From: Andrea Arcangeli <aarcange@redhat.com>
To: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>
Cc: 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: Sat, 14 Jan 2012 18:00:26 +0100 [thread overview]
Message-ID: <20120114170026.GF3236@redhat.com> (raw)
In-Reply-To: <1326396898-5579-2-git-send-email-n-horiguchi@ah.jp.nec.com>
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.
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.
I don't get this pme thing for something as trivial as above that
shouldn't require any cast at all.
next prev parent reply other threads:[~2012-01-14 17:00 UTC|newest]
Thread overview: 20+ messages / expand[flat|nested] mbox.gz Atom feed top
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
2012-01-14 17:00 ` Andrea Arcangeli [this message]
2012-01-15 12:06 ` Andrea Arcangeli
2012-01-16 17:18 ` Naoya Horiguchi
2012-01-12 19:34 ` [PATCH 2/6] thp: optimize away unnecessary page table locking Naoya Horiguchi
2012-01-13 12:04 ` Hillf Danton
2012-01-13 15:14 ` Naoya Horiguchi
2012-01-14 3:24 ` Hillf Danton
2012-01-14 17:19 ` Andrea Arcangeli
2012-01-12 19:34 ` [PATCH 3/6] pagemap: export KPF_THP Naoya Horiguchi
2012-01-12 19:34 ` [PATCH 4/6] pagemap: document KPF_THP and make page-types aware of it Naoya Horiguchi
2012-01-12 19:34 ` [PATCH 5/6] introduce thp_ptep_get() Naoya Horiguchi
2012-01-12 19:34 ` [PATCH 6/6] pagemap: introduce data structure for pagemap entry Naoya Horiguchi
2012-01-13 21:54 ` [PATCH 0/6 v3] pagemap handles transparent hugepage Andrew Morton
2012-01-16 17:18 [PATCH 1/6] pagemap: avoid splitting thp when reading /proc/pid/pagemap 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
2012-01-29 13:17 ` Hillf Danton
2012-01-30 19:23 ` Naoya Horiguchi
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
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