5.5 - CVE-2025-21849

In the Linux kernel, the following vulnerability has been resolved:

drm/i915/gt: Use spin_lock_irqsave() in interruptible context

spin_lock/unlock() functions used in interrupt contexts could result in a deadlock, as seen in GitLab issue #13399, which occurs when interrupt comes in while holding a lock.

Try to remedy the problem by saving irq state before spin lock acquisition.

v2: add irqs' state save/restore calls to all locks/unlocks in
signal_irq_work() execution (Maciej)

v3: use with spin_lock_irqsave() in guc_lrc_desc_unpin() instead
of other lock/unlock calls and add Fixes and Cc tags (Tvrtko);
change title and commit message

(cherry picked from commit c088387ddd6482b40f21ccf23db1125e8fa4af7e)