linux-kernel - Re: [PATCH v2 3/5] uprobes: kill write_opcode()->lock_page(new

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Message-ID: <20120709102952.GE32393@linux.vnet.ibm.com>
Date:	Mon, 9 Jul 2012 15:59:52 +0530
From:	Srikar Dronamraju <srikar@...ux.vnet.ibm.com>
To:	Oleg Nesterov <oleg@...hat.com>
Cc:	Ingo Molnar <mingo@...e.hu>, Peter Zijlstra <peterz@...radead.org>,
	Ananth N Mavinakayanahalli <ananth@...ibm.com>,
	Anton Arapov <anton@...hat.com>,
	Hugh Dickins <hughd@...gle.com>, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v2 3/5] uprobes: kill
 write_opcode()->lock_page(new_page)

* Oleg Nesterov <oleg@...hat.com> [2012-06-24 17:00:35]:

> write_opcode() does lock_page(new_page) for no reason. Nobody can
> see this page until __replace_page() exposes it under ptl lock, and
> we do nothing with this page after pte_unmap_unlock().
> 
> If nothing else, the similar code in do_wp_page() doesn't lock the
> new page for page_add_new_anon_rmap/set_pte_at_notify.
> 
> Signed-off-by: Oleg Nesterov <oleg@...hat.com>

Acked-by: Srikar Dronamraju<srikar@...ux.vnet.ibm.com>

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