From: "Aneesh Kumar K.V" <aneesh.kumar@linux.vnet.ibm.com>
To: Paul Mackerras <paulus@ozlabs.org>
Cc: benh@kernel.crashing.org, mpe@ellerman.id.au,
linuxppc-dev@lists.ozlabs.org
Subject: Re: [PATCH V4 03/18] powerpc/mm: add _PAGE_HASHPTE similar to 4K hash
Date: Tue, 23 Feb 2016 14:52:07 +0530 [thread overview]
Message-ID: <87si0jhjcw.fsf@linux.vnet.ibm.com> (raw)
In-Reply-To: <20160223053847.GA14286@fergus.ozlabs.ibm.com>
Paul Mackerras <paulus@ozlabs.org> writes:
> On Tue, Feb 23, 2016 at 10:18:05AM +0530, Aneesh Kumar K.V wrote:
>> The difference between 64K and 4K hash fault handling is confusing
>> with respect to when we set _PAGE_HASHPTE in the linux pte.
>> I was trying to find out whether we miss a hpte flush in any
>> scenario because of this. ie, a pte update on a linux pte, for which we
>> are doing a parallel hash pte insert. After looking at it closer my
>> understanding is this won't happen because pte update also look at
>> _PAGE_BUSY and we will wait for hash pte insert to finish before going
>> ahead with the pte update. But to avoid further confusion keep the
>> hash fault handler for all the page size similar to __hash_page_4k.
>>
>> This partially reverts commit 41743a4e34f0 ("powerpc: Free a PTE bit on ppc64 with 64K pages"
>
> In each of the functions you are modifying below, there is already an
> explicit setting of _PAGE_HASHPTE in new_pte. So I don't think this
> is necessary, or if we do this, we can eliminate the separate setting
> of _PAGE_HASHPTE later on.
>
> In general I think it's better to leave the setting of _PAGE_HASHPTE
> until we know what slot the HPTE is going to go into. That way we
> have less chance of ending up with _PAGE_HASHPTE set but bogus
> information in _PAGE_F_GIX and _PAGE_F_SECOND.
>
Ok. I will do a variant that remove _PAGE_HASHPTE setting from 4k. ie,
diff --git a/arch/powerpc/mm/hash64_4k.c b/arch/powerpc/mm/hash64_4k.c
index e3e76b929f33..47d1b26effc6 100644
--- a/arch/powerpc/mm/hash64_4k.c
+++ b/arch/powerpc/mm/hash64_4k.c
@@ -44,7 +44,7 @@ int __hash_page_4K(unsigned long ea, unsigned long access, unsigned long vsid,
* a write access. Since this is 4K insert of 64K page size
* also add _PAGE_COMBO
*/
- new_pte = old_pte | _PAGE_BUSY | _PAGE_ACCESSED | _PAGE_HASHPTE;
+ new_pte = old_pte | _PAGE_BUSY | _PAGE_ACCESSED;
if (access & _PAGE_RW)
new_pte |= _PAGE_DIRTY;
} while (old_pte != __cmpxchg_u64((unsigned long *)ptep,
next prev parent reply other threads:[~2016-02-23 9:22 UTC|newest]
Thread overview: 38+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-02-23 4:48 [PATCH V4 00/18] Book3s abstraction in preparation for new MMU model Aneesh Kumar K.V
2016-02-23 4:48 ` [PATCH V4 01/18] powerp/mm: Update code comments Aneesh Kumar K.V
2016-02-23 4:48 ` [PATCH V4 02/18] mm: Some arch may want to use HPAGE_PMD related values as variables Aneesh Kumar K.V
2016-02-25 5:06 ` Balbir Singh
2016-02-23 4:48 ` [PATCH V4 03/18] powerpc/mm: add _PAGE_HASHPTE similar to 4K hash Aneesh Kumar K.V
2016-02-23 5:38 ` Paul Mackerras
2016-02-23 9:22 ` Aneesh Kumar K.V [this message]
2016-02-23 4:48 ` [PATCH V4 04/18] powerpc/mm: Split pgtable types to separate header Aneesh Kumar K.V
2016-02-25 3:12 ` Paul Mackerras
2016-02-25 5:35 ` Balbir Singh
2016-02-23 4:48 ` [PATCH V4 05/18] powerpc/mm: Don't have conditional defines for real_pte_t Aneesh Kumar K.V
2016-02-25 3:24 ` Paul Mackerras
2016-02-25 6:03 ` Balbir Singh
2016-02-23 4:48 ` [PATCH V4 06/18] powerpc/mm: Switch book3s 64 with 64K page size to 4 level page table Aneesh Kumar K.V
2016-02-25 3:39 ` Paul Mackerras
2016-02-26 2:07 ` Aneesh Kumar K.V
2016-02-23 4:48 ` [PATCH V4 07/18] powerpc/mm: Update masked bits for linux " Aneesh Kumar K.V
2016-02-25 3:41 ` Paul Mackerras
2016-02-26 2:08 ` Aneesh Kumar K.V
2016-02-23 4:48 ` [PATCH V4 08/18] powerpc/mm: Copy pgalloc (part 1) Aneesh Kumar K.V
2016-02-25 4:27 ` Paul Mackerras
2016-02-26 2:11 ` Aneesh Kumar K.V
2016-02-23 4:48 ` [PATCH V4 09/18] powerpc/mm: Copy pgalloc (part 2) Aneesh Kumar K.V
2016-02-23 4:48 ` [PATCH V4 10/18] powerpc/mm: Copy pgalloc (part 3) Aneesh Kumar K.V
2016-02-23 4:48 ` [PATCH V4 11/18] powerpc/mm: Hugetlbfs is book3s_64 and fsl_book3e (32 or 64) Aneesh Kumar K.V
2016-02-25 5:41 ` Paul Mackerras
2016-02-26 9:57 ` Aneesh Kumar K.V
2016-02-23 4:48 ` [PATCH V4 12/18] powerpc/mm: Use flush_tlb_page in ptep_clear_flush_young Aneesh Kumar K.V
2016-02-23 4:48 ` [PATCH V4 13/18] powerpc/mm: Move hash related mmu-*.h headers to book3s/ Aneesh Kumar K.V
2016-02-23 4:48 ` [PATCH V4 14/18] powerpc/mm: Create a new headers for tlbflush for hash64 Aneesh Kumar K.V
2016-02-23 4:48 ` [PATCH V4 15/18] powerpc/mm: Move hash page table related functions to pgtable-hash64.c Aneesh Kumar K.V
2016-02-25 4:32 ` Scott Wood
2016-02-26 10:00 ` Aneesh Kumar K.V
2016-02-23 4:48 ` [PATCH V4 16/18] powerpc/mm: THP is only available on hash64 as of now Aneesh Kumar K.V
2016-02-23 4:48 ` [PATCH V4 17/18] powerpc/mm: Use generic version of pmdp_clear_flush_young Aneesh Kumar K.V
2016-02-23 4:48 ` [PATCH V4 18/18] powerpc/mm: Move hash64 specific definitions to separate header Aneesh Kumar K.V
2016-02-23 9:26 ` [PATCH V4 00/18] Book3s abstraction in preparation for new MMU model Aneesh Kumar K.V
2016-02-25 4:34 ` Scott Wood
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