work_cancel() used to return -ENOENT when the work structure was not
in the queue, and callers depend on that: aio_cancel() tears down the
AIO container (file_put() + aioc_free()) only when work_cancel()
reports success, because a work item that is not queued may already be
executing on a worker thread (see the comment in fs/aio/aio_cancel.c).
Since commit 6f72f5481d ("sched/wqueue: Refactor delayed and periodical
workqueue") work_cancel() returns OK unconditionally, and commit
d2e01b9055 ("sched/wqueue: harden custom queue lifecycle") kept that
behaviour and dropped -ENOENT from the function documentation. Under
SMP the LTP aio_cancel tests then free the aio container and its file
while the lpwork thread is still executing aio_write_worker() on it,
which ends in a page fault in file_write() (f_inode == NULL) and a
panic.
Return -ENOENT again when the work is not queued, and document it.
For the synchronous variant "not queued" alone does not tell whether
the callback is running: the worker scan does, so report OK when a
running callback was found and waited for, and -ENOENT only when the
work was neither queued nor running.
Assisted-by: Claude Code
Signed-off-by: raiden00pl <raiden00@railab.me>
5a209a853e