From: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>
To: Mel Gorman <mgorman@suse.de>
Cc: Naoya Horiguchi <nao.horiguchi@gmail.com>,
"linux-mm@kvack.org" <linux-mm@kvack.org>,
Andrew Morton <akpm@linux-foundation.org>,
Hugh Dickins <hughd@google.com>,
"Kirill A. Shutemov" <kirill@shutemov.name>,
"David Rientjes" <rientjes@google.com>,
Rik van Riel <riel@redhat.com>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>
Subject: [PATCH] mm: numa: disable change protection for vma(VM_HUGETLB)
Date: Tue, 31 Mar 2015 01:45:55 +0000 [thread overview]
Message-ID: <20150331014554.GA8128@hori1.linux.bs1.fc.nec.co.jp> (raw)
In-Reply-To: <20150330115901.GR4701@suse.de>
On Mon, Mar 30, 2015 at 12:59:01PM +0100, Mel Gorman wrote:
> On Mon, Mar 30, 2015 at 07:42:13PM +0900, Naoya Horiguchi wrote:
...
>
> I note now that the patch was too hasty. By rights, that check
> should be covered by vma_migratable() but it's only checked if
> CONFIG_ARCH_ENABLE_HUGEPAGE_MIGRATION which means it's x86-only. If you
> are seeing this problem on any other arch then a more correct fix might be
> to remove the CONFIG_ARCH_ENABLE_HUGEPAGE_MIGRATION check in vma_migratable.
Changing vma_migratable() affects other usecases of hugepage migration like
mbind(), so simply removing the ifdef doesn't work for such usecases.
I didn't test other archs, but I guess that this problem could happen on all
archs enabling numa balancing, whether it supports CONFIG_ARCH_ENABLE_HUGEPAGE_MIGRATION.
So I'd like pick/push your first suggestion. It passed my testing.
Thanks,
Naoya Horiguchi
---
From: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>
Subject: [PATCH] mm: numa: disable change protection for vma(VM_HUGETLB)
Currently when a process accesses to hugetlb range protected with PROTNONE,
unexpected COWs are triggered, which finally put hugetlb subsystem into
broken/uncontrollable state, where for example h->resv_huge_pages is subtracted
too much and wrapped around to a very large number, and free hugepage pool
is no longer maintainable.
This patch simply stops changing protection for vma(VM_HUGETLB) to fix the
problem. And this also allows us to avoid useless overhead of minor faults.
Suggested-by: Mel Gorman <mgorman@suse.de>
Signed-off-by: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>
---
kernel/sched/fair.c | 4 +++-
1 file changed, 3 insertions(+), 1 deletion(-)
diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c
index 7ce18f3c097a..6ad0d570f38e 100644
--- a/kernel/sched/fair.c
+++ b/kernel/sched/fair.c
@@ -2161,8 +2161,10 @@ void task_numa_work(struct callback_head *work)
vma = mm->mmap;
}
for (; vma; vma = vma->vm_next) {
- if (!vma_migratable(vma) || !vma_policy_mof(vma))
+ if (!vma_migratable(vma) || !vma_policy_mof(vma) ||
+ is_vm_hugetlb_page(vma)) {
continue;
+ }
/*
* Shared library pages mapped by multiple processes are not
--
1.9.3
next prev parent reply other threads:[~2015-03-31 1:47 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-03-30 9:40 [RFC][PATCH] mm: hugetlb: add stub-like do_hugetlb_numa() Naoya Horiguchi
2015-03-30 10:28 ` Mel Gorman
2015-03-30 10:42 ` Naoya Horiguchi
2015-03-30 11:59 ` Mel Gorman
2015-03-31 1:45 ` Naoya Horiguchi [this message]
2015-03-31 21:35 ` [PATCH] mm: numa: disable change protection for vma(VM_HUGETLB) Andrew Morton
2015-04-01 4:14 ` Naoya Horiguchi
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