Merge tag 'locking-urgent-2026-09-20' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tipgrafted

Pull futex fix from Ingo Molnar:

 - Also allocate a default private futex hash on vfork() as well, to
   avoid races with (private) futex waiters (Peter Zijlstra)

* tag 'locking-urgent-2026-09-20' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  futex: Also allocate private hash on vfork()

1 files changed, 37 insertions, 0 deletions

diff --git a/include/uapi/asm-generic/ipcbuf.h b/include/uapi/asm-generic/ipcbuf.h
new file mode 100644
index 000000000..41a01b494
--- /dev/null
+++ b/include/uapi/asm-generic/ipcbuf.h
@@ -0,0 +1,37 @@
+/* SPDX-License-Identifier: GPL-2.0 WITH Linux-syscall-note */
+#ifndef __ASM_GENERIC_IPCBUF_H
+#define __ASM_GENERIC_IPCBUF_H
+
+#include <linux/posix_types.h>
+
+/*
+ * The generic ipc64_perm structure:
+ * Note extra padding because this structure is passed back and forth
+ * between kernel and user space.
+ *
+ * ipc64_perm was originally meant to be architecture specific, but
+ * everyone just ended up making identical copies without specific
+ * optimizations, so we may just as well all use the same one.
+ *
+ * Pad space is left for:
+ * - 32-bit mode_t on architectures that only had 16 bit
+ * - 32-bit seq
+ * - 2 miscellaneous 32-bit values
+ */
+
+struct ipc64_perm {
+	__kernel_key_t		key;
+	__kernel_uid32_t	uid;
+	__kernel_gid32_t	gid;
+	__kernel_uid32_t	cuid;
+	__kernel_gid32_t	cgid;
+	__kernel_mode_t		mode;
+				/* pad if mode_t is u16: */
+	unsigned char		__pad1[4 - sizeof(__kernel_mode_t)];
+	unsigned short		seq;
+	unsigned short		__pad2;
+	__kernel_ulong_t	__unused1;
+	__kernel_ulong_t	__unused2;
+};
+
+#endif /* __ASM_GENERIC_IPCBUF_H */