linux-kernel - Re: memleaks, acpi + ext4 + tty

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Message-ID: <20090830182424.GB20822@mit.edu>
Date:	Sun, 30 Aug 2009 14:24:24 -0400
From:	Theodore Tso <tytso@....edu>
To:	"Luis R. Rodriguez" <mcgrof@...il.com>
Cc:	"Aneesh Kumar K.V" <aneesh.kumar@...ux.vnet.ibm.com>,
	Catalin Marinas <catalin.marinas@....com>,
	linux-kernel@...r.kernel.org, Greg Kroah-Hartman <gregkh@...e.de>
Subject: Re: memleaks, acpi + ext4 + tty

On Sun, Aug 30, 2009 at 10:29:01AM -0700, Luis R. Rodriguez wrote:
> > Yes, as soon as the next merge window opens.  The leak only shows up
> > when you mount and unmount a filesystem, which under normal
> > circumstances doesn't happen a huge number of times on most systems.
> > By the time it showed up it was late enough in the 2.6.31-rcX series
> > that I figured it was better to wait until the next merge window.  I
> > didn't consider it a high priority bug.
> 
> That's odd I run into this kmemleak with a single bootup, no manual remounts.
> 

Yeah, but it's a singleton leak.  Let me be a bit more precise this
time: the leak happens at mount time because we're essentially doing
this due to some code that was accidentally duplicated when it was
being refactored:

	a = kmalloc(sizeof(...)*N, GFP_ATOMIC);
	  ...
	a = kmalloc(sizeof(...)*N, GFP_ATOMIC);

So a small amount of memory is leaked each time a filesystem is
mounted.  It doesn't become a huge problem unless you are repeatedly
mounting and unmounting the same filesystem in a tight loop.

	     		    	 	       	 - Ted
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