linux-kernel - Re: [PATCH 1/2] zram: free meta table in zram_meta

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Message-ID: <20150128231723.GB4706@blaptop>
Date:	Thu, 29 Jan 2015 08:17:23 +0900
From:	Minchan Kim <minchan@...nel.org>
To:	Sergey Senozhatsky <sergey.senozhatsky@...il.com>
Cc:	Andrew Morton <akpm@...ux-foundation.org>,
	linux-kernel@...r.kernel.org, linux-mm@...ck.org,
	Nitin Gupta <ngupta@...are.org>,
	Jerome Marchand <jmarchan@...hat.com>,
	Ganesh Mahendran <opensource.ganesh@...il.com>,
	sergey.senozhatsky.work@...il.com
Subject: Re: [PATCH 1/2] zram: free meta table in zram_meta_free

On Wed, Jan 28, 2015 at 11:19:17PM +0900, Sergey Senozhatsky wrote:
> On (01/28/15 17:15), Minchan Kim wrote:
> > zram_meta_alloc() and zram_meta_free() are a pair.
> > In zram_meta_alloc(), meta table is allocated. So it it better to free
> > it in zram_meta_free().
> > 
> > Signed-off-by: Ganesh Mahendran <opensource.ganesh@...il.com>
> > Signed-off-by: Minchan Kim <minchan@...nel.org>
> > ---
> >  drivers/block/zram/zram_drv.c | 30 ++++++++++++++----------------
> >  drivers/block/zram/zram_drv.h |  1 +
> >  2 files changed, 15 insertions(+), 16 deletions(-)
> > 
> > diff --git a/drivers/block/zram/zram_drv.c b/drivers/block/zram/zram_drv.c
> > index 9250b3f54a8f..a598ada817f0 100644
> > --- a/drivers/block/zram/zram_drv.c
> > +++ b/drivers/block/zram/zram_drv.c
> > @@ -309,6 +309,18 @@ static inline int valid_io_request(struct zram *zram,
> >  
> >  static void zram_meta_free(struct zram_meta *meta)
> >  {
> > +	size_t index;
> 
> 
> I don't like how we bloat structs w/o any need.
> zram keeps ->disksize, so let's use `zram->disksize >> PAGE_SHIFT'
> instead of introducing ->num_pages.

Right. I overlooked it. I just want to send my patch[2/2] and I thought
it would be better ganesh's patch to merge first although it's orthogonal.

Ganesh, I hope you resend this patch with Sergey's suggestion.
If you are busy, please tell me. I will do it instead of you.

> 
> 	-ss
> 
> > +	/* Free all pages that are still in this zram device */
> > +	for (index = 0; index < meta->num_pages; index++) {
> > +		unsigned long handle = meta->table[index].handle;
> > +
> > +		if (!handle)
> > +			continue;
> > +
> > +		zs_free(meta->mem_pool, handle);
> > +	}
> > +
> >  	zs_destroy_pool(meta->mem_pool);
> >  	vfree(meta->table);
> >  	kfree(meta);
> > @@ -316,15 +328,14 @@ static void zram_meta_free(struct zram_meta *meta)
> >  
> >  static struct zram_meta *zram_meta_alloc(int device_id, u64 disksize)
> >  {
> > -	size_t num_pages;
> >  	char pool_name[8];
> >  	struct zram_meta *meta = kmalloc(sizeof(*meta), GFP_KERNEL);
> >  
> >  	if (!meta)
> >  		return NULL;
> >  
> > -	num_pages = disksize >> PAGE_SHIFT;
> > -	meta->table = vzalloc(num_pages * sizeof(*meta->table));
> > +	meta->num_pages = disksize >> PAGE_SHIFT;
> > +	meta->table = vzalloc(meta->num_pages * sizeof(*meta->table));
> >  	if (!meta->table) {
> >  		pr_err("Error allocating zram address table\n");
> >  		goto out_error;
> > @@ -706,9 +717,6 @@ static void zram_bio_discard(struct zram *zram, u32 index,
> >  
> >  static void zram_reset_device(struct zram *zram, bool reset_capacity)
> >  {
> > -	size_t index;
> > -	struct zram_meta *meta;
> > -
> >  	down_write(&zram->init_lock);
> >  
> >  	zram->limit_pages = 0;
> > @@ -718,16 +726,6 @@ static void zram_reset_device(struct zram *zram, bool reset_capacity)
> >  		return;
> >  	}
> >  
> > -	meta = zram->meta;
> > -	/* Free all pages that are still in this zram device */
> > -	for (index = 0; index < zram->disksize >> PAGE_SHIFT; index++) {
> > -		unsigned long handle = meta->table[index].handle;
> > -		if (!handle)
> > -			continue;
> > -
> > -		zs_free(meta->mem_pool, handle);
> > -	}
> > -
> >  	zcomp_destroy(zram->comp);
> >  	zram->max_comp_streams = 1;
> >  
> > diff --git a/drivers/block/zram/zram_drv.h b/drivers/block/zram/zram_drv.h
> > index b05a816b09ac..e492f6bf11f1 100644
> > --- a/drivers/block/zram/zram_drv.h
> > +++ b/drivers/block/zram/zram_drv.h
> > @@ -96,6 +96,7 @@ struct zram_stats {
> >  struct zram_meta {
> >  	struct zram_table_entry *table;
> >  	struct zs_pool *mem_pool;
> > +	size_t num_pages;
> >  };
> >  
> >  struct zram {
> > -- 
> > 1.9.1
> > 

-- 
Kind regards,
Minchan Kim
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