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Date: Tue, 19 Jan 2016 10:43:36 +0800 From: Gavin Guo <gavin.guo@...onical.com> To: SeongJae Park <sj38.park@...il.com> Cc: Liang Chen <liangchen.linux@...il.com>, n-horiguchi@...jp.nec.com, linux-mm@...ck.org, riel@...hat.com, Mel Gorman <mgorman@...e.de>, Andrew Morton <akpm@...ux-foundation.org>, linux-kernel <linux-kernel@...r.kernel.org> Subject: Re: [PATCH] mm:mempolicy: skip VM_HUGETLB and VM_MIXEDMAP VMA for lazy mbind Hi SeongJae, On Tue, Jan 19, 2016 at 9:12 AM, SeongJae Park <sj38.park@...il.com> 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 <liangchen.linux@...il.com> >> Signed-off-by: Gavin Guo <gavin.guo@...onical.com> >> --- >> 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. > + !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@...ck.org. For more info on Linux MM, >> see: http://www.linux-mm.org/ . >> Don't email: <a href=mailto:"dont@...ck.org"> email@...ck.org </a> >> >
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