From: Peter Xu <peterx@redhat.com>
To: Gerald Schaefer <gerald.schaefer@de.ibm.com>
Cc: linux-kernel@vger.kernel.org, linux-mm@kvack.org,
Andrew Morton <akpm@linux-foundation.org>,
Andrea Arcangeli <aarcange@redhat.com>,
Will Deacon <will@kernel.org>,
Michael Ellerman <mpe@ellerman.id.au>,
Linus Torvalds <torvalds@linux-foundation.org>,
Heiko Carstens <heiko.carstens@de.ibm.com>,
Vasily Gorbik <gor@linux.ibm.com>,
Christian Borntraeger <borntraeger@de.ibm.com>,
linux-s390@vger.kernel.org
Subject: Re: [PATCH 18/26] mm/s390: Use general page fault accounting
Date: Wed, 24 Jun 2020 16:40:47 -0400 [thread overview]
Message-ID: <20200624204047.GC64004@xz-x1> (raw)
In-Reply-To: <20200624204930.2445bcd6@thinkpad>
On Wed, Jun 24, 2020 at 08:49:30PM +0200, Gerald Schaefer wrote:
> On Fri, 19 Jun 2020 12:13:35 -0400
> Peter Xu <peterx@redhat.com> wrote:
>
> > Use the general page fault accounting by passing regs into handle_mm_fault().
> > It naturally solve the issue of multiple page fault accounting when page fault
> > retry happened.
> >
> > CC: Heiko Carstens <heiko.carstens@de.ibm.com>
> > CC: Vasily Gorbik <gor@linux.ibm.com>
> > CC: Christian Borntraeger <borntraeger@de.ibm.com>
> > CC: linux-s390@vger.kernel.org
> > Signed-off-by: Peter Xu <peterx@redhat.com>
> > ---
> > arch/s390/mm/fault.c | 16 +---------------
> > 1 file changed, 1 insertion(+), 15 deletions(-)
> >
> > diff --git a/arch/s390/mm/fault.c b/arch/s390/mm/fault.c
> > index ab6d7eedcfab..4d62ca7d3e09 100644
> > --- a/arch/s390/mm/fault.c
> > +++ b/arch/s390/mm/fault.c
> > @@ -479,7 +479,7 @@ static inline vm_fault_t do_exception(struct pt_regs *regs, int access)
> > * make sure we exit gracefully rather than endlessly redo
> > * the fault.
> > */
> > - fault = handle_mm_fault(vma, address, flags, NULL);
> > + fault = handle_mm_fault(vma, address, flags, regs);
> > if (fault_signal_pending(fault, regs)) {
> > fault = VM_FAULT_SIGNAL;
> > if (flags & FAULT_FLAG_RETRY_NOWAIT)
> > @@ -489,21 +489,7 @@ static inline vm_fault_t do_exception(struct pt_regs *regs, int access)
> > if (unlikely(fault & VM_FAULT_ERROR))
> > goto out_up;
>
> There are two cases here where we skipped the accounting,
> fault_signal_pending() and VM_FAULT_ERROR, similar to other archs.
>
> fault_signal_pending() should be ok, because that only seems to be true
> for fault & VM_FAULT_RETRY, in which case the new approach also skips
> the accounting.
IMHO it's still possible to have fault_signal_pending() return true even if the
fault is not with VM_FAULT_RETRY, e.g., when the signal is delivered right
after the fault is correctly handled for the thread. However I hope we can
avoid considering that too even if so...
>
> But for VM_FAULT_ERROR, the new approach would do accounting, IIUC. Is
> that changed on purpose? See also my reply on [PATCH 01/26].
(replied in the other thread)
Thanks,
--
Peter Xu
next prev parent reply other threads:[~2020-06-24 20:40 UTC|newest]
Thread overview: 38+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-06-19 16:05 [PATCH 00/26] mm: Page fault accounting cleanups Peter Xu
2020-06-19 16:05 ` [PATCH 01/26] mm: Do page fault accounting in handle_mm_fault Peter Xu
2020-06-24 18:49 ` Gerald Schaefer
2020-06-24 20:34 ` Peter Xu
2020-06-26 19:54 ` Gerald Schaefer
2020-06-26 21:53 ` Peter Xu
2020-06-26 22:27 ` Peter Xu
2020-06-19 16:05 ` [PATCH 02/26] mm/alpha: Use general page fault accounting Peter Xu
2020-06-19 16:05 ` [PATCH 03/26] mm/arc: " Peter Xu
2020-06-19 16:05 ` [PATCH 04/26] mm/arm: " Peter Xu
2020-06-19 16:05 ` [PATCH 05/26] mm/arm64: " Peter Xu
2020-06-19 16:05 ` [PATCH 06/26] mm/csky: " Peter Xu
2020-06-20 1:44 ` Guo Ren
2020-06-20 16:08 ` Peter Xu
2020-06-19 16:05 ` [PATCH 07/26] mm/hexagon: " Peter Xu
2020-06-19 16:05 ` [PATCH 08/26] mm/ia64: " Peter Xu
2020-06-19 16:05 ` [PATCH 09/26] mm/m68k: " Peter Xu
2020-06-19 16:05 ` [PATCH 10/26] mm/microblaze: " Peter Xu
2020-06-19 16:05 ` [PATCH 11/26] mm/mips: " Peter Xu
2020-06-25 8:28 ` Thomas Bogendoerfer
2020-06-19 16:05 ` [PATCH 12/26] mm/nds32: " Peter Xu
2020-06-19 16:12 ` [PATCH 13/26] mm/nios2: " Peter Xu
2020-06-19 16:12 ` [PATCH 14/26] mm/openrisc: " Peter Xu
2020-06-19 16:13 ` [PATCH 15/26] mm/parisc: " Peter Xu
2020-06-19 16:13 ` [PATCH 16/26] mm/powerpc: " Peter Xu
2020-06-19 16:13 ` [PATCH 17/26] mm/riscv: " Peter Xu
2020-06-19 16:13 ` [PATCH 18/26] mm/s390: " Peter Xu
2020-06-24 18:49 ` Gerald Schaefer
2020-06-24 20:40 ` Peter Xu [this message]
2020-06-19 16:13 ` [PATCH 19/26] mm/sh: " Peter Xu
2020-06-19 16:13 ` [PATCH 20/26] mm/sparc32: " Peter Xu
2020-06-19 16:13 ` [PATCH 21/26] mm/sparc64: " Peter Xu
2020-06-19 16:13 ` [PATCH 22/26] mm/unicore32: " Peter Xu
2020-06-19 16:13 ` [PATCH 23/26] mm/x86: " Peter Xu
2020-06-19 16:13 ` [PATCH 24/26] mm/xtensa: " Peter Xu
2020-06-19 16:14 ` [PATCH 25/26] mm: Clean up the last pieces of page fault accountings Peter Xu
2020-06-19 16:14 ` [PATCH 26/26] mm/gup: Remove task_struct pointer for all gup code Peter Xu
2020-06-26 22:31 [PATCH 00/26] mm: Page fault accounting cleanups Peter Xu
2020-06-26 22:36 ` [PATCH 18/26] mm/s390: Use general page fault accounting Peter Xu
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