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From: Will Deacon <will@kernel.org>
To: Nadav Amit <nadav.amit@gmail.com>
Cc: Peter Zijlstra <peterz@infradead.org>,
	Andrea Arcangeli <aarcange@redhat.com>,
	Andrew Morton <akpm@linux-foundation.org>,
	Andy Lutomirski <luto@kernel.org>,
	Dave Hansen <dave.hansen@linux.intel.com>,
	Thomas Gleixner <tglx@linutronix.de>, Yu Zhao <yuzhao@google.com>,
	Nick Piggin <npiggin@gmail.com>, X86 ML <x86@kernel.org>,
	Linux-MM <linux-mm@kvack.org>,
	LKML <linux-kernel@vger.kernel.org>
Subject: Re: [RFC 01/20] mm/tlb: fix fullmm semantics
Date: Wed, 3 Feb 2021 09:44:59 +0000	[thread overview]
Message-ID: <20210203094459.GA18493@willie-the-truck> (raw)
In-Reply-To: <5E9B0429-7E72-4E86-B91B-4718C4134B0F@gmail.com>

On Tue, Feb 02, 2021 at 01:35:38PM -0800, Nadav Amit wrote:
> > On Feb 2, 2021, at 3:00 AM, Peter Zijlstra <peterz@infradead.org> wrote:
> > 
> > On Tue, Feb 02, 2021 at 01:32:36AM -0800, Nadav Amit wrote:
> >>> On Feb 1, 2021, at 3:36 AM, Peter Zijlstra <peterz@infradead.org> wrote:
> >>> 
> >>> 
> >>> https://lkml.kernel.org/r/20210127235347.1402-1-will@kernel.org
> >> 
> >> I have seen this series, and applied my patches on it.
> >> 
> >> Despite Will’s patches, there were still inconsistencies between fullmm
> >> and need_flush_all.
> >> 
> >> Am I missing something?
> > 
> > I wasn't aware you were on top. I'll look again.
> 
> Looking on arm64’s tlb_flush() makes me think that there is currently a bug
> that this patch fixes. Arm64’s tlb_flush() does:
> 
>        /*
>         * If we're tearing down the address space then we only care about
>         * invalidating the walk-cache, since the ASID allocator won't
>         * reallocate our ASID without invalidating the entire TLB.
>         */
>        if (tlb->fullmm) {
>                if (!last_level)
>                        flush_tlb_mm(tlb->mm);
>                return;
>        } 
> 
> But currently tlb_mmu_finish() can mistakenly set fullmm incorrectly (if
> mm_tlb_flush_nested() is true), which might skip the TLB flush.

But in that case isn't 'freed_tables' set to 1, so 'last_level' will be
false and we'll do the flush in the code above?

Will


  reply	other threads:[~2021-02-03  9:45 UTC|newest]

