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-rw-r--r--arch/x86/include/asm/kmsan.h17
1 files changed, 16 insertions, 1 deletions
diff --git a/arch/x86/include/asm/kmsan.h b/arch/x86/include/asm/kmsan.h
index 8fa6ac0e2..d91b37f5b 100644
--- a/arch/x86/include/asm/kmsan.h
+++ b/arch/x86/include/asm/kmsan.h
@@ -64,6 +64,7 @@ static inline bool kmsan_virt_addr_valid(void *addr)
{
unsigned long x = (unsigned long)addr;
unsigned long y = x - __START_KERNEL_map;
+ bool ret;
/* use the carry flag to determine if x was < __START_KERNEL_map */
if (unlikely(x > y)) {
@@ -79,7 +80,21 @@ static inline bool kmsan_virt_addr_valid(void *addr)
return false;
}
- return pfn_valid(x >> PAGE_SHIFT);
+ /*
+ * pfn_valid() relies on RCU, and may call into the scheduler on exiting
+ * the critical section. However, this would result in recursion with
+ * KMSAN. Therefore, disable preemption here, and re-enable preemption
+ * below while suppressing reschedules to avoid recursion.
+ *
+ * Note, this sacrifices occasionally breaking scheduling guarantees.
+ * Although, a kernel compiled with KMSAN has already given up on any
+ * performance guarantees due to being heavily instrumented.
+ */
+ preempt_disable();
+ ret = pfn_valid(x >> PAGE_SHIFT);
+ preempt_enable_no_resched();
+
+ return ret;
}
#endif /* !MODULE */