From: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>
To: Wanpeng Li <liwanp@linux.vnet.ibm.com>
Cc: Andrew Morton <akpm@linux-foundation.org>,
Andi Kleen <andi@firstfloor.org>,
Fengguang Wu <fengguang.wu@intel.com>,
Tony Luck <tony.luck@intel.com>,
gong.chen@linux.intel.com, linux-mm@kvack.org,
linux-kernel@vger.kernel.org
Subject: Re: [PATCH 3/6] mm/hwpoison: fix num_poisoned_pages error statistics for thp
Date: Thu, 22 Aug 2013 13:00:37 -0400 [thread overview]
Message-ID: <1377190837-ry9saqra-mutt-n-horiguchi@ah.jp.nec.com> (raw)
In-Reply-To: <1377189788-xv5ewgmb-mutt-n-horiguchi@ah.jp.nec.com>
On Thu, Aug 22, 2013 at 12:43:08PM -0400, Naoya Horiguchi wrote:
> On Thu, Aug 22, 2013 at 05:48:24PM +0800, Wanpeng Li wrote:
> > There is a race between hwpoison page and unpoison page, memory_failure
> > set the page hwpoison and increase num_poisoned_pages without hold page
> > lock, and one page count will be accounted against thp for num_poisoned_pages.
> > However, unpoison can occur before memory_failure hold page lock and
> > split transparent hugepage, unpoison will decrease num_poisoned_pages
> > by 1 << compound_order since memory_failure has not yet split transparent
> > hugepage with page lock held. That means we account one page for hwpoison
> > and 1 << compound_order for unpoison. This patch fix it by decrease one
> > account for num_poisoned_pages against no hugetlbfs pages case.
> >
> > Signed-off-by: Wanpeng Li <liwanp@linux.vnet.ibm.com>
>
> I think that a thp never becomes hwpoisoned without splitting, so "trying
> to unpoison thp" never happens (I think that this implicit fact should be
> commented somewhere or asserted with VM_BUG_ON().)
> And nr_pages in unpoison_memory() can be greater than 1 for hugetlbfs page.
> So does this patch break counting when unpoisoning free hugetlbfs pages?
Sorry, the latter part of this remark was incorrect. Please ignore it.
- Naoya
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next prev parent reply other threads:[~2013-08-22 17:00 UTC|newest]
Thread overview: 26+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-08-22 9:48 [PATCH 1/6] mm/hwpoison: fix lose PG_dirty flag for errors on mlocked pages Wanpeng Li
2013-08-22 9:48 ` [PATCH 2/6] mm/hwpoison: don't need to hold compound lock for hugetlbfs page Wanpeng Li
2013-08-22 15:52 ` Naoya Horiguchi
2013-08-22 23:54 ` Wanpeng Li
2013-08-22 23:54 ` Wanpeng Li
2013-08-22 9:48 ` [PATCH 3/6] mm/hwpoison: fix num_poisoned_pages error statistics for thp Wanpeng Li
2013-08-22 16:43 ` Naoya Horiguchi
2013-08-22 17:00 ` Naoya Horiguchi [this message]
2013-08-22 23:52 ` Wanpeng Li
2013-08-22 23:52 ` Wanpeng Li
[not found] ` <5216a46f.a800310a.2351.ffffa95cSMTPIN_ADDED_BROKEN@mx.google.com>
2013-08-23 3:27 ` Naoya Horiguchi
2013-08-23 4:24 ` Wanpeng Li
2013-08-23 4:24 ` Wanpeng Li
2013-08-22 9:48 ` [PATCH 4/6] mm/hwpoison: don't set migration type twice to avoid hold heavy contend zone->lock Wanpeng Li
2013-08-22 19:06 ` Naoya Horiguchi
2013-08-23 0:15 ` Wanpeng Li
2013-08-23 0:15 ` Wanpeng Li
2013-08-22 9:48 ` [PATCH 5/6] mm/hwpoison: drop forward reference declarations __soft_offline_page() Wanpeng Li
2013-08-22 19:24 ` Naoya Horiguchi
2013-08-22 9:48 ` [PATCH 6/6] mm/hwpoison: centralize set PG_hwpoison flag and increase num_poisoned_pages Wanpeng Li
2013-08-22 20:13 ` Naoya Horiguchi
2013-08-23 0:03 ` Wanpeng Li
2013-08-23 0:03 ` Wanpeng Li
2013-08-22 15:51 ` [PATCH 1/6] mm/hwpoison: fix lose PG_dirty flag for errors on mlocked pages Naoya Horiguchi
2013-08-22 23:34 ` Wanpeng Li
2013-08-22 23:34 ` Wanpeng Li
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