From: Michael Ellerman <mpe@ellerman.id.au>
To: Nicholas Piggin <npiggin@gmail.com>,
Linus Torvalds <torvalds@linux-foundation.org>
Cc: linux-arch <linux-arch@vger.kernel.org>,
Hillf Danton <hdanton@sina.com>,
mm-commits@vger.kernel.org,
Catalin Marinas <catalin.marinas@arm.com>,
Hugh Dickins <hughd@google.com>,
Josef Bacik <josef@toxicpanda.com>,
Will Deacon <will.deacon@arm.com>, Linux-MM <linux-mm@kvack.org>,
Matthew Wilcox <willy@infradead.org>,
Johannes Weiner <hannes@cmpxchg.org>,
Yu Xu <xuyu@linux.alibaba.com>,
Andrew Morton <akpm@linux-foundation.org>,
linuxppc-dev <linuxppc-dev@lists.ozlabs.org>,
Yang Shi <yang.shi@linux.alibaba.com>,
"Kirill A . Shutemov" <kirill.shutemov@linux.intel.com>
Subject: Re: [patch 01/15] mm/memory.c: avoid access flag update TLB flush for retried page fault
Date: Wed, 29 Jul 2020 23:58:02 +1000 [thread overview]
Message-ID: <87o8ny5sph.fsf@mpe.ellerman.id.au> (raw)
In-Reply-To: <1595974242.esf9644sf3.astroid@bobo.none>
Nicholas Piggin <npiggin@gmail.com> writes:
> Excerpts from Linus Torvalds's message of July 29, 2020 5:02 am:
>> On Tue, Jul 28, 2020 at 3:53 AM Nicholas Piggin <npiggin@gmail.com> wrote:
>>>
>>> The quirk is a problem with coprocessor where it's supposed to
>>> invalidate the translation after a fault but it doesn't, so we can get a
>>> read-only TLB stuck after something else does a RO->RW upgrade on the
>>> TLB. Something like that IIRC. Coprocessors have their own MMU which
>>> lives in the nest not the core, so you need a global TLB flush to
>>> invalidate that thing.
>>
>> So I assumed, but it does seem confused.
>>
>> Why? Because if there are stale translations on the co-processor,
>> there's no guarantee that one of the CPU's will have them and take a
>> fault.
>>
>> So I'm not seeing why a core CPU doing spurious TLB invalidation would
>> follow from "stale TLB in the Nest".
>
> If the nest MMU access faults, it sends an interrupt to the CPU and
> the driver tries to handle the page fault for it (I think that's how
> it works).
Yeah AFAIK. I think they all end up calling copro_handle_mm_fault().
Except for NX/vas, where the model is a fault just causes the request to
be dropped and sent back to userspace to fix things up.
cheers
next prev parent reply other threads:[~2020-07-29 13:58 UTC|newest]
Thread overview: 69+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-07-24 4:14 incoming Andrew Morton
2020-07-24 4:15 ` [patch 01/15] mm/memory.c: avoid access flag update TLB flush for retried page fault Andrew Morton
2020-07-24 4:38 ` Yang Shi
2020-07-24 4:56 ` Andrew Morton
2020-07-24 19:27 ` Linus Torvalds
2020-07-24 20:22 ` Linus Torvalds
2020-07-25 0:36 ` Yang Shi
2020-07-25 1:29 ` Linus Torvalds
2020-07-25 15:58 ` Catalin Marinas
2020-07-28 9:22 ` Will Deacon
2020-07-28 9:39 ` Catalin Marinas
2020-07-28 10:07 ` Yu Xu
2020-07-28 11:46 ` Catalin Marinas
2020-07-28 10:21 ` Will Deacon
2020-07-28 18:28 ` Linus Torvalds
2020-07-27 17:52 ` Yang Shi
2020-07-27 18:04 ` Linus Torvalds
