diff options
| -rw-r--r-- | arch/x86/include/asm/kmsan.h | 17 | ||||
| -rw-r--r-- | include/linux/mmzone.h | 6 |
2 files changed, 19 insertions, 4 deletions
diff --git a/arch/x86/include/asm/kmsan.h b/arch/x86/include/asm/kmsan.h index 8fa6ac0e2d76..d91b37f5b4bb 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 */ diff --git a/include/linux/mmzone.h b/include/linux/mmzone.h index f43a1cdcc6e7..0f62786269d0 100644 --- a/include/linux/mmzone.h +++ b/include/linux/mmzone.h @@ -2006,9 +2006,9 @@ static inline int pfn_valid(unsigned long pfn) if (pfn_to_section_nr(pfn) >= NR_MEM_SECTIONS) return 0; ms = __pfn_to_section(pfn); - rcu_read_lock(); + rcu_read_lock_sched(); if (!valid_section(ms)) { - rcu_read_unlock(); + rcu_read_unlock_sched(); return 0; } /* @@ -2016,7 +2016,7 @@ static inline int pfn_valid(unsigned long pfn) * the entire section-sized span. */ ret = early_section(ms) || pfn_section_valid(ms, pfn); - rcu_read_unlock(); + rcu_read_unlock_sched(); return ret; } |