Date:	Tue, 22 Jan 2013 09:07:33 +0900
From:	Minchan Kim <minchan@...nel.org>
To:	Greg Kroah-Hartman <gregkh@...uxfoundation.org>
Cc:	Nitin Gupta <ngupta@...are.org>,
	Seth Jennings <sjenning@...ux.vnet.ibm.com>,
	Dan Magenheimer <dan.magenheimer@...cle.com>,
	Konrad Rzeszutek Wilk <konrad@...nok.org>,
	Jerome Marchand <jmarchan@...hat.com>,
	Pekka Enberg <penberg@...helsinki.fi>, linux-mm@...ck.org,
	linux-kernel@...r.kernel.org, Minchan Kim <minchan@...nel.org>
Subject: [PATCH v4 4/4] zram: get rid of lockdep warning

Lockdep complains about recursive deadlock of zram->init_lock.
[1] in this thread made it false positive because we can't request IO to zram
before setting disksize. Anyway, we should shut lockdep up to
avoid many reporting from user.

[1] zram: force disksize setting before using zram

Cc: Jerome Marchand <jmarchan@...hat.com>
Cc: Nitin Gupta <ngupta@...are.org>
Signed-off-by: Minchan Kim <minchan@...nel.org>
---
 drivers/staging/zram/zram_drv.c   |  189 +++++++++++++++++++------------------
 drivers/staging/zram/zram_drv.h   |   12 ++-
 drivers/staging/zram/zram_sysfs.c |   11 ++-
 3 files changed, 116 insertions(+), 96 deletions(-)

diff --git a/drivers/staging/zram/zram_drv.c b/drivers/staging/zram/zram_drv.c
index 4264121..0a7fc8d 100644
--- a/drivers/staging/zram/zram_drv.c
+++ b/drivers/staging/zram/zram_drv.c
@@ -61,22 +61,22 @@ static void zram_stat64_inc(struct zram *zram, u64 *v)
 	zram_stat64_add(zram, v, 1);
 }
 
-static int zram_test_flag(struct zram *zram, u32 index,
+static int zram_test_flag(struct zram_meta *meta, u32 index,
 			enum zram_pageflags flag)
 {
-	return zram->table[index].flags & BIT(flag);
+	return meta->table[index].flags & BIT(flag);
 }
 
-static void zram_set_flag(struct zram *zram, u32 index,
+static void zram_set_flag(struct zram_meta *meta, u32 index,
 			enum zram_pageflags flag)
 {
-	zram->table[index].flags |= BIT(flag);
+	meta->table[index].flags |= BIT(flag);
 }
 
-static void zram_clear_flag(struct zram *zram, u32 index,
+static void zram_clear_flag(struct zram_meta *meta, u32 index,
 			enum zram_pageflags flag)
 {
-	zram->table[index].flags &= ~BIT(flag);
+	meta->table[index].flags &= ~BIT(flag);
 }
 
 static int page_zero_filled(void *ptr)
@@ -96,16 +96,17 @@ static int page_zero_filled(void *ptr)
 
 static void zram_free_page(struct zram *zram, size_t index)
 {
-	unsigned long handle = zram->table[index].handle;
-	u16 size = zram->table[index].size;
+	struct zram_meta *meta = zram->meta;
+	unsigned long handle = meta->table[index].handle;
+	u16 size = meta->table[index].size;
 
 	if (unlikely(!handle)) {
 		/*
 		 * No memory is allocated for zero filled pages.
 		 * Simply clear zero page flag.
 		 */
-		if (zram_test_flag(zram, index, ZRAM_ZERO)) {
-			zram_clear_flag(zram, index, ZRAM_ZERO);
+		if (zram_test_flag(meta, index, ZRAM_ZERO)) {
+			zram_clear_flag(meta, index, ZRAM_ZERO);
 			zram->stats.pages_zero--;
 		}
 		return;
@@ -114,17 +115,17 @@ static void zram_free_page(struct zram *zram, size_t index)
 	if (unlikely(size > max_zpage_size))
 		zram->stats.bad_compress--;
 
-	zs_free(zram->mem_pool, handle);
+	zs_free(meta->mem_pool, handle);
 
 	if (size <= PAGE_SIZE / 2)
 		zram->stats.good_compress--;
 
 	zram_stat64_sub(zram, &zram->stats.compr_size,
-			zram->table[index].size);
+			meta->table[index].size);
 	zram->stats.pages_stored--;
 
