From: "Aneesh Kumar K.V" <aneesh.kumar@linux.vnet.ibm.com>
To: Scott Wood <scottwood@freescale.com>
Cc: linux-mm@kvack.org, paulus@samba.org,
linuxppc-dev@lists.ozlabs.org, dwg@au1.ibm.com
Subject: Re: [PATCH -V7 09/18] powerpc: Switch 16GB and 16MB explicit hugepages to a different page table format
Date: Fri, 07 Jun 2013 09:25:22 +0530 [thread overview]
Message-ID: <87zjv2wp5h.fsf@linux.vnet.ibm.com> (raw)
In-Reply-To: <1370558559.32518.4@snotra>
Scott Wood <scottwood@freescale.com> writes:
> On 04/28/2013 02:37:30 PM, Aneesh Kumar K.V wrote:
>> From: "Aneesh Kumar K.V" <aneesh.kumar@linux.vnet.ibm.com>
>>
>> We will be switching PMD_SHIFT to 24 bits to facilitate THP
>> impmenetation.
>> With PMD_SHIFT set to 24, we now have 16MB huge pages allocated at
>> PGD level.
>> That means with 32 bit process we cannot allocate normal pages at
>> all, because we cover the entire address space with one pgd entry.
>> Fix this
>> by switching to a new page table format for hugepages. With the new
>> page table
>> format for 16GB and 16MB hugepages we won't allocate hugepage
>> directory. Instead
>> we encode the PTE information directly at the directory level. This
>> forces 16MB
>> hugepage at PMD level. This will also make the page take walk much
>> simpler later
>> when we add the THP support.
>>
>> With the new table format we have 4 cases for pgds and pmds:
>> (1) invalid (all zeroes)
>> (2) pointer to next table, as normal; bottom 6 bits == 0
>> (3) leaf pte for huge page, bottom two bits != 00
>> (4) hugepd pointer, bottom two bits == 00, next 4 bits indicate size
>> of table
>>
>> Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
>> ---
>> arch/powerpc/include/asm/page.h | 2 +
>> arch/powerpc/include/asm/pgtable.h | 2 +
>> arch/powerpc/mm/gup.c | 18 +++-
>> arch/powerpc/mm/hugetlbpage.c | 176
>> +++++++++++++++++++++++++++++++------
>> 4 files changed, 168 insertions(+), 30 deletions(-)
>
> After this patch, on 64-bit book3e (e5500, and thus 4K pages), I see
> messages like this after exiting a program that uses hugepages
> (specifically, qemu):
>
> /home/scott/fsl/git/linux/upstream/mm/memory.c:407: bad pmd
> 40000001fc221516.
> /home/scott/fsl/git/linux/upstream/mm/memory.c:407: bad pmd
> 40000001fc221516.
> /home/scott/fsl/git/linux/upstream/mm/memory.c:407: bad pmd
> 40000001fc2214d6.
> /home/scott/fsl/git/linux/upstream/mm/memory.c:407: bad pmd
> 40000001fc2214d6.
> /home/scott/fsl/git/linux/upstream/mm/memory.c:407: bad pmd
> 40000001fc221916.
> /home/scott/fsl/git/linux/upstream/mm/memory.c:407: bad pmd
> 40000001fc221916.
> /home/scott/fsl/git/linux/upstream/mm/memory.c:407: bad pmd
> 40000001fc2218d6.
> /home/scott/fsl/git/linux/upstream/mm/memory.c:407: bad pmd
> 40000001fc2218d6.
> /home/scott/fsl/git/linux/upstream/mm/memory.c:407: bad pmd
> 40000001fc221496.
> /home/scott/fsl/git/linux/upstream/mm/memory.c:407: bad pmd
> 40000001fc221496.
> /home/scott/fsl/git/linux/upstream/mm/memory.c:407: bad pmd
> 40000001fc221856.
> /home/scott/fsl/git/linux/upstream/mm/memory.c:407: bad pmd
> 40000001fc221856.
> /home/scott/fsl/git/linux/upstream/mm/memory.c:407: bad pmd
> 40000001fc221816.
hmm that implies some of the code paths are not properly #ifdef.
