zram: switch to unsigned long indexing

zram has always used "unsigned int" for (page) index calculations, which
unnecessarily limited max zram disksize.

Switch to "unsigned long" and permit much larger zram devices.

Link: https://lore.kernel.org/20260806031640.536615-1-senozhatsky@chromium.org
Suggested-by: Andrew Morton <akpm@linux-foundation.org>
Co-developed-by: Longlong Xia <xialonglong2025@163.com>
Signed-off-by: Sergey Senozhatsky <senozhatsky@chromium.org>
Cc: Minchan Kim <minchan@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

1 files changed, 77 insertions, 60 deletions

diff --git a/drivers/block/zram/zram_drv.c b/drivers/block/zram/zram_drv.c
index 82b78e6e55b2..d09fdca49cbd 100644
--- a/drivers/block/zram/zram_drv.c
+++ b/drivers/block/zram/zram_drv.c
@@ -56,7 +56,7 @@ static size_t huge_class_size;
 
 static const struct block_device_operations zram_devops;
 
-static void slot_free(struct zram *zram, u32 index);
+static void slot_free(struct zram *zram, unsigned long index);
 
 /*
  * entry locking rules:
@@ -70,7 +70,7 @@ static void slot_free(struct zram *zram, u32 index);
  * 4) Use TRY lock variant when in atomic context
  *    - must check return value and handle locking failers
  */
-static __must_check bool slot_trylock(struct zram *zram, u32 index)
+static __must_check bool slot_trylock(struct zram *zram, unsigned long index)
 {
 	unsigned long *lock = &zram->table[index].__lock;
 
@@ -83,7 +83,7 @@ static __must_check bool slot_trylock(struct zram *zram, u32 index)
 	return false;
 }
 
-static void slot_lock(struct zram *zram, u32 index)
+static void slot_lock(struct zram *zram, unsigned long index)
 {
 	unsigned long *lock = &zram->table[index].__lock;
 
@@ -92,7 +92,7 @@ static void slot_lock(struct zram *zram, u32 index)
 	lock_acquired(&zram->table_lock_map, _RET_IP_);
 }
 
-static void slot_unlock(struct zram *zram, u32 index)
+static void slot_unlock(struct zram *zram, unsigned long index)
 {
 	unsigned long *lock = &zram->table[index].__lock;
 
@@ -110,55 +110,56 @@ static inline struct zram *dev_to_zram(struct device *dev)
 	return (struct zram *)dev_to_disk(dev)->private_data;
 }
 
-static unsigned long get_slot_handle(struct zram *zram, u32 index)
+static unsigned long get_slot_handle(struct zram *zram, unsigned long index)
 {
 	return zram->table[index].handle;
 }
 
-static void set_slot_handle(struct zram *zram, u32 index, unsigned long handle)
+static void set_slot_handle(struct zram *zram, unsigned long index,
+			    unsigned long handle)
 {
 	zram->table[index].handle = handle;
 }
 
-static bool test_slot_flag(struct zram *zram, u32 index,
+static bool test_slot_flag(struct zram *zram, unsigned long index,
 			   enum zram_pageflags flag)
 {
 	return zram->table[index].attr.flags & BIT(flag);
 }
 
-static void set_slot_flag(struct zram *zram, u32 index,
+static void set_slot_flag(struct zram *zram, unsigned long index,
 			  enum zram_pageflags flag)
 {
 	zram->table[index].attr.flags |= BIT(flag);
 }
 
-static void clear_slot_flag(struct zram *zram, u32 index,
+static void clear_slot_flag(struct zram *zram, unsigned long index,
 			    enum zram_pageflags flag)
 {
 	zram->table[index].attr.flags &= ~BIT(flag);
 }
 
-static size_t get_slot_size(struct zram *zram, u32 index)
+static size_t get_slot_size(struct zram *zram, unsigned long index)
 {
 	return zram->table[index].attr.flags & (BIT(ZRAM_FLAG_SHIFT) - 1);
 }
 
-static void set_slot_size(struct zram *zram, u32 index, size_t size)
+static void set_slot_size(struct zram *zram, unsigned long index, size_t size)
 {
 	unsigned long flags = zram->table[index].attr.flags >> ZRAM_FLAG_SHIFT;
 
 	zram->table[index].attr.flags = (flags << ZRAM_FLAG_SHIFT) | size;
 }
 
-static inline bool slot_allocated(struct zram *zram, u32 index)
+static inline bool slot_allocated(struct zram *zram, unsigned long index)
 {
 	return get_slot_size(zram, index) ||
 		test_slot_flag(zram, index, ZRAM_SAME) ||
 		test_slot_flag(zram, index, ZRAM_WB);
 }
 
