Is pte_offset_map allowed to happen within lazy mmu? I presume not,
because you definitely don't want the mapping pte update to be deferred.
Or, more specifically, is kunmap_atomic ever allowed within lazy mmu?
I'm looking at kpte_clear_flush; I've already got a patch which turns
this into a pv_op, along with a Xen implementation. But I think its
probably an excess pv_op for a relatively minor corner case. It seems
to me that it would be better to define kpte_clear_flush as:
#define kpte_clear_flush(ptep, vaddr) \
do { \
arch_enter_lazy_mmu_mode(); \
pte_clear(&init_mm, vaddr, ptep); \
__flush_tlb_one(vaddr); \
arch_leave_lazy_mmu_mode(); \
} while (0)
and take advantage of mmu batching to make this operation efficient.
But I'm not sure if this is safe.
(Also, kmap_atomic could use set_pte_at rather than set_pte.)
What do you think?
J
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