From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-yw1-f69.google.com (mail-yw1-f69.google.com [209.85.161.69]) by kanga.kvack.org (Postfix) with ESMTP id 3389A6B0269 for ; Wed, 14 Nov 2018 19:46:01 -0500 (EST) Received: by mail-yw1-f69.google.com with SMTP id r25-v6so6215500ywa.22 for ; Wed, 14 Nov 2018 16:46:01 -0800 (PST) Received: from hqemgate14.nvidia.com (hqemgate14.nvidia.com. [216.228.121.143]) by mx.google.com with ESMTPS id h129-v6si15546211ywe.313.2018.11.14.16.46.00 for (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Wed, 14 Nov 2018 16:46:00 -0800 (PST) Subject: Re: [PATCH v2 1/6] mm/gup: finish consolidating error handling References: <20181110085041.10071-1-jhubbard@nvidia.com> <20181110085041.10071-2-jhubbard@nvidia.com> <20181112154127.GA8247@localhost.localdomain> From: John Hubbard Message-ID: Date: Wed, 14 Nov 2018 16:45:57 -0800 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset="utf-8"; format=flowed Content-Language: en-US Content-Transfer-Encoding: 7bit Sender: owner-linux-mm@kvack.org List-ID: To: Dan Williams , Keith Busch Cc: John Hubbard , Linux MM , Andrew Morton , Linux Kernel Mailing List , linux-rdma , linux-fsdevel , "Kirill A. Shutemov" , Dave Hansen On 11/12/18 8:14 AM, Dan Williams wrote: > On Mon, Nov 12, 2018 at 7:45 AM Keith Busch wrote: >> >> On Sat, Nov 10, 2018 at 12:50:36AM -0800, john.hubbard@gmail.com wrote: >>> From: John Hubbard >>> >>> An upcoming patch wants to be able to operate on each page that >>> get_user_pages has retrieved. In order to do that, it's best to >>> have a common exit point from the routine. Most of this has been >>> taken care of by commit df06b37ffe5a4 ("mm/gup: cache dev_pagemap while >>> pinning pages"), but there was one case remaining. >>> >>> Also, there was still an unnecessary shadow declaration (with a >>> different type) of the "ret" variable, which this commit removes. >>> >>> Cc: Keith Busch >>> Cc: Dan Williams >>> Cc: Kirill A. Shutemov >>> Cc: Dave Hansen >>> Signed-off-by: John Hubbard >>> --- >>> mm/gup.c | 3 +-- >>> 1 file changed, 1 insertion(+), 2 deletions(-) >>> >>> diff --git a/mm/gup.c b/mm/gup.c >>> index f76e77a2d34b..55a41dee0340 100644 >>> --- a/mm/gup.c >>> +++ b/mm/gup.c >>> @@ -696,12 +696,11 @@ static long __get_user_pages(struct task_struct *tsk, struct mm_struct *mm, >>> if (!vma || start >= vma->vm_end) { >>> vma = find_extend_vma(mm, start); >>> if (!vma && in_gate_area(mm, start)) { >>> - int ret; >>> ret = get_gate_page(mm, start & PAGE_MASK, >>> gup_flags, &vma, >>> pages ? &pages[i] : NULL); >>> if (ret) >>> - return i ? : ret; >>> + goto out; >>> ctx.page_mask = 0; >>> goto next_page; >>> } >> >> This also fixes a potentially leaked dev_pagemap reference count if a >> failure occurs when an iteration crosses a vma boundary. I don't think >> it's normal to have different vma's on a users mapped zone device memory, >> but good to fix anyway. > > Does not sound abnormal to me, we should promote this as a fix for the > current cycle with an updated changelog. > Andrew, should I send this patch separately, or do you have what you need already? thanks, -- John Hubbard NVIDIA