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From: Will Deacon <will.deacon@arm.com>
To: Peter Zijlstra <peterz@infradead.org>
Cc: aneesh.kumar@linux.vnet.ibm.com, akpm@linux-foundation.org,
	npiggin@gmail.com, linux-arch@vger.kernel.org,
	linux-mm@kvack.org, linux-kernel@vger.kernel.org,
	linux@armlinux.org.uk, heiko.carstens@de.ibm.com,
	riel@surriel.com, tony.luck@intel.com
Subject: Re: [PATCH v6 06/18] asm-generic/tlb: Conditionally provide tlb_migrate_finish()
Date: Wed, 20 Feb 2019 14:47:05 +0000
Message-ID: <20190220144705.GH7523@fuggles.cambridge.arm.com> (raw)
In-Reply-To: <20190219134147.GZ32494@hirez.programming.kicks-ass.net>

On Tue, Feb 19, 2019 at 02:41:47PM +0100, Peter Zijlstra wrote:
> On Tue, Feb 19, 2019 at 12:47:38PM +0000, Will Deacon wrote:
> > Fine for now, but I agree that we should drop the hook altogether. AFAICT,
> > this only exists to help an ia64 optimisation which looks suspicious to
> > me since it uses:
> > 
> >     mm == current->active_mm && atomic_read(&mm->mm_users) == 1
> > 
> > to identify a "single-threaded fork()" and therefore perform only local TLB
> > invalidation. Even if this was the right thing to do, it's not clear to me
> > that tlb_migrate_finish() is called on the right CPU anyway.
> > 
> > So I'd be keen to remove this hook before it spreads, but in the meantime:
> 
> Agreed :-)
> 
> The obvious slash and kill patch ... untested

I'm also unable to test this, unfortunately. Can we get it into next after
the merge window and see if anybody reports issues?

Will


  reply index

Thread overview: 44+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-02-19 10:31 [PATCH v6 00/18] generic mmu_gather patches Peter Zijlstra
2019-02-19 10:31 ` [PATCH v6 01/18] asm-generic/tlb: Provide a comment Peter Zijlstra
2019-02-19 10:31 ` [PATCH v6 02/18] asm-generic/tlb: Provide HAVE_MMU_GATHER_PAGE_SIZE Peter Zijlstra
2019-02-19 10:31 ` [PATCH v6 03/18] asm-generic/tlb: Provide generic VIPT cache flush Peter Zijlstra
2019-02-19 10:31 ` [PATCH v6 04/18] asm-generic/tlb: Provide generic tlb_flush() based on flush_tlb_range() Peter Zijlstra
2019-02-19 10:31 ` [PATCH v6 05/18] asm-generic/tlb: Provide generic tlb_flush() based on flush_tlb_mm() Peter Zijlstra
2019-02-19 12:47   ` Will Deacon
2019-02-19 10:31 ` [PATCH v6 06/18] asm-generic/tlb: Conditionally provide tlb_migrate_finish() Peter Zijlstra
2019-02-19 12:47   ` Will Deacon
2019-02-19 13:41     ` Peter Zijlstra
2019-02-20 14:47       ` Will Deacon [this message]
2019-02-20 15:02         ` Matthew Wilcox
2019-02-19 10:31 ` [PATCH v6 07/18] asm-generic/tlb: Invert HAVE_RCU_TABLE_INVALIDATE Peter Zijlstra
2019-02-19 10:31 ` [PATCH v6 08/18] arm/tlb: Convert to generic mmu_gather Peter Zijlstra
2019-02-19 10:31 ` [PATCH v6 09/18] ia64/tlb: Conver " Peter Zijlstra
2019-02-19 12:47   ` Will Deacon
2019-02-21  2:52   ` Souptick Joarder
2019-02-19 10:31 ` [PATCH v6 10/18] sh/tlb: Convert SH " Peter Zijlstra
2019-12-03 11:19   ` Geert Uytterhoeven
2019-12-04 10:47     ` Peter Zijlstra
2019-12-04 12:32       ` Geert Uytterhoeven
2019-12-04 13:22         ` Guenter Roeck
2019-12-04 15:17           ` Geert Uytterhoeven
2019-12-04 19:03             ` Guenter Roeck
2019-12-04 13:34         ` Peter Zijlstra
2019-12-04 15:07           ` Geert Uytterhoeven
2019-12-04 16:41             ` Peter Zijlstra
2019-12-05 15:26               ` Geert Uytterhoeven
2019-12-05 19:24       ` Rob Landley
2019-12-05 19:23         ` Rich Felker
2019-12-05 19:30       ` John Paul Adrian Glaubitz
2019-12-05 22:56         ` Guenter Roeck
2019-12-06 13:38           ` John Paul Adrian Glaubitz
2019-12-06 14:03             ` Guenter Roeck
2019-02-19 10:31 ` [PATCH v6 11/18] um/tlb: Convert " Peter Zijlstra
2019-02-19 10:32 ` [PATCH v6 12/18] arch/tlb: Clean up simple architectures Peter Zijlstra
2019-02-19 10:32 ` [PATCH v6 13/18] asm-generic/tlb: Introduce HAVE_MMU_GATHER_NO_GATHER Peter Zijlstra
2019-02-19 12:47   ` Will Deacon
2019-02-19 10:32 ` [PATCH v6 14/18] s390/tlb: convert to generic mmu_gather Peter Zijlstra
2019-02-19 12:47   ` Will Deacon
2019-02-19 10:32 ` [PATCH v6 15/18] asm-generic/tlb: Remove arch_tlb*_mmu() Peter Zijlstra
2019-02-19 10:32 ` [PATCH v6 16/18] asm-generic/tlb: Remove HAVE_GENERIC_MMU_GATHER Peter Zijlstra
2019-02-19 10:32 ` [PATCH v6 17/18] asm-generic/tlb: Remove tlb_flush_mmu_free() Peter Zijlstra
2019-02-19 10:32 ` [PATCH v6 18/18] asm-generic/tlb: Remove tlb_table_flush() Peter Zijlstra

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