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Date: Thu, 9 Jun 2011 11:13:04 +0530
From: Srikar Dronamraju <srikar@linux.vnet.ibm.com>
Subject: Re: [PATCH v4 3.0-rc2-tip 4/22]  4: Uprobes: register/unregister
 probes.
Message-ID: <20110609054304.GC6123@linux.vnet.ibm.com>
Reply-To: Srikar Dronamraju <srikar@linux.vnet.ibm.com>
References: <20110607125804.28590.92092.sendpatchset@localhost6.localdomain6>
 <20110607125900.28590.16071.sendpatchset@localhost6.localdomain6>
 <20110608221032.GA9965@wicker.gateway.2wire.net>
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To: Stephen Wilson <wilsons@start.ca>
Cc: Peter Zijlstra <peterz@infradead.org>, Ingo Molnar <mingo@elte.hu>, Steven Rostedt <rostedt@goodmis.org>, Linux-mm <linux-mm@kvack.org>, Arnaldo Carvalho de Melo <acme@infradead.org>, Linus Torvalds <torvalds@linux-foundation.org>, Ananth N Mavinakayanahalli <ananth@in.ibm.com>, Hugh Dickins <hughd@google.com>, Christoph Hellwig <hch@infradead.org>, Jonathan Corbet <corbet@lwn.net>, Thomas Gleixner <tglx@linutronix.de>, Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com>, Oleg Nesterov <oleg@redhat.com>, Andrew Morton <akpm@linux-foundation.org>, Jim Keniston <jkenisto@linux.vnet.ibm.com>, Roland McGrath <roland@hack.frob.com>, Andi Kleen <andi@firstfloor.org>, LKML <linux-kernel@vger.kernel.org>

> > +
> > +		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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