-static inline void set_slot_comp_priority(struct zram *zram, u32 index,
-					  u32 prio)
+static inline void set_slot_comp_priority(struct zram *zram,
+					  unsigned long index, u32 prio)
 {
 	prio &= ZRAM_COMP_PRIORITY_MASK;
 	/*
@@ -170,14 +171,14 @@ static inline void set_slot_comp_priority(struct zram *zram, u32 index,
 	zram->table[index].attr.flags |= (prio << ZRAM_COMP_PRIORITY_BIT1);
 }
 
-static inline u32 get_slot_comp_priority(struct zram *zram, u32 index)
+static inline u32 get_slot_comp_priority(struct zram *zram, unsigned long index)
 {
 	u32 prio = zram->table[index].attr.flags >> ZRAM_COMP_PRIORITY_BIT1;
 
 	return prio & ZRAM_COMP_PRIORITY_MASK;
 }
 
-static void mark_slot_accessed(struct zram *zram, u32 index)
+static void mark_slot_accessed(struct zram *zram, unsigned long index)
 {
 	clear_slot_flag(zram, index, ZRAM_IDLE);
 	clear_slot_flag(zram, index, ZRAM_PP_SLOT);
@@ -284,7 +285,7 @@ static void release_pp_ctl(struct zram *zram, struct zram_pp_ctl *ctl)
 }
 
 static bool place_pp_slot(struct zram *zram, struct zram_pp_ctl *ctl,
-			  u32 index)
+			  unsigned long index)
 {
 	struct zram_pp_slot *pps;
 	u32 bid;
@@ -418,7 +419,7 @@ static void mark_idle(struct zram *zram, ktime_t cutoff)
 {
 	int is_idle = 1;
 	unsigned long nr_pages = zram->disksize >> PAGE_SHIFT;
-	int index;
+	unsigned long index;
 
 	for (index = 0; index < nr_pages; index++) {
 		/*
@@ -485,8 +486,9 @@ static ssize_t idle_store(struct device *dev, struct device_attribute *attr,
 #define INVALID_BDEV_BLOCK		(~0UL)
 
 static int read_from_zspool_raw(struct zram *zram, struct page *page,
-				u32 index);
-static int read_from_zspool(struct zram *zram, struct page *page, u32 index);
+				unsigned long index);
+static int read_from_zspool(struct zram *zram, struct page *page,
+			    unsigned long index);
 
 struct zram_wb_ctl {
 	/* idle list is accessed only by the writeback task, no concurency */
@@ -522,7 +524,7 @@ struct zram_rb_req {
 		/* error status (sync read) */
 		int error;
 	};
-	u32 index;
+	unsigned long index;
 };
 
 #define FOUR_K(x) ((x) * (1 << (PAGE_SHIFT - 12)))
@@ -910,7 +912,7 @@ static void zram_account_writeback_submit(struct zram *zram)
 
 static int zram_writeback_complete(struct zram *zram, struct zram_wb_req *req)
 {
-	u32 index = req->pps->index;
+	unsigned long index = req->pps->index;
 	int err;
 
 	err = blk_status_to_errno(req->bio.bi_status);
@@ -1032,7 +1034,7 @@ static int zram_writeback_slots(struct zram *zram,
 	struct zram_wb_req *req = NULL;
 	struct zram_pp_slot *pps;
 	int ret = 0, err = 0;
-	u32 index = 0;
+	unsigned long index = 0;
 
 	while ((pps = select_pp_slot(ctl))) {
 		if (zram->wb_limit_enable && !zram->bd_wb_limit) {
@@ -1198,7 +1200,7 @@ static void scan_slots_for_writeback(struct zram *zram, u32 mode,
 				     unsigned long lo, unsigned long hi,
 				     struct zram_pp_ctl *ctl)
 {
-	u32 index = lo;
+	unsigned long index = lo;
 
 	while (index < hi) {
 		bool ok = true;
@@ -1235,7 +1237,7 @@ static ssize_t writeback_store(struct device *dev,
 			       const char *buf, size_t len)
 {
 	struct zram *zram = dev_to_zram(dev);
-	u64 nr_pages;
+	unsigned long nr_pages;
 	unsigned long lo = 0, hi;
 	struct zram_pp_ctl *pp_ctl = NULL;
 	struct zram_wb_ctl *wb_ctl = NULL;
@@ -1336,7 +1338,8 @@ out:
 	return ret;
 }
 