-	zram->table[index].handle = 0;
-	zram->table[index].size = 0;
+	meta->table[index].handle = 0;
+	meta->table[index].size = 0;
 }
 
 static void handle_zero_page(struct bio_vec *bvec)
@@ -149,20 +150,21 @@ static int zram_decompress_page(struct zram *zram, char *mem, u32 index)
 	int ret = LZO_E_OK;
 	size_t clen = PAGE_SIZE;
 	unsigned char *cmem;
-	unsigned long handle = zram->table[index].handle;
+	struct zram_meta *meta = zram->meta;
+	unsigned long handle = meta->table[index].handle;
 
-	if (!handle || zram_test_flag(zram, index, ZRAM_ZERO)) {
+	if (!handle || zram_test_flag(meta, index, ZRAM_ZERO)) {
 		memset(mem, 0, PAGE_SIZE);
 		return 0;
 	}
 
-	cmem = zs_map_object(zram->mem_pool, handle, ZS_MM_RO);
-	if (zram->table[index].size == PAGE_SIZE)
+	cmem = zs_map_object(meta->mem_pool, handle, ZS_MM_RO);
+	if (meta->table[index].size == PAGE_SIZE)
 		memcpy(mem, cmem, PAGE_SIZE);
 	else
-		ret = lzo1x_decompress_safe(cmem, zram->table[index].size,
+		ret = lzo1x_decompress_safe(cmem, meta->table[index].size,
 						mem, &clen);
-	zs_unmap_object(zram->mem_pool, handle);
+	zs_unmap_object(meta->mem_pool, handle);
 
 	/* Should NEVER happen. Return bio error if it does. */
 	if (unlikely(ret != LZO_E_OK)) {
@@ -180,11 +182,11 @@ static int zram_bvec_read(struct zram *zram, struct bio_vec *bvec,
 	int ret;
 	struct page *page;
 	unsigned char *user_mem, *uncmem = NULL;
-
+	struct zram_meta *meta = zram->meta;
 	page = bvec->bv_page;
 
-	if (unlikely(!zram->table[index].handle) ||
-			zram_test_flag(zram, index, ZRAM_ZERO)) {
+	if (unlikely(!meta->table[index].handle) ||
+			zram_test_flag(meta, index, ZRAM_ZERO)) {
 		handle_zero_page(bvec);
 		return 0;
 	}
@@ -231,9 +233,10 @@ static int zram_bvec_write(struct zram *zram, struct bio_vec *bvec, u32 index,
 	unsigned long handle;
 	struct page *page;
 	unsigned char *user_mem, *cmem, *src, *uncmem = NULL;
+	struct zram_meta *meta = zram->meta;
 
 	page = bvec->bv_page;
-	src = zram->compress_buffer;
+	src = meta->compress_buffer;
 
 	if (is_partial_io(bvec)) {
 		/*
@@ -255,8 +258,8 @@ static int zram_bvec_write(struct zram *zram, struct bio_vec *bvec, u32 index,
 	 * System overwrites unused sectors. Free memory associated
 	 * with this sector now.
 	 */
-	if (zram->table[index].handle ||
-	    zram_test_flag(zram, index, ZRAM_ZERO))
+	if (meta->table[index].handle ||
+	    zram_test_flag(meta, index, ZRAM_ZERO))
 		zram_free_page(zram, index);
 
 	user_mem = kmap_atomic(page);
@@ -274,13 +277,13 @@ static int zram_bvec_write(struct zram *zram, struct bio_vec *bvec, u32 index,
 		if (!is_partial_io(bvec))
 			kunmap_atomic(user_mem);
 		zram->stats.pages_zero++;
-		zram_set_flag(zram, index, ZRAM_ZERO);
+		zram_set_flag(meta, index, ZRAM_ZERO);
 		ret = 0;
 		goto out;
 	}
 
 	ret = lzo1x_1_compress(uncmem, PAGE_SIZE, src, &clen,
-			       zram->compress_workmem);
+			       meta->compress_workmem);
 
 	if (!is_partial_io(bvec)) {
 		kunmap_atomic(user_mem);
@@ -301,14 +304,14 @@ static int zram_bvec_write(struct zram *zram, struct bio_vec *bvec, u32 index,
 			src = uncmem;
 	}
 
-	handle = zs_malloc(zram->mem_pool, clen);
+	handle = zs_malloc(meta->mem_pool, clen);
 	if (!handle) {
 		pr_info("Error allocating memory for compressed "
 			"page: %u, size=%zu\n", index, clen);
 		ret = -ENOMEM;
 		goto out;
 	}
-	cmem = zs_map_object(zram->mem_pool, handle, ZS_MM_WO);
+	cmem = zs_map_object(meta->mem_pool, handle, ZS_MM_WO);
 
 	if ((clen == PAGE_SIZE) && !is_partial_io(bvec))
 		src = kmap_atomic(page);
@@ -316,10 +319,10 @@ static int zram_bvec_write(struct zram *zram, struct bio_vec *bvec, u32 index,
 	if ((clen == PAGE_SIZE) && !is_partial_io(bvec))
 		kunmap_atomic(src);
 
