Re: [PATCH v2 2.6.38-rc8-tip 3/20] 3: uprobes: Breakground pagereplacement.

[Thomas Gleixner]

On Tue, 15 Mar 2011, Srikar Dronamraju wrote:

> * Thomas Gleixner <tglx@xxxxxxxxxxxxx> [2011-03-15 14:22:09]:
> 
> > On Mon, 14 Mar 2011, Srikar Dronamraju wrote:
> > > +/*
> > > + * Called with tsk->mm->mmap_sem held (either for read or write and
> > > + * with a reference to tsk->mm
> > 
> > Hmm, why is holding it for read sufficient?
> 
> We are not adding a new vma to the mm; but just replacing a page with
> another after holding the locks for the pages. Existing routines
> doing close to similar things like the
> access_process_vm/get_user_pages seem to be taking the read_lock. Do
> you see a resaon why readlock wouldnt suffice?

No, I just was confused by the comment. Probably should have asked why
you want to call it write locked.
 
Thanks,

	tglx
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