Pull io_uring updates part two from Jens Axboe:
- Misc fixes (me, Lin)
- Series from Pavel extending the single task exclusive ring mode,
yielding nice improvements for the common case of having a single
ring per thread (Pavel)
- Cleanup for MSG_RING, removing our IOPOLL hack (Pavel)
- Further poll cleanups and fixes (Pavel)
- Misc cleanups and fixes (Pavel)
* tag 'for-6.2/io_uring-next-2022-12-08' of git://git.kernel.dk/linux: (22 commits)
io_uring/msg_ring: flag target ring as having task_work, if needed
io_uring: skip spinlocking for ->task_complete
io_uring: do msg_ring in target task via tw
io_uring: extract a io_msg_install_complete helper
io_uring: get rid of double locking
io_uring: never run tw and fallback in parallel
io_uring: use tw for putting rsrc
io_uring: force multishot CQEs into task context
io_uring: complete all requests in task context
io_uring: don't check overflow flush failures
io_uring: skip overflow CQE posting for dying ring
io_uring: improve io_double_lock_ctx fail handling
io_uring: dont remove file from msg_ring reqs
io_uring: reshuffle issue_flags
io_uring: don't reinstall quiesce node for each tw
io_uring: improve rsrc quiesce refs checks
io_uring: don't raw spin unlock to match cq_lock
io_uring: combine poll tw handlers
io_uring: improve poll warning handling
io_uring: remove ctx variable in io_poll_check_events
...
Pull io_uring updates from Jens Axboe:
- Always ensure proper ordering in case of CQ ring overflow, which then
means we can remove some work-arounds for that (Dylan)
- Support completion batching for multishot, greatly increasing the
efficiency for those (Dylan)
- Flag epoll/eventfd wakeups done from io_uring, so that we can easily
tell if we're recursing into io_uring again.
Previously, this would have resulted in repeated multishot
notifications if we had a dependency there. That could happen if an
eventfd was registered as the ring eventfd, and we multishot polled
for events on it. Or if an io_uring fd was added to epoll, and
io_uring had a multishot request for the epoll fd.
Test cases here:
https://git.kernel.dk/cgit/liburing/commit/?id=919755a7d0096fda08fb6d65ac54ad8d0fe027cd
Previously these got terminated when the CQ ring eventually
overflowed, now it's handled gracefully (me).
- Tightening of the IOPOLL based completions (Pavel)
- Optimizations of the networking zero-copy paths (Pavel)
- Various tweaks and fixes (Dylan, Pavel)
* tag 'for-6.2/io_uring-2022-12-08' of git://git.kernel.dk/linux: (41 commits)
io_uring: keep unlock_post inlined in hot path
io_uring: don't use complete_post in kbuf
io_uring: spelling fix
io_uring: remove io_req_complete_post_tw
io_uring: allow multishot polled reqs to defer completion
io_uring: remove overflow param from io_post_aux_cqe
io_uring: add lockdep assertion in io_fill_cqe_aux
io_uring: make io_fill_cqe_aux static
io_uring: add io_aux_cqe which allows deferred completion
io_uring: allow defer completion for aux posted cqes
io_uring: defer all io_req_complete_failed
io_uring: always lock in io_apoll_task_func
io_uring: remove iopoll spinlock
io_uring: iopoll protect complete_post
io_uring: inline __io_req_complete_put()
io_uring: remove io_req_tw_post_queue
io_uring: use io_req_task_complete() in timeout
io_uring: hold locks for io_req_complete_failed
io_uring: add completion locking for iopoll
io_uring: kill io_cqring_ev_posted() and __io_cq_unlock_post()
...
->task_complete was added to serialised CQE posting by doing it from
the task context only (or fallback wq when the task is dead), and now we
can use that to avoid taking ->completion_lock while filling CQ entries.
The patch skips spinlocking only in two spots,
__io_submit_flush_completions() and flushing in io_aux_cqe, it's safer
and covers all cases we care about. Extra care is taken to force taking
the lock while queueing overflow entries.
