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<think>
</think>
The backtrace you provided shows the call stack for two threads in a QEMU process. Here's a breakdown of what each thread is doing:
### Thread 2 (Thread 0x7fffef0864c0 (LWP 323692) "qemu-system-x86"):
1. **futex_wait**: This function is waiting on a futex (fast userspace mutex). The `expected` parameter indicates the value being waited for, and `futex_word` points to the memory location of the futex.
2. **__GI___lll_lock_wait**: This is part of the NPTL (Native POSIX Threads Library) implementation, waiting for a lock to become available.
3. **lll_mutex_lock_optimized** and **___pthread_mutex_lock**: These functions are part of the pthread library and handle mutex locking.
4. **qemu_mutex_lock_impl**: This is QEMU's internal function for acquiring a mutex.
5. **bql_lock_impl**: This is related to QEMU's "BQL" (Basic Query Language) lock, used for synchronizing access to certain resources.
6. **os_host_main_loop_wait**: This function waits on the main event loop with a specified timeout.
7. **main_loop_wait**: This is part of QEMU's main loop handling, waiting for events non-blocking.
8. **qemu_default_main**: This is QEMU's default main function.
### Thread 1 (Thread 0x7fffef0864c0 (LWP 323692) "qemu-system-x86"):
1. **futex_wait**: Similar to the other thread, this is waiting on a futex.
2. **__GI___lll_lock_wait**: Again, part of NPTL for lock waiting.
3. **lll_mutex_lock_optimized** and **___pthread_mutex_lock**: pthread mutex locking functions.
4. **qemu_mutex_lock_impl**: QEMU's internal mutex acquisition.
5. **bql_lock_impl**: Another BQL lock acquisition.
### Summary:
- Both threads are blocked on mutex locks, specifically waiting for futexes to be signaled or for mutexes to become available.
- Thread 2 is involved in the main event loop and RCU (Read-Copy-Update) thread synchronization.
- Thread 1 is also blocked on a BQL lock, which is used for certain QEMU operations.
This indicates that the process is waiting for some locks to be released or events to be signaled, which could be part of normal operation or an indication of a deadlock.
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