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

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Message-ID: <ff09d22f-8eb8-ea19-0a65-7f5b38928cea@nvidia.com>
Date:   Fri, 22 Feb 2019 13:25:03 -0800
From:   Ralph Campbell <rcampbell@...dia.com>
To:     <jglisse@...hat.com>, <linux-mm@...ck.org>,
        Andrew Morton <akpm@...ux-foundation.org>
CC:     <linux-kernel@...r.kernel.org>,
        Christian König <christian.koenig@....com>,
        Joonas Lahtinen <joonas.lahtinen@...ux.intel.com>,
        Jani Nikula <jani.nikula@...ux.intel.com>,
        Rodrigo Vivi <rodrigo.vivi@...el.com>, Jan Kara <jack@...e.cz>,
        Andrea Arcangeli <aarcange@...hat.com>,
        Peter Xu <peterx@...hat.com>,
        Felix Kuehling <Felix.Kuehling@....com>,
        Jason Gunthorpe <jgg@...lanox.com>,
        Ross Zwisler <zwisler@...nel.org>,
        Dan Williams <dan.j.williams@...el.com>,
        Paolo Bonzini <pbonzini@...hat.com>,
        Radim Krčmář <rkrcmar@...hat.com>,
        Michal Hocko <mhocko@...nel.org>,
        John Hubbard <jhubbard@...dia.com>, <kvm@...r.kernel.org>,
        <dri-devel@...ts.freedesktop.org>, <linux-rdma@...r.kernel.org>,
        Arnd Bergmann <arnd@...db.de>
Subject: Re: [PATCH v5 5/9] mm/mmu_notifier: contextual information for event
 triggering invalidation v2


On 2/19/19 12:04 PM, jglisse@...hat.com wrote:
> From: Jérôme Glisse <jglisse@...hat.com>
> 
> 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: Jérôme Glisse <jglisse@...hat.com>
> Cc: Christian König <christian.koenig@....com>
> Cc: Joonas Lahtinen <joonas.lahtinen@...ux.intel.com>
> Cc: Jani Nikula <jani.nikula@...ux.intel.com>
> Cc: Rodrigo Vivi <rodrigo.vivi@...el.com>
> Cc: Jan Kara <jack@...e.cz>
> Cc: Andrea Arcangeli <aarcange@...hat.com>
> Cc: Peter Xu <peterx@...hat.com>
> Cc: Felix Kuehling <Felix.Kuehling@....com>
> Cc: Jason Gunthorpe <jgg@...lanox.com>
> Cc: Ross Zwisler <zwisler@...nel.org>
> Cc: Dan Williams <dan.j.williams@...el.com>
> Cc: Paolo Bonzini <pbonzini@...hat.com>
> Cc: Radim Krčmář <rkrcmar@...hat.com>
> Cc: Michal Hocko <mhocko@...nel.org>
> Cc: Christian Koenig <christian.koenig@....com>
> Cc: Ralph Campbell <rcampbell@...dia.com>
> Cc: John Hubbard <jhubbard@...dia.com>
> Cc: kvm@...r.kernel.org
> Cc: dri-devel@...ts.freedesktop.org
> Cc: linux-rdma@...r.kernel.org
> Cc: Arnd Bergmann <arnd@...db.de>
> ---

Reviewed-by: Ralph Campbell <rcampbell@...dia.com>