| Description: | In the Linux kernel, the following vulnerability has been resolved:
nilfs2: fix potential hang in nilfs_detach_log_writer() Syzbot has
reported a potential hang in nilfs_detach_log_writer() called during
nilfs2 unmount. Analysis revealed that this is because
nilfs_segctor_sync(), which synchronizes with the log writer thread,
can be called after nilfs_segctor_destroy() terminates that thread, as
shown in the call trace below: nilfs_detach_log_writer
nilfs_segctor_destroy nilfs_segctor_kill_thread --> Shut down log
writer thread flush_work nilfs_iput_work_func nilfs_dispose_list iput
nilfs_evict_inode nilfs_transaction_commit nilfs_construct_segment (if
inode needs sync) nilfs_segctor_sync --> Attempt to synchronize with
log writer thread *** DEADLOCK *** Fix this issue by changing
nilfs_segctor_sync() so that the log writer thread returns normally
without synchronizing after it terminates, and by forcing tasks that
are already waiting to complete once after the thread terminates. The
skipped inode metadata flushout will then be processed together in the
subsequent cleanup work in nilfs_segctor_destroy().
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