There are lots of spots open-coding this functionality, add a generic
helper that does the node lookup in a speculation safe way.
Signed-off-by: Jens Axboe <axboe@kernel.dk>
For files, there's nr_user_files/file_table/file_data, and buffers have
nr_user_bufs/user_bufs/buf_data. There's no reason why file_table and
file_data can't be the same thing, and ditto for the buffer side. That
gets rid of more io_ring_ctx state that's in two spots rather than just
being in one spot, as it should be. Put all the registered file data in
one locations, and ditto on the buffer front.
This also avoids having both io_rsrc_data->nodes being an allocated
array, and ->user_bufs[] or ->file_table.nodes. There's no reason to
have this information duplicated. Keep it in one spot, io_rsrc_data,
along with how many resources are available.
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Add the empty node initializing to the preinit part of the io_kiocb
allocation, and reset them if they have been used.
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Rather than allocate an io_rsrc_node for an empty/sparse buffer entry,
add a const entry that can be used for that. This just needs checking
for writing the tag, and the put check needs to check for that sparse
node rather than NULL for validity.
This avoids allocating rsrc nodes for sparse buffer entries.
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Work in progress, but get rid of the per-ring serialization of resource
nodes, like registered buffers and files. Main issue here is that one
node can otherwise hold up a bunch of other nodes from getting freed,
which is especially a problem for file resource nodes and networked
workloads where some descriptors may not see activity in a long time.
As an example, instantiate an io_uring ring fd and create a sparse
registered file table. Even 2 will do. Then create a socket and register
it as fixed file 0, F0. The number of open files in the app is now 5,
with 0/1/2 being the usual stdin/out/err, 3 being the ring fd, and 4
being the socket. Register this socket (eg "the listener") in slot 0 of
the registered file table. Now add an operation on the socket that uses
slot 0. Finally, loop N times, where each loop creates a new socket,
registers said socket as a file, then unregisters the socket, and
finally closes the socket. This is roughly similar to what a basic
accept loop would look like.
At the end of this loop, it's not unreasonable to expect that there
would still be 5 open files. Each socket created and registered in the
loop is also unregistered and closed. But since the listener socket
registered first still has references to its resource node due to still
being active, each subsequent socket unregistration is stuck behind it
for reclaim. Hence 5 + N files are still open at that point, where N is
awaiting the final put held up by the listener socket.
Rewrite the io_rsrc_node handling to NOT rely on serialization. Struct
io_kiocb now gets explicit resource nodes assigned, with each holding a
reference to the parent node. A parent node is either of type FILE or
BUFFER, which are the two types of nodes that exist. A request can have
two nodes assigned, if it's using both registered files and buffers.
Since request issue and task_work completion is both under the ring
private lock, no atomics are needed to handle these references. It's a
simple unlocked inc/dec. As before, the registered buffer or file table
each hold a reference as well to the registered nodes. Final put of the
node will remove the node and free the underlying resource, eg unmap the
buffer or put the file.
Outside of removing the stall in resource reclaim described above, it
has the following advantages:
1) It's a lot simpler than the previous scheme, and easier to follow.
No need to specific quiesce handling anymore.
2) There are no resource node allocations in the fast path, all of that
happens at resource registration time.
3) The structs related to resource handling can all get simplified
quite a bit, like io_rsrc_node and io_rsrc_data. io_rsrc_put can
go away completely.
4) Handling of resource tags is much simpler, and doesn't require
persistent storage as it can simply get assigned up front at
registration time. Just copy them in one-by-one at registration time
and assign to the resource node.
The only real downside is that a request is now explicitly limited to
pinning 2 resources, one file and one buffer, where before just
assigning a resource node to a request would pin all of them. The upside
is that it's easier to follow now, as an individual resource is
explicitly referenced and assigned to the request.
With this in place, the above mentioned example will be using exactly 5
files at the end of the loop, not N.
Signed-off-by: Jens Axboe <axboe@kernel.dk>
When io_uring starts a write, it'll call kiocb_start_write() to bump the
super block rwsem, preventing any freezes from happening while that
write is in-flight. The freeze side will grab that rwsem for writing,
excluding any new writers from happening and waiting for existing writes
to finish. But io_uring unconditionally uses kiocb_start_write(), which
will block if someone is currently attempting to freeze the mount point.
This causes a deadlock where freeze is waiting for previous writes to
complete, but the previous writes cannot complete, as the task that is
supposed to complete them is blocked waiting on starting a new write.
