diff --git a/libc/kernel/uapi/linux/userfaultfd.h b/libc/kernel/uapi/linux/userfaultfd.h
index 816198f..6037746 100644
--- a/libc/kernel/uapi/linux/userfaultfd.h
+++ b/libc/kernel/uapi/linux/userfaultfd.h
@@ -23,10 +23,10 @@
 #define USERFAULTFD_IOC_NEW _IO(USERFAULTFD_IOC, 0x00)
 #define UFFD_API ((__u64) 0xAA)
 #define UFFD_API_REGISTER_MODES (UFFDIO_REGISTER_MODE_MISSING | UFFDIO_REGISTER_MODE_WP | UFFDIO_REGISTER_MODE_MINOR)
-#define UFFD_API_FEATURES (UFFD_FEATURE_PAGEFAULT_FLAG_WP | UFFD_FEATURE_EVENT_FORK | UFFD_FEATURE_EVENT_REMAP | UFFD_FEATURE_EVENT_REMOVE | UFFD_FEATURE_EVENT_UNMAP | UFFD_FEATURE_MISSING_HUGETLBFS | UFFD_FEATURE_MISSING_SHMEM | UFFD_FEATURE_SIGBUS | UFFD_FEATURE_THREAD_ID | UFFD_FEATURE_MINOR_HUGETLBFS | UFFD_FEATURE_MINOR_SHMEM | UFFD_FEATURE_EXACT_ADDRESS | UFFD_FEATURE_WP_HUGETLBFS_SHMEM | UFFD_FEATURE_WP_UNPOPULATED)
+#define UFFD_API_FEATURES (UFFD_FEATURE_PAGEFAULT_FLAG_WP | UFFD_FEATURE_EVENT_FORK | UFFD_FEATURE_EVENT_REMAP | UFFD_FEATURE_EVENT_REMOVE | UFFD_FEATURE_EVENT_UNMAP | UFFD_FEATURE_MISSING_HUGETLBFS | UFFD_FEATURE_MISSING_SHMEM | UFFD_FEATURE_SIGBUS | UFFD_FEATURE_THREAD_ID | UFFD_FEATURE_MINOR_HUGETLBFS | UFFD_FEATURE_MINOR_SHMEM | UFFD_FEATURE_EXACT_ADDRESS | UFFD_FEATURE_WP_HUGETLBFS_SHMEM | UFFD_FEATURE_WP_UNPOPULATED | UFFD_FEATURE_POISON)
 #define UFFD_API_IOCTLS ((__u64) 1 << _UFFDIO_REGISTER | (__u64) 1 << _UFFDIO_UNREGISTER | (__u64) 1 << _UFFDIO_API)
-#define UFFD_API_RANGE_IOCTLS ((__u64) 1 << _UFFDIO_WAKE | (__u64) 1 << _UFFDIO_COPY | (__u64) 1 << _UFFDIO_ZEROPAGE | (__u64) 1 << _UFFDIO_WRITEPROTECT | (__u64) 1 << _UFFDIO_CONTINUE)
-#define UFFD_API_RANGE_IOCTLS_BASIC ((__u64) 1 << _UFFDIO_WAKE | (__u64) 1 << _UFFDIO_COPY | (__u64) 1 << _UFFDIO_CONTINUE | (__u64) 1 << _UFFDIO_WRITEPROTECT)
+#define UFFD_API_RANGE_IOCTLS ((__u64) 1 << _UFFDIO_WAKE | (__u64) 1 << _UFFDIO_COPY | (__u64) 1 << _UFFDIO_ZEROPAGE | (__u64) 1 << _UFFDIO_WRITEPROTECT | (__u64) 1 << _UFFDIO_CONTINUE | (__u64) 1 << _UFFDIO_POISON)
+#define UFFD_API_RANGE_IOCTLS_BASIC ((__u64) 1 << _UFFDIO_WAKE | (__u64) 1 << _UFFDIO_COPY | (__u64) 1 << _UFFDIO_WRITEPROTECT | (__u64) 1 << _UFFDIO_CONTINUE | (__u64) 1 << _UFFDIO_POISON)
 #define _UFFDIO_REGISTER (0x00)
 #define _UFFDIO_UNREGISTER (0x01)
 #define _UFFDIO_WAKE (0x02)
@@ -34,6 +34,7 @@
 #define _UFFDIO_ZEROPAGE (0x04)
 #define _UFFDIO_WRITEPROTECT (0x06)
 #define _UFFDIO_CONTINUE (0x07)
+#define _UFFDIO_POISON (0x08)
 #define _UFFDIO_API (0x3F)
 #define UFFDIO 0xAA
 #define UFFDIO_API _IOWR(UFFDIO, _UFFDIO_API, struct uffdio_api)
@@ -44,6 +45,7 @@
 #define UFFDIO_ZEROPAGE _IOWR(UFFDIO, _UFFDIO_ZEROPAGE, struct uffdio_zeropage)
 #define UFFDIO_WRITEPROTECT _IOWR(UFFDIO, _UFFDIO_WRITEPROTECT, struct uffdio_writeprotect)
 #define UFFDIO_CONTINUE _IOWR(UFFDIO, _UFFDIO_CONTINUE, struct uffdio_continue)
+#define UFFDIO_POISON _IOWR(UFFDIO, _UFFDIO_POISON, struct uffdio_poison)
 struct uffd_msg {
   __u8 event;
   __u8 reserved1;
@@ -100,6 +102,7 @@
 #define UFFD_FEATURE_EXACT_ADDRESS (1 << 11)
 #define UFFD_FEATURE_WP_HUGETLBFS_SHMEM (1 << 12)
 #define UFFD_FEATURE_WP_UNPOPULATED (1 << 13)
+#define UFFD_FEATURE_POISON (1 << 14)
   __u64 features;
   __u64 ioctls;
 };
@@ -143,5 +146,11 @@
   __u64 mode;
   __s64 mapped;
 };
+struct uffdio_poison {
+  struct uffdio_range range;
+#define UFFDIO_POISON_MODE_DONTWAKE ((__u64) 1 << 0)
+  __u64 mode;
+  __s64 updated;
+};
 #define UFFD_USER_MODE_ONLY 1
 #endif