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Date: Mon, 04 Feb 2013 01:39:24 -0600
From: Ric Mason <ric.masonn@...il.com>
To: Minchan Kim <minchan@...nel.org>
Cc: Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
linux-mm@...ck.org, linux-kernel@...r.kernel.org,
Nitin Gupta <ngupta@...are.org>,
Seth Jennings <sjenning@...ux.vnet.ibm.com>,
Konrad Rzeszutek Wilk <konrad@...nok.org>,
Dan Magenheimer <dan.magenheimer@...cle.com>,
Pekka Enberg <penberg@...helsinki.fi>, jmarchan@...hat.com,
Andrew Morton <akpm@...ux-foundation.org>
Subject: Re: [PATCH v7 4/4] zram: get rid of lockdep warning
On Mon, 2013-02-04 at 08:46 +0900, Minchan Kim wrote:
> Lockdep complains about recursive deadlock of zram->init_lock.
> [1] 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
>
> Acked-by: Jerome Marchand <jmarchan@...hat.com>
> 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 85055c4..56e3203 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;
> }
> @@ -232,9 +234,10 @@ 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;
Could you explain compress_buffer is used for what? Thanks for your
clarify!
>
> if (is_partial_io(bvec)) {
> /*
> @@ -256,8 +259,8 @@ 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);
> @@ -276,13 +279,13 @@ static int zram_bvec_write(struct zram *zram, struct bio_vec *bvec, u32 index,
> if (is_partial_io(bvec))
> kfree(uncmem);
> 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);
> @@ -303,14 +306,14 @@ 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);
> @@ -318,10 +321,10 @@ 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);
> @@ -464,34 +467,25 @@ 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));
>
> @@ -506,12 +500,65 @@ 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(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 "
> @@ -526,51 +573,13 @@ 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(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);
> }
--
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