-	zs_unmap_object(zram->mem_pool, handle);
+	zs_unmap_object(meta->mem_pool, handle);
 
-	zram->table[index].handle = handle;
-	zram->table[index].size = clen;
+	meta->table[index].handle = handle;
+	meta->table[index].size = clen;
 
 	/* Update stats */
 	zram_stat64_add(zram, &zram->stats.compr_size, clen);
@@ -462,34 +465,25 @@ error:
 void __zram_reset_device(struct zram *zram)
 {
 	size_t index;
+	struct zram_meta *meta;
 
 	if (!zram->init_done)
 		return;
 
+	meta = zram->meta;
 	zram->init_done = 0;
 
-	/* Free various per-device buffers */
-	kfree(zram->compress_workmem);
-	free_pages((unsigned long)zram->compress_buffer, 1);
-
-	zram->compress_workmem = NULL;
-	zram->compress_buffer = NULL;
-
 	/* Free all pages that are still in this zram device */
 	for (index = 0; index < zram->disksize >> PAGE_SHIFT; index++) {
-		unsigned long handle = zram->table[index].handle;
+		unsigned long handle = meta->table[index].handle;
 		if (!handle)
 			continue;
 
-		zs_free(zram->mem_pool, handle);
+		zs_free(meta->mem_pool, handle);
 	}
 
-	vfree(zram->table);
-	zram->table = NULL;
-
-	zs_destroy_pool(zram->mem_pool);
-	zram->mem_pool = NULL;
-
+	zram_meta_free(zram->meta);
+	zram->meta = NULL;
 	/* Reset stats */
 	memset(&zram->stats, 0, sizeof(zram->stats));
 
@@ -504,12 +498,65 @@ void zram_reset_device(struct zram *zram)
 	up_write(&zram->init_lock);
 }
 
-/* zram->init_lock should be held */
-int zram_init_device(struct zram *zram)
+void zram_meta_free(struct zram_meta *meta)
+{
+	zs_destroy_pool(meta->mem_pool);
+	kfree(meta->compress_workmem);
+	free_pages((unsigned long)meta->compress_buffer, 1);
+	vfree(meta->table);
+	kfree(meta);
+}
+
+struct zram_meta *zram_meta_alloc(u64 disksize)
 {
-	int ret;
 	size_t num_pages;
+	struct zram_meta *meta = kmalloc(sizeof(*meta), GFP_KERNEL);
+	if (!meta)
+		goto out;
+
+	meta->compress_workmem = kzalloc(LZO1X_MEM_COMPRESS, GFP_KERNEL);
+	if (!meta->compress_workmem) {
+		pr_err("Error allocating compressor working memory!\n");
+		goto free_meta;
+	}
+
+	meta->compress_buffer =
+		(void *)__get_free_pages(GFP_KERNEL | __GFP_ZERO, 1);
+	if (!meta->compress_buffer) {
+		pr_err("Error allocating compressor buffer space\n");
+		goto free_workmem;
+	}
+
+	num_pages = disksize >> PAGE_SHIFT;
+	meta->table = vzalloc(num_pages * sizeof(*meta->table));
+	if (!meta->table) {
+		pr_err("Error allocating zram address table\n");
+		goto free_buffer;
+	}
+
+	meta->mem_pool = zs_create_pool("zram", GFP_NOIO | __GFP_HIGHMEM);
+	if (!meta->mem_pool) {
+		pr_err("Error creating memory pool\n");
+		goto free_table;
+	}
+
+	return meta;
+
+free_table:
+	vfree(meta->table);
+free_buffer:
+	free_pages((unsigned long)meta->compress_buffer, 1);
+free_workmem:
+	kfree(meta->compress_workmem);
+free_meta:
+	kfree(meta);
+	meta = NULL;
+out:
+	return meta;
+}
 
+void zram_init_device(struct zram *zram, struct zram_meta *meta)
+{
 	if (zram->disksize > 2 * (totalram_pages << PAGE_SHIFT)) {
 		pr_info(
 		"There is little point creating a zram of greater than "
@@ -524,51 +571,13 @@ int zram_init_device(struct zram *zram)
 		);
 	}
 
