On Mon, May 01, 2023 at 10:50:24AM -0700, Suren Baghdasaryan wrote:
> migration_entry_wait does not need VMA lock, therefore it can be dropped
> before waiting. Introduce VM_FAULT_VMA_UNLOCKED to indicate that VMA
> lock was dropped while in handle_mm_fault().
> Note that once VMA lock is dropped, the VMA reference can't be used as
> there are no guarantees it was not freed.
How about we introduce:
void vmf_end_read(struct vm_fault *vmf)
{
if (!vmf->vma)
return;
vma_end_read(vmf->vma);
vmf->vma = NULL;
}
Now we don't need a new flag, and calling vmf_end_read() is idempotent.
Oh, argh, we create the vmf too late. We really need to hoist the
creation of vm_fault to the callers of handle_mm_fault().
