count(old_tb);
- if (count)
+ if (__swp_tb_get_count(old_tb))
folio_swapped = true;
else
need_free = true;
/* If shadow is NULL, we set an empty shadow. */
- __swap_table_set(ci, ci_off, shadow_to_swp_tb(shadow, count));
+ __swap_table_set(ci, ci_off, shadow_to_swp_tb(shadow,
+ __swp_tb_get_flags(old_tb)));
} while (++ci_off < ci_end);

folio->swap.val = 0;
@@ -366,7 +368,7 @@ void __swap_cache_replace_folio(struct swap_cluster_info *ci,
do {
old_tb = __swap_table_get(ci, ci_off);
WARN_ON_ONCE(!swp_tb_is_folio(old_tb) || swp_tb_to_folio(old_tb) != old);
- __swap_table_set(ci, ci_off, pfn_to_swp_tb(pfn, __swp_tb_get_count(old_tb)));
+ __swap_table_set(ci, ci_off, pfn_to_swp_tb(pfn, __swp_tb_get_flags(old_tb)));
} while (++ci_off < ci_end);

/*
diff --git a/mm/swap_table.h b/mm/swap_table.h
index b2b02ee161b1..a87100dd5fda 100644
--- a/mm/swap_table.h
+++ b/mm/swap_table.h
@@ -26,12 +26,14 @@ struct swap_memcg_table {
* Swap table entry type and bits layouts:
*
* NULL: |---------------- 0 ---------------| - Free slot
- * Shadow: | SWAP_COUNT |---- SHADOW_VAL ---|1| - Swapped out slot
- * PFN: | SWAP_COUNT |------ PFN -------|10| - Cached slot
+ * Shadow: |SWAP_COUNT|Z|---- SHADOW_VAL ---|1| - Swapped out slot
+ * PFN: |SWAP_COUNT|Z|------ PFN -------|10| - Cached slot
* Pointer: |----------- Pointer ----------|100| - (Unused)
* Bad: |------------- 1 -------------|1000| - Bad slot
*
- * SWAP_COUNT is `SWP_TB_COUNT_BITS` long, each entry is an atomic long.
+ * COUNT is `SWP_TB_COUNT_BITS` long, Z is the `SWP_TB_ZERO_MARK` bit,
+ * and together they form the `SWP_TB_FLAGS_BITS` wide flags field.
+ * Each entry is an atomic long.
*
* Usages:
*
@@ -74,17 +76,22 @@ struct swap_memcg_table {
#define SWP_TB_PFN_MARK_BITS 2
#define SWP_TB_PFN_MARK_MASK (BIT(SWP_TB_PFN_MARK_BITS) - 1)

-/* SWAP_COUNT part for PFN or shadow, the width can be shrunk or extended */
-#define SWP_TB_COUNT_BITS min(4, BITS_PER_LONG - SWP_TB_PFN_BITS)
+/* SWAP_COUNT and flags for PFN or shadow, width can be shrunk or extended */
+#define SWP_TB_FLAGS_BITS min(5, BITS_PER_LONG - SWP_TB_PFN_BITS)
+#define SWP_TB_COUNT_BITS (SWP_TB_FLAGS_BITS - 1)
+#define SWP_TB_FLAGS_MASK (~((~0UL) >> SWP_TB_FLAGS_BITS))
#define SWP_TB_COUNT_MASK (~((~0UL) >> SWP_TB_COUNT_BITS))
+#define SWP_TB_FLAGS_SHIFT (BITS_PER_LONG - SWP_TB_FLAGS_BITS)
#define SWP_TB_COUNT_SHIFT (BITS_PER_LONG - SWP_TB_COUNT_BITS)
#define SWP_TB_COUNT_MAX ((1 << SWP_TB_COUNT_BITS) - 1)

+#define SWP_TB_ZERO_MARK BIT(BITS_PER_LONG - SWP_TB_COUNT_BITS - 1)
+
/* Bad slot: ends with 0b1000 and rests of bits are all 1 */
#define SWP_TB_BAD ((~0UL) << 3)

/* Macro for shadow offset calculation */
-#define SWAP_COUNT_SHIFT SWP_TB_COUNT_BITS
+#define SWAP_COUNT_SHIFT SWP_TB_FLAGS_BITS

/*
* Helpers for casting one type of info into a swap table entry.
@@ -107,35 +114,42 @@ static inline unsigned long __count_to_swp_tb(unsigned char count)
return ((unsigned long)count) << SWP_TB_COUNT_SHIFT;
}

