Re: [PATCH v5 5/9] mm/mmu_notifier: contextual information for event triggering invalidation v2

[Ralph Campbell]

On 2/19/19 12:04 PM, jglisse@xxxxxxxxxx wrote:
> From: JÃrÃme Glisse <jglisse@xxxxxxxxxx>
>
> CPU page table update can happens for many reasons, not only as a result
> of a syscall (munmap(), mprotect(), mremap(), madvise(), ...) but also
> as a result of kernel activities (memory compression, reclaim, migration,
> ...).
>
> Users of mmu notifier API track changes to the CPU page table and take
> specific action for them. While current API only provide range of virtual
> address affected by the change, not why the changes is happening.
>
> This patchset do the initial mechanical convertion of all the places that
> calls mmu_notifier_range_init to also provide the default MMU_NOTIFY_UNMAP
> event as well as the vma if it is know (most invalidation happens against
> a given vma). Passing down the vma allows the users of mmu notifier to
> inspect the new vma page protection.
>
> The MMU_NOTIFY_UNMAP is always the safe default as users of mmu notifier
> should assume that every for the range is going away when that event
> happens. A latter patch do convert mm call path to use a more appropriate
> events for each call.
>
> Changes since v1:
>      - add the flags parameter to init range flags
>
> This is done as 2 patches so that no call site is forgotten especialy
> as it uses this following coccinelle patch:
>
> %<----------------------------------------------------------------------
> @@
> identifier I1, I2, I3, I4;
> @@
> static inline void mmu_notifier_range_init(struct mmu_notifier_range *I1,
> +enum mmu_notifier_event event,
> +unsigned flags,
> +struct vm_area_struct *vma,
> struct mm_struct *I2, unsigned long I3, unsigned long I4) { ... }
>
> @@
> @@
> -#define mmu_notifier_range_init(range, mm, start, end)
> +#define mmu_notifier_range_init(range, event, flags, vma, mm, start, end)
>
> @@
> expression E1, E3, E4;
> identifier I1;
> @@
> <...
> mmu_notifier_range_init(E1,
> +MMU_NOTIFY_UNMAP, 0, I1,
> I1->vm_mm, E3, E4)
> ...>
>
> @@
> expression E1, E2, E3, E4;
> identifier FN, VMA;
> @@
> FN(..., struct vm_area_struct *VMA, ...) {
> <...
> mmu_notifier_range_init(E1,
> +MMU_NOTIFY_UNMAP, 0, VMA,
> E2, E3, E4)
> ...> }
>
> @@
> expression E1, E2, E3, E4;
> identifier FN, VMA;
> @@
> FN(...) {
> struct vm_area_struct *VMA;
> <...
> mmu_notifier_range_init(E1,
> +MMU_NOTIFY_UNMAP, 0, VMA,
> E2, E3, E4)
> ...> }
>
> @@
> expression E1, E2, E3, E4;
> identifier FN;
> @@
> FN(...) {
> <...
> mmu_notifier_range_init(E1,
> +MMU_NOTIFY_UNMAP, 0, NULL,
> E2, E3, E4)
> ...> }
> ---------------------------------------------------------------------->%
>
> Applied with:
> spatch --all-includes --sp-file mmu-notifier.spatch fs/proc/task_mmu.c --in-place
> spatch --sp-file mmu-notifier.spatch --dir kernel/events/ --in-place
> spatch --sp-file mmu-notifier.spatch --dir mm --in-place
>
> Signed-off-by: JÃrÃme Glisse <jglisse@xxxxxxxxxx>
> Cc: Christian KÃnig <christian.koenig@xxxxxxx>
> Cc: Joonas Lahtinen <joonas.lahtinen@xxxxxxxxxxxxxxx>
> Cc: Jani Nikula <jani.nikula@xxxxxxxxxxxxxxx>
> Cc: Rodrigo Vivi <rodrigo.vivi@xxxxxxxxx>
> Cc: Jan Kara <jack@xxxxxxx>
> Cc: Andrea Arcangeli <aarcange@xxxxxxxxxx>
> Cc: Peter Xu <peterx@xxxxxxxxxx>
> Cc: Felix Kuehling <Felix.Kuehling@xxxxxxx>
> Cc: Jason Gunthorpe <jgg@xxxxxxxxxxxx>
> Cc: Ross Zwisler <zwisler@xxxxxxxxxx>
> Cc: Dan Williams <dan.j.williams@xxxxxxxxx>
> Cc: Paolo Bonzini <pbonzini@xxxxxxxxxx>
> Cc: Radim KrÄmÃÅ <rkrcmar@xxxxxxxxxx>
> Cc: Michal Hocko <mhocko@xxxxxxxxxx>
> Cc: Christian Koenig <christian.koenig@xxxxxxx>
> Cc: Ralph Campbell <rcampbell@xxxxxxxxxx>
> Cc: John Hubbard <jhubbard@xxxxxxxxxx>
> Cc: kvm@xxxxxxxxxxxxxxx
> Cc: dri-devel@xxxxxxxxxxxxxxxxxxxxx
> Cc: linux-rdma@xxxxxxxxxxxxxxx
> Cc: Arnd Bergmann <arnd@xxxxxxxx>
> ---

Reviewed-by: Ralph Campbell <rcampbell@xxxxxxxxxx>