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?
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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