From: Laurent Dufour <ldufour@linux.vnet.ibm.com>
To: Anshuman Khandual <khandual@linux.vnet.ibm.com>,
paulmck@linux.vnet.ibm.com, peterz@infradead.org,
akpm@linux-foundation.org, kirill@shutemov.name,
ak@linux.intel.com, mhocko@kernel.org, dave@stgolabs.net,
jack@suse.cz, Matthew Wilcox <willy@infradead.org>
Cc: linux-kernel@vger.kernel.org, linux-mm@kvack.org,
haren@linux.vnet.ibm.com, npiggin@gmail.com,
bsingharora@gmail.com, Tim Chen <tim.c.chen@linux.intel.com>
Subject: Re: [RFC v5 01/11] mm: Dont assume page-table invariance during faults
Date: Tue, 8 Aug 2017 14:11:44 +0200 [thread overview]
Message-ID: <e1d576f4-82f9-04f1-3387-19fb72bdb161@linux.vnet.ibm.com> (raw)
In-Reply-To: <57cbb4ca-7f04-ac50-3321-2c34ac08307b@linux.vnet.ibm.com>
On 08/08/2017 11:45, Anshuman Khandual wrote:
> On 06/16/2017 11:22 PM, Laurent Dufour wrote:
>> From: Peter Zijlstra <peterz@infradead.org>
>>
>> One of the side effects of speculating on faults (without holding
>> mmap_sem) is that we can race with free_pgtables() and therefore we
>> cannot assume the page-tables will stick around.
>>
>> Remove the relyance on the pte pointer.
>
> Looking into other parts of the series, it seemed like now we have
> sequence lock both at MM and VMA level but then after that we still
> need to take page table lock before handling page faults (in turn
> manipulating PTE which includes swap in paths as well). Is not that
> true ?
Page table locking is still required as several VMAs can reference the same
page table.
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next prev parent reply other threads:[~2017-08-08 12:11 UTC|newest]
Thread overview: 37+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-06-16 17:52 [RFC v5 00/11] Speculative page faults Laurent Dufour
2017-06-16 17:52 ` [RFC v5 01/11] mm: Dont assume page-table invariance during faults Laurent Dufour
2017-07-07 7:07 ` Balbir Singh
2017-07-10 17:48 ` Laurent Dufour
2017-07-11 4:26 ` Balbir Singh
2017-08-08 10:04 ` Anshuman Khandual
2017-08-08 9:45 ` Anshuman Khandual
2017-08-08 12:11 ` Laurent Dufour [this message]
2017-06-16 17:52 ` [RFC v5 02/11] mm: Prepare for FAULT_FLAG_SPECULATIVE Laurent Dufour
2017-08-08 10:24 ` Anshuman Khandual
2017-08-08 10:42 ` Peter Zijlstra
2017-06-16 17:52 ` [RFC v5 03/11] mm: Introduce pte_spinlock " Laurent Dufour
2017-08-08 10:35 ` Anshuman Khandual
2017-08-08 12:16 ` Laurent Dufour
2017-06-16 17:52 ` [RFC v5 04/11] mm: VMA sequence count Laurent Dufour
2017-08-08 10:59 ` Anshuman Khandual
2017-08-08 11:04 ` Peter Zijlstra
2017-06-16 17:52 ` [RFC v5 05/11] mm: fix lock dependency against mapping->i_mmap_rwsem Laurent Dufour
2017-08-08 11:17 ` Anshuman Khandual
2017-08-08 12:20 ` Laurent Dufour
2017-08-08 12:49 ` Jan Kara
2017-08-08 13:08 ` Laurent Dufour
2017-08-08 13:15 ` Peter Zijlstra
2017-08-08 13:34 ` Laurent Dufour
2017-06-16 17:52 ` [RFC v5 06/11] mm: Protect VMA modifications using VMA sequence count Laurent Dufour
2017-06-16 17:52 ` [RFC v5 07/11] mm: RCU free VMAs Laurent Dufour
2017-06-16 17:52 ` [RFC v5 08/11] mm: Provide speculative fault infrastructure Laurent Dufour
2017-06-16 17:52 ` [RFC v5 09/11] mm: Try spin lock in speculative path Laurent Dufour
2017-07-05 18:50 ` Peter Zijlstra
2017-07-06 13:46 ` Laurent Dufour
2017-07-06 14:48 ` Peter Zijlstra
2017-07-06 15:29 ` Laurent Dufour
2017-07-06 16:13 ` Peter Zijlstra
2017-06-16 17:52 ` [RFC v5 10/11] x86/mm: Add speculative pagefault handling Laurent Dufour
2017-06-16 17:52 ` [RFC v5 11/11] powerpc/mm: Add speculative page fault Laurent Dufour
2017-07-03 17:32 ` [RFC v5 00/11] Speculative page faults Laurent Dufour
2017-07-07 1:54 ` Balbir Singh
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