From: Peter Zijlstra <peterz@infradead.org>
To: Nadav Amit <nadav.amit@gmail.com>
Cc: linux-mm@kvack.org, linux-kernel@vger.kernel.org,
Nadav Amit <namit@vmware.com>,
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>,
Will Deacon <will@kernel.org>, Yu Zhao <yuzhao@google.com>,
Nick Piggin <npiggin@gmail.com>,
x86@kernel.org
Subject: Re: [RFC 12/20] mm/tlb: save the VMA that is flushed during tlb_start_vma()
Date: Mon, 1 Feb 2021 13:28:32 +0100 [thread overview]
Message-ID: <YBfz8MMQ25xkjO7e@hirez.programming.kicks-ass.net> (raw)
In-Reply-To: <20210131001132.3368247-13-namit@vmware.com>
On Sat, Jan 30, 2021 at 04:11:24PM -0800, Nadav Amit wrote:
> @@ -283,12 +290,6 @@ struct mmu_gather {
> unsigned int cleared_puds : 1;
> unsigned int cleared_p4ds : 1;
>
> - /*
> - * tracks VM_EXEC | VM_HUGETLB in tlb_start_vma
> - */
> - unsigned int vma_exec : 1;
> - unsigned int vma_huge : 1;
> -
> unsigned int batch_count;
>
> #ifndef CONFIG_MMU_GATHER_NO_GATHER
> @@ -372,38 +369,20 @@ static inline void tlb_flush(struct mmu_gather *tlb)
> if (tlb->fullmm || tlb->need_flush_all) {
> flush_tlb_mm(tlb->mm);
> } else if (tlb->end) {
> - struct vm_area_struct vma = {
> - .vm_mm = tlb->mm,
> - .vm_flags = (tlb->vma_exec ? VM_EXEC : 0) |
> - (tlb->vma_huge ? VM_HUGETLB : 0),
> - };
> -
> - flush_tlb_range(&vma, tlb->start, tlb->end);
> + VM_BUG_ON(!tlb->vma);
> + flush_tlb_range(tlb->vma, tlb->start, tlb->end);
> }
> }
I don't much like this, and I think this is a step in the wrong
direction.
The idea is to extend the tlb_{remove,flush}_*() API to provide the
needed information to do TLB flushing. In fact, I think
tlb_remove_huge*() is already sufficient to set the VM_EXEC 'hint'. We
just don't have anything that covers the EXEC thing.
(also, I suspect the page_size crud we have also covers that)
Constructing a fake vma very much ensures arch tlb routines don't go
about and look at anything else either.
> +tlb_update_vma(struct mmu_gather *tlb, struct vm_area_struct *vma)
> {
> - /*
> - * flush_tlb_range() implementations that look at VM_HUGETLB (tile,
> - * mips-4k) flush only large pages.
> - *
> - * flush_tlb_range() implementations that flush I-TLB also flush D-TLB
> - * (tile, xtensa, arm), so it's ok to just add VM_EXEC to an existing
> - * range.
> - *
> - * We rely on tlb_end_vma() to issue a flush, such that when we reset
> - * these values the batch is empty.
> - */
> - tlb->vma_huge = is_vm_hugetlb_page(vma);
> - tlb->vma_exec = !!(vma->vm_flags & VM_EXEC);
> + tlb->vma = vma;
> }
And you're also removing the useful information about arch tlb flush
functions.
next prev parent reply other threads:[~2021-02-01 12:29 UTC|newest]
Thread overview: 65+ 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
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 [this message]
2021-01-31 0:11 ` [RFC 13/20] mm/tlb: introduce tlb_start_ptes() and tlb_end_ptes() Nadav Amit
[not found] ` <YBaBcc2jEGaxuxH0@fedora.tometzki.de>
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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