This is the mail archive of the
systemtap@sourceware.org
mailing list for the systemtap project.
Re: [PATCH v2 2.6.38-rc8-tip 3/20] 3: uprobes: Breakground page replacement.
- From: Srikar Dronamraju <srikar at linux dot vnet dot ibm dot com>
- To: Thomas Gleixner <tglx at linutronix dot de>
- Cc: Peter Zijlstra <peterz at infradead dot org>, Ingo Molnar <mingo at elte dot hu>, Steven Rostedt <rostedt at goodmis dot org>, Linux-mm <linux-mm at kvack dot org>, Arnaldo Carvalho de Melo <acme at infradead dot org>, Linus Torvalds <torvalds at linux-foundation dot org>, Ananth N Mavinakayanahalli <ananth at in dot ibm dot com>, Christoph Hellwig <hch at infradead dot org>, Andi Kleen <andi at firstfloor dot org>, Masami Hiramatsu <masami dot hiramatsu dot pt at hitachi dot com>, Oleg Nesterov <oleg at redhat dot com>, LKML <linux-kernel at vger dot kernel dot org>, Jim Keniston <jkenisto at linux dot vnet dot ibm dot com>, Roland McGrath <roland at hack dot frob dot com>, SystemTap <systemtap at sources dot redhat dot com>, Andrew Morton <akpm at linux-foundation dot org>, "Paul E. McKenney" <paulmck at linux dot vnet dot ibm dot com>
- Date: Tue, 15 Mar 2011 23:37:43 +0530
- Subject: Re: [PATCH v2 2.6.38-rc8-tip 3/20] 3: uprobes: Breakground page replacement.
- References: <20110314133403.27435.7901.sendpatchset@localhost6.localdomain6> <20110314133433.27435.49566.sendpatchset@localhost6.localdomain6> <alpine.LFD.2.00.1103151206430.2787@localhost6.localdomain6> <20110315175048.GC24254@linux.vnet.ibm.com> <alpine.LFD.2.00.1103151902020.2787@localhost6.localdomain6>
- Reply-to: Srikar Dronamraju <srikar at linux dot vnet dot ibm dot com>
* Thomas Gleixner <tglx@linutronix.de> [2011-03-15 19:03:44]:
> On Tue, 15 Mar 2011, Srikar Dronamraju wrote:
>
> > * Thomas Gleixner <tglx@linutronix.de> [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.
We no more call it write locked. So we can drop the reference to
write lock.