The goal was to limit the new format CONFIG_PPC_BOOK3S_64 as seen in the
definition of huge_pte_alloc. Can you send me the .config ?
-aneesh
next prev parent reply other threads:[~2013-06-07 3:55 UTC|newest]
Thread overview: 40+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-04-28 19:37 [PATCH -V7 00/18] THP support for PPC64 (Patchset 1) Aneesh Kumar K.V
2013-04-28 19:37 ` [PATCH -V7 01/18] mm/THP: HPAGE_SHIFT is not a #define on some arch Aneesh Kumar K.V
2013-04-30 2:21 ` David Gibson
2013-04-30 2:24 ` David Gibson
2013-04-30 3:42 ` Aneesh Kumar K.V
2013-04-30 5:01 ` David Gibson
2013-05-03 18:51 ` Aneesh Kumar K.V
2013-04-28 19:37 ` [PATCH -V7 02/18] mm/THP: Add pmd args to pgtable deposit and withdraw APIs Aneesh Kumar K.V
2013-04-28 19:37 ` [PATCH -V7 03/18] mm/THP: withdraw the pgtable after pmdp related operations Aneesh Kumar K.V
2013-04-28 19:37 ` [PATCH -V7 04/18] powerpc: Use signed formatting when printing error Aneesh Kumar K.V
2013-04-28 19:37 ` [PATCH -V7 05/18] powerpc: Save DAR and DSISR in pt_regs on MCE Aneesh Kumar K.V
2013-04-28 19:37 ` [PATCH -V7 06/18] powerpc: Don't hard code the size of pte page Aneesh Kumar K.V
2013-04-28 19:37 ` [PATCH -V7 07/18] powerpc: Don't truncate pgd_index wrongly Aneesh Kumar K.V
2013-04-28 19:37 ` [PATCH -V7 08/18] powerpc: New hugepage directory format Aneesh Kumar K.V
2013-04-30 5:16 ` David Gibson
2013-04-28 19:37 ` [PATCH -V7 09/18] powerpc: Switch 16GB and 16MB explicit hugepages to a different page table format Aneesh Kumar K.V
2013-04-30 5:17 ` David Gibson
2013-06-06 22:42 ` Scott Wood
2013-06-07 3:55 ` Aneesh Kumar K.V [this message]
2013-06-07 19:17 ` Scott Wood
2013-06-08 16:57 ` Aneesh Kumar K.V
2013-06-11 20:53 ` Scott Wood
2013-06-11 22:50 ` Scott Wood
2013-06-12 6:30 ` Aneesh Kumar K.V
2013-04-28 19:37 ` [PATCH -V7 10/18] powerpc: Reduce the PTE_INDEX_SIZE Aneesh Kumar K.V
2013-04-28 19:37 ` [PATCH -V7 11/18] powerpc: Move the pte free routines from common header Aneesh Kumar K.V
2013-04-28 19:37 ` [PATCH -V7 12/18] powerpc: Reduce PTE table memory wastage Aneesh Kumar K.V
2013-04-28 19:37 ` [PATCH -V7 13/18] powerpc: Use encode avpn where we need only avpn values Aneesh Kumar K.V
2013-04-28 19:37 ` [PATCH -V7 14/18] powerpc: Decode the pte-lp-encoding bits correctly Aneesh Kumar K.V
2013-04-28 19:37 ` [PATCH -V7 15/18] powerpc: Fix hpte_decode to use the correct decoding for page sizes Aneesh Kumar K.V
2013-04-28 19:37 ` [PATCH -V7 16/18] powerpc: print both base and actual page size on hash failure Aneesh Kumar K.V
2013-04-28 19:37 ` [PATCH -V7 17/18] powerpc: Print page size info during boot Aneesh Kumar K.V
2013-04-28 19:37 ` [PATCH -V7 18/18] powerpc: Update tlbie/tlbiel as per ISA doc Aneesh Kumar K.V
2013-04-30 6:15 ` David Gibson
2013-04-30 17:21 ` Aneesh Kumar K.V
2013-05-01 5:26 ` David Gibson
2013-05-01 7:47 ` Aneesh Kumar K.V
2013-05-01 7:52 ` Simon Jeons
2013-05-01 11:36 ` David Gibson
2013-05-02 5:23 ` David Gibson
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