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From: Nitin Gupta <ngupta@vflare.org>
To: Pekka Enberg <penberg@cs.helsinki.fi>
Cc: Hugh Dickins <hugh.dickins@tiscali.co.uk>,
	Andrew Morton <akpm@linux-foundation.org>,
	Greg KH <greg@kroah.com>,
	Dan Magenheimer <dan.magenheimer@oracle.com>,
	Rik van Riel <riel@redhat.com>, Avi Kivity <avi@redhat.com>,
	Christoph Hellwig <hch@infradead.org>,
	Minchan Kim <minchan.kim@gmail.com>,
	Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>,
	linux-mm <linux-mm@kvack.org>,
	linux-kernel <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH 7/8] Use xvmalloc to store compressed chunks
Date: Sun, 18 Jul 2010 13:51:34 +0530	[thread overview]
Message-ID: <4C42B98E.4020208@vflare.org> (raw)
In-Reply-To: <4C42B2E4.4040504@cs.helsinki.fi>

On 07/18/2010 01:23 PM, Pekka Enberg wrote:
> Nitin Gupta wrote:
>> @@ -528,17 +581,32 @@ static int zcache_store_page(struct zcache_inode_rb *znode,
>>          goto out;
>>      }
>>  
>> -    dest_data = kmap_atomic(zpage, KM_USER0);
>> +    local_irq_save(flags);
> 
> Does xv_malloc() required interrupts to be disabled? If so, why doesn't the function do it by itself?
> 


xvmalloc itself doesn't require disabling interrupts but zcache needs that since
otherwise, we can have deadlock between xvmalloc pool lock and mapping->tree_lock
which zcache_put_page() is called. OTOH, zram does not require this disabling of
interrupts. So, interrupts are disable separately for zcache case.

Thanks,
Nitin

WARNING: multiple messages have this Message-ID (diff)
From: Nitin Gupta <ngupta@vflare.org>
To: Pekka Enberg <penberg@cs.helsinki.fi>
Cc: Hugh Dickins <hugh.dickins@tiscali.co.uk>,
	Andrew Morton <akpm@linux-foundation.org>,
	Greg KH <greg@kroah.com>,
	Dan Magenheimer <dan.magenheimer@oracle.com>,
	Rik van Riel <riel@redhat.com>, Avi Kivity <avi@redhat.com>,
	Christoph Hellwig <hch@infradead.org>,
	Minchan Kim <minchan.kim@gmail.com>,
	Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>,
	linux-mm <linux-mm@kvack.org>,
	linux-kernel <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH 7/8] Use xvmalloc to store compressed chunks
Date: Sun, 18 Jul 2010 13:51:34 +0530	[thread overview]
Message-ID: <4C42B98E.4020208@vflare.org> (raw)
In-Reply-To: <4C42B2E4.4040504@cs.helsinki.fi>

On 07/18/2010 01:23 PM, Pekka Enberg wrote:
> Nitin Gupta wrote:
>> @@ -528,17 +581,32 @@ static int zcache_store_page(struct zcache_inode_rb *znode,
>>          goto out;
>>      }
>>  
>> -    dest_data = kmap_atomic(zpage, KM_USER0);
>> +    local_irq_save(flags);
> 
> Does xv_malloc() required interrupts to be disabled? If so, why doesn't the function do it by itself?
> 


xvmalloc itself doesn't require disabling interrupts but zcache needs that since
otherwise, we can have deadlock between xvmalloc pool lock and mapping->tree_lock
which zcache_put_page() is called. OTOH, zram does not require this disabling of
interrupts. So, interrupts are disable separately for zcache case.

Thanks,
Nitin

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  reply	other threads:[~2010-07-18  8:21 UTC|newest]