This results in the following stuck trace showing that dependency with
the write blocked starting a new write:
task:fio state:D stack:0 pid:886 tgid:886 ppid:876
Call trace:
__switch_to+0x1d8/0x348
__schedule+0x8e8/0x2248
schedule+0x110/0x3f0
percpu_rwsem_wait+0x1e8/0x3f8
__percpu_down_read+0xe8/0x500
io_write+0xbb8/0xff8
io_issue_sqe+0x10c/0x1020
io_submit_sqes+0x614/0x2110
__arm64_sys_io_uring_enter+0x524/0x1038
invoke_syscall+0x74/0x268
el0_svc_common.constprop.0+0x160/0x238
do_el0_svc+0x44/0x60
el0_svc+0x44/0xb0
el0t_64_sync_handler+0x118/0x128
el0t_64_sync+0x168/0x170
INFO: task fsfreeze:7364 blocked for more than 15 seconds.
Not tainted 6.12.0-rc5-00063-g76aaf945701c #7963
with the attempting freezer stuck trying to grab the rwsem:
task:fsfreeze state:D stack:0 pid:7364 tgid:7364 ppid:995
Call trace:
__switch_to+0x1d8/0x348
__schedule+0x8e8/0x2248
schedule+0x110/0x3f0
percpu_down_write+0x2b0/0x680
freeze_super+0x248/0x8a8
do_vfs_ioctl+0x149c/0x1b18
__arm64_sys_ioctl+0xd0/0x1a0
invoke_syscall+0x74/0x268
el0_svc_common.constprop.0+0x160/0x238
do_el0_svc+0x44/0x60
el0_svc+0x44/0xb0
el0t_64_sync_handler+0x118/0x128
el0t_64_sync+0x168/0x170
Fix this by having the io_uring side honor IOCB_NOWAIT, and only attempt a
blocking grab of the super block rwsem if it isn't set. For normal issue
where IOCB_NOWAIT would always be set, this returns -EAGAIN which will
have io_uring core issue a blocking attempt of the write. That will in
turn also get completions run, ensuring forward progress.
Since freezing requires CAP_SYS_ADMIN in the first place, this isn't
something that can be triggered by a regular user.
Cc: stable@vger.kernel.org # 5.10+
Reported-by: Peter Mann <peter.mann@sh.cz>
Link: https://lore.kernel.org/io-uring/38c94aec-81c9-4f62-b44e-1d87f5597644@sh.cz
Signed-off-by: Jens Axboe <axboe@kernel.dk>
It's only used from __io_req_set_rsrc_node(), and it takes both the ctx
and node itself, while never using the ctx. Just open-code the basic
refs++ in __io_req_set_rsrc_node() instead.
Signed-off-by: Jens Axboe <axboe@kernel.dk>
In preparation for not pinning the whole registered file table, open
code the second potential direct file assignment. This will be handled
by appropriate helpers in the future, for now just do it manually.
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Doesn't matter right now as there's still some bytes left for it, but
let's prepare for the io_kiocb potentially growing and add a specific
freeptr offset for it.
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Useful for testing performance/efficiency impact of registered files
and buffers, vs (particularly) non-registered files.
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Generally applications have 1 or a few waits of waiting, yet they pass
in a struct io_uring_getevents_arg every time. This needs to get copied
and, in turn, the timeout value needs to get copied.
Rather than do this for every invocation, allow the application to
register a fixed set of wait regions that can simply be indexed when
asking the kernel to wait on events.
At ring setup time, the application can register a number of these wait
regions and initialize region/index 0 upfront:
struct io_uring_reg_wait *reg;
reg = io_uring_setup_reg_wait(ring, nr_regions, &ret);
/* set timeout and mark as set, sigmask/sigmask_sz as needed */
reg->ts.tv_sec = 0;
reg->ts.tv_nsec = 100000;
reg->flags = IORING_REG_WAIT_TS;
where nr_regions >= 1 && nr_regions <= PAGE_SIZE / sizeof(*reg). The
above initializes index 0, but 63 other regions can be initialized,
if needed. Now, instead of doing:
struct __kernel_timespec timeout = { .tv_nsec = 100000, };
io_uring_submit_and_wait_timeout(ring, &cqe, nr, &t, NULL);
to wait for events for each submit_and_wait, or just wait, operation, it
can just reference the above region at offset 0 and do:
io_uring_submit_and_wait_reg(ring, &cqe, nr, 0);
to achieve the same goal of waiting 100usec without needing to copy
both struct io_uring_getevents_arg (24b) and struct __kernel_timeout
(16b) for each invocation. Struct io_uring_reg_wait looks as follows:
struct io_uring_reg_wait {
struct __kernel_timespec ts;
__u32 min_wait_usec;
__u32 flags;
__u64 sigmask;
__u32 sigmask_sz;
__u32 pad[3];
__u64 pad2[2];
};
embedding the timeout itself in the region, rather than passing it as
a pointer as well. Note that the signal mask is still passed as a
pointer, both for compatability reasons, but also because there doesn't
seem to be a lot of high frequency waits scenarios that involve setting
and resetting the signal mask for each wait.
The application is free to modify any region before a wait call, or it
can use keep multiple regions with different settings to avoid needing to
modify the same one for wait calls. Up to a page size of regions is mapped
by default, allowing PAGE_SIZE / 64 available regions for use.
