From: Rik van Riel <riel@surriel.com>
To: linux-kernel@vger.kernel.org
Cc: kernel-team@fb.com, peterz@infradead.org, luto@kernel.org,
x86@kernel.org, vkuznets@redhat.com, mingo@kernel.org,
efault@gmx.de, dave.hansen@intel.com, will.daecon@arm.com,
catalin.marinas@arm.com, benh@kernel.crashing.org,
Rik van Riel <riel@surriel.com>
Subject: [PATCH 01/10] x86,tlb: clarify memory barrier in switch_mm_irqs_off
Date: Sat, 28 Jul 2018 17:53:48 -0400 [thread overview]
Message-ID: <20180728215357.3249-2-riel@surriel.com> (raw)
In-Reply-To: <20180728215357.3249-1-riel@surriel.com>
Clarify exactly what the memory barrier synchronizes with.
Suggested-by: Peter Zijlstra <peterz@infradead.org>
Signed-off-by: Rik van Riel <riel@surriel.com>
---
arch/x86/mm/tlb.c | 7 +++++--
1 file changed, 5 insertions(+), 2 deletions(-)
diff --git a/arch/x86/mm/tlb.c b/arch/x86/mm/tlb.c
index 752dbf4e0e50..5321e02c4e09 100644
--- a/arch/x86/mm/tlb.c
+++ b/arch/x86/mm/tlb.c
@@ -263,8 +263,11 @@ void switch_mm_irqs_off(struct mm_struct *prev, struct mm_struct *next,
/*
* Read the tlb_gen to check whether a flush is needed.
* If the TLB is up to date, just use it.
- * The barrier synchronizes with the tlb_gen increment in
- * the TLB shootdown code.
+ * The TLB shootdown code first increments tlb_gen, and then
+ * sends IPIs to CPUs that have this CPU loaded and are not
+ * in lazy TLB mode. The barrier ensures we handle
+ * cpu_tlbstate.is_lazy before tlb_gen, keeping this code
+ * synchronized with the TLB flush code.
*/
smp_mb();
next_tlb_gen = atomic64_read(&next->context.tlb_gen);
--
2.14.4
next prev parent reply other threads:[~2018-07-28 21:54 UTC|newest]
Thread overview: 43+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-07-28 21:53 [PATCH 0/10] x86,tlb,mm: more lazy TLB cleanups & optimizations Rik van Riel
2018-07-28 21:53 ` Rik van Riel [this message]
2018-07-29 2:59 ` [PATCH 01/10] x86,tlb: clarify memory barrier in switch_mm_irqs_off Andy Lutomirski
2018-07-28 21:53 ` [PATCH 02/10] smp: use __cpumask_set_cpu in on_each_cpu_cond Rik van Riel
2018-07-29 2:59 ` Andy Lutomirski
2018-07-28 21:53 ` [PATCH 03/10] smp,cpumask: introduce on_each_cpu_cond_mask Rik van Riel
2018-07-29 2:57 ` Andy Lutomirski
2018-07-29 12:00 ` Rik van Riel
[not found] ` <E710FBA5-CC5E-4941-ACBF-4AB3424F1F68@amacapital.net>
2018-07-29 17:39 ` Rik van Riel
2018-07-29 17:51 ` Rik van Riel
2018-07-29 18:55 ` Andy Lutomirski
2018-07-29 19:56 ` Linus Torvalds
2018-07-28 21:53 ` [PATCH 04/10] x86,mm: use on_each_cpu_cond for TLB flushes Rik van Riel
2018-07-29 2:58 ` Andy Lutomirski
2018-07-29 12:02 ` Rik van Riel
2018-07-28 21:53 ` [PATCH 05/10] mm,tlb: turn dummy defines into inline functions Rik van Riel
2018-07-28 21:53 ` [PATCH 06/10] mm,x86: skip cr4 and ldt reload when mm stays the same Rik van Riel
2018-07-29 4:21 ` Andy Lutomirski
2018-07-28 21:53 ` [PATCH 07/10] x86,mm: remove leave_mm cpu argument Rik van Riel
2018-07-28 21:53 ` [PATCH 08/10] arch,mm: add config variable to skip lazy TLB mm refcounting Rik van Riel
2018-07-28 21:53 ` [PATCH 09/10] mm,x86: shoot down lazy TLB references at exit_mmap time Rik van Riel
2018-07-28 21:53 ` [PATCH 10/10] mm,sched: conditionally skip lazy TLB mm refcounting Rik van Riel
2018-07-29 4:21 ` Andy Lutomirski
2018-07-29 12:11 ` Rik van Riel
2018-07-29 15:29 ` Andy Lutomirski
2018-07-29 16:55 ` Rik van Riel
2018-07-29 19:54 ` [PATCH v2 10/11] x86,tlb: really leave mm on shootdown Rik van Riel
2018-07-29 19:54 ` [PATCH v2 11/11] mm,sched: conditionally skip lazy TLB mm refcounting Rik van Riel
2018-07-30 9:55 ` Peter Zijlstra
2018-07-30 14:30 ` Rik van Riel
2018-07-30 16:26 ` Peter Zijlstra
2018-07-30 19:15 ` Rik van Riel
2018-07-30 19:30 ` Andy Lutomirski
2018-07-30 19:36 ` Rik van Riel
2018-07-30 19:49 ` Andy Lutomirski
2018-07-30 21:46 ` Rik van Riel
2018-07-30 22:00 ` Andy Lutomirski
2018-07-31 1:05 ` Rik van Riel
2018-07-31 9:12 ` Peter Zijlstra
2018-07-31 14:29 ` Andy Lutomirski
2018-07-31 15:03 ` Rik van Riel
2018-07-31 15:12 ` Peter Zijlstra
2018-07-30 11:32 ` [PATCH 0/10] x86,tlb,mm: more lazy TLB cleanups & optimizations Ingo Molnar
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