It fundamentally relies on SINGLE_ISSUER to have only one task posting
events. It also need to take into account overflowed CQEs, flushing of
which happens in the cq wait path, and so this implementation also needs
DEFER_TASKRUN to limit waiters. For the same reason we disable it for
SQPOLL, and for IOPOLL as it won't benefit from it in any case.
DEFER_TASKRUN, SQPOLL and IOPOLL requirement may be relaxed in the
future.
Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
Link: https://lore.kernel.org/r/2a8c91fd82cfcdcc1d2e5bac7051fe2c183bda73.1670384893.git.asml.silence@gmail.com
[axboe: modify to apply]
Signed-off-by: Jens Axboe <axboe@kernel.dk>
The only way to fail overflowed CQEs flush is for CQ to be fully packed.
There is one place checking for flush failures, i.e. io_cqring_wait(),
but we limit the number to be waited for by the CQ size, so getting a
failure automatically means that we're done with waiting.
Don't check for failures, rarely but they might spuriously fail CQ
waiting with -EBUSY.
Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
Link: https://lore.kernel.org/r/6b720a45c03345655517f8202cbd0bece2848fb2.1670384893.git.asml.silence@gmail.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
After io_ring_ctx_wait_and_kill() is called there should be no users
poking into rings and so there is no need to post CQEs. So, instead of
trying to post overflowed CQEs into the CQ, drop them. Also, do it
in io_ring_exit_work() in a loop to reduce the number of contexts it
can be executed from and even when it struggles to quiesce the ring we
won't be leaving memory allocated for longer than needed.
Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
Link: https://lore.kernel.org/r/26d13751155a735a3029e24f8d9ca992f810419d.1670384893.git.asml.silence@gmail.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Syzkaller reports a NULL deref bug as follows:
BUG: KASAN: null-ptr-deref in io_tctx_exit_cb+0x53/0xd3
Read of size 4 at addr 0000000000000138 by task file1/1955
CPU: 1 PID: 1955 Comm: file1 Not tainted 6.1.0-rc7-00103-gef4d3ea40565 #75
Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.11.0-2.el7 04/01/2014
Call Trace:
<TASK>
dump_stack_lvl+0xcd/0x134
? io_tctx_exit_cb+0x53/0xd3
kasan_report+0xbb/0x1f0
? io_tctx_exit_cb+0x53/0xd3
kasan_check_range+0x140/0x190
io_tctx_exit_cb+0x53/0xd3
task_work_run+0x164/0x250
? task_work_cancel+0x30/0x30
get_signal+0x1c3/0x2440
? lock_downgrade+0x6e0/0x6e0
? lock_downgrade+0x6e0/0x6e0
? exit_signals+0x8b0/0x8b0
? do_raw_read_unlock+0x3b/0x70
? do_raw_spin_unlock+0x50/0x230
arch_do_signal_or_restart+0x82/0x2470
? kmem_cache_free+0x260/0x4b0
? putname+0xfe/0x140
? get_sigframe_size+0x10/0x10
? do_execveat_common.isra.0+0x226/0x710
? lockdep_hardirqs_on+0x79/0x100
? putname+0xfe/0x140
? do_execveat_common.isra.0+0x238/0x710
exit_to_user_mode_prepare+0x15f/0x250
syscall_exit_to_user_mode+0x19/0x50
do_syscall_64+0x42/0xb0
entry_SYSCALL_64_after_hwframe+0x63/0xcd
RIP: 0023:0x0
Code: Unable to access opcode bytes at 0xffffffffffffffd6.
RSP: 002b:00000000fffb7790 EFLAGS: 00000200 ORIG_RAX: 000000000000000b
RAX: 0000000000000000 RBX: 0000000000000000 RCX: 0000000000000000
RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000000
RBP: 0000000000000000 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000000 R12: 0000000000000000
R13: 0000000000000000 R14: 0000000000000000 R15: 0000000000000000
</TASK>
Kernel panic - not syncing: panic_on_warn set ...
This happens because the adding of task_work from io_ring_exit_work()
isn't synchronized with canceling all work items from eg exec. The
execution of the two are ordered in that they are both run by the task
itself, but if io_tctx_exit_cb() is queued while we're canceling all
work items off exec AND gets executed when the task exits to userspace
rather than in the main loop in io_uring_cancel_generic(), then we can
find current->io_uring == NULL and hit the above crash.
