From: Laurent Dufour <ldufour@linux.vnet.ibm.com>
To: Matthew Wilcox <willy@infradead.org>
Cc: 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, benh@kernel.crashing.org, mpe@ellerman.id.au,
paulus@samba.org, Thomas Gleixner <tglx@linutronix.de>,
Ingo Molnar <mingo@redhat.com>,
hpa@zytor.com, Will Deacon <will.deacon@arm.com>,
Sergey Senozhatsky <sergey.senozhatsky@gmail.com>,
Andrea Arcangeli <aarcange@redhat.com>,
Alexei Starovoitov <alexei.starovoitov@gmail.com>,
kemi.wang@intel.com, sergey.senozhatsky.work@gmail.com,
linux-kernel@vger.kernel.org, linux-mm@kvack.org,
haren@linux.vnet.ibm.com, khandual@linux.vnet.ibm.com,
npiggin@gmail.com, bsingharora@gmail.com,
Tim Chen <tim.c.chen@linux.intel.com>,
linuxppc-dev@lists.ozlabs.org, x86@kernel.org
Subject: Re: [PATCH v6 18/24] mm: Try spin lock in speculative path
Date: Tue, 16 Jan 2018 14:24:39 +0100 [thread overview]
Message-ID: <fd55ce33-2d7d-2613-7483-b6e2764e8865@linux.vnet.ibm.com> (raw)
In-Reply-To: <20180112181840.GA7590@bombadil.infradead.org>
On 12/01/2018 19:18, Matthew Wilcox wrote:
> On Fri, Jan 12, 2018 at 06:26:02PM +0100, Laurent Dufour wrote:
>> There is a deadlock when a CPU is doing a speculative page fault and
>> another one is calling do_unmap().
>>
>> The deadlock occurred because the speculative path try to spinlock the
>> pte while the interrupt are disabled. When the other CPU in the
>> unmap's path has locked the pte then is waiting for all the CPU to
>> invalidate the TLB. As the CPU doing the speculative fault have the
>> interrupt disable it can't invalidate the TLB, and can't get the lock.
>>
>> Since we are in a speculative path, we can race with other mm action.
>> So let assume that the lock may not get acquired and fail the
>> speculative page fault.
>
> It seems like you introduced this bug in the previous patch, and now
> you're fixing it in this patch? Why not merge the two?
You're right this is a fix from the previous patch. Initially my idea was
to keep the original Peter's patch as is, but sounds that this is not a
good idea.
I'll merge it in the previous one.
Thanks,
Laurent.
next prev parent reply other threads:[~2018-01-16 13:29 UTC|newest]
Thread overview: 41+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-01-12 17:25 [PATCH v6 00/24] Speculative page faults Laurent Dufour
2018-01-12 17:25 ` [PATCH v6 01/24] x86/mm: Define CONFIG_SPF Laurent Dufour
2018-01-12 18:57 ` Thomas Gleixner
2018-01-15 17:37 ` Laurent Dufour
2018-01-15 17:49 ` Thomas Gleixner
2018-01-15 18:37 ` Laurent Dufour
2018-01-12 17:25 ` [PATCH v6 02/24] powerpc/mm: " Laurent Dufour
2018-01-12 17:25 ` [PATCH v6 03/24] mm: Dont assume page-table invariance during faults Laurent Dufour
2018-01-17 3:04 ` Andi Kleen
2018-01-17 8:57 ` Laurent Dufour
2018-01-12 17:25 ` [PATCH v6 04/24] mm: Prepare for FAULT_FLAG_SPECULATIVE Laurent Dufour
2018-01-12 17:25 ` [PATCH v6 05/24] mm: Introduce pte_spinlock " Laurent Dufour
2018-01-12 17:25 ` [PATCH v6 06/24] mm: VMA sequence count Laurent Dufour
2018-01-12 17:25 ` [PATCH v6 07/24] mm: Protect VMA modifications using " Laurent Dufour
2018-01-12 17:25 ` [PATCH v6 08/24] mm: protect mremap() against SPF hanlder Laurent Dufour
2018-01-12 17:25 ` [PATCH v6 09/24] mm: Protect SPF handler against anon_vma changes Laurent Dufour
2018-01-12 17:25 ` [PATCH v6 10/24] mm: Cache some VMA fields in the vm_fault structure Laurent Dufour
2018-01-12 17:25 ` [PATCH v6 11/24] mm/migrate: Pass vm_fault pointer to migrate_misplaced_page() Laurent Dufour
2018-01-12 17:25 ` [PATCH v6 12/24] mm: Introduce __lru_cache_add_active_or_unevictable Laurent Dufour
2018-01-12 17:25 ` [PATCH v6 13/24] mm: Introduce __maybe_mkwrite() Laurent Dufour
2018-01-12 17:25 ` [PATCH v6 14/24] mm: Introduce __vm_normal_page() Laurent Dufour
2018-01-12 17:25 ` [PATCH v6 15/24] mm: Introduce __page_add_new_anon_rmap() Laurent Dufour
2018-01-12 17:26 ` [PATCH v6 16/24] mm: Protect mm_rb tree with a rwlock Laurent Dufour
2018-01-12 18:48 ` Matthew Wilcox
2018-01-15 17:42 ` Laurent Dufour
2018-01-12 17:26 ` [PATCH v6 17/24] mm: Provide speculative fault infrastructure Laurent Dufour
2018-01-12 17:26 ` [PATCH v6 18/24] mm: Try spin lock in speculative path Laurent Dufour
2018-01-12 18:18 ` Matthew Wilcox
2018-01-16 13:24 ` Laurent Dufour [this message]
2018-01-12 17:26 ` [PATCH v6 19/24] mm: Adding speculative page fault failure trace events Laurent Dufour
2018-01-12 17:26 ` [PATCH v6 20/24] perf: Add a speculative page fault sw event Laurent Dufour
2018-01-12 17:26 ` [PATCH v6 21/24] perf tools: Add support for the SPF perf event Laurent Dufour
2018-01-12 17:26 ` [PATCH v6 22/24] mm: Speculative page fault handler return VMA Laurent Dufour
2018-01-12 19:02 ` Matthew Wilcox
2018-01-13 4:23 ` Matthew Wilcox
2018-01-16 14:47 ` Laurent Dufour
2018-01-16 14:58 ` Matthew Wilcox
2018-01-12 17:26 ` [PATCH v6 23/24] x86/mm: Add speculative pagefault handling Laurent Dufour
2018-01-12 17:26 ` [PATCH v6 24/24] powerpc/mm: Add speculative page fault Laurent Dufour
2018-01-16 15:11 ` [PATCH v6 00/24] Speculative page faults Kirill A. Shutemov
2018-01-17 15:15 ` Laurent Dufour
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