X-Git-Url: http://review.tizen.org/git/?a=blobdiff_plain;f=arch%2Fx86%2Finclude%2Fasm%2Fkmsan.h;h=d91b37f5b4bb45106ee927fcd98b66f1b82a54c1;hb=6335c0cdb2ea0ea02c999e04d34fd84f69fb27ff;hp=8fa6ac0e2d7665f936756748c0e1b4ab08a2c5a7;hpb=e50c55c295d4641e1ed31757146a72145cb4f167;p=platform%2Fkernel%2Flinux-starfive.git

diff --git a/arch/x86/include/asm/kmsan.h b/arch/x86/include/asm/kmsan.h
index 8fa6ac0..d91b37f 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 */