From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mx0.aculab.com (mx0.aculab.com [213.249.233.131]) by ozlabs.org (Postfix) with SMTP id 6F5CA1007D1 for ; Fri, 15 Jul 2011 20:35:08 +1000 (EST) Received: from mx0.aculab.com ([127.0.0.1]) by localhost (mx0.aculab.com [127.0.0.1]) (amavisd-new, port 10024) with SMTP id 04784-05 for ; Fri, 15 Jul 2011 11:35:05 +0100 (BST) MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Subject: RE: [PATCH 0/1] Fixup write permission of TLB on powerpc e500 core Date: Fri, 15 Jul 2011 11:32:49 +0100 Message-ID: In-Reply-To: <4E20112C.6040307@gmail.com> From: "David Laight" To: "Shan Hai" , "Peter Zijlstra" Cc: tony.luck@intel.com, linux-kernel@vger.kernel.org, cmetcalf@tilera.com, dhowells@redhat.com, paulus@samba.org, tglx@linutronix.de, walken@google.com, linuxppc-dev@lists.ozlabs.org, akpm@linux-foundation.org List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , =20 > The fault causing futex_atomic_cmpxchg_inatomic() is > protected by pagefault_disable(), so the page fault handler has > no chance to toggle the SW dirty/young tracking. Perhaps that is the bug! Whatever pagefault_disable() does, it shouldn't disable the SW dirty/young tracking - which should only needs bits moving in the page table itself (and TLB update??) rather than any operations on the rest of the data areas. It looks to me as though this could happen any time a page is marked inaccessible by the dirty/young tracking. Not just as a result of COW. David