Thread overview: 67+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-01-31  0:11 [RFC 00/20] TLB batching consolidation and enhancements Nadav Amit
2021-01-31  0:11 ` [RFC 01/20] mm/tlb: fix fullmm semantics Nadav Amit
2021-01-31  1:02   ` Andy Lutomirski
2021-01-31  1:19     ` Nadav Amit
2021-01-31  2:57       ` Andy Lutomirski
2021-02-01  7:30         ` Nadav Amit
2021-02-01 11:36   ` Peter Zijlstra
2021-02-02  9:32     ` Nadav Amit
2021-02-02 11:00       ` Peter Zijlstra
2021-02-02 21:35         ` Nadav Amit
2021-02-03  9:44           ` Will Deacon [this message]
2021-02-04  3:20             ` Nadav Amit
2021-01-31  0:11 ` [RFC 02/20] mm/mprotect: use mmu_gather Nadav Amit
2021-01-31  0:11 ` [RFC 03/20] mm/mprotect: do not flush on permission promotion Nadav Amit
2021-01-31  1:07   ` Andy Lutomirski
2021-01-31  1:17     ` Nadav Amit
2021-01-31  2:59       ` Andy Lutomirski
     [not found]     ` <7a6de15a-a570-31f2-14d6-a8010296e694@citrix.com>
2021-02-01  5:58       ` Nadav Amit
2021-02-01 15:38         ` Andrew Cooper
2021-01-31  0:11 ` [RFC 04/20] mm/mapping_dirty_helpers: use mmu_gather Nadav Amit
2021-01-31  0:11 ` [RFC 05/20] mm/tlb: move BATCHED_UNMAP_TLB_FLUSH to tlb.h Nadav Amit
2021-01-31  0:11 ` [RFC 06/20] fs/task_mmu: use mmu_gather interface of clear-soft-dirty Nadav Amit
2021-01-31  0:11 ` [RFC 07/20] mm: move x86 tlb_gen to generic code Nadav Amit
2021-01-31 18:26   ` Andy Lutomirski
2021-01-31  0:11 ` [RFC 08/20] mm: store completed TLB generation Nadav Amit
2021-01-31 20:32   ` Andy Lutomirski
2021-02-01  7:28     ` Nadav Amit
2021-02-01 16:53       ` Andy Lutomirski
2021-02-01 11:52   ` Peter Zijlstra
2021-01-31  0:11 ` [RFC 09/20] mm: create pte/pmd_tlb_flush_pending() Nadav Amit
2021-01-31  0:11 ` [RFC 10/20] mm: add pte_to_page() Nadav Amit
2021-01-31  0:11 ` [RFC 11/20] mm/tlb: remove arch-specific tlb_start/end_vma() Nadav Amit
2021-02-01 12:09   ` Peter Zijlstra
2021-02-02  6:41     ` Nicholas Piggin
2021-02-02  7:20       ` Nadav Amit
2021-02-02  9:31         ` Peter Zijlstra
2021-02-02  9:54           ` Nadav Amit
2021-02-02 11:04             ` Peter Zijlstra
2021-01-31  0:11 ` [RFC 12/20] mm/tlb: save the VMA that is flushed during tlb_start_vma() Nadav Amit
2021-02-01 12:28   ` Peter Zijlstra
2021-01-31  0:11 ` [RFC 13/20] mm/tlb: introduce tlb_start_ptes() and tlb_end_ptes() Nadav Amit
2021-01-31  9:57   ` Damian Tometzki
2021-01-31 10:07   ` Damian Tometzki
2021-02-01  7:29     ` Nadav Amit
2021-02-01 13:19   ` Peter Zijlstra
2021-02-01 23:00     ` Nadav Amit
2021-01-31  0:11 ` [RFC 14/20] mm: move inc/dec_tlb_flush_pending() to mmu_gather.c Nadav Amit
2021-01-31  0:11 ` [RFC 15/20] mm: detect deferred TLB flushes in vma granularity Nadav Amit
2021-02-01 22:04   ` Nadav Amit
2021-02-02  0:14     ` Andy Lutomirski
2021-02-02 20:51       ` Nadav Amit
2021-02-04  4:35         ` Andy Lutomirski
2021-01-31  0:11 ` [RFC 16/20] mm/tlb: per-page table generation tracking Nadav Amit
2021-01-31  0:11 ` [RFC 17/20] mm/tlb: updated completed deferred TLB flush conditionally Nadav Amit
2021-01-31  0:11 ` [RFC 18/20] mm: make mm_cpumask() volatile Nadav Amit
2021-01-31  0:11 ` [RFC 19/20] lib/cpumask: introduce cpumask_atomic_or() Nadav Amit
2021-01-31  0:11 ` [RFC 20/20] mm/rmap: avoid potential races Nadav Amit
2021-08-23  8:05   ` Huang, Ying
2021-08-23 15:50     ` Nadav Amit
2021-08-24  0:36       ` Huang, Ying
2021-01-31  0:39 ` [RFC 00/20] TLB batching consolidation and enhancements Andy Lutomirski
2021-01-31  1:08   ` Nadav Amit
2021-01-31  3:30 ` Nicholas Piggin
2021-01-31  7:57   ` Nadav Amit
2021-01-31  8:14     ` Nadav Amit
2021-02-01 12:44     ` Peter Zijlstra
2021-02-02  7:14       ` Nicholas Piggin

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