From: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>
To: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>
Cc: Wu Fengguang <fengguang.wu@intel.com>,
David Rientjes <rientjes@google.com>,
KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>,
Andrew Morton <akpm@linux-foundation.org>,
Andi Kleen <andi.kleen@intel.com>,
linux-mm@kvack.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH] pagemap: fix wrong KPF_THP on slab pages
Date: Wed, 26 Sep 2012 02:06:08 -0400 [thread overview]
Message-ID: <1348639568-10648-1-git-send-email-n-horiguchi@ah.jp.nec.com> (raw)
In-Reply-To: <1348632154-31508-1-git-send-email-n-horiguchi@ah.jp.nec.com>
On Wed, Sep 26, 2012 at 12:02:34AM -0400, Naoya Horiguchi wrote:
...
> > > + * page is a thp, not a non-huge compound page.
> > > + */
> > > + else if (PageTransCompound(page) && !PageSlab(page))
> > > u |= 1 << KPF_THP;
> >
> > Good catch!
> >
> > Will this report THP for the various drivers that do __GFP_COMP
> > page allocations?
>
> I'm afraid it will. I think of checking PageLRU as an alternative,
> but it needs compound_head() to report tail pages correctly.
> In this context, pages are not pinned or locked, so it's unsafe to
> use compound_head() because it can return a dangling pointer.
> Maybe it's a thp's/hugetlbfs's (not kpageflags specific) problem,
> so going forward with compound_head() expecting that it will be
> fixed in the future work can be an option.
It seems that compound_trans_head() solves this problem, so I'll
simply use it.
Naoya
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next prev parent reply other threads:[~2012-09-26 6:06 UTC|newest]
Thread overview: 12+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-09-25 13:56 Naoya Horiguchi
2012-09-25 15:59 ` KOSAKI Motohiro
2012-09-25 17:05 ` Naoya Horiguchi
2012-09-25 19:03 ` KOSAKI Motohiro
2012-09-26 0:20 ` David Rientjes
2012-09-26 2:06 ` Naoya Horiguchi
2012-09-26 2:26 ` David Rientjes
2012-09-26 2:47 ` Fengguang Wu
2012-09-26 4:02 ` Naoya Horiguchi
2012-09-26 6:06 ` Naoya Horiguchi [this message]
2012-09-26 7:38 ` Fengguang Wu
2012-09-26 14:42 ` Naoya Horiguchi
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