-static inline unsigned long pfn_to_swp_tb(unsigned long pfn, unsigned int count)
+static inline unsigned long __flags_to_swp_tb(unsigned char flags)
+{
+ BUILD_BUG_ON(SWP_TB_FLAGS_BITS > BITS_PER_BYTE);
+ VM_WARN_ON((flags >> 1) > SWP_TB_COUNT_MAX);
+ return ((unsigned long)flags) << SWP_TB_FLAGS_SHIFT;
+}
+
+static inline unsigned long pfn_to_swp_tb(unsigned long pfn, unsigned char flags)
{
unsigned long swp_tb;

BUILD_BUG_ON(sizeof(unsigned long) != sizeof(void *));
BUILD_BUG_ON(SWAP_CACHE_PFN_BITS >
- (BITS_PER_LONG - SWP_TB_PFN_MARK_BITS - SWP_TB_COUNT_BITS));
+ (BITS_PER_LONG - SWP_TB_PFN_MARK_BITS - SWP_TB_FLAGS_BITS));

swp_tb = (pfn << SWP_TB_PFN_MARK_BITS) | SWP_TB_PFN_MARK;
- VM_WARN_ON_ONCE(swp_tb & SWP_TB_COUNT_MASK);
+ VM_WARN_ON_ONCE(swp_tb & SWP_TB_FLAGS_MASK);

- return swp_tb | __count_to_swp_tb(count);
+ return swp_tb | __flags_to_swp_tb(flags);
}

-static inline unsigned long folio_to_swp_tb(struct folio *folio, unsigned int count)
+static inline unsigned long folio_to_swp_tb(struct folio *folio, unsigned char flags)
{
- return pfn_to_swp_tb(folio_pfn(folio), count);
+ return pfn_to_swp_tb(folio_pfn(folio), flags);
}

-static inline unsigned long shadow_to_swp_tb(void *shadow, unsigned int count)
+static inline unsigned long shadow_to_swp_tb(void *shadow, unsigned char flags)
{
BUILD_BUG_ON((BITS_PER_XA_VALUE + 1) !=
BITS_PER_BYTE * sizeof(unsigned long));
BUILD_BUG_ON((unsigned long)xa_mk_value(0) != SWP_TB_SHADOW_MARK);

VM_WARN_ON_ONCE(shadow && !xa_is_value(shadow));
- VM_WARN_ON_ONCE(shadow && ((unsigned long)shadow & SWP_TB_COUNT_MASK));
+ VM_WARN_ON_ONCE(shadow && ((unsigned long)shadow & SWP_TB_FLAGS_MASK));

- return (unsigned long)shadow | __count_to_swp_tb(count) | SWP_TB_SHADOW_MARK;
+ return (unsigned long)shadow | SWP_TB_SHADOW_MARK | __flags_to_swp_tb(flags);
}

/*
@@ -167,20 +181,26 @@ static inline bool swp_tb_is_countable(unsigned long swp_tb)
swp_tb_is_null(swp_tb));
}

+static inline bool __swp_tb_is_zero(unsigned long swp_tb)
+{
+ VM_WARN_ON_ONCE(!swp_tb_is_countable(swp_tb));
+ return swp_tb & SWP_TB_ZERO_MARK;
+}
+
/*
* Helpers for retrieving info from swap table.
*/
static inline struct folio *swp_tb_to_folio(unsigned long swp_tb)
{
VM_WARN_ON(!swp_tb_is_folio(swp_tb));
- return pfn_folio((swp_tb & ~SWP_TB_COUNT_MASK) >> SWP_TB_PFN_MARK_BITS);
+ return pfn_folio((swp_tb & ~SWP_TB_FLAGS_MASK) >> SWP_TB_PFN_MARK_BITS);
}

static inline void *swp_tb_to_shadow(unsigned long swp_tb)
{
VM_WARN_ON(!swp_tb_is_shadow(swp_tb));
/* No shift needed, xa_value is stored as it is in the lower bits. */
- return (void *)(swp_tb & ~SWP_TB_COUNT_MASK);
+ return (void *)(swp_tb & ~SWP_TB_FLAGS_MASK);
}

static inline unsigned char __swp_tb_get_count(unsigned long swp_tb)
@@ -189,6 +209,12 @@ static inline unsigned char __swp_tb_get_count(unsigned long swp_tb)
return ((swp_tb & SWP_TB_COUNT_MASK) >> SWP_TB_COUNT_SHIFT);
}

+static inline unsigned char __swp_tb_get_flags(unsigned long swp_tb)
+{
+ VM_WARN_ON(!swp_tb_is_countable(swp_tb));
+ return ((swp_tb & SWP_TB_FLAGS_MASK) >> SWP_TB_FLAGS_SHIFT);
+}
+
static inline int swp_tb_get_count(unsigned long swp_tb)
{
if (swp_tb_is_countable(swp_tb))
@@ -253,6 +279,26 @@ static inline unsigned long swap_table_get(struct swap_cluster_info *ci,
return swp_tb;
}

