From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-la0-f43.google.com (mail-la0-f43.google.com [209.85.215.43]) by kanga.kvack.org (Postfix) with ESMTP id D6DA46B0069 for ; Fri, 24 Oct 2014 06:00:13 -0400 (EDT) Received: by mail-la0-f43.google.com with SMTP id mc6so2574685lab.2 for ; Fri, 24 Oct 2014 03:00:13 -0700 (PDT) Received: from galahad.ideasonboard.com (galahad.ideasonboard.com. [2001:4b98:dc2:45:216:3eff:febb:480d]) by mx.google.com with ESMTPS id ao5si6197703lbc.58.2014.10.24.03.00.11 for (version=TLSv1.2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Fri, 24 Oct 2014 03:00:12 -0700 (PDT) From: Laurent Pinchart Subject: Re: [PATCH 3/4] mm: cma: Ensure that reservations never cross the low/high mem boundary Date: Fri, 24 Oct 2014 13:00:11 +0300 Message-ID: <1874192.vbdvJooA5D@avalon> In-Reply-To: <20141024025325.GB15243@js1304-P5Q-DELUXE> References: <1414074828-4488-1-git-send-email-laurent.pinchart+renesas@ideasonboard.com> <1414074828-4488-4-git-send-email-laurent.pinchart+renesas@ideasonboard.com> <20141024025325.GB15243@js1304-P5Q-DELUXE> MIME-Version: 1.0 Content-Transfer-Encoding: 7Bit Content-Type: text/plain; charset="us-ascii" Sender: owner-linux-mm@kvack.org List-ID: To: Joonsoo Kim Cc: Laurent Pinchart , linux-mm@kvack.org, linux-kernel@vger.kernel.org, linux-arm-kernel@lists.infradead.org, linux-sh@vger.kernel.org, Marek Szyprowski , Russell King - ARM Linux , Michal Nazarewicz Hi Joonsoo, Thank you for the review. On Friday 24 October 2014 11:53:25 Joonsoo Kim wrote: > On Thu, Oct 23, 2014 at 05:33:47PM +0300, Laurent Pinchart wrote: > > Commit 95b0e655f914 ("ARM: mm: don't limit default CMA region only to > > low memory") extended CMA memory reservation to allow usage of high > > memory. It relied on commit f7426b983a6a ("mm: cma: adjust address limit > > to avoid hitting low/high memory boundary") to ensure that the reserved > > block never crossed the low/high memory boundary. While the > > implementation correctly lowered the limit, it failed to consider the > > case where the base..limit range crossed the low/high memory boundary > > with enough space on each side to reserve the requested size on either > > low or high memory. > > > > Rework the base and limit adjustment to fix the problem. The function > > now starts by rejecting the reservation altogether for fixed > > reservations that cross the boundary, then adjust the limit if > > reservation from high memory is impossible, and finally first try to > > reserve from high memory first and then falls back to low memory. > > > > Signed-off-by: Laurent Pinchart > > > > --- > > > > mm/cma.c | 58 ++++++++++++++++++++++++++++++++++++++++++++-------------- > > 1 file changed, 44 insertions(+), 14 deletions(-) > > > > diff --git a/mm/cma.c b/mm/cma.c > > index 6b14346..b83597b 100644 > > --- a/mm/cma.c > > +++ b/mm/cma.c > > @@ -247,23 +247,38 @@ int __init cma_declare_contiguous(phys_addr_t base, > > return -EINVAL; > > > > /* > > - * adjust limit to avoid crossing low/high memory boundary for > > + * Adjust limit and base to avoid crossing low/high memory boundary > > for > > * automatically allocated regions > > */ > > > > - if (((limit == 0 || limit > memblock_end) && > > - (memblock_end - size < highmem_start && > > - memblock_end > highmem_start)) || > > - (!fixed && limit > highmem_start && limit - size < > > highmem_start)) { > > - limit = highmem_start; > > - } > > > > - if (fixed && base < highmem_start && base+size > highmem_start) { > > + /* > > + * If allocating at a fixed base the request region must not cross > > the > > + * low/high memory boundary. > > + */ > > + if (fixed && base < highmem_start && base + size > highmem_start) { > > ret = -EINVAL; > > pr_err("Region at %08lx defined on low/high memory boundary > > (%08lx)\n", > > (unsigned long)base, (unsigned long)highmem_start); > > goto err; > > } > > > > + /* > > + * If the limit is unspecified or above the memblock end, its > > effective > > + * value will be the memblock end. Set it explicitly to simplify > > further > > + * checks. > > + */ > > + if (limit == 0 || limit > memblock_end) > > + limit = memblock_end; > > + > > + /* > > + * If the limit is above the highmem start by less than the reserved > > + * size allocation in highmem won't be possible. Lower the limit to > > the > > + * lowmem end. > > + */ > > + if (limit > highmem_start && limit - size < highmem_start) > > + limit = highmem_start; > > + > > How about removing this check? > Without this check, memblock_alloc_range would be failed and we can > go fallback correctly. So, this is redundant, IMO. Good point. I'll remove the check in v2. -- Regards, Laurent Pinchart -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: email@kvack.org