-	zram->compress_workmem = kzalloc(LZO1X_MEM_COMPRESS, GFP_KERNEL);
-	if (!zram->compress_workmem) {
-		pr_err("Error allocating compressor working memory!\n");
-		ret = -ENOMEM;
-		goto fail_no_table;
-	}
-
-	zram->compress_buffer =
-		(void *)__get_free_pages(GFP_KERNEL | __GFP_ZERO, 1);
-	if (!zram->compress_buffer) {
-		pr_err("Error allocating compressor buffer space\n");
-		ret = -ENOMEM;
-		goto fail_no_table;
-	}
-
-	num_pages = zram->disksize >> PAGE_SHIFT;
-	zram->table = vzalloc(num_pages * sizeof(*zram->table));
-	if (!zram->table) {
-		pr_err("Error allocating zram address table\n");
-		ret = -ENOMEM;
-		goto fail_no_table;
-	}
-
 	/* zram devices sort of resembles non-rotational disks */
 	queue_flag_set_unlocked(QUEUE_FLAG_NONROT, zram->disk->queue);
 
-	zram->mem_pool = zs_create_pool("zram", GFP_NOIO | __GFP_HIGHMEM);
-	if (!zram->mem_pool) {
-		pr_err("Error creating memory pool\n");
-		ret = -ENOMEM;
-		goto fail;
-	}
-
+	zram->meta = meta;
 	zram->init_done = 1;
 
 	pr_debug("Initialization done!\n");
-	return 0;
-
-fail_no_table:
-	/* To prevent accessing table entries during cleanup */
-	zram->disksize = 0;
-fail:
-	__zram_reset_device(zram);
-	pr_err("Initialization failed: err=%d\n", ret);
-	return ret;
 }
 
 static void zram_slot_free_notify(struct block_device *bdev,
diff --git a/drivers/staging/zram/zram_drv.h b/drivers/staging/zram/zram_drv.h
index 5b671d1..2d1a3f1 100644
--- a/drivers/staging/zram/zram_drv.h
+++ b/drivers/staging/zram/zram_drv.h
@@ -83,11 +83,15 @@ struct zram_stats {
 	u32 bad_compress;	/* % of pages with compression ratio>=75% */
 };
 
-struct zram {
-	struct zs_pool *mem_pool;
+struct zram_meta {
 	void *compress_workmem;
 	void *compress_buffer;
 	struct table *table;
+	struct zs_pool *mem_pool;
+};
+
+struct zram {
+	struct zram_meta *meta;
 	spinlock_t stat64_lock;	/* protect 64-bit stats */
 	struct rw_semaphore lock; /* protect compression buffers and table
 				   * against concurrent read and writes */
@@ -111,7 +115,9 @@ unsigned int zram_get_num_devices(void);
 extern struct attribute_group zram_disk_attr_group;
 #endif
 
-extern int zram_init_device(struct zram *zram);
 extern void zram_reset_device(struct zram *zram);
+extern struct zram_meta *zram_meta_alloc(u64 disksize);
+extern void zram_meta_free(struct zram_meta *meta);
+extern void zram_init_device(struct zram *zram, struct zram_meta *meta);
 
 #endif
diff --git a/drivers/staging/zram/zram_sysfs.c b/drivers/staging/zram/zram_sysfs.c
index 369db12..e6a929d 100644
--- a/drivers/staging/zram/zram_sysfs.c
+++ b/drivers/staging/zram/zram_sysfs.c
@@ -56,22 +56,26 @@ static ssize_t disksize_store(struct device *dev,
 		struct device_attribute *attr, const char *buf, size_t len)
 {
 	u64 disksize;
+	struct zram_meta *meta;
 	struct zram *zram = dev_to_zram(dev);
 
 	disksize = memparse(buf, NULL);
 	if (!disksize)
 		return -EINVAL;
 
+	disksize = PAGE_ALIGN(disksize);
+	meta = zram_meta_alloc(disksize);
 	down_write(&zram->init_lock);
 	if (zram->init_done) {
 		up_write(&zram->init_lock);
+		zram_meta_free(meta);
 		pr_info("Cannot change disksize for initialized device\n");
 		return -EBUSY;
 	}
 
-	zram->disksize = PAGE_ALIGN(disksize);
+	zram->disksize = disksize;
 	set_capacity(zram->disk, zram->disksize >> SECTOR_SHIFT);
-	zram_init_device(zram);
+	zram_init_device(zram, meta);
 	up_write(&zram->init_lock);
 
 	return len;
@@ -182,9 +186,10 @@ static ssize_t mem_used_total_show(struct device *dev,
 {
 	u64 val = 0;
 	struct zram *zram = dev_to_zram(dev);
+	struct zram_meta *meta = zram->meta;
 
 	if (zram->init_done)
-		val = zs_get_total_size_bytes(zram->mem_pool);
+		val = zs_get_total_size_bytes(meta->mem_pool);
 
 	return sprintf(buf, "%llu\n", val);
 }
-- 
1.7.9.5

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