mm: bail out of lazy_mmu_mode_* in interrupt context
The lazy MMU mode cannot be used in interrupt context. This is
documented in <linux/pgtable.h>, but isn't consistently handled
across architectures.
arm64 ensures that calls to lazy_mmu_mode_* have no effect in
interrupt context, because such calls do occur in certain
configurations - see commit b81c688426a9 ("arm64/mm: Disable barrier
batching in interrupt contexts"). Other architectures do not check
this situation, most likely because it hasn't occurred so far.
Both arm64 and x86/Xen also ensure that any lazy MMU optimisation is
disabled while in interrupt mode (see queue_pte_barriers() and
xen_get_lazy_mode() respectively).
Let's handle this in the new generic lazy_mmu layer, in the same
fashion as arm64: bail out of lazy_mmu_mode_* if in_interrupt(), and
have in_lazy_mmu_mode() return false to disable any optimisation.
Also remove the arm64 handling that is now redundant; x86/Xen has
its own internal tracking so it is left unchanged.
Signed-off-by: Kevin Brodsky <kevin.brodsky@arm.com>
3 files changed