The registered region must fit within a page. On a 4kb page size system,
that allows for 64 wait regions if a full page is used, as the size of
struct io_uring_reg_wait is 64b. The region registered must be aligned
to io_uring_reg_wait in size. It's valid to register less than 64
entries.
In network performance testing with zero-copy, this reduced the time
spent waiting on the TX side from 3.12% to 0.3% and the RX side from 4.4%
to 0.3%.
Wait regions are fixed for the lifetime of the ring - once registered,
they are persistent until the ring is torn down. The regions support
minimum wait timeout as well as the regular waits.
Signed-off-by: Jens Axboe <axboe@kernel.dk>
In scenarios where a high frequency of wait events are seen, the copy
of the struct io_uring_getevents_arg is quite noticeable in the
profiles in terms of time spent. It can be seen as up to 3.5-4.5%.
Rewrite the copy-in logic, saving about 0.5% of the time.
Reviewed-by: Keith Busch <kbusch@kernel.org>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
This avoids intermediate storage for turning a __kernel_timespec
user pointer into an on-stack struct timespec64, only then to turn it
into a ktime_t.
Signed-off-by: Jens Axboe <axboe@kernel.dk>
io_sqd_handle_event() just does a mutex unlock/lock dance when it's
supposed to park, somewhat relying on full ordering with the thread
trying to park it which does a similar unlock/lock dance on sqd->lock.
However, with adaptive spinning on mutexes, this can waste an awful
lot of time. Normally this isn't very noticeable, as parking and
unparking the thread isn't a common (or fast path) occurence. However,
in testing ring resizing, it's testing exactly that, as each resize
will require the SQPOLL to safely park and unpark.
Have io_sq_thread_park() explicitly wait on sqd->park_pending being
zero before attempting to grab the sqd->lock again.
In a resize test, this brings the runtime of SQPOLL down from about
60 seconds to a few seconds, just like the !SQPOLL tests. And saves
a ton of spinning time on the mutex, on both sides.
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Once a ring has been created, the size of the CQ and SQ rings are fixed.
Usually this isn't a problem on the SQ ring side, as it merely controls
the available number of requests that can be submitted in a single
system call, and there's rarely a need to change that.
For the CQ ring, it's a different story. For most efficient use of
io_uring, it's important that the CQ ring never overflows. This means
that applications must size it for the worst case scenario, which can
be wasteful.
Add IORING_REGISTER_RESIZE_RINGS, which allows an application to resize
the existing rings. It takes a struct io_uring_params argument, the same
one which is used to setup the ring initially, and resizes rings
according to the sizes given.
Certain properties are always inherited from the original ring setup,
like SQE128/CQE32 and other setup options. The implementation only
allows flag associated with how the CQ ring is sized and clamped.
Existing unconsumed SQE and CQE entries are copied as part of the
process. If either the SQ or CQ resized destination ring cannot hold the
entries already present in the source rings, then the operation is failed
with -EOVERFLOW. Any register op holds ->uring_lock, which prevents new
submissions, and the internal mapping holds the completion lock as well
across moving CQ ring state.
To prevent races between mmap and ring resizing, add a mutex that's
solely used to serialize ring resize and mmap. mmap_sem can't be used
here, as as fork'ed process may be doing mmaps on the ring as well.
The ctx->resize_lock is held across mmap operations, and the resize
will grab it before swapping out the already mapped new data.
Signed-off-by: Jens Axboe <axboe@kernel.dk>
The later mapping will actually check this too, but in terms of code
clarify, explicitly check for whether or not the rings and sqes are
valid during validation. That makes it explicit that if they are
non-NULL, they are valid and can get mapped.
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Abstract out a io_uring_fill_params() helper, which fills out the
necessary bits of struct io_uring_params. Add it to io_uring.h as well,
in preparation for having another internal user of it.
Signed-off-by: Jens Axboe <axboe@kernel.dk>
In preparation for needing this somewhere else, move the definitions
for the maximum CQ and SQ ring size into io_uring.h. Make the
rings_size() helper available as well, and have it take just the setup
flags argument rather than the fill ring pointer. That's all that is
needed.
Signed-off-by: Jens Axboe <axboe@kernel.dk>
We keep user pointers in an union, which could be a user buffer or a
user pointer to msghdr. What is confusing is that it potenitally reads
and assigns sqe->addr as one type but then uses it as another via the
union. Even more, it's not even consistent across copy and zerocopy
versions.
Make send and sendmsg setup helpers read sqe->addr and treat it as the
right type from the beginning. The end goal would be to get rid of
the use of struct io_sr_msg::umsg for send requests as we only need it
at the prep side.
Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
Link: https://lore.kernel.org/r/685d788605f5d78af18802fcabf61ba65cfd8002.1729607201.git.asml.silence@gmail.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
For non "msg" requests we copy the address at the prep stage and there
is no need to store the address user pointer long term. Pass the SQE
into io_send_setup(), let it parse it, and remove struct io_sr_msg addr
addr_len fields. It saves some space and also less confusing.
Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
Link: https://lore.kernel.org/r/db3dce544e17ca9d4b17d2506fbbac1da8a87824.1729607201.git.asml.silence@gmail.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Let's keep it close with the actual import, there's no reason to do this
on the prep side. With that, we can drop one of the branches checking
for whether or not IORING_RECVSEND_FIXED_BUF is set.
As a side-effect, get rid of req->imu usage.
Signed-off-by: Jens Axboe <axboe@kernel.dk>
All callers already hold the ring lock and hence are passing '0',
remove the argument and the conditional locking that it controlled.
Suggested-by: Pavel Begunkov <asml.silence@gmail.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
It's assigned in the same function that it's being used, get rid of
it. A local variable will do just fine.
Signed-off-by: Jens Axboe <axboe@kernel.dk>
It's pretty pointless to use io_kiocb as intermediate storage for this,
so split the validity check and the actual usage. The resource node is
assigned upfront at prep time, to prevent it from going away. The actual
import is never called with the ctx->uring_lock held, so grab it for
the import.
Signed-off-by: Jens Axboe <axboe@kernel.dk>
iter->bvec is already set to imu->bvec - remove the one dead assignment
and turn the other one into an addition instead.
Signed-off-by: Jens Axboe <axboe@kernel.dk>
We have too many helpers posting CQEs, instead of tracing completion
events before filling in a CQE and thus having to pass all the data,
set the CQE first, pass it to the tracing helper and let it extract
everything it needs.
Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
Link: https://lore.kernel.org/r/b83c1ca9ee5aed2df0f3bb743bf5ed699cce4c86.1729267437.git.asml.silence@gmail.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Convert to using kvmalloc/kfree() for the hash tables, and while at it,
make it handle low memory situations better.
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Any access to the table is protected by ctx->uring_lock now anyway, the
per-bucket locking doesn't buy us anything.
Signed-off-by: Jens Axboe <axboe@kernel.dk>
It serves no purposes anymore, all it does is delete the hash list
entry. task_work always has the ring locked.
Signed-off-by: Jens Axboe <axboe@kernel.dk>
io_uring maintains two hash lists of inflight requests:
1) ctx->cancel_table_locked. This is used when the caller has the
ctx->uring_lock held already. This is only an issue side parameter,
as removal or task_work will always have it held.
2) ctx->cancel_table. This is used when the issuer does NOT have the
ctx->uring_lock held, and relies on the table spinlocks for access.
However, it's pretty trivial to simply grab the lock in the one spot
where we care about it, for insertion. With that, we can kill the
unlocked table (and get rid of the _locked postfix for the other one).
Signed-off-by: Jens Axboe <axboe@kernel.dk>
It's always req->ctx being used anyway, having this as a separate
argument (that is then not even used) just makes it more confusing.
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Normally MSG_RING requires both a source and a destination ring. But
some users don't always have a ring avilable to send a message from, yet
they still need to notify a target ring.
Add support for using io_uring_register(2) without having a source ring,
using a file descriptor of -1 for that. Internally those are called
blind registration opcodes. Implement IORING_REGISTER_SEND_MSG_RING as a
blind opcode, which simply takes an sqe that the application can put on
the stack and use the normal liburing helpers to initialize it. Then the
app can call:
io_uring_register(-1, IORING_REGISTER_SEND_MSG_RING, &sqe, 1);
and get the same behavior in terms of the target, where a CQE is posted
with the details given in the sqe.
For now this takes a single sqe pointer argument, and hence arg must
be set to that, and nr_args must be 1. Could easily be extended to take
an array of sqes, but for now let's keep it simple.
Link: https://lore.kernel.org/r/20240924115932.116167-3-axboe@kernel.dk
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Mostly just to skip them taking an io_kiocb, rather just pass in the
ctx and io_msg directly.
In preparation for being able to issue a MSG_RING request without
having an io_kiocb. No functional changes in this patch.
Link: https://lore.kernel.org/r/20240924115932.116167-2-axboe@kernel.dk
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Everything else about the io_uring eventfd support is nicely kept
private to that code, except the cached_cq_tail tracking. With
everything else in place, move io_eventfd_flush_signal() to using
the ev_fd grab+release helpers, which then enables the direct use of
io_ev_fd for this tracking too.
Link: https://lore.kernel.org/r/20240921080307.185186-7-axboe@kernel.dk
Signed-off-by: Jens Axboe <axboe@kernel.dk>
It's a bit hard to read what guards the triggering, move it into a
helper and add a comment explaining it too. This additionally moves
the ev_fd == NULL check in there as well.