-static int decompress_bdev_page(struct zram *zram, struct page *page, u32 index)
+static int decompress_bdev_page(struct zram *zram, struct page *page,
+				unsigned long index)
 {
 	struct zcomp_strm *zstrm;
 	unsigned int size;
@@ -1378,7 +1381,7 @@ static void zram_deferred_decompress(struct work_struct *w)
 	struct zram_rb_req *req = container_of(w, struct zram_rb_req, work);
 	struct page *page = bio_first_page_all(req->bio);
 	struct zram *zram = req->zram;
-	u32 index = req->index;
+	unsigned long index = req->index;
 	int ret;
 
 	ret = decompress_bdev_page(zram, page, index);
@@ -1429,7 +1432,7 @@ static void zram_async_read_endio(struct bio *bio)
 }
 
 static int read_from_bdev_async(struct zram *zram, struct page *page,
-				u32 index, unsigned long blk_idx,
+				unsigned long index, unsigned long blk_idx,
 				struct bio *parent)
 {
 	struct zram_rb_req *req;
@@ -1479,8 +1482,8 @@ static void zram_sync_read(struct work_struct *w)
  * chained IO with parent IO in same context, it's a deadlock. To avoid that,
  * use a worker thread context.
  */
-static int read_from_bdev_sync(struct zram *zram, struct page *page, u32 index,
-			       unsigned long blk_idx)
+static int read_from_bdev_sync(struct zram *zram, struct page *page,
+			       unsigned long index, unsigned long blk_idx)
 {
 	struct zram_rb_req req;
 
@@ -1499,8 +1502,9 @@ static int read_from_bdev_sync(struct zram *zram, struct page *page, u32 index,
 	return decompress_bdev_page(zram, page, index);
 }
 
-static int read_from_bdev(struct zram *zram, struct page *page, u32 index,
-			  unsigned long blk_idx, struct bio *parent)
+static int read_from_bdev(struct zram *zram, struct page *page,
+			  unsigned long index, unsigned long blk_idx,
+			  struct bio *parent)
 {
 	atomic64_inc(&zram->stats.bd_reads);
 	if (!parent) {
@@ -1512,8 +1516,9 @@ static int read_from_bdev(struct zram *zram, struct page *page, u32 index,
 }
 #else
 static inline void reset_bdev(struct zram *zram) {};
-static int read_from_bdev(struct zram *zram, struct page *page, u32 index,
-			  unsigned long blk_idx, struct bio *parent)
+static int read_from_bdev(struct zram *zram, struct page *page,
+			  unsigned long index, unsigned long blk_idx,
+			  struct bio *parent)
 {
 	return -EIO;
 }
@@ -1541,7 +1546,8 @@ static ssize_t read_block_state(struct file *file, char __user *buf,
 				size_t count, loff_t *ppos)
 {
 	char *kbuf;
-	ssize_t index, written = 0;
+	unsigned long index;
+	ssize_t written = 0;
 	struct zram *zram = file->private_data;
 	unsigned long nr_pages;
 
@@ -1565,7 +1571,7 @@ static ssize_t read_block_state(struct file *file, char __user *buf,
 			goto next;
 
 		copied = snprintf(kbuf + written, count,
-			"%12zd %12u.%06d %c%c%c%c%c%c\n",
+			"%12lu %12u.%06d %c%c%c%c%c%c\n",
 			index, zram->table[index].attr.ac_time, 0,
 			test_slot_flag(zram, index, ZRAM_SAME) ? 's' : '.',
 			test_slot_flag(zram, index, ZRAM_WB) ? 'w' : '.',
@@ -1972,8 +1978,8 @@ static ssize_t debug_stat_show(struct device *dev,
 
 static void zram_meta_free(struct zram *zram, u64 disksize)
 {
-	size_t num_pages = disksize >> PAGE_SHIFT;
-	size_t index;
+	unsigned long num_pages = disksize >> PAGE_SHIFT;
+	unsigned long index;
 
 	if (!zram->table)
 		return;
@@ -1990,7 +1996,7 @@ static void zram_meta_free(struct zram *zram, u64 disksize)
 
 static bool zram_meta_alloc(struct zram *zram, u64 disksize)
 {
-	size_t num_pages;
+	unsigned long num_pages;
 
 	num_pages = disksize >> PAGE_SHIFT;
 	zram->table = vzalloc(array_size(num_pages, sizeof(*zram->table)));
@@ -2013,7 +2019,7 @@ static bool zram_meta_alloc(struct zram *zram, u64 disksize)
 	return true;
 }
 
