From: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>
To: Andrea Arcangeli <aarcange@redhat.com>
Cc: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>,
linux-mm@kvack.org, Andrew Morton <akpm@linux-foundation.org>,
David Rientjes <rientjes@google.com>,
Andi Kleen <andi@firstfloor.org>,
Wu Fengguang <fengguang.wu@intel.com>,
KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>,
KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>,
linux-kernel@vger.kernel.org
Subject: Re: [PATCH 1/6] pagemap: avoid splitting thp when reading /proc/pid/pagemap
Date: Mon, 16 Jan 2012 12:18:31 -0500 [thread overview]
Message-ID: <4F145BE7.1060802@ah.jp.nec.com> (raw)
On Sat, Jan 14, 2012 at 06:00:26PM +0100, Andrea Arcangeli wrote:
> On Thu, Jan 12, 2012 at 02:34:53PM -0500, Naoya Horiguchi wrote:
> > + if (pmd_trans_splitting(*pmd)) {
> > + spin_unlock(&walk->mm->page_table_lock);
> > + wait_split_huge_page(vma->anon_vma, pmd);
> > + } else {
> > + for (; addr != end; addr += PAGE_SIZE) {
> > + unsigned long offset = (addr & ~PAGEMAP_WALK_MASK)
> > + >> PAGE_SHIFT;
> > + pfn = thp_pte_to_pagemap_entry(*(pte_t *)pmd,
> > + offset);
>
> What is this that then morphs into a pme (which still has a cast
> inside its creation)? thp_pte_to_pagemap_entry don't seem to be passed
> ptes too. The only case where it is valid to do a cast like that is
> when a function is used by both ptes sand pmds and the code tends to
> work for both with minimal modification to differentiate the two
> cases. Considering the function that gets the cast is called thp_ this
> is hardly the case here.
Agreed.
> Why don't you pass the pmd and then do "if (pmd_present(pmd))
> page_to_pfn(pmd_page(pmd)) ? What's the argument for the cast. I'm
> just reviewing this series and maybe it was covered in previous
> versions.
OK, I can do this by introducing pmd_pte as you commented in another email.
> I don't get this pme thing for something as trivial as above that
> shouldn't require any cast at all.
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WARNING: multiple messages have this Message-ID (diff)
From: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>
To: Andrea Arcangeli <aarcange@redhat.com>
Cc: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>,
linux-mm@kvack.org, Andrew Morton <akpm@linux-foundation.org>,
David Rientjes <rientjes@google.com>,
Andi Kleen <andi@firstfloor.org>,
Wu Fengguang <fengguang.wu@intel.com>,
KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>,
KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>,
linux-kernel@vger.kernel.org
Subject: Re: [PATCH 1/6] pagemap: avoid splitting thp when reading /proc/pid/pagemap
Date: Mon, 16 Jan 2012 12:18:31 -0500 [thread overview]
Message-ID: <4F145BE7.1060802@ah.jp.nec.com> (raw)
On Sat, Jan 14, 2012 at 06:00:26PM +0100, Andrea Arcangeli wrote:
> On Thu, Jan 12, 2012 at 02:34:53PM -0500, Naoya Horiguchi wrote:
> > + if (pmd_trans_splitting(*pmd)) {
> > + spin_unlock(&walk->mm->page_table_lock);
> > + wait_split_huge_page(vma->anon_vma, pmd);
> > + } else {
> > + for (; addr != end; addr += PAGE_SIZE) {
> > + unsigned long offset = (addr & ~PAGEMAP_WALK_MASK)
> > + >> PAGE_SHIFT;
> > + pfn = thp_pte_to_pagemap_entry(*(pte_t *)pmd,
> > + offset);
>
> What is this that then morphs into a pme (which still has a cast
> inside its creation)? thp_pte_to_pagemap_entry don't seem to be passed
> ptes too. The only case where it is valid to do a cast like that is
> when a function is used by both ptes sand pmds and the code tends to
> work for both with minimal modification to differentiate the two
> cases. Considering the function that gets the cast is called thp_ this
> is hardly the case here.
Agreed.
> Why don't you pass the pmd and then do "if (pmd_present(pmd))
> page_to_pfn(pmd_page(pmd)) ? What's the argument for the cast. I'm
> just reviewing this series and maybe it was covered in previous
> versions.
OK, I can do this by introducing pmd_pte as you commented in another email.
> I don't get this pme thing for something as trivial as above that
> shouldn't require any cast at all.
next reply other threads:[~2012-01-16 17:20 UTC|newest]
Thread overview: 18+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-01-16 17:18 Naoya Horiguchi [this message]
2012-01-16 17:18 ` [PATCH 1/6] pagemap: avoid splitting thp when reading /proc/pid/pagemap Naoya Horiguchi
-- strict thread matches above, loose matches on Subject: below --
2012-02-08 15:51 [PATCH 0/6 v5] pagemap handles transparent hugepage Naoya Horiguchi
2012-02-08 15:51 ` [PATCH 1/6] pagemap: avoid splitting thp when reading /proc/pid/pagemap Naoya Horiguchi
2012-02-08 15:51 ` Naoya Horiguchi
2012-01-27 23:02 [PATCH 0/6 v4] pagemap handles transparent hugepage Naoya Horiguchi
2012-01-27 23:02 ` [PATCH 1/6] pagemap: avoid splitting thp when reading /proc/pid/pagemap Naoya Horiguchi
2012-01-27 23:02 ` Naoya Horiguchi
2012-01-29 13:17 ` Hillf Danton
2012-01-29 13:17 ` Hillf Danton
2012-01-30 19:23 ` Naoya Horiguchi
2012-01-30 19:23 ` Naoya Horiguchi
2012-01-12 19:34 [PATCH 0/6 v3] pagemap handles transparent hugepage Naoya Horiguchi
2012-01-12 19:34 ` [PATCH 1/6] pagemap: avoid splitting thp when reading /proc/pid/pagemap Naoya Horiguchi
2012-01-12 19:34 ` Naoya Horiguchi
2012-01-14 17:00 ` Andrea Arcangeli
2012-01-14 17:00 ` Andrea Arcangeli
2012-01-15 12:06 ` Andrea Arcangeli
2012-01-15 12:06 ` Andrea Arcangeli
2012-01-16 17:18 ` Naoya Horiguchi
2012-01-16 17:18 ` Naoya Horiguchi
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