From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mx1.redhat.com (mx1.redhat.com [209.132.183.28]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by lists.ozlabs.org (Postfix) with ESMTPS id 3yVlbr3JDnzDr8P for ; Mon, 6 Nov 2017 19:10:16 +1100 (AEDT) Subject: Re: POWER: Unexpected fault when writing to brk-allocated memory To: "Aneesh Kumar K.V" , Nicholas Piggin , "Kirill A. Shutemov" Cc: linuxppc-dev@lists.ozlabs.org, linux-mm References: <20171105231850.5e313e46@roar.ozlabs.ibm.com> <871slcszfl.fsf@linux.vnet.ibm.com> From: Florian Weimer Message-ID: Date: Mon, 6 Nov 2017 09:10:10 +0100 MIME-Version: 1.0 In-Reply-To: <871slcszfl.fsf@linux.vnet.ibm.com> Content-Type: text/plain; charset=utf-8; format=flowed List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , On 11/06/2017 07:18 AM, Aneesh Kumar K.V wrote: > We should not return that address, unless we requested with a hint value > of > 128TB. IIRC we discussed this early during the mmap interface > change and said, we will return an address > 128T only if the hint > address is above 128TB (not hint addr + length). I am not sure why > we are finding us returning and address > 128TB with paca limit set to > 128TB? See the memory maps I posted. I think it was not anticipated that the heap could be near the 128 TiB limit because it is placed next to the initially mapped object. I think this could become worse once we have static PIE support because static PIE binaries likely have the same memory layout. (Ordinary PIE does not.) Thanks, Florian