It's safe to add this NULL check here, because the execution of the two
paths are done by the task itself.
Cc: stable@vger.kernel.org
Fixes: d56d938b4b ("io_uring: do ctx initiated file note removal")
Reported-by: syzkaller <syzkaller@googlegroups.com>
Signed-off-by: Harshit Mogalapalli <harshit.m.mogalapalli@oracle.com>
Link: https://lore.kernel.org/r/20221206093833.3812138-1-harshit.m.mogalapalli@oracle.com
[axboe: add code comment and also put an explanation in the commit msg]
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Use the just introduced deferred post cqe completion state when possible
in io_aux_cqe. If not possible fallback to io_post_aux_cqe.
This introduces a complication because of allow_overflow. For deferred
completions we cannot know without locking the completion_lock if it will
overflow (and even if we locked it, another post could sneak in and cause
this cqe to be in overflow).
However since overflow protection is mostly a best effort defence in depth
to prevent infinite loops of CQEs for poll, just checking the overflow bit
is going to be good enough and will result in at most 16 (array size of
deferred cqes) overflows.
Suggested-by: Pavel Begunkov <asml.silence@gmail.com>
Signed-off-by: Dylan Yudaken <dylany@meta.com>
Link: https://lore.kernel.org/r/20221124093559.3780686-6-dylany@meta.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Multishot ops cannot use the compl_reqs list as the request must stay in
the poll list, but that means they need to run each completion without
benefiting from batching.
Here introduce batching infrastructure for only small (ie 16 byte)
CQEs. This restriction is ok because there are no use cases posting 32
byte CQEs.
In the ring keep a batch of up to 16 posted results, and flush in the same
way as compl_reqs.
16 was chosen through experimentation on a microbenchmark ([1]), as well
as trying not to increase the size of the ring too much. This increases
the size to 1472 bytes from 1216.
[1]: 9ac66b36bc
Run with $ make -j && ./benchmark/reg.b -s 1 -t 2000 -r 10
Gives results:
baseline 8309 k/s
8 18807 k/s
16 19338 k/s
32 20134 k/s
Suggested-by: Pavel Begunkov <asml.silence@gmail.com>
Signed-off-by: Dylan Yudaken <dylany@meta.com>
Link: https://lore.kernel.org/r/20221124093559.3780686-5-dylany@meta.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
All failures happen under lock now, and can be deferred. To be consistent
when the failure has happened after some multishot cqe has been
deferred (and keep ordering), always defer failures.
To make this obvious at the caller (and to help prevent a future bug)
rename io_req_complete_failed to io_req_defer_failed.
Signed-off-by: Dylan Yudaken <dylany@meta.com>
Link: https://lore.kernel.org/r/20221124093559.3780686-4-dylany@meta.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
__io_cq_unlock_post() is identical to io_cq_unlock_post(), and
io_cqring_ev_posted() has a single caller so migth as well just inline
it there.
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Pass in EPOLL_URING_WAKE when signaling eventfd or doing poll related
wakups, so that we can check for a circular event dependency between
eventfd and epoll. If this flag is set when our wakeup handlers are
called, then we know we have a dependency that needs to terminate
multishot requests.
eventfd and epoll are the only such possible dependencies.
Cc: stable@vger.kernel.org # 6.0
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Running task work when not needed can unnecessarily delay
operations. Specifically IORING_SETUP_DEFER_TASKRUN tries to avoid running
task work until the user requests it. Therefore do not run it in
io_uring_register any more.
The one catch is that io_rsrc_ref_quiesce expects it to have run in order
to process all outstanding references, and so reorder it's loop to do this.
Signed-off-by: Dylan Yudaken <dylany@meta.com>
Link: https://lore.kernel.org/r/20221107123349.4106213-1-dylany@meta.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
io_cqring_wait (and it's wake function io_has_work) used cached_cq_tail in
order to calculate the number of CQEs. cached_cq_tail is set strictly
before the user visible rings->cq.tail
However as far as userspace is concerned, if io_uring_enter(2) is called
with a minimum number of events, they will verify by checking
rings->cq.tail.
