From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-pd0-f181.google.com (mail-pd0-f181.google.com [209.85.192.181]) by kanga.kvack.org (Postfix) with ESMTP id ED9E96B006E for ; Tue, 24 Feb 2015 16:43:52 -0500 (EST) Received: by pdbfp1 with SMTP id fp1so36259437pdb.9 for ; Tue, 24 Feb 2015 13:43:52 -0800 (PST) Received: from mail-gw1-out.broadcom.com (mail-gw1-out.broadcom.com. [216.31.210.62]) by mx.google.com with ESMTP id f10si8144205pas.19.2015.02.24.13.43.51 for ; Tue, 24 Feb 2015 13:43:52 -0800 (PST) Message-ID: <54ECF091.8070508@broadcom.com> Date: Tue, 24 Feb 2015 13:43:45 -0800 From: Danesh Petigara MIME-Version: 1.0 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: owner-linux-mm@kvack.org List-ID: To: Michal Nazarewicz , akpm@linux-foundation.org Cc: m.szyprowski@samsung.com, iamjoonsoo.kim@lge.com, aneesh.kumar@linux.vnet.ibm.com, laurent.pinchart+renesas@ideasonboard.com, gregory.0xf0@gmail.com, linux-mm@kvack.org, linux-kernel@vger.kernel.org, stable@vger.kernel.org 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, 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