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x86/mm, KVM: fix warning when !CONFIG_PREEMPT_COUNT

Message ID 20170717094907.6089-1-rkagan@virtuozzo.com (mailing list archive)
State New, archived
Headers show

Commit Message

Roman Kagan July 17, 2017, 9:49 a.m. UTC 
Recent commit d6e41f1151fe ("x86/mm, KVM: Teach KVM's VMX code that CR3
isn't a constant") introduced a VM_WARN_ON(!in_atomic()) which generates
false positives on every vm entry on !CONFIG_PREEMPT_COUNT kernels.

Replace it with a test for preemptible(), which appears to match the
original intent and works across different CONFIG_PREEMPT* variations.

Cc: Andy Lutomirski <luto@kernel.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Arjan van de Ven <arjan@linux.intel.com>
Cc: Borislav Petkov <bpetkov@suse.de>
Cc: Dave Hansen <dave.hansen@intel.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Mel Gorman <mgorman@suse.de>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Nadav Amit <nadav.amit@gmail.com>
Cc: Nadav Amit <namit@vmware.com>
Cc: Paolo Bonzini <pbonzini@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Radim Krčmář <rkrcmar@redhat.com>
Cc: Rik van Riel <riel@redhat.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: X86 ML <x86@kernel.org>
Cc: kvm@vger.kernel.org
Cc: linux-mm@kvack.org
Cc: Ingo Molnar <mingo@kernel.org>
Fixes: d6e41f1151fe ("x86/mm, KVM: Teach KVM's VMX code that CR3 isn't a constant")
Signed-off-by: Roman Kagan <rkagan@virtuozzo.com>
---
 arch/x86/include/asm/mmu_context.h | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)
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Patch

diff --git a/arch/x86/include/asm/mmu_context.h b/arch/x86/include/asm/mmu_context.h
index ecfcb6643c9b..265c907d7d4c 100644
--- a/arch/x86/include/asm/mmu_context.h
+++ b/arch/x86/include/asm/mmu_context.h
@@ -293,7 +293,7 @@  static inline unsigned long __get_current_cr3_fast(void)
 	unsigned long cr3 = __pa(this_cpu_read(cpu_tlbstate.loaded_mm)->pgd);
 
 	/* For now, be very restrictive about when this can be called. */
-	VM_WARN_ON(in_nmi() || !in_atomic());
+	VM_WARN_ON(in_nmi() || preemptible());
 
 	VM_BUG_ON(cr3 != __read_cr3());
 	return cr3;