Hi, This crash can be triggered by repeatedly executing a syzkaller test case that stresses the signal handling path and EXT4 filesystem operations. The reproducer causes the kernel to process signals (e.g., via do_group_exit) while performing delayed block allocation on a corrupted EXT4 filesystem. The call trace shows the task is stuck in get_signal (kernel/signal.c:3036) and exit_to_user_mode_prepare (include/linux/entry-common.h:329) while handling signals.I think the key failure occurs in ext4_validate_block_bitmap due to inconsistent block bitmap padding, combined with an ENOSPC error during delayed allocation. This leads to RCU stalls when the task (syz-executor.4) fails to exit the RCU read-side critical section during resource cleanup. Maybe we can add sanity checks for block bitmap padding in ext4_validate_block_bitmap? This can be reproduced on: HEAD commit: 38fec10eb60d687e30c8c6b5420d86e8149f7557 report: https://pastebin.com/raw/A7yVpRQJ console output : https://pastebin.com/raw/Me02WbSY kernel config : https://pastebin.com/raw/u0Efyj5P C reproducer : https://pastebin.com/raw/TLx7rz0Q
