The issue reported is related to how QEMU handles the `madvise` system call, specifically when using `MADV_DONTNEED`. The user provided a reproducer that demonstrates the problem where the application's assertion fails when run under QEMU but works correctly on native Linux.

Upon reviewing the QEMU source code (as linked), there is a comment indicating that `MADV_DONTNEED` is being ignored with a return of success. However, according to the man pages for `madvise`, `MADV_DONTNEED` changes the semantics of memory access, which can affect application behavior.

This suggests that QEMU's current implementation does not correctly handle the `MADV_DONTNEED` advice, leading to incorrect program execution in certain cases. The problem arises during system call handling within QEMU, as it does not properly process this specific `madvise` operation.

Therefore, the bug falls under the **syscall** category because it involves an error with how a system call (`madvise`) is being handled by QEMU.
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The issue relates to how QEMU handles the `MADV_DONTNEED` advice during the `madvise` system call. The problem occurs in the runtime when executing applications that rely on this specific behavior, which is not correctly implemented in QEMU.

**syscall**