From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-yk0-f172.google.com (mail-yk0-f172.google.com [209.85.160.172]) by kanga.kvack.org (Postfix) with ESMTP id C562E6B0009 for ; Mon, 18 Jan 2016 22:01:21 -0500 (EST) Received: by mail-yk0-f172.google.com with SMTP id v14so540344215ykd.3 for ; Mon, 18 Jan 2016 19:01:21 -0800 (PST) Received: from mail-yk0-x22c.google.com (mail-yk0-x22c.google.com. [2607:f8b0:4002:c07::22c]) by mx.google.com with ESMTPS id 205si16274477ywl.10.2016.01.18.19.01.20 for (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Mon, 18 Jan 2016 19:01:20 -0800 (PST) Received: by mail-yk0-x22c.google.com with SMTP id a85so555958667ykb.1 for ; Mon, 18 Jan 2016 19:01:20 -0800 (PST) MIME-Version: 1.0 In-Reply-To: References: <1453125834-16546-1-git-send-email-liangchen.linux@gmail.com> From: SeongJae Park Date: Tue, 19 Jan 2016 12:00:51 +0900 Message-ID: Subject: Re: [PATCH] mm:mempolicy: skip VM_HUGETLB and VM_MIXEDMAP VMA for lazy mbind Content-Type: text/plain; charset=UTF-8 Sender: owner-linux-mm@kvack.org List-ID: To: Gavin Guo Cc: Liang Chen , n-horiguchi@ah.jp.nec.com, linux-mm@kvack.org, Rik van Riel , Mel Gorman , Andrew Morton , linux-kernel Hi Gavin, On Tue, Jan 19, 2016 at 11:43 AM, Gavin Guo wrote: > Hi SeongJae, > > On Tue, Jan 19, 2016 at 9:12 AM, SeongJae Park wrote: >> Hello Liang, >> >> Just trivial comment below. >> >> On Mon, 18 Jan 2016, Liang Chen wrote: >> >>> VM_HUGETLB and VM_MIXEDMAP vma needs to be excluded to avoid compound >>> pages being marked for migration and unexpected COWs when handling >>> hugetlb fault. >>> >>> Thanks to Naoya Horiguchi for reminding me on these checks. >>> >>> Signed-off-by: Liang Chen >>> Signed-off-by: Gavin Guo >>> --- >>> mm/mempolicy.c | 5 +++-- >>> 1 file changed, 3 insertions(+), 2 deletions(-) >>> >>> diff --git a/mm/mempolicy.c b/mm/mempolicy.c >>> index 436ff411..415de70 100644 >>> --- a/mm/mempolicy.c >>> +++ b/mm/mempolicy.c >>> @@ -610,8 +610,9 @@ static int queue_pages_test_walk(unsigned long start, >>> unsigned long end, >>> >>> if (flags & MPOL_MF_LAZY) { >>> /* Similar to task_numa_work, skip inaccessible VMAs */ >>> - if (vma_migratable(vma) && >>> - vma->vm_flags & (VM_READ | VM_EXEC | VM_WRITE)) >>> + if (vma_migratable(vma) && !is_vm_hugetlb_page(vma) && >>> + (vma->vm_flags & (VM_READ | VM_EXEC | VM_WRITE)) >>> && >>> + !(vma->vm_flags & VM_MIXEDMAP)) >> >> >> Isn't there exists few unnecessary parenthesis? IMHO, it makes me hard to >> read the code. >> >> How about below code, instead? >> >> + if (vma_migratable(vma) && !is_vm_hugetlb_page(vma) && >> + vma->vm_flags & (VM_READ | VM_EXEC | VM_WRITE) && > > Thanks for your suggestion, it's good for the above. However, it should be > a typo for the following and I think you mean: > > ~vma->vm_flags & VM_MIXEDMAP > > Even though the result is correct, I feel it's a bit of ambiguous for > people to understand and away from it's original meaning. Ah, you're right. That's my fault. Thanks for noting that. BTW, now I think the line could be expressed in this way: vma->vm_flags & ~VM_MIXEDMAP I feel this is sufficiently explicit and follows the meaning well. However, I agree that Liang's first one is good enough, too. Thanks, SeongJae Park. > >> + !vma->vm_flags & VM_MIXEDMAP) >> >> >> Thanks, >> SeongJae Park. >> >>> change_prot_numa(vma, start, endvma); >>> return 1; >>> } >>> -- >>> 1.9.1 >>> >>> -- >>> 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 >>> >> -- 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