Link: https://lore.kernel.org/r/20240921080307.185186-5-axboe@kernel.dk
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Rejection of IOSQE_FIXED_FILE combined with IORING_OP_[GS]ETXATTR
is fine - these do not take a file descriptor, so such combination
makes no sense. The checks are misplaced, though - as it is, they
triggers on IORING_OP_F[GS]ETXATTR as well, and those do take
a file reference, no matter the origin.
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
A previous commit improved how !FMODE_NOWAIT is dealt with, but
inadvertently negated a check whilst doing so. This caused -EAGAIN to be
returned from reading files with O_NONBLOCK set. Fix up the check for
REQ_F_SUPPORT_NOWAIT.
Reported-by: Julian Orth <ju.orth@gmail.com>
Link: https://github.com/axboe/liburing/issues/1270
Fixes: f7c9134385 ("io_uring/rw: allow pollable non-blocking attempts for !FMODE_NOWAIT")
Signed-off-by: Jens Axboe <axboe@kernel.dk>
When the sqpoll is exiting and cancels pending work items, it may need
to run task_work. If this happens from within io_uring_cancel_generic(),
then it may be under waiting for the io_uring_task waitqueue. This
results in the below splat from the scheduler, as the ring mutex may be
attempted grabbed while in a TASK_INTERRUPTIBLE state.
Ensure that the task state is set appropriately for that, just like what
is done for the other cases in io_run_task_work().
do not call blocking ops when !TASK_RUNNING; state=1 set at [<0000000029387fd2>] prepare_to_wait+0x88/0x2fc
WARNING: CPU: 6 PID: 59939 at kernel/sched/core.c:8561 __might_sleep+0xf4/0x140
Modules linked in:
CPU: 6 UID: 0 PID: 59939 Comm: iou-sqp-59938 Not tainted 6.12.0-rc3-00113-g8d020023b155 #7456
Hardware name: linux,dummy-virt (DT)
pstate: 61400005 (nZCv daif +PAN -UAO -TCO +DIT -SSBS BTYPE=--)
pc : __might_sleep+0xf4/0x140
lr : __might_sleep+0xf4/0x140
sp : ffff80008c5e7830
x29: ffff80008c5e7830 x28: ffff0000d93088c0 x27: ffff60001c2d7230
x26: dfff800000000000 x25: ffff0000e16b9180 x24: ffff80008c5e7a50
x23: 1ffff000118bcf4a x22: ffff0000e16b9180 x21: ffff0000e16b9180
x20: 000000000000011b x19: ffff80008310fac0 x18: 1ffff000118bcd90
x17: 30303c5b20746120 x16: 74657320313d6574 x15: 0720072007200720
x14: 0720072007200720 x13: 0720072007200720 x12: ffff600036c64f0b
x11: 1fffe00036c64f0a x10: ffff600036c64f0a x9 : dfff800000000000
x8 : 00009fffc939b0f6 x7 : ffff0001b6327853 x6 : 0000000000000001
x5 : ffff0001b6327850 x4 : ffff600036c64f0b x3 : ffff8000803c35bc
x2 : 0000000000000000 x1 : 0000000000000000 x0 : ffff0000e16b9180
Call trace:
__might_sleep+0xf4/0x140
mutex_lock+0x84/0x124
io_handle_tw_list+0xf4/0x260
tctx_task_work_run+0x94/0x340
io_run_task_work+0x1ec/0x3c0
io_uring_cancel_generic+0x364/0x524
io_sq_thread+0x820/0x124c
ret_from_fork+0x10/0x20
Cc: stable@vger.kernel.org
Fixes: af5d68f889 ("io_uring/sqpoll: manage task_work privately")
Signed-off-by: Jens Axboe <axboe@kernel.dk>
For placeholder buffers, &dummy_ubuf is assigned which is a static
value. When buffers are attempted cloned, don't attempt to grab a
reference to it, as we both don't need it and it'll actively fail as
dummy_ubuf doesn't have a valid reference count setup.
Link: https://lore.kernel.org/io-uring/Zw8dkUzsxQ5LgAJL@ly-workstation/
Reported-by: Lai, Yi <yi1.lai@linux.intel.com>
Fixes: 7cc2a6eadc ("io_uring: add IORING_REGISTER_COPY_BUFFERS method")
Signed-off-by: Jens Axboe <axboe@kernel.dk>
When an application uses SQPOLL, it must wait for the SQPOLL thread to
consume SQE entries, if it fails to get an sqe when calling
io_uring_get_sqe(). It can do so by calling io_uring_enter(2) with the
flag value of IORING_ENTER_SQ_WAIT. In liburing, this is generally done
with io_uring_sqring_wait(). There's a natural expectation that once
this call returns, a new SQE entry can be retrieved, filled out, and
submitted. However, the kernel uses the cached sq head to determine if
the SQRING is full or not. If the SQPOLL thread is currently in the
process of submitting SQE entries, it may have updated the cached sq
head, but not yet committed it to the SQ ring. Hence the kernel may find
that there are SQE entries ready to be consumed, and return successfully
to the application. If the SQPOLL thread hasn't yet committed the SQ
ring entries by the time the application returns to userspace and
attempts to get a new SQE, it will fail getting a new SQE.