-static void slot_free(struct zram *zram, u32 index)
+static void slot_free(struct zram *zram, unsigned long index)
 {
 	unsigned long handle;
 
@@ -2067,7 +2073,7 @@ out:
 }
 
 static int read_same_filled_page(struct zram *zram, struct page *page,
-				 u32 index)
+				 unsigned long index)
 {
 	void *mem;
 
@@ -2078,7 +2084,7 @@ static int read_same_filled_page(struct zram *zram, struct page *page,
 }
 
 static int read_incompressible_page(struct zram *zram, struct page *page,
-				    u32 index)
+				    unsigned long index)
 {
 	unsigned long handle;
 	void *src, *dst;
@@ -2093,7 +2099,8 @@ static int read_incompressible_page(struct zram *zram, struct page *page,
 	return 0;
 }
 
-static int read_compressed_page(struct zram *zram, struct page *page, u32 index)
+static int read_compressed_page(struct zram *zram, struct page *page,
+				unsigned long index)
 {
 	struct zcomp_strm *zstrm;
 	unsigned long handle;
@@ -2118,7 +2125,8 @@ static int read_compressed_page(struct zram *zram, struct page *page, u32 index)
 }
 
 #if defined CONFIG_ZRAM_WRITEBACK
-static int read_from_zspool_raw(struct zram *zram, struct page *page, u32 index)
+static int read_from_zspool_raw(struct zram *zram, struct page *page,
+				unsigned long index)
 {
 	struct zcomp_strm *zstrm;
 	unsigned long handle;
@@ -2150,7 +2158,8 @@ static int read_from_zspool_raw(struct zram *zram, struct page *page, u32 index)
  * Reads (decompresses if needed) a page from zspool (zsmalloc).
  * Corresponding ZRAM slot should be locked.
  */
-static int read_from_zspool(struct zram *zram, struct page *page, u32 index)
+static int read_from_zspool(struct zram *zram, struct page *page,
+			    unsigned long index)
 {
 	if (test_slot_flag(zram, index, ZRAM_SAME) ||
 	    !get_slot_handle(zram, index))
@@ -2162,8 +2171,8 @@ static int read_from_zspool(struct zram *zram, struct page *page, u32 index)
 		return read_incompressible_page(zram, page, index);
 }
 
-static int zram_read_page(struct zram *zram, struct page *page, u32 index,
-			  struct bio *parent)
+static int zram_read_page(struct zram *zram, struct page *page,
+			  unsigned long index, struct bio *parent)
 {
 	int ret;
 
@@ -2185,7 +2194,7 @@ static int zram_read_page(struct zram *zram, struct page *page, u32 index,
 
 	/* Should NEVER happen. Return bio error if it does. */
 	if (WARN_ON(ret < 0))
-		pr_err("Decompression failed! err=%d, page=%u\n", ret, index);
+		pr_err("Decompression failed! err=%d, page=%lu\n", ret, index);
 
 	return ret;
 }
@@ -2195,7 +2204,7 @@ static int zram_read_page(struct zram *zram, struct page *page, u32 index,
  * always expects a full page for the output.
  */
 static int zram_bvec_read_partial(struct zram *zram, struct bio_vec *bvec,
-				  u32 index, int offset)
+				  unsigned long index, int offset)
 {
 	struct page *page = alloc_page(GFP_NOIO);
 	int ret;
@@ -2210,7 +2219,7 @@ static int zram_bvec_read_partial(struct zram *zram, struct bio_vec *bvec,
 }
 
 static int zram_bvec_read(struct zram *zram, struct bio_vec *bvec,
-			  u32 index, int offset, struct bio *bio)
+			  unsigned long index, int offset, struct bio *bio)
 {
 	if (is_partial_io(bvec))
 		return zram_bvec_read_partial(zram, bvec, index, offset);
@@ -2218,7 +2227,7 @@ static int zram_bvec_read(struct zram *zram, struct bio_vec *bvec,
 }
 
 static int write_same_filled_page(struct zram *zram, unsigned long fill,
-				  u32 index)
+				  unsigned long index)
 {
 	slot_lock(zram, index);
 	slot_free(zram, index);
@@ -2233,7 +2242,7 @@ static int write_same_filled_page(struct zram *zram, unsigned long fill,
 }
 
 static int write_incompressible_page(struct zram *zram, struct page *page,
-				     u32 index)
+				     unsigned long index)
 {
 	unsigned long handle;
 	void *src;
@@ -2273,7 +2282,8 @@ static int write_incompressible_page(struct zram *zram, struct page *page,
 	return 0;
 }
 
