linux-kernel - Re: [PATCH v4 3.0-rc2-tip 4/22] 4: Uprobes: register/unregister probes.

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Date:	Thu, 9 Jun 2011 11:13:04 +0530
From:	Srikar Dronamraju <srikar@...ux.vnet.ibm.com>
To:	Stephen Wilson <wilsons@...rt.ca>
Cc:	Peter Zijlstra <peterz@...radead.org>, Ingo Molnar <mingo@...e.hu>,
	Steven Rostedt <rostedt@...dmis.org>,
	Linux-mm <linux-mm@...ck.org>,
	Arnaldo Carvalho de Melo <acme@...radead.org>,
	Linus Torvalds <torvalds@...ux-foundation.org>,
	Ananth N Mavinakayanahalli <ananth@...ibm.com>,
	Hugh Dickins <hughd@...gle.com>,
	Christoph Hellwig <hch@...radead.org>,
	Jonathan Corbet <corbet@....net>,
	Thomas Gleixner <tglx@...utronix.de>,
	Masami Hiramatsu <masami.hiramatsu.pt@...achi.com>,
	Oleg Nesterov <oleg@...hat.com>,
	Andrew Morton <akpm@...ux-foundation.org>,
	Jim Keniston <jkenisto@...ux.vnet.ibm.com>,
	Roland McGrath <roland@...k.frob.com>,
	Andi Kleen <andi@...stfloor.org>,
	LKML <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v4 3.0-rc2-tip 4/22]  4: Uprobes: register/unregister
 probes.

> > +
> > +		mm = vma->vm_mm;
> > +		if (!valid_vma(vma)) {
> > +			mmput(mm);
> > +			continue;
> > +		}
> > +
> > +		vaddr = vma->vm_start + offset;
> > +		vaddr -= vma->vm_pgoff << PAGE_SHIFT;
> > +		if (vaddr < vma->vm_start || vaddr > vma->vm_end) {
> 
> This check looks like it is off by one?  vma->vm_end is already one byte
> past the last valid address in the vma, so we should compare using ">="
> here I think.

Right, we are off-by one.
Will correct in the next patchset. 
Will also correct the other places where we check for vm_end.

> > +
> > +	if (!del_consumer(uprobe, consumer)) {
> > +		pr_debug("No uprobe found with consumer %p\n",
> > +				consumer);
> > +		return;
> > +	}
> 
> When del_consumer() fails dont we still need to do a put_uprobe(uprobe)
> to drop the extra access ref?
> 

Yes, we need to check and drop the reference.
Will correct in the next patchset. 

> > +
> > +	INIT_LIST_HEAD(&tmp_list);
> > +
> > +	mapping = inode->i_mapping;

-- 
Thanks and Regards
Srikar
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