Fix this by having io_sqring_full() always use the user visible SQ ring
head entry, rather than the internally cached one.
Cc: stable@vger.kernel.org # 5.10+
Link: https://github.com/axboe/liburing/discussions/1267
Reported-by: Benedek Thaler <thaler@thaler.hu>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
some of those used to be needed, some had been cargo-culted for
no reason...
Reviewed-by: Christian Brauner <brauner@kernel.org>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
The checking for whether or not io_uring can do a non-blocking read or
write attempt is gated on FMODE_NOWAIT. However, if the file is
pollable, it's feasible to just check if it's currently in a state in
which it can sanely receive or send _some_ data.
This avoids unnecessary io-wq punts, and repeated worthless retries
before doing that punt, by assuming that some data can get delivered
or received if poll tells us that is true. It also allows multishot
reads to properly work with these types of files, enabling a bit of
a cleanup of the logic that:
c9d952b910 ("io_uring/rw: fix cflags posting for single issue multishot read")
had to put in place.
Signed-off-by: Jens Axboe <axboe@kernel.dk>
If multishot gets disabled, and hence the request will get terminated
rather than persist for more iterations, then posting the CQE with the
right cflags is still important. Most notably, the buffer reference
needs to be included.
Refactor the return of __io_read() a bit, so that the provided buffer
is always put correctly, and hence returned to the application.
Reported-by: Sharon Rosner <Sharon Rosner>
Link: https://github.com/axboe/liburing/issues/1257
Cc: stable@vger.kernel.org
Fixes: 2a975d426c ("io_uring/rw: don't allow multishot reads without NOWAIT support")
Signed-off-by: Jens Axboe <axboe@kernel.dk>
If the recv returns zero, or an error, then it doesn't matter if more
data has already been received for this buffer. A condition like that
should terminate the multishot receive. Rather than pass in the
collected return value, pass in whether to terminate or keep the recv
going separately.
Note that this isn't a bug right now, as the only way to get there is
via setting MSG_WAITALL with multishot receive. And if an application
does that, then -EINVAL is returned anyway. But it seems like an easy
bug to introduce, so let's make it a bit more explicit.
Link: https://github.com/axboe/liburing/issues/1246
Cc: stable@vger.kernel.org
Fixes: b3fdea6ecb ("io_uring: multishot recv")
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Apply __force cast to restricted io_req_flags_t type to fix
the following sparse warning:
io_uring/io_uring.c:2026:23: sparse: warning: cast to restricted io_req_flags_t
No functional changes intended.
Signed-off-by: Min-Hua Chen <minhuadotchen@gmail.com>
Link: https://lore.kernel.org/r/20240922104132.157055-1-minhuadotchen@gmail.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Exit the percpu ref when cache init fails to free the data memory with
in struct percpu_ref.
Fixes: 206aefde4f ("io_uring: reduce/pack size of io_ring_ctx")
Signed-off-by: Guixin Liu <kanie@linux.alibaba.com>
Reviewed-by: Gabriel Krisman Bertazi <krisman@suse.de>
Link: https://lore.kernel.org/r/20240923100512.64638-1-kanie@linux.alibaba.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
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Merge tag 'for-6.12/io_uring-20240922' of git://git.kernel.dk/linux
Pull more io_uring updates from Jens Axboe:
"Mostly just a set of fixes in here, or little changes that didn't get
included in the initial pull request. This contains:
- Move the SQPOLL napi polling outside the submission lock (Olivier)
- Rename of the "copy buffers" API that got added in the 6.12 merge
window. There's really no copying going on, it's just referencing
the buffers. After a bit of consideration, decided that it was
better to simply rename this to avoid potential confusion (me)
- Shrink struct io_mapped_ubuf from 48 to 32 bytes, by changing it to
start + len tracking rather than having start / end in there, and
by removing the caching of folio_mask when we can just calculate it
from folio_shift when we need it (me)
- Fixes for the SQPOLL affinity checking (me, Felix)
- Fix for how cqring waiting checks for the presence of task_work.
Just check it directly rather than check for a specific
notification mechanism (me)
- Tweak to how request linking is represented in tracing (me)
- Fix a syzbot report that deliberately sets up a huge list of
overflow entries, and then hits rcu stalls when flushing this list.
