From: Andrew Morton <akpm@linux-foundation.org>
To: "Aneesh Kumar K.V" <aneesh.kumar@linux.vnet.ibm.com>
Cc: mpe@ellerman.id.au, paulus@samba.org, benh@kernel.crashing.org,
kirill.shutemov@linux.intel.com, aarcange@redhat.com,
linux-mm@kvack.org, linux-kernel@vger.kernel.org,
linuxppc-dev@lists.ozlabs.org
Subject: Re: [PATCH V2 2/2] powerpc/thp: Serialize pmd clear against a linux page table walk.
Date: Fri, 8 May 2015 15:21:49 -0700 [thread overview]
Message-ID: <20150508152149.7fd52bb4b7c2a0911c33be00@linux-foundation.org> (raw)
In-Reply-To: <1430983408-24924-2-git-send-email-aneesh.kumar@linux.vnet.ibm.com>
On Thu, 7 May 2015 12:53:28 +0530 "Aneesh Kumar K.V" <aneesh.kumar@linux.vnet.ibm.com> wrote:
> Serialize against find_linux_pte_or_hugepte which does lock-less
> lookup in page tables with local interrupts disabled. For huge pages
> it casts pmd_t to pte_t. Since format of pte_t is different from
> pmd_t we want to prevent transit from pmd pointing to page table
> to pmd pointing to huge page (and back) while interrupts are disabled.
> We clear pmd to possibly replace it with page table pointer in
> different code paths. So make sure we wait for the parallel
> find_linux_pte_or_hugepage to finish.
I'm not seeing here any description of the problem which is being
fixed. Does the patch make the machine faster? Does the machine
crash?
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next prev parent reply other threads:[~2015-05-08 22:21 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-05-07 7:23 [PATCH V2 1/2] mm/thp: Split out pmd collpase flush into a seperate functions Aneesh Kumar K.V
2015-05-07 7:23 ` [PATCH V2 2/2] powerpc/thp: Serialize pmd clear against a linux page table walk Aneesh Kumar K.V
2015-05-08 22:21 ` Andrew Morton [this message]
2015-05-11 6:30 ` Aneesh Kumar K.V
2015-05-07 9:20 ` [PATCH V2 1/2] mm/thp: Split out pmd collpase flush into a seperate functions Kirill A. Shutemov
2015-05-07 11:18 ` Aneesh Kumar K.V
2015-05-08 22:24 ` Andrew Morton
2015-05-11 6:32 ` Aneesh Kumar K.V
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