[PATCH v4 4/4] zram: get rid of lockdep warning

From: Minchan Kim
Date: Mon Jan 21 2013 - 19:07:31 EST

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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@xxxxxxxxxx>
Cc: Nitin Gupta <ngupta@xxxxxxxxxx>
Signed-off-by: Minchan Kim <minchan@xxxxxxxxxx>
---
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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Next message: Russell King - ARM Linux: "Re: One of these things (CONFIG_HZ) is not like the others.."
Previous message: Minchan Kim: "[PATCH v4 1/4] zram: Fix deadlock bug in partial write"
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Next in thread: Minchan Kim: "[PATCH v4 3/4] zram: give up lazy initialization of zram metadata"
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