Messages in this thread | | | Subject | Re: [PATCH 3/5] mm/notifier: add migration invalidation type | From | Ralph Campbell <> | Date | Fri, 10 Jul 2020 13:17:50 -0700 |
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On 7/10/20 12:39 PM, Jason Gunthorpe wrote: > On Mon, Jul 06, 2020 at 03:23:45PM -0700, Ralph Campbell wrote: >> Currently migrate_vma_setup() calls mmu_notifier_invalidate_range_start() >> which flushes all device private page mappings whether or not a page >> is being migrated to/from device private memory. In order to not disrupt >> device mappings that are not being migrated, shift the responsibility >> for clearing device private mappings to the device driver and leave >> CPU page table unmapping handled by migrate_vma_setup(). To support >> this, the caller of migrate_vma_setup() should always set struct >> migrate_vma::src_owner to a non NULL value that matches the device >> private page->pgmap->owner. This value is then passed to the struct >> mmu_notifier_range with a new event type which the driver's invalidation >> function can use to avoid device MMU invalidations. >> >> Signed-off-by: Ralph Campbell <rcampbell@nvidia.com> >> include/linux/mmu_notifier.h | 7 +++++++ >> mm/migrate.c | 8 +++++++- >> 2 files changed, 14 insertions(+), 1 deletion(-) >> >> diff --git a/include/linux/mmu_notifier.h b/include/linux/mmu_notifier.h >> index fc68f3570e19..bd0b34dbe4de 100644 >> +++ b/include/linux/mmu_notifier.h >> @@ -38,6 +38,10 @@ struct mmu_interval_notifier; >> * >> * @MMU_NOTIFY_RELEASE: used during mmu_interval_notifier invalidate to signal >> * that the mm refcount is zero and the range is no longer accessible. >> + * >> + * @MMU_NOTIFY_MIGRATE: used during migrate_vma_collect() invalidate to signal >> + * a device driver to possibly ignore the invalidation if the src_own >> + * field matches. >> */ >> enum mmu_notifier_event { >> MMU_NOTIFY_UNMAP = 0, >> @@ -46,6 +50,7 @@ enum mmu_notifier_event { >> MMU_NOTIFY_PROTECTION_PAGE, >> MMU_NOTIFY_SOFT_DIRTY, >> MMU_NOTIFY_RELEASE, >> + MMU_NOTIFY_MIGRATE, >> }; >> >> #define MMU_NOTIFIER_RANGE_BLOCKABLE (1 << 0) >> @@ -264,6 +269,7 @@ struct mmu_notifier_range { >> unsigned long end; >> unsigned flags; >> enum mmu_notifier_event event; >> + void *data; >> }; > > This generic member usually ends up a bit ugly, can we do a tagged > union instead? > > union > { > void *migrate_pgmap_owner; > }; > > and probably drop the union until we actually need two things here. > > Jason
OK, I'll send a v2 with this change.
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