-static int zram_write_page(struct zram *zram, struct page *page, u32 index)
+static int zram_write_page(struct zram *zram, struct page *page,
+			   unsigned long index)
 {
 	int ret = 0;
 	unsigned long handle;
@@ -2340,7 +2350,7 @@ static int zram_write_page(struct zram *zram, struct page *page, u32 index)
  * This is a partial IO. Read the full page before writing the changes.
  */
 static int zram_bvec_write_partial(struct zram *zram, struct bio_vec *bvec,
-				   u32 index, int offset)
+				   unsigned long index, int offset)
 {
 	struct page *page = alloc_page(GFP_NOIO);
 	int ret;
@@ -2358,7 +2368,7 @@ static int zram_bvec_write_partial(struct zram *zram, struct bio_vec *bvec,
 }
 
 static int zram_bvec_write(struct zram *zram, struct bio_vec *bvec,
-			   u32 index, int offset)
+			   unsigned long index, int offset)
 {
 	if (is_partial_io(bvec))
 		return zram_bvec_write_partial(zram, bvec, index, offset);
@@ -2426,8 +2436,9 @@ next:
  *
  * Corresponding ZRAM slot should be locked.
  */
-static int recompress_slot(struct zram *zram, u32 index, struct page *page,
-			   u64 *num_recomp_pages, u32 threshold, u32 prio)
+static int recompress_slot(struct zram *zram, unsigned long index,
+			   struct page *page, u64 *num_recomp_pages,
+			   u32 threshold, u32 prio)
 {
 	struct zcomp_strm *zstrm = NULL;
 	unsigned long handle_old;
@@ -2679,7 +2690,7 @@ out:
 static void zram_bio_discard(struct zram *zram, struct bio *bio)
 {
 	size_t n = bio->bi_iter.bi_size;
-	u32 index = bio->bi_iter.bi_sector >> SECTORS_PER_PAGE_SHIFT;
+	unsigned long index = bio->bi_iter.bi_sector >> SECTORS_PER_PAGE_SHIFT;
 	u32 offset = (bio->bi_iter.bi_sector & (SECTORS_PER_PAGE - 1)) <<
 			SECTOR_SHIFT;
 
@@ -2720,7 +2731,7 @@ static void zram_bio_read(struct zram *zram, struct bio *bio)
 	struct bvec_iter iter = bio->bi_iter;
 
 	do {
-		u32 index = iter.bi_sector >> SECTORS_PER_PAGE_SHIFT;
+		unsigned long index = iter.bi_sector >> SECTORS_PER_PAGE_SHIFT;
 		u32 offset = (iter.bi_sector & (SECTORS_PER_PAGE - 1)) <<
 				SECTOR_SHIFT;
 		struct bio_vec bv = bio_iter_iovec(bio, iter);
@@ -2751,7 +2762,7 @@ static void zram_bio_write(struct zram *zram, struct bio *bio)
 	struct bvec_iter iter = bio->bi_iter;
 
 	do {
-		u32 index = iter.bi_sector >> SECTORS_PER_PAGE_SHIFT;
+		unsigned long index = iter.bi_sector >> SECTORS_PER_PAGE_SHIFT;
 		u32 offset = (iter.bi_sector & (SECTORS_PER_PAGE - 1)) <<
 				SECTOR_SHIFT;
 		struct bio_vec bv = bio_iter_iovec(bio, iter);
@@ -2865,6 +2876,7 @@ static void zram_reset_device(struct zram *zram)
 static ssize_t disksize_store(struct device *dev, struct device_attribute *attr,
 			      const char *buf, size_t len)
 {
+	unsigned long num_pages;
 	u64 disksize;
 	struct zcomp *comp;
 	struct zram *zram = dev_to_zram(dev);
@@ -2882,6 +2894,11 @@ static ssize_t disksize_store(struct device *dev, struct device_attribute *attr,
 	}
 
 	disksize = PAGE_ALIGN(disksize);
+	num_pages = disksize >> PAGE_SHIFT;
+	/* Slots are addressed by an unsigned long index */
+	if (!num_pages || ((u64)num_pages << PAGE_SHIFT) != disksize)
+		return -EINVAL;
+
 	if (!zram_meta_alloc(zram, disksize))
 		return -ENOMEM;