2020-07-27 18:42 ` Catalin Marinas
2020-07-27 20:56 ` Linus Torvalds
2020-07-27 22:34 ` Yang Shi
2020-07-27 7:31 ` Yu Xu
2020-07-27 11:05 ` Catalin Marinas
2020-07-27 17:01 ` Linus Torvalds
2020-07-28 11:19 ` Catalin Marinas
2020-07-27 17:12 ` Yu Xu
2020-07-27 18:04 ` Yang Shi
2020-07-27 18:37 ` Linus Torvalds
2020-07-27 22:43 ` Yang Shi
2020-07-28 0:38 ` Linus Torvalds
2020-07-28 0:13 ` Yu Xu
2020-07-28 10:53 ` Nicholas Piggin
2020-07-28 19:02 ` Linus Torvalds
2020-07-28 22:53 ` Nicholas Piggin
2020-07-29 13:58 ` Michael Ellerman [this message]
2020-07-28 6:41 ` Yu Xu
2020-07-24 4:15 ` [patch 02/15] mm/mmap.c: close race between munmap() and expand_upwards()/downwards() Andrew Morton
2020-07-24 4:15 ` [patch 03/15] vfs/xattr: mm/shmem: kernfs: release simple xattr entry in a right way Andrew Morton
2020-07-24 4:15 ` [patch 04/15] mm: initialize return of vm_insert_pages Andrew Morton
2020-07-24 4:15 ` [patch 05/15] mm/memcontrol: fix OOPS inside mem_cgroup_get_nr_swap_pages() Andrew Morton
2020-07-24 4:15 ` [patch 06/15] mm/memcg: fix refcount error while moving and swapping Andrew Morton
2020-07-24 13:41 ` Alex Shi
2020-07-24 4:15 ` [patch 07/15] mm: memcg/slab: fix memory leak at non-root kmem_cache destroy Andrew Morton
2020-07-24 4:15 ` [patch 08/15] mm/hugetlb: avoid hardcoding while checking if cma is enabled Andrew Morton
2020-07-24 4:15 ` [patch 09/15] khugepaged: fix null-pointer dereference due to race Andrew Morton
2020-07-24 4:15 ` [patch 10/15] mailmap: add entry for Mike Rapoport Andrew Morton
2020-07-24 4:15 ` [patch 11/15] squashfs: fix length field overlap check in metadata reading Andrew Morton
2020-07-24 4:15 ` [patch 12/15] scripts/decode_stacktrace: strip basepath from all paths Andrew Morton
2020-07-24 4:15 ` [patch 13/15] io-mapping: indicate mapping failure Andrew Morton
2020-07-24 4:15 ` [patch 14/15] MAINTAINERS: add KCOV section Andrew Morton
2020-07-24 4:15 ` [patch 15/15] scripts/gdb: fix lx-symbols 'gdb.error' while loading modules Andrew Morton
2020-07-28 1:19 ` mmotm 2020-07-27-18-18 uploaded Andrew Morton
2020-07-28 2:14 ` Stephen Rothwell
2020-07-28 3:22 ` mmotm 2020-07-27-18-18 uploaded (drivers/scsi/ufs/: SCSI_UFS_EXYNOS) Randy Dunlap
2020-07-28 8:23 ` Alim Akhtar
2020-07-28 12:33 ` mmotm 2020-07-27-18-18 uploaded (mm/page_alloc.c) Randy Dunlap
2020-07-28 21:55 ` Andrew Morton
2020-07-28 22:20 ` Stephen Rothwell
2020-07-28 22:31 ` Andrew Morton
2020-07-29 14:18 ` Michael S. Tsirkin
2020-07-29 14:38 ` David Hildenbrand
2020-07-29 16:14 ` David Hildenbrand
2020-07-29 17:29 ` Randy Dunlap
2020-07-28 22:39 ` Randy Dunlap
2020-07-29 1:43 ` Nathan Chancellor
2020-07-29 1:44 ` Andrew Morton
2020-07-29 2:04 ` Randy Dunlap
2020-07-29 14:09 ` make oldconfig (Re: mmotm 2020-07-27-18-18 uploaded (mm/page_alloc.c)) Alexey Dobriyan
2020-07-31 23:46 ` mmotm 2020-07-31-16-45 uploaded Andrew Morton
2020-08-01 5:24 ` mmotm 2020-07-31-16-45 uploaded (drivers/staging/vc04_services/) Randy Dunlap
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