On Tue, Apr 26, 2022, Paolo Bonzini wrote: > On 4/26/22 18:45, Sean Christopherson wrote: > > On Tue, Apr 26, 2022, Maxim Levitsky wrote: > > > [ 390.511995] BUG: sleeping function called from invalid context at include/linux/highmem-internal.h:161 > > > [ 390.513681] in_atomic(): 1, irqs_disabled(): 1, non_block: 0, pid: 4439, name: CPU 0/KVM > > > > This is my fault. memremap() can sleep as well. I'll work on a fix. > > Indeed, "KVM: Fix race between mmu_notifier invalidation and pfncache > refresh" hadn't gone through a full test cycle yet. And I didn't run with PROVE_LOCKING :-( I'm pretty sure there's an existing memory leak too. If a refresh occurs, but the pfn ends up being the same, KVM will keep references to both the "old" and the "new", but only release one when the cache is destroyed. The refcounting bug begs the question of why KVM even keeps a reference. This code really should look exactly like the page fault path, i.e. should drop the reference to the pfn once the pfn has been installed into the cache and obtained protection via the mmu_notifier.
