Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753008AbbBXVny (ORCPT ); Tue, 24 Feb 2015 16:43:54 -0500 Received: from mail-gw1-out.broadcom.com ([216.31.210.62]:21840 "EHLO mail-gw1-out.broadcom.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752411AbbBXVnw (ORCPT ); Tue, 24 Feb 2015 16:43:52 -0500 X-IronPort-AV: E=Sophos;i="5.09,641,1418112000"; d="scan'208";a="58081302" Message-ID: <54ECF091.8070508@broadcom.com> Date: Tue, 24 Feb 2015 13:43:45 -0800 From: Danesh Petigara User-Agent: Mozilla/5.0 (Windows NT 6.1; rv:24.0) Gecko/20100101 Thunderbird/24.4.0 MIME-Version: 1.0 To: Michal Nazarewicz , CC: , , , , , , , Subject: Re: [PATCH] mm: cma: fix CMA aligned offset calculation References: <1424807759-23311-1-git-send-email-dpetigara@broadcom.com> In-Reply-To: Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1990 Lines: 64 On 2/24/2015 1:10 PM, Michal Nazarewicz wrote: > On Tue, Feb 24 2015, Danesh Petigara wrote: >> The CMA aligned offset calculation is incorrect for >> non-zero order_per_bit values. >> >> For example, if cma->order_per_bit=1, cma->base_pfn= >> 0x2f800000 and align_order=12, the function returns >> a value of 0x17c00 instead of 0x400. >> >> This patch fixes the CMA aligned offset calculation. >> >> Cc: stable@vger.kernel.org >> Signed-off-by: Danesh Petigara >> Reviewed-by: Gregory Fong > > Acked-by: Michal Nazarewicz > >> --- >> mm/cma.c | 10 +++++++--- >> 1 file changed, 7 insertions(+), 3 deletions(-) >> >> diff --git a/mm/cma.c b/mm/cma.c >> index 75016fd..58f37bd 100644 >> --- a/mm/cma.c >> +++ b/mm/cma.c >> @@ -70,9 +70,13 @@ static unsigned long cma_bitmap_aligned_offset(struct cma *cma, int align_order) >> >> if (align_order <= cma->order_per_bit) >> return 0; >> - alignment = 1UL << (align_order - cma->order_per_bit); >> - return ALIGN(cma->base_pfn, alignment) - >> - (cma->base_pfn >> cma->order_per_bit); >> + >> + /* >> + * Find a PFN aligned to the specified order and return >> + * an offset represented in order_per_bits. >> + */ > > It probably makes sense to move this comment outside of the function as > function documentation. > Thanks for the feedback. Will send out patch v2 with the comment moved outside the function and also remove the unused 'alignment' variable. >> + return (ALIGN(cma->base_pfn, (1UL << align_order)) >> + - cma->base_pfn) >> cma->order_per_bit; >> } >> >> static unsigned long cma_bitmap_maxno(struct cma *cma) >> -- >> 1.9.1 >> > Best regards, Danesh Petigara -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/