linux-kernel - Re: [PATCH 0/3] powerpc/mm: page fault handler cleaning

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Message-Id: <f4693d88-9142-dfd5-4182-9921e67c1c2c@linux.vnet.ibm.com>
Date:   Thu, 2 Mar 2017 13:30:38 +0100
From:   Laurent Dufour <ldufour@...ux.vnet.ibm.com>
To:     mpe@...erman.id.au, benh@...nel.crashing.org, paulus@...ba.org,
        aneesh.kumar@...ux.vnet.ibm.com, bsingharora@...il.com,
        npiggin@...il.com
Cc:     linuxppc-dev@...ts.ozlabs.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH 0/3] powerpc/mm: page fault handler cleaning

Kindly ping...

On 14/02/2017 17:45, Laurent Dufour wrote:
> This series attempts to clean the page fault handler in the way it has
> been done previously for the x86 architecture [1].
> 
> The goal is to manage the mmap_sem earlier and only in
> do_page_fault(). This done by handling the retry case earlier, before
> handling the error case.  This way the semaphore can be released
> earlier and the error path processed without holding it.
> 
> The first patch is just moving a unlock to the caller of the service,
> which as no functional impact.
> 
> The second patch is handling the retry case earlier in
> do_page_fault(). This is where most the change are done, but I was
> conservative here, not changing the use of mm_fault_error() in the
> case of the second retry. It may be smarter to handle that case
> separately but this may create duplicate code.
> 
> The last patch is moving up semaphore releasing from mm_fault_error()
> to do_page_fault().
> 
> [1] see commits from Linus Torvalds
>  26178ec11ef3 ("x86: mm: consolidate VM_FAULT_RETRY handling")
>  7fb08eca4527 ("x86: mm: move mmap_sem unlock from mm_fault_error() to
> caller")
> 
> Laurent Dufour (3):
>   powerpc/mm: move mmap_sem unlock up from do_sigbus
>   powerpc/mm: handle VM_FAULT_RETRY earlier
>   powerpc/mm: move mmap_sem unlocking in do_page_fault()
> 
>  arch/powerpc/mm/fault.c | 82 ++++++++++++++++++++++++-------------------------
>  1 file changed, 40 insertions(+), 42 deletions(-)
>