Just check for the need to preempt, and drop/reacquire locks in the
loop. There's no state maintained over the loop itself, and each
entry is yanked from head-of-list (me)"
* tag 'for-6.12/io_uring-20240922' of git://git.kernel.dk/linux:
io_uring: check if we need to reschedule during overflow flush
io_uring: improve request linking trace
io_uring: check for presence of task_work rather than TIF_NOTIFY_SIGNAL
io_uring/sqpoll: do the napi busy poll outside the submission block
io_uring: clean up a type in io_uring_register_get_file()
io_uring/sqpoll: do not put cpumask on stack
io_uring/sqpoll: retain test for whether the CPU is valid
io_uring/rsrc: change ubuf->ubuf_end to length tracking
io_uring/rsrc: get rid of io_mapped_ubuf->folio_mask
io_uring: rename "copy buffers" to "clone buffers"
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Merge tag 'pull-stable-struct_fd' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs
Pull 'struct fd' updates from Al Viro:
"Just the 'struct fd' layout change, with conversion to accessor
helpers"
* tag 'pull-stable-struct_fd' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs:
add struct fd constructors, get rid of __to_fd()
struct fd: representation change
introduce fd_file(), convert all accessors to it.
In terms of normal application usage, this list will always be empty.
And if an application does overflow a bit, it'll have a few entries.
However, nothing obviously prevents syzbot from running a test case
that generates a ton of overflow entries, and then flushing them can
take quite a while.
Check for needing to reschedule while flushing, and drop our locks and
do so if necessary. There's no state to maintain here as overflows
always prune from head-of-list, hence it's fine to drop and reacquire
the locks at the end of the loop.
Link: https://lore.kernel.org/io-uring/66ed061d.050a0220.29194.0053.GAE@google.com/
Reported-by: syzbot+5fca234bd7eb378ff78e@syzkaller.appspotmail.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Right now any link trace is listed as being linked after the head
request in the chain, but it's more useful to note explicitly which
request a given new request is chained to. Change the link trace to dump
the tail request so that chains are immediately apparent when looking at
traces.
Signed-off-by: Jens Axboe <axboe@kernel.dk>
If some part of the kernel adds task_work that needs executing, in terms
of signaling it'll generally use TWA_SIGNAL or TWA_RESUME. Those two
directly translate to TIF_NOTIFY_SIGNAL or TIF_NOTIFY_RESUME, and can
be used for a variety of use case outside of task_work.
However, io_cqring_wait_schedule() only tests explicitly for
TIF_NOTIFY_SIGNAL. This means it can miss if task_work got added for
the task, but used a different kind of signaling mechanism (or none at
all). Normally this doesn't matter as any task_work will be run once
the task exits to userspace, except if:
1) The ring is setup with DEFER_TASKRUN
2) The local work item may generate normal task_work
For condition 2, this can happen when closing a file and it's the final
put of that file, for example. This can cause stalls where a task is
waiting to make progress inside io_cqring_wait(), but there's nothing else
that will wake it up. Hence change the "should we schedule or loop around"
check to check for the presence of task_work explicitly, rather than just
TIF_NOTIFY_SIGNAL as the mechanism. While in there, also change the
ordering of what type of task_work first in terms of ordering, to both
make it consistent with other task_work runs in io_uring, but also to
better handle the case of defer task_work generating normal task_work,
like in the above example.
Reported-by: Jan Hendrik Farr <kernel@jfarr.cc>
Link: https://github.com/axboe/liburing/issues/1235
Cc: stable@vger.kernel.org
Fixes: 846072f16e ("io_uring: mimimise io_cqring_wait_schedule")
Signed-off-by: Jens Axboe <axboe@kernel.dk>
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Merge tag 'slab-for-6.12' of git://git.kernel.org/pub/scm/linux/kernel/git/vbabka/slab
Pull slab updates from Vlastimil Babka:
"This time it's mostly refactoring and improving APIs for slab users in
the kernel, along with some debugging improvements.
- kmem_cache_create() refactoring (Christian Brauner)
Over the years have been growing new parameters to
kmem_cache_create() where most of them are needed only for a small
number of caches - most recently the rcu_freeptr_offset parameter.
To avoid adding new parameters to kmem_cache_create() and adjusting
all its callers, or creating new wrappers such as
kmem_cache_create_rcu(), we can now pass extra parameters using the
new struct kmem_cache_args. Not explicitly initialized fields
default to values interpreted as unused.
kmem_cache_create() is for now a wrapper that works both with the
new form: kmem_cache_create(name, object_size, args, flags) and the
legacy form: kmem_cache_create(name, object_size, align, flags,
ctor)
- kmem_cache_destroy() waits for kfree_rcu()'s in flight (Vlastimil
Babka, Uladislau Rezki)
Since SLOB removal, kfree() is allowed for freeing objects
allocated by kmem_cache_create(). By extension kfree_rcu() as
allowed as well, which can allow converting simple call_rcu()
callbacks that only do kmem_cache_free(), as there was never a
kmem_cache_free_rcu() variant. However, for caches that can be
destroyed e.g. on module removal, the cache owners knew to issue
rcu_barrier() first to wait for the pending call_rcu()'s, and this
is not sufficient for pending kfree_rcu()'s due to its internal
batching optimizations. Ulad has provided a new
kvfree_rcu_barrier() and to make the usage less error-prone,
kmem_cache_destroy() calls it. Additionally, destroying
SLAB_TYPESAFE_BY_RCU caches now again issues rcu_barrier()
synchronously instead of using an async work, because the past
motivation for async work no longer applies. Users of custom
call_rcu() callbacks should however keep calling rcu_barrier()
before cache destruction.
