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<think>
Okay, I need to classify this bug report as either user-mode or system-mode related. Let me read through the description carefully.
The problem occurs when compiling Erlang/OTP 25 using JIT in QEMU's user mode, causing a segfault. It works fine in system mode. The developers mention that in user mode, QEMU uses mprotect to set regions as PROT_READ after translation and invalidates translations via a signal handler. However, since they only write to the writable region (not executable), the code doesn't get invalidated properly, leading to issues.
In contrast, system mode correctly handles the MMU and sees both regions pointing to the same memory, thus invalidating the executable region when writing to the writable one. So, the issue is specific to user mode's handling of memory protection and translation invalidation.
This suggests that the problem lies in how QEMU emulates user-mode environments, specifically how it handles JIT code regions and their translations when writes occur. Therefore, this bug is related to user-mode emulation.
</think>
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