Hello, I encountered a reproducible kernel BUG related to buffered writes on an NTFS3 filesystem. The crash occurs inside the generic iomap buffered‑IO path, called from ntfs_file_write_iter() . This appears to be a real kernel‑side logic error rather than a userspace issue. Below is a complete report including system details, stack trace, and reproduction context. System Information Distribution: CachyOS (Arch‑based) Kernel: 7.0.1‑1‑cachyos (PREEMPT) Hardware: MSI MAG X570S Tomahawk Max WiFi (MS‑7D54) BIOS 1.C0 (2025‑09‑03) CPU: AMD Ryzen (8 cores visible in trace) Filesystem involved: ntfs3 Taint flags: G O (NVIDIA out‑of‑tree module loaded) Full system log: https://paste.cachyos.org/81db076.txt Summary of the Issue A kernel BUG is triggered during a buffered write to an NTFS3 filesystem. The BUG originates in: fs/iomap/buffered-io.c:1061 iomap_write_end+0x205/0x210 The write originates from a 32‑bit userspace process ( Comm: CGenericAsyncFi ), likely via int80 syscall emulation (Wine/Proton or similar). This suggests a logic error in the interaction between NTFS3’s write_iter implementation and the generic iomap buffered write path. Kernel Trace (excerpt) kernel BUG at fs/iomap/buffered-io.c:1061! Oops: invalid opcode: 0000 [#1] SMP NOPTI CPU: 8 PID: 33291 Comm: CGenericAsyncFi Tainted: G O 7.0.1-1-cachyos RIP: 0010:iomap_write_end+0x205/0x210 Call Trace: iomap_file_buffered_write+0x283/0x490 ntfs_file_write_iter+0x2b3/0x300 [ntfs3] vfs_write+0x2b6/0x3e0 __ia32_sys_write+0x84/0xf0 do_int80_emulation+0x136/0xa40 The full trace is included in the linked log file. Reproduction Context The crash occurs during writes to an NTFS3‑mounted volume . Triggered by a 32‑bit userspace process performing write operations. The issue appears during buffered I/O , not direct I/O. The crash is fully reproducible on this system. Mount options used for the NTFS3 volume (if relevant) can be provided on request. Expected Behavior The write operation should complete normally without triggering a BUG in the iomap buffered‑IO path. Actual Behavior The kernel hits a BUG() assertion in iomap_write_end() , causing an Oops and stack trace. The system remains running but the process crashes. Additional Notes Although the kernel is tainted due to NVIDIA modules, the crash occurs entirely within the filesystem and iomap code paths. The BUG location strongly suggests a logic error in the iomap end‑write accounting or page state handling triggered by NTFS3’s write_iter implementation. I can test a vanilla kernel or provide additional logs if needed. Please let me know if further debugging information, mount options, or a minimal reproducer would be helpful. I can reproduce the issue reliably and am available to test patches. Thank you.