From: Peter Zijlstra <peterz@infradead.org>
To: Nicholas Piggin <npiggin@gmail.com>
Cc: linux-arch@vger.kernel.org, x86@kernel.org,
Mathieu Desnoyers <mathieu.desnoyers@efficios.com>,
Arnd Bergmann <arnd@arndb.de>,
linux-kernel@vger.kernel.org, linuxppc-dev@lists.ozlabs.org,
linux-mm@kvack.org, Anton Blanchard <anton@ozlabs.org>
Subject: Re: [RFC PATCH 4/7] x86: use exit_lazy_tlb rather than membarrier_mm_sync_core_before_usermode
Date: Fri, 10 Jul 2020 11:42:01 +0200 [thread overview]
Message-ID: <20200710094201.GZ4800@hirez.programming.kicks-ass.net> (raw)
In-Reply-To: <20200710015646.2020871-5-npiggin@gmail.com>
On Fri, Jul 10, 2020 at 11:56:43AM +1000, Nicholas Piggin wrote:
> And get rid of the generic sync_core_before_usermode facility.
>
> This helper is the wrong way around I think. The idea that membarrier
> state requires a core sync before returning to user is the easy one
> that does not need hiding behind membarrier calls. The gap in core
> synchronization due to x86's sysret/sysexit and lazy tlb mode, is the
> tricky detail that is better put in x86 lazy tlb code.
>
> Consider if an arch did not synchronize core in switch_mm either, then
> membarrier_mm_sync_core_before_usermode would be in the wrong place
> but arch specific mmu context functions would still be the right place.
> There is also a exit_lazy_tlb case that is not covered by this call, which
> could be a bugs (kthread use mm the membarrier process's mm then context
> switch back to the process without switching mm or lazy mm switch).
>
> This makes lazy tlb code a bit more modular.
Hurmph, I know I've been staring at this at some point. I think I meant
to have a TIF to force the IRET path in the case of MEMBAR_SYNC_CORE.
But I was discouraged by amluto.
WARNING: multiple messages have this Message-ID (diff)
From: Peter Zijlstra <peterz@infradead.org>
To: Nicholas Piggin <npiggin@gmail.com>
Cc: linux-arch@vger.kernel.org, Arnd Bergmann <arnd@arndb.de>,
x86@kernel.org, linux-kernel@vger.kernel.org, linux-mm@kvack.org,
Mathieu Desnoyers <mathieu.desnoyers@efficios.com>,
linuxppc-dev@lists.ozlabs.org
Subject: Re: [RFC PATCH 4/7] x86: use exit_lazy_tlb rather than membarrier_mm_sync_core_before_usermode
Date: Fri, 10 Jul 2020 11:42:01 +0200 [thread overview]
Message-ID: <20200710094201.GZ4800@hirez.programming.kicks-ass.net> (raw)
In-Reply-To: <20200710015646.2020871-5-npiggin@gmail.com>
On Fri, Jul 10, 2020 at 11:56:43AM +1000, Nicholas Piggin wrote:
> And get rid of the generic sync_core_before_usermode facility.
>
> This helper is the wrong way around I think. The idea that membarrier
> state requires a core sync before returning to user is the easy one
> that does not need hiding behind membarrier calls. The gap in core
> synchronization due to x86's sysret/sysexit and lazy tlb mode, is the
> tricky detail that is better put in x86 lazy tlb code.
>
> Consider if an arch did not synchronize core in switch_mm either, then
> membarrier_mm_sync_core_before_usermode would be in the wrong place
> but arch specific mmu context functions would still be the right place.
> There is also a exit_lazy_tlb case that is not covered by this call, which
> could be a bugs (kthread use mm the membarrier process's mm then context
> switch back to the process without switching mm or lazy mm switch).
>
> This makes lazy tlb code a bit more modular.
Hurmph, I know I've been staring at this at some point. I think I meant
to have a TIF to force the IRET path in the case of MEMBAR_SYNC_CORE.