It is therefore possible for io_uring_enter(2) to return early with fewer
events visible to the user.
Instead make the wait functions read from the user visible value, so there
will be no discrepency.
This is triggered eventually by the following reproducer:
struct io_uring_sqe *sqe;
struct io_uring_cqe *cqe;
unsigned int cqe_ready;
struct io_uring ring;
int ret, i;
ret = io_uring_queue_init(N, &ring, 0);
assert(!ret);
while(true) {
for (i = 0; i < N; i++) {
sqe = io_uring_get_sqe(&ring);
io_uring_prep_nop(sqe);
sqe->flags |= IOSQE_ASYNC;
}
ret = io_uring_submit(&ring);
assert(ret == N);
do {
ret = io_uring_wait_cqes(&ring, &cqe, N, NULL, NULL);
} while(ret == -EINTR);
cqe_ready = io_uring_cq_ready(&ring);
assert(!ret);
assert(cqe_ready == N);
io_uring_cq_advance(&ring, N);
}
Fixes: ad3eb2c89f ("io_uring: split overflow state into SQ and CQ side")
Signed-off-by: Dylan Yudaken <dylany@meta.com>
Link: https://lore.kernel.org/r/20221108153016.1854297-1-dylany@meta.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
It is possible for tw to lock the ring, and this was not propogated out to
io_run_local_work. This can cause an unlock to be missed.
Instead pass a pointer to locked into __io_run_local_work.
Fixes: 8ac5d85a89 ("io_uring: add local task_work run helper that is entered locked")
Signed-off-by: Dylan Yudaken <dylany@meta.com>
Link: https://lore.kernel.org/r/20221027144429.3971400-3-dylany@meta.com
[axboe: WARN_ON() -> WARN_ON_ONCE() and add a minor comment]
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Remove submitter parameter from __io_uring_add_tctx_node.
It was only called from one place, and we can do that logic in that one
place.
Signed-off-by: Dylan Yudaken <dylany@fb.com>
Fixes: 97bbdc06a4 ("io_uring: add IORING_SETUP_SINGLE_ISSUER")
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Pull block updates from Jens Axboe:
- NVMe pull requests via Christoph:
- handle number of queue changes in the TCP and RDMA drivers
(Daniel Wagner)
- allow changing the number of queues in nvmet (Daniel Wagner)
- also consider host_iface when checking ip options (Daniel
Wagner)
- don't map pages which can't come from HIGHMEM (Fabio M. De
Francesco)
- avoid unnecessary flush bios in nvmet (Guixin Liu)
- shrink and better pack the nvme_iod structure (Keith Busch)
- add comment for unaligned "fake" nqn (Linjun Bao)
- print actual source IP address through sysfs "address" attr
(Martin Belanger)
- various cleanups (Jackie Liu, Wolfram Sang, Genjian Zhang)
- handle effects after freeing the request (Keith Busch)
- copy firmware_rev on each init (Keith Busch)
- restrict management ioctls to admin (Keith Busch)
- ensure subsystem reset is single threaded (Keith Busch)
- report the actual number of tagset maps in nvme-pci (Keith
Busch)
- small fabrics authentication fixups (Christoph Hellwig)
- add common code for tagset allocation and freeing (Christoph
Hellwig)
- stop using the request_queue in nvmet (Christoph Hellwig)
- set min_align_mask before calculating max_hw_sectors (Rishabh
Bhatnagar)
- send a rediscover uevent when a persistent discovery controller
reconnects (Sagi Grimberg)
- misc nvmet-tcp fixes (Varun Prakash, zhenwei pi)
- MD pull request via Song:
- Various raid5 fix and clean up, by Logan Gunthorpe and David
Sloan.
- Raid10 performance optimization, by Yu Kuai.
