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SubjectRe: [PATCH v3 0/2] Allow gmap fault to retry
On Mon, Jan 04, 2016 at 12:19:53PM +0100, Dominik Dingel wrote:
> Hello,
>
> sorry for the delay since the last version.
>
> During Jasons work with postcopy migration support for s390 a problem regarding
> gmap faults was discovered.
>
> The gmap code will call fixup_user_fault which will end up always in
> handle_mm_fault. Till now we never cared about retries, but as the userfaultfd
> code kind of relies on it. this needs some fix.
>
> This patchset does not take care of the futex code. I will now look closer at
> this.
>
> Thanks,
> Dominik
>
> v2 -> v3:
> - In case of retrying check vma again
> - Do the accounting of major/minor faults once

Reviewed-by: Andrea Arcangeli <aarcange@redhat.com>


>
> v1 -> v2:
> - Instread of passing the VM_FAULT_RETRY from fixup_user_fault we do retries
> within fixup_user_fault, like get_user_pages_locked do.
> - gmap code will now take retry if fixup_user_fault drops the lock.
>
> Dominik Dingel (2):
> mm: bring in additional flag for fixup_user_fault to signal unlock
> s390/mm: enable fixup_user_fault retrying
>
> arch/s390/mm/pgtable.c | 31 ++++++++++++++++++++++++++++---
> include/linux/mm.h | 5 +++--
> kernel/futex.c | 2 +-
> mm/gup.c | 30 +++++++++++++++++++++++++-----
> 4 files changed, 57 insertions(+), 11 deletions(-)
>
> --
> 2.3.0
>


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