But I was discouraged by amluto.
next prev parent reply other threads:[~2020-07-10 9:42 UTC|newest]
Thread overview: 136+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-07-10 1:56 [RFC PATCH 0/7] mmu context cleanup, lazy tlb cleanup, Nicholas Piggin
2020-07-10 1:56 ` Nicholas Piggin
2020-07-10 1:56 ` [RFC PATCH 1/7] asm-generic: add generic MMU versions of mmu context functions Nicholas Piggin
2020-07-10 1:56 ` Nicholas Piggin
2020-07-10 1:56 ` [RFC PATCH 2/7] arch: use asm-generic mmu context for no-op implementations Nicholas Piggin
2020-07-10 1:56 ` Nicholas Piggin
2020-07-10 1:56 ` [RFC PATCH 3/7] mm: introduce exit_lazy_tlb Nicholas Piggin
2020-07-10 1:56 ` Nicholas Piggin
2020-07-10 1:56 ` [RFC PATCH 4/7] x86: use exit_lazy_tlb rather than membarrier_mm_sync_core_before_usermode Nicholas Piggin
2020-07-10 1:56 ` Nicholas Piggin
2020-07-10 9:42 ` Peter Zijlstra [this message]
2020-07-10 9:42 ` Peter Zijlstra
2020-07-10 14:02 ` Mathieu Desnoyers
2020-07-10 14:02 ` Mathieu Desnoyers
2020-07-10 14:02 ` Mathieu Desnoyers
2020-07-10 17:04 ` Andy Lutomirski
2020-07-10 17:04 ` Andy Lutomirski
2020-07-10 17:04 ` Andy Lutomirski
2020-07-13 4:45 ` Nicholas Piggin
2020-07-13 4:45 ` Nicholas Piggin
2020-07-13 13:47 ` Nicholas Piggin
2020-07-13 13:47 ` Nicholas Piggin
2020-07-13 14:13 ` Mathieu Desnoyers
2020-07-13 14:13 ` Mathieu Desnoyers
2020-07-13 14:13 ` Mathieu Desnoyers
2020-07-13 15:48 ` Andy Lutomirski
2020-07-13 15:48 ` Andy Lutomirski
2020-07-13 15:48 ` Andy Lutomirski
2020-07-13 16:37 ` Nicholas Piggin
2020-07-13 16:37 ` Nicholas Piggin
2020-07-16 4:15 ` Nicholas Piggin
2020-07-16 4:15 ` Nicholas Piggin
2020-07-16 4:42 ` Nicholas Piggin
2020-07-16 4:42 ` Nicholas Piggin
2020-07-16 15:46 ` Mathieu Desnoyers
2020-07-16 15:46 ` Mathieu Desnoyers
2020-07-16 15:46 ` Mathieu Desnoyers
2020-07-16 16:03 ` Mathieu Desnoyers
2020-07-16 16:03 ` Mathieu Desnoyers
2020-07-16 16:03 ` Mathieu Desnoyers
2020-07-16 18:58 ` Mathieu Desnoyers
2020-07-16 18:58 ` Mathieu Desnoyers
2020-07-16 18:58 ` Mathieu Desnoyers
2020-07-16 21:24 ` Alan Stern
2020-07-16 21:24 ` Alan Stern
2020-07-17 13:39 ` Mathieu Desnoyers
2020-07-17 13:39 ` Mathieu Desnoyers
2020-07-17 13:39 ` Mathieu Desnoyers
2020-07-17 14:51 ` Alan Stern
2020-07-17 14:51 ` Alan Stern
2020-07-17 15:39 ` Mathieu Desnoyers
2020-07-17 15:39 ` Mathieu Desnoyers
2020-07-17 15:39 ` Mathieu Desnoyers
2020-07-17 16:11 ` Alan Stern
2020-07-17 16:11 ` Alan Stern
2020-07-17 16:22 ` Mathieu Desnoyers
2020-07-17 16:22 ` Mathieu Desnoyers
2020-07-17 16:22 ` Mathieu Desnoyers
2020-07-17 17:44 ` Alan Stern
2020-07-17 17:44 ` Alan Stern
2020-07-17 17:52 ` Mathieu Desnoyers
2020-07-17 17:52 ` Mathieu Desnoyers
2020-07-17 17:52 ` Mathieu Desnoyers
2020-07-17 0:00 ` Nicholas Piggin