- sbitmap wakeup hang fixes (Hugh, Keith, Jan, Yu)
- IO scheduler switching quisce fix (Keith)
- s390/dasd block driver updates (Stefan)
- support for recovery for the ublk driver (ZiyangZhang)
- rnbd drivers fixes and updates (Guoqing, Santosh, ye, Christoph)
- blk-mq and null_blk map fixes (Bart)
- various bcache fixes (Coly, Jilin, Jules)
- nbd signal hang fix (Shigeru)
- block writeback throttling fix (Yu)
- optimize the passthrough mapping handling (me)
- prepare block cgroups to being gendisk based (Christoph)
- get rid of an old PSI hack in the block layer, moving it to the
callers instead where it belongs (Christoph)
- blk-throttle fixes and cleanups (Yu)
- misc fixes and cleanups (Liu Shixin, Liu Song, Miaohe, Pankaj,
Ping-Xiang, Wolfram, Saurabh, Li Jinlin, Li Lei, Lin, Li zeming,
Miaohe, Bart, Coly, Gaosheng
* tag 'for-6.1/block-2022-10-03' of git://git.kernel.dk/linux: (162 commits)
sbitmap: fix lockup while swapping
block: add rationale for not using blk_mq_plug() when applicable
block: adapt blk_mq_plug() to not plug for writes that require a zone lock
s390/dasd: use blk_mq_alloc_disk
blk-cgroup: don't update the blkg lookup hint in blkg_conf_prep
nvmet: don't look at the request_queue in nvmet_bdev_set_limits
nvmet: don't look at the request_queue in nvmet_bdev_zone_mgmt_emulate_all
blk-mq: use quiesced elevator switch when reinitializing queues
block: replace blk_queue_nowait with bdev_nowait
nvme: remove nvme_ctrl_init_connect_q
nvme-loop: use the tagset alloc/free helpers
nvme-loop: store the generic nvme_ctrl in set->driver_data
nvme-loop: initialize sqsize later
nvme-fc: use the tagset alloc/free helpers
nvme-fc: store the generic nvme_ctrl in set->driver_data
nvme-fc: keep ctrl->sqsize in sync with opts->queue_size
nvme-rdma: use the tagset alloc/free helpers
nvme-rdma: store the generic nvme_ctrl in set->driver_data
nvme-tcp: use the tagset alloc/free helpers
nvme-tcp: store the generic nvme_ctrl in set->driver_data
...
Pull io_uring updates from Jens Axboe:
- Add supported for more directly managed task_work running.
This is beneficial for real world applications that end up issuing
lots of system calls as part of handling work. Normal task_work will
always execute as we transition in and out of the kernel, even for
"unrelated" system calls. It's more efficient to defer the handling
of io_uring's deferred work until the application wants it to be run,
generally in batches.
As part of ongoing work to write an io_uring network backend for
Thrift, this has been shown to greatly improve performance. (Dylan)
- Add IOPOLL support for passthrough (Kanchan)
- Improvements and fixes to the send zero-copy support (Pavel)
- Partial IO handling fixes (Pavel)
- CQE ordering fixes around CQ ring overflow (Pavel)
- Support sendto() for non-zc as well (Pavel)
- Support sendmsg for zerocopy (Pavel)
- Networking iov_iter fix (Stefan)
- Misc fixes and cleanups (Pavel, me)
* tag 'for-6.1/io_uring-2022-10-03' of git://git.kernel.dk/linux: (56 commits)
io_uring/net: fix notif cqe reordering
io_uring/net: don't update msg_name if not provided
io_uring: don't gate task_work run on TIF_NOTIFY_SIGNAL
io_uring/rw: defer fsnotify calls to task context
io_uring/net: fix fast_iov assignment in io_setup_async_msg()
io_uring/net: fix non-zc send with address
io_uring/net: don't skip notifs for failed requests
io_uring/rw: don't lose short results on io_setup_async_rw()
io_uring/rw: fix unexpected link breakage
io_uring/net: fix cleanup double free free_iov init
io_uring: fix CQE reordering
io_uring/net: fix UAF in io_sendrecv_fail()
selftest/net: adjust io_uring sendzc notif handling
io_uring: ensure local task_work marks task as running
io_uring/net: zerocopy sendmsg
io_uring/net: combine fail handlers
io_uring/net: rename io_sendzc()
io_uring/net: support non-zerocopy sendto
io_uring/net: refactor io_setup_async_addr
io_uring/net: don't lose partial send_zc on fail
...
