From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-pf0-x244.google.com (mail-pf0-x244.google.com [IPv6:2607:f8b0:400e:c00::244]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by lists.ozlabs.org (Postfix) with ESMTPS id 3r0lJL1J5nzDq5y for ; Thu, 5 May 2016 16:25:06 +1000 (AEST) Received: by mail-pf0-x244.google.com with SMTP id 145so7234134pfz.1 for ; Wed, 04 May 2016 23:25:06 -0700 (PDT) From: Oliver O'Halloran To: linuxppc-dev@lists.ozlabs.org Cc: Oliver O'Halloran Subject: [PATCH 2/2] powerpc/mm: Ensure "special" zones are empty Date: Thu, 5 May 2016 16:24:42 +1000 Message-Id: <1462429482-1801-2-git-send-email-oohall@gmail.com> In-Reply-To: <1462429482-1801-1-git-send-email-oohall@gmail.com> References: <1462429482-1801-1-git-send-email-oohall@gmail.com> List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , The mm zone mechanism was traditionally used by arch specific code to partition memory into allocation zones. However there are several zones that are managed by the mm subsystem rather than the architecture. Most architectures set the max PFN of these special zones to zero, however on powerpc we set them to ~0ul. This, in conjunction with a bug in free_area_init_nodes() results in all of system memory being placed being placed in ZONE_DEVICE when enabled. Device memory cannot be used for regular kernel memory allocations so this will cause a kernel panic at boot. Given the planned addition of more mm managed zones (ZONE_CMA) we should aim to be consistent with every other architecture and set the max PFN for these zones to zero Signed-off-by: Oliver O'Halloran --- arch/powerpc/mm/mem.c | 8 +++++++- 1 file changed, 7 insertions(+), 1 deletion(-) diff --git a/arch/powerpc/mm/mem.c b/arch/powerpc/mm/mem.c index 8f4c19789a38..f0a058ebb6d7 100644 --- a/arch/powerpc/mm/mem.c +++ b/arch/powerpc/mm/mem.c @@ -239,8 +239,14 @@ static int __init mark_nonram_nosave(void) static bool zone_limits_final; +/* + * The memory zones past TOP_ZONE are managed by the generic + * mm subsystem which expects the max PFN for these zones + * to be set to zero. + */ static unsigned long max_zone_pfns[MAX_NR_ZONES] = { - [0 ... MAX_NR_ZONES - 1] = ~0UL + [0 ... TOP_ZONE - 1] = ~0UL, + [TOP_ZONE ... MAX_NR_ZONES - 1] = 0 }; /* -- 2.5.5