Thread overview: 82+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2010-07-16 12:37 [PATCH 0/8] zcache: page cache compression support Nitin Gupta
2010-07-16 12:37 ` Nitin Gupta
2010-07-16 12:37 ` [PATCH 1/8] Allow sharing xvmalloc for zram and zcache Nitin Gupta
2010-07-16 12:37   ` Nitin Gupta
2010-07-17 18:10   ` Rik van Riel
2010-07-17 18:10     ` Rik van Riel
2010-07-16 12:37 ` [PATCH 2/8] Basic zcache functionality Nitin Gupta
2010-07-16 12:37   ` Nitin Gupta
2010-07-18  8:14   ` Pekka Enberg
2010-07-18  8:14     ` Pekka Enberg
2010-07-18  9:45     ` Nitin Gupta
2010-07-18  9:45       ` Nitin Gupta
2010-07-18  8:27   ` Pekka Enberg
2010-07-18  8:27     ` Pekka Enberg
2010-07-18  8:44   ` Eric Dumazet
2010-07-18  8:44     ` Eric Dumazet
2010-07-18  9:51     ` Nitin Gupta
2010-07-18  9:51       ` Nitin Gupta
2010-07-16 12:37 ` [PATCH 3/8] Create sysfs nodes and export basic statistics Nitin Gupta
2010-07-16 12:37   ` Nitin Gupta
2010-07-16 12:37 ` [PATCH 4/8] Shrink zcache based on memlimit Nitin Gupta
2010-07-16 12:37   ` Nitin Gupta
2010-07-20 23:03   ` Minchan Kim
2010-07-20 23:03     ` Minchan Kim
2010-07-21  4:52     ` Nitin Gupta
2010-07-21  4:52       ` Nitin Gupta
2010-07-21 11:32       ` Ed Tomlinson
2010-07-21 11:32         ` Ed Tomlinson
2010-07-23 19:23         ` Nitin Gupta
2010-07-23 19:23           ` Nitin Gupta
2010-07-16 12:37 ` [PATCH 5/8] Eliminate zero-filled pages Nitin Gupta
2010-07-16 12:37   ` Nitin Gupta
2010-07-16 12:37 ` [PATCH 6/8] Compress pages using LZO Nitin Gupta
2010-07-16 12:37   ` Nitin Gupta
2010-07-16 12:37 ` [PATCH 7/8] Use xvmalloc to store compressed chunks Nitin Gupta
2010-07-16 12:37   ` Nitin Gupta
2010-07-18  7:53   ` Pekka Enberg
2010-07-18  7:53     ` Pekka Enberg
2010-07-18  8:21     ` Nitin Gupta [this message]
2010-07-18  8:21       ` Nitin Gupta
2010-07-19  4:36       ` Minchan Kim
2010-07-19  4:36         ` Minchan Kim
2010-07-19  6:48         ` Nitin Gupta
2010-07-19  6:48           ` Nitin Gupta
2010-07-16 12:37 ` [PATCH 8/8] Document sysfs entries Nitin Gupta
2010-07-16 12:37   ` Nitin Gupta
2010-07-17 21:13 ` [PATCH 0/8] zcache: page cache compression support Ed Tomlinson
2010-07-17 21:13   ` Ed Tomlinson
2010-07-18  2:23   ` Nitin Gupta
2010-07-18  2:23     ` Nitin Gupta
2010-07-18  7:50 ` Pekka Enberg
2010-07-18  7:50   ` Pekka Enberg
2010-07-18  8:12   ` Nitin Gupta
2010-07-18  8:12     ` Nitin Gupta
2010-07-19 19:57 ` Dan Magenheimer
2010-07-19 19:57   ` Dan Magenheimer
2010-07-20 13:50   ` Nitin Gupta
2010-07-20 13:50     ` Nitin Gupta
2010-07-20 14:28     ` Dan Magenheimer
2010-07-20 14:28       ` Dan Magenheimer
2010-07-21  4:27       ` Nitin Gupta
2010-07-21  4:27         ` Nitin Gupta
2010-07-21 17:37         ` Dan Magenheimer
2010-07-21 17:37           ` Dan Magenheimer
2010-07-22 19:14 ` Greg KH
2010-07-22 19:14   ` Greg KH
2010-07-22 19:54   ` Dan Magenheimer
2010-07-22 19:54     ` Dan Magenheimer
2010-07-22 21:00     ` Greg KH
2010-07-22 21:00       ` Greg KH
2011-01-10 13:16 ` Kirill A. Shutemov
2011-01-10 13:16   ` Kirill A. Shutemov
2011-01-18 17:53   ` Dan Magenheimer
2011-01-18 17:53     ` Dan Magenheimer
2011-01-20 12:33     ` Nitin Gupta
2011-01-20 12:33       ` Nitin Gupta
2011-01-20 12:47       ` Christoph Hellwig
2011-01-20 12:47         ` Christoph Hellwig
2011-01-20 13:16         ` Pekka Enberg
2011-01-20 13:16           ` Pekka Enberg
2011-01-20 13:58           ` Nitin Gupta
2011-01-20 13:58             ` Nitin Gupta

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