2020-07-17 0:00 ` Nicholas Piggin
2020-07-16 5:18 ` Andy Lutomirski
2020-07-16 5:18 ` Andy Lutomirski
2020-07-16 6:06 ` Nicholas Piggin
2020-07-16 6:06 ` Nicholas Piggin
2020-07-16 8:50 ` Peter Zijlstra
2020-07-16 8:50 ` Peter Zijlstra
2020-07-16 10:03 ` Nicholas Piggin
2020-07-16 10:03 ` Nicholas Piggin
2020-07-16 11:00 ` peterz
2020-07-16 11:00 ` peterz
2020-07-16 15:34 ` Mathieu Desnoyers
2020-07-16 15:34 ` Mathieu Desnoyers
2020-07-16 15:34 ` Mathieu Desnoyers
2020-07-16 23:26 ` Nicholas Piggin
2020-07-16 23:26 ` Nicholas Piggin
2020-07-17 13:42 ` Mathieu Desnoyers
2020-07-17 13:42 ` Mathieu Desnoyers
2020-07-17 13:42 ` Mathieu Desnoyers
2020-07-20 3:03 ` Nicholas Piggin
2020-07-20 3:03 ` Nicholas Piggin
2020-07-20 16:46 ` Mathieu Desnoyers
2020-07-20 16:46 ` Mathieu Desnoyers
2020-07-20 16:46 ` Mathieu Desnoyers
2020-07-21 10:04 ` Nicholas Piggin
2020-07-21 10:04 ` Nicholas Piggin
2020-07-21 13:11 ` Mathieu Desnoyers
2020-07-21 13:11 ` Mathieu Desnoyers
2020-07-21 13:11 ` Mathieu Desnoyers
2020-07-21 14:30 ` Nicholas Piggin
2020-07-21 14:30 ` Nicholas Piggin
2020-07-21 15:06 ` peterz
2020-07-21 15:06 ` peterz
2020-07-21 15:15 ` Mathieu Desnoyers
2020-07-21 15:15 ` Mathieu Desnoyers
2020-07-21 15:15 ` Mathieu Desnoyers
2020-07-21 15:19 ` Peter Zijlstra
2020-07-21 15:19 ` Peter Zijlstra
2020-07-21 15:22 ` Mathieu Desnoyers
2020-07-21 15:22 ` Mathieu Desnoyers
2020-07-21 15:22 ` Mathieu Desnoyers
2020-07-10 1:56 ` [RFC PATCH 5/7] lazy tlb: introduce lazy mm refcount helper functions Nicholas Piggin
2020-07-10 1:56 ` Nicholas Piggin
2020-07-10 9:48 ` Peter Zijlstra
2020-07-10 9:48 ` Peter Zijlstra
2020-07-10 1:56 ` [RFC PATCH 6/7] lazy tlb: allow lazy tlb mm switching to be configurable Nicholas Piggin
2020-07-10 1:56 ` Nicholas Piggin
2020-07-10 1:56 ` [RFC PATCH 7/7] lazy tlb: shoot lazies, a non-refcounting lazy tlb option Nicholas Piggin
2020-07-10 1:56 ` Nicholas Piggin
2020-07-10 9:35 ` Peter Zijlstra
2020-07-10 9:35 ` Peter Zijlstra
2020-07-13 4:58 ` Nicholas Piggin
2020-07-13 4:58 ` Nicholas Piggin
2020-07-13 15:59 ` Andy Lutomirski
2020-07-13 15:59 ` Andy Lutomirski
2020-07-13 15:59 ` Andy Lutomirski
2020-07-13 16:48 ` Nicholas Piggin
2020-07-13 16:48 ` Nicholas Piggin
2020-07-13 18:18 ` Andy Lutomirski
2020-07-13 18:18 ` Andy Lutomirski
2020-07-14 5:04 ` Nicholas Piggin
2020-07-14 5:04 ` Nicholas Piggin
2020-07-14 6:31 ` Nicholas Piggin
2020-07-14 6:31 ` Nicholas Piggin
2020-07-14 12:46 ` Andy Lutomirski
2020-07-14 12:46 ` Andy Lutomirski
2020-07-14 13:23 ` Peter Zijlstra
2020-07-14 13:23 ` Peter Zijlstra
2020-07-16 2:26 ` Nicholas Piggin
2020-07-16 2:26 ` Nicholas Piggin
2020-07-16 2:35 ` Nicholas Piggin
2020-07-16 2:35 ` Nicholas Piggin
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