From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-oi0-f50.google.com (mail-oi0-f50.google.com [209.85.218.50]) by kanga.kvack.org (Postfix) with ESMTP id 59CAD6B0005 for ; Wed, 20 Jan 2016 08:44:02 -0500 (EST) Received: by mail-oi0-f50.google.com with SMTP id w75so5188372oie.0 for ; Wed, 20 Jan 2016 05:44:02 -0800 (PST) Received: from mail-ob0-x229.google.com (mail-ob0-x229.google.com. [2607:f8b0:4003:c01::229]) by mx.google.com with ESMTPS id c67si37540912oig.1.2016.01.20.05.44.00 for (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Wed, 20 Jan 2016 05:44:00 -0800 (PST) Received: by mail-ob0-x229.google.com with SMTP id py5so6862203obc.2 for ; Wed, 20 Jan 2016 05:44:00 -0800 (PST) MIME-Version: 1.0 In-Reply-To: References: <1453125834-16546-1-git-send-email-liangchen.linux@gmail.com> Date: Wed, 20 Jan 2016 21:44:00 +0800 Message-ID: Subject: Re: [PATCH] mm:mempolicy: skip VM_HUGETLB and VM_MIXEDMAP VMA for lazy mbind From: Liang Chen Content-Type: text/plain; charset=UTF-8 Sender: owner-linux-mm@kvack.org List-ID: To: SeongJae Park Cc: Gavin Guo , Naoya Horiguchi , linux-mm@kvack.org, Rik van Riel , Mel Gorman , Andrew Morton , linux-kernel Thanks a lot for the checking and discussion. So I will just leave it as it was:) Thanks, Liang On Tue, Jan 19, 2016 at 11:00 AM, SeongJae Park wrote: > 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