+static inline void __swap_table_set_zero(struct swap_cluster_info *ci,
+ unsigned int ci_off)
+{
+ unsigned long swp_tb = __swap_table_get(ci, ci_off);
+
+ VM_WARN_ON(!swp_tb_is_countable(swp_tb));
+ swp_tb |= SWP_TB_ZERO_MARK;
+ __swap_table_set(ci, ci_off, swp_tb);
+}
+
+static inline void __swap_table_clear_zero(struct swap_cluster_info *ci,
+ unsigned int ci_off)
+{
+ unsigned long swp_tb = __swap_table_get(ci, ci_off);
+
+ VM_WARN_ON(!swp_tb_is_countable(swp_tb));
+ swp_tb &= ~SWP_TB_ZERO_MARK;
+ __swap_table_set(ci, ci_off, swp_tb);
+}
+
#ifdef CONFIG_MEMCG
static inline void __swap_cgroup_set(struct swap_cluster_info *ci,
unsigned int ci_off, unsigned long nr, unsigned short id)
diff --git a/mm/swapfile.c b/mm/swapfile.c
index 0753a62ebc25..e100908d4129 100644
--- a/mm/swapfile.c
+++ b/mm/swapfile.c
@@ -964,7 +964,7 @@ static bool __swap_cluster_alloc_entries(struct swap_info_struct *si,
nr_pages = 1;
swap_cluster_assert_empty(ci, ci_off, 1, false);
/* Sets a fake shadow as placeholder */
- __swap_table_set(ci, ci_off, shadow_to_swp_tb(NULL, 1));
+ __swap_table_set(ci, ci_off, __swp_tb_mk_count(shadow_to_swp_tb(NULL, 0), 1));
} else {
/* Allocation without folio is only possible with hibernation */
WARN_ON_ONCE(1);
@@ -1336,14 +1336,8 @@ static void swap_range_free(struct swap_info_struct *si, unsigned long offset,
void (*swap_slot_free_notify)(struct block_device *, unsigned long);
unsigned int i;

- /*
- * Use atomic clear_bit operations only on zeromap instead of non-atomic
- * bitmap_clear to prevent adjacent bits corruption due to simultaneous writes.
- */
- for (i = 0; i < nr_entries; i++) {
- clear_bit(offset + i, si->zeromap);
+ for (i = 0; i < nr_entries; i++)
zswap_invalidate(swp_entry(si->type, offset + i));
- }

if (si->flags & SWP_BLKDEV)
swap_slot_free_notify =
@@ -3061,7 +3055,6 @@ static void flush_percpu_swap_cluster(struct swap_info_struct *si)
SYSCALL_DEFINE1(swapoff, const char __user *, specialfile)
{
struct swap_info_struct *p = NULL;
- unsigned long *zeromap;
struct swap_cluster_info *cluster_info;
struct file *swap_file, *victim;
struct address_space *mapping;
@@ -3157,8 +3150,6 @@ SYSCALL_DEFINE1(swapoff, const char __user *, specialfile)

swap_file = p->swap_file;
p->swap_file = NULL;
- zeromap = p->zeromap;
- p->zeromap = NULL;
maxpages = p->max;
cluster_info = p->cluster_info;
p->max = 0;
@@ -3170,7 +3161,6 @@ SYSCALL_DEFINE1(swapoff, const char __user *, specialfile)
mutex_unlock(&swapon_mutex);
kfree(p->global_cluster);
p->global_cluster = NULL;
- kvfree(zeromap);
free_swap_cluster_info(cluster_info, maxpages);

inode = mapping->host;
@@ -3702,17 +3692,6 @@ SYSCALL_DEFINE2(swapon, const char __user *, specialfile, int, swap_flags)
if (error)
goto bad_swap_unlock_inode;

- /*
- * Use kvmalloc_array instead of bitmap_zalloc as the allocation order might
- * be above MAX_PAGE_ORDER incase of a large swap file.
- */
- si->zeromap = kvmalloc_array(BITS_TO_LONGS(maxpages), sizeof(long),
- GFP_KERNEL | __GFP_ZERO);
- if (!si->zeromap) {
- error = -ENOMEM;
- goto bad_swap_unlock_inode;
- }
-
if (si->bdev && bdev_stable_writes(si->bdev))
si->flags |= SWP_STABLE_WRITES;

@@ -3814,8 +3793,6 @@ SYSCALL_DEFINE2(swapon, const char __user *, specialfile, int, swap_flags)
destroy_swap_extents(si, swap_file);
free_swap_cluster_info(si->cluster_info, si->max);
si->cluster_info = NULL;
- kvfree(si->zeromap);
- si->zeromap = NULL;
/*
* Clear the SWP_USED flag after all resources are freed so
* alloc_swap_info can reuse this si safely.

--
2.53.0