[PATCH kernel 05/15] powerpc/iommu: Stop using @current in mm_iommu_xxx
aik at ozlabs.ru
Tue Aug 9 15:29:52 AEST 2016
On 05/08/16 17:00, Michael Ellerman wrote:
> Alexey Kardashevskiy <aik at ozlabs.ru> writes:
>> In some situations the userspace memory context may live longer than
>> the userspace process itself so if we need to do proper memory context
>> cleanup, we better cache @mm and use it later when the process is gone
>> (@current or @current->mm are NULL).
>> This changes mm_iommu_xxx API to receive mm_struct instead of using one
>> from @current.
>> This is needed by the following patch to do proper cleanup in time.
>> This depends on "powerpc/powernv/ioda: Fix endianness when reading TCEs"
>> to do proper cleanup via tce_iommu_clear() patch.
>> To keep API consistent, this replaces mm_context_t with mm_struct;
>> we stick to mm_struct as mm_iommu_adjust_locked_vm() helper needs
>> access to &mm->mmap_sem.
>> This should cause no behavioral change.
> Is this a theoretical bug, or do we hit it in practice?
> In other words, should I merge this as a fix for 4.8, or can it wait for
> 4.9 with the rest of the series?
Assuming this does not have "rb" or "ab" from anyone familiar with IOMMU on
powernv, this has to wait :-/
>> Signed-off-by: Alexey Kardashevskiy <aik at ozlabs.ru>
>> arch/powerpc/include/asm/mmu_context.h | 20 +++++++------
>> arch/powerpc/kernel/setup-common.c | 2 +-
>> arch/powerpc/mm/mmu_context_book3s64.c | 4 +--
>> arch/powerpc/mm/mmu_context_iommu.c | 54 ++++++++++++++--------------------
>> drivers/vfio/vfio_iommu_spapr_tce.c | 41 ++++++++++++++++----------
> I'd need an ACK from Alex for that part.
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