From: Peter Xu <peterx@redhat.com>
To: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Guo Ren <guoren@kernel.org>,
Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
Gerald Schaefer <gerald.schaefer@de.ibm.com>,
Andrew Morton <akpm@linux-foundation.org>,
Andrea Arcangeli <aarcange@redhat.com>,
linux-csky@vger.kernel.org
Subject: Re: [PATCH 07/25] mm/csky: Use mm_fault_accounting()
Date: Wed, 17 Jun 2020 15:58:07 -0400 [thread overview]
Message-ID: <20200617195807.GH76766@xz-x1> (raw)
In-Reply-To: <CAHk-=wi=58J7d5iyFyYyHrU+pzjWB55cit_LQCkSkavpH-trsg@mail.gmail.com>
On Wed, Jun 17, 2020 at 10:53:23AM -0700, Linus Torvalds wrote:
> On Wed, Jun 17, 2020 at 8:49 AM Peter Xu <peterx@redhat.com> wrote:
> >
> > I don't think it's a must, but mmap_sem should not be required at least by
> > observing current code. E.g., do_user_addr_fault() of x86 does the accounting
> > without mmap_sem even before this series.
>
> All the accounting should be per-thread and not need any locking.
>
> Which is why a remote GUP should never account to the remote mm - not
> only isn't there an unambiguous thread to account to (an mm can share
> many threads), but it would require locking not just for the remote
> update, but for all normal page faults.
But currently remote GUP will still do the page fault accounting on the remote
task_struct, am I right? E.g., when the get_user_pages_remote() is called with
"tsk != current", it seems the faultin_page() will still do maj_flt/min_flt
accounting for that remote task/thread?
Thanks,
--
Peter Xu
next prev parent reply other threads:[~2020-06-17 19:58 UTC|newest]
Thread overview: 60+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-06-15 22:15 [PATCH 00/25] mm: Page fault accounting cleanups Peter Xu
2020-06-15 22:15 ` [PATCH 01/25] mm/um: Fix extra accounting for page fault retries Peter Xu
2020-06-15 22:15 ` [PATCH 02/25] mm: Introduce mm_fault_accounting() Peter Xu
2020-06-15 22:32 ` Linus Torvalds
2020-06-15 23:19 ` Peter Xu
2020-06-16 19:00 ` Andrew Morton
2020-06-17 16:26 ` Peter Xu
2020-06-15 22:15 ` [PATCH 03/25] mm/alpha: Use mm_fault_accounting() Peter Xu
2020-06-15 22:15 ` [PATCH 04/25] mm/arc: " Peter Xu
2020-06-15 22:15 ` [PATCH 05/25] mm/arm: " Peter Xu
2020-06-15 22:15 ` [PATCH 06/25] mm/arm64: " Peter Xu
2020-06-16 7:43 ` Will Deacon
2020-06-16 15:59 ` Peter Xu
2020-06-15 22:15 ` [PATCH 07/25] mm/csky: " Peter Xu
2020-06-17 7:04 ` Guo Ren
2020-06-17 15:49 ` Peter Xu
2020-06-17 17:53 ` Linus Torvalds
2020-06-17 19:58 ` Peter Xu [this message]
2020-06-17 20:15 ` Linus Torvalds
2020-06-18 14:38 ` Peter Xu
2020-06-18 17:15 ` Linus Torvalds
2020-06-18 21:24 ` Peter Xu
2020-06-18 22:28 ` Peter Xu
2020-06-18 22:59 ` Linus Torvalds
2020-06-15 22:15 ` [PATCH 08/25] mm/hexagon: " Peter Xu
2020-06-15 22:15 ` [PATCH 09/25] mm/ia64: " Peter Xu
2020-06-15 22:15 ` [PATCH 10/25] mm/m68k: " Peter Xu
2020-06-15 22:15 ` [PATCH 11/25] mm/microblaze: " Peter Xu
2020-06-15 22:15 ` [PATCH 12/25] mm/mips: " Peter Xu
2020-06-15 22:15 ` [PATCH 13/25] mm/nds32: " Peter Xu
2020-06-17 1:05 ` Greentime Hu
2020-06-15 22:15 ` [PATCH 14/25] mm/nios2: " Peter Xu
2020-06-15 22:15 ` [PATCH 15/25] mm/openrisc: " Peter Xu
2020-06-16 18:11 ` Stafford Horne
2020-06-15 22:15 ` [PATCH 16/25] mm/parisc: " Peter Xu
2020-06-15 22:15 ` [PATCH 17/25] mm/powerpc: " Peter Xu
2020-06-15 22:16 ` [PATCH 18/25] mm/riscv: " Peter Xu
2020-06-18 23:49 ` Palmer Dabbelt
2020-06-19 0:12 ` Peter Xu
2020-06-15 22:23 ` [PATCH 19/25] mm/s390: " Peter Xu
2020-06-16 15:59 ` Alexander Gordeev
2020-06-16 16:35 ` Peter Xu
2020-06-17 6:19 ` Christian Borntraeger
2020-06-17 16:06 ` Peter Xu
2020-06-17 16:14 ` Christian Borntraeger
2020-06-17 16:44 ` Peter Xu
2020-06-15 22:23 ` [PATCH 20/25] mm/sh: " Peter Xu
2020-07-20 21:25 ` Rich Felker
2020-07-20 22:05 ` Peter Xu
2020-06-15 22:23 ` [PATCH 21/25] mm/sparc32: " Peter Xu
2020-06-15 22:23 ` [PATCH 22/25] mm/sparc64: " Peter Xu
2020-06-15 22:23 ` [PATCH 23/25] mm/unicore32: " Peter Xu
2020-06-15 22:23 ` [PATCH 24/25] mm/x86: " Peter Xu
2020-06-15 22:23 ` [PATCH 25/25] mm/xtensa: " Peter Xu
2020-06-15 23:13 ` Max Filippov
2020-06-16 18:55 ` [PATCH 00/25] mm: Page fault accounting cleanups Linus Torvalds
2020-06-16 21:03 ` Peter Xu
2020-06-17 0:55 ` Michael Ellerman
2020-06-17 8:04 ` Will Deacon
2020-06-17 16:10 ` Peter Xu
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