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8c9cb6cd9a
Now io_complete_rw_common() puts a ref, extra io_req_put() in
io_iopoll_queue() causes undeflow. Remove it.
[ 455.998620] refcount_t: underflow; use-after-free.
[ 455.998743] WARNING: CPU: 6 PID: 285394 at lib/refcount.c:28
refcount_warn_saturate+0xae/0xf0
[ 455.998772] CPU: 6 PID: 285394 Comm: read-write2 Tainted: G
I E 5.8.0-rc2-00048-g1b1aa738f167-dirty #509
[ 455.998772] RIP: 0010:refcount_warn_saturate+0xae/0xf0
...
[ 455.998778] Call Trace:
[ 455.998778] io_put_req+0x44/0x50
[ 455.998778] io_iopoll_complete+0x245/0x370
[ 455.998779] io_iopoll_getevents+0x12f/0x1a0
[ 455.998779] io_iopoll_reap_events.part.0+0x5e/0xa0
[ 455.998780] io_ring_ctx_wait_and_kill+0x132/0x1c0
[ 455.998780] io_uring_release+0x20/0x30
[ 455.998780] __fput+0xcd/0x230
[ 455.998781] ____fput+0xe/0x10
[ 455.998781] task_work_run+0x67/0xa0
[ 455.998781] do_exit+0x35d/0xb70
[ 455.998782] do_group_exit+0x43/0xa0
[ 455.998783] get_signal+0x140/0x900
[ 455.998783] do_signal+0x37/0x780
[ 455.998784] __prepare_exit_to_usermode+0x126/0x1c0
[ 455.998785] __syscall_return_slowpath+0x3b/0x1c0
[ 455.998785] do_syscall_64+0x5f/0xa0
[ 455.998785] entry_SYSCALL_64_after_hwframe+0x44/0xa9
Fixes: a1d7c393c4 ("io_uring: enable READ/WRITE to use deferred completions")
Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Linux kernel
============
There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.
In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``. The formatted documentation can also be read online at:
https://www.kernel.org/doc/html/latest/
There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.
Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.