Subject: Re: (Re)boot hangs and refcount errors on next-20250829

From: Bert Karwatzki <[email-masked]>
Date: Sun, 31 Aug 2025 17:21:13 +0200

I've found the missing piece of the patch here:
https://lore.kernel.org/all/175664303766.1920.13212322629796216488.tip-bot2@tip-bot2/#t

diff --git a/kernel/futex/core.c b/kernel/futex/core.c
index fb63c13aa66f..125804fbb5cb 100644
--- a/kernel/futex/core.c
+++ b/kernel/futex/core.c
@@ -1722,6 +1722,7 @@ int futex_mm_init(struct mm_struct *mm)
        RCU_INIT_POINTER(mm->futex_phash, NULL);
        mm->futex_phash_new = NULL;
        /* futex-ref */
+       mm->futex_ref = NULL;
        atomic_long_set(&mm->futex_atomic, 0);
        mm->futex_batches = get_state_synchronize_rcu();
        return 0;

This solves all the mentioned Problems!

Bert Karwatzki