[Crash-utility] [PATCH] Fix memory leaks in dump_mem_map when SPARSEMEM is enabled

[yangoliver]

> Date: Wed, 17 Jun 2015 09:19:50 -0400
> From: anderson at redhat.com
> To: crash-utility at redhat.com
> Subject: Re: [Crash-utility] [PATCH] Fix memory leaks in dump_mem_map when SPARSEMEM is enabled
> 
> 
> 
> ----- Original Message -----
> > 
> > 
> > > Date: Tue, 16 Jun 2015 12:32:29 -0400
> > > From: anderson at redhat.com
> > > To: crash-utility at redhat.com
> > > Subject: Re: [Crash-utility] [PATCH] Fix memory leaks in dump_mem_map when
> > > SPARSEMEM is enabled
> > > 
> > > 
> > > 
> > > ----- Original Message -----
> > > > > Date: Tue, 16 Jun 2015 11:14:51 -0400
> > > > > From: anderson at redhat.com
> > > > > To: crash-utility at redhat.com
> > > > > Subject: Re: [Crash-utility] [PATCH] Fix memory leaks in dump_mem_map
> > > > > when
> > > > > SPARSEMEM is enabled
> > > > > 
> > > > > 
> > > > > Hi Oliver,
> > > > > 
> > > > > Since it's a GETBUF() call, it's not really a memory leak (by design).
> > > > 
> > > > Dave,
> > > > 
> > > > Sorry, I'm not familiar the code.
> > > > 
> > > > If the dump_mem_map get called in a thousand loop, the crash could
> > > > reported
> > > > memory allocation errors and exit the loop.
> > > 
> > > Yes, except for the fact that dump_mem_map() is never called in a loop.
> > > But since your proposed patch does that, then yes, it would be a problem.
> > > 
> > > Dave
> > Thanks!
> > 
> > I got your point. GET_BUF just use the memory allocated by shared buffer.
> > 
> > You said this is not a memory leak because crash could free all memory after crash exit.
> >
> > But if crash didn't exit, we just repeat to execute the kmem command in crash, it would cause below issue as well.
> > 
> > error(FATAL, "cannot allocate any more memory!\n"));
> > 
> > My "files -M" patch will make this issue more serious.
> 
> The buffer is not freed "after crash exit", but rather immediately after your command is complete.
> 
> To clarify, all buffers allocated by GETBUF() will be freed prior to the next "crash> " prompt,
> so they only exist for the period of time it takes for the single command to run.  Since you are
> calling dump_mem_map() multiple times within your single command, your fix is required.

Got it. Thanks for your explanations. :)

 		 	   		  
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