- Debugging use-after-free in SLAB_TYPESAFE_BY_RCU caches (Jann Horn)
Currently, KASAN cannot catch UAFs in such caches as it is legal to
access them within a grace period, and we only track the grace
period when trying to free the underlying slab page. The new
CONFIG_SLUB_RCU_DEBUG option changes the freeing of individual
object to be RCU-delayed, after which KASAN can poison them.
- Delayed memcg charging (Shakeel Butt)
In some cases, the memcg is uknown at allocation time, such as
receiving network packets in softirq context. With
kmem_cache_charge() these may be now charged later when the user
and its memcg is known.
- Misc fixes and improvements (Pedro Falcato, Axel Rasmussen,
Christoph Lameter, Yan Zhen, Peng Fan, Xavier)"
* tag 'slab-for-6.12' of git://git.kernel.org/pub/scm/linux/kernel/git/vbabka/slab: (34 commits)
mm, slab: restore kerneldoc for kmem_cache_create()
io_uring: port to struct kmem_cache_args
slab: make __kmem_cache_create() static inline
slab: make kmem_cache_create_usercopy() static inline
slab: remove kmem_cache_create_rcu()
file: port to struct kmem_cache_args
slab: create kmem_cache_create() compatibility layer
slab: port KMEM_CACHE_USERCOPY() to struct kmem_cache_args
slab: port KMEM_CACHE() to struct kmem_cache_args
slab: remove rcu_freeptr_offset from struct kmem_cache
slab: pass struct kmem_cache_args to do_kmem_cache_create()
slab: pull kmem_cache_open() into do_kmem_cache_create()
slab: pass struct kmem_cache_args to create_cache()
slab: port kmem_cache_create_usercopy() to struct kmem_cache_args
slab: port kmem_cache_create_rcu() to struct kmem_cache_args
slab: port kmem_cache_create() to struct kmem_cache_args
slab: add struct kmem_cache_args
slab: s/__kmem_cache_create/do_kmem_cache_create/g
memcg: add charging of already allocated slab objects
mm/slab: Optimize the code logic in find_mergeable()
...
there are many small reasons justifying this change.
1. busy poll must be performed even on rings that have no iopoll and no
new sqe. It is quite possible that a ring configured for inbound
traffic with multishot be several hours without receiving new request
submissions
2. NAPI busy poll does not perform any credential validation
3. If the thread is awaken by task work, processing the task work is
prioritary over NAPI busy loop. This is why a second loop has been
created after the io_sq_tw() call instead of doing the busy loop in
__io_sq_thread() outside its credential acquisition block.
Signed-off-by: Olivier Langlois <olivier@trillion01.com>
Link: https://lore.kernel.org/r/de7679adf1249446bd47426db01d82b9603b7224.1726161831.git.olivier@trillion01.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Originally "fd" was unsigned int but it was changed to int when we pulled
this code into a separate function in commit 0b6d253e08
("io_uring/register: provide helper to get io_ring_ctx from 'fd'"). This
doesn't really cause a runtime problem because the call to
array_index_nospec() will clamp negative fds to 0 and nothing else uses
the negative values.
Signed-off-by: Dan Carpenter <dan.carpenter@linaro.org>
Link: https://lore.kernel.org/r/6f6cb630-079f-4fdf-bf95-1082e0a3fc6e@stanley.mountain
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Putting the cpumask on the stack is deprecated for a long time (since
2d3854a37e), as these can be big. Given that, change the on-stack
allocation of allowed_mask to be dynamically allocated.
Fixes: f011c9cf04 ("io_uring/sqpoll: do not allow pinning outside of cpuset")
Signed-off-by: Felix Moessbauer <felix.moessbauer@siemens.com>
Link: https://lore.kernel.org/r/20240916111150.1266191-1-felix.moessbauer@siemens.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
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Merge tag 'for-6.12/io_uring-discard-20240913' of git://git.kernel.dk/linux
Pull io_uring async discard support from Jens Axboe:
"Sitting on top of both the 6.12 block and io_uring core branches,
here's support for async discard through io_uring.
This allows applications to issue async discards, rather than rely on
the blocking sync ioctl discards we already have. The sync support is
difficult to use outside of idle/cleanup periods.
On a real (but slow) device, testing shows the following results when
compared to sync discard:
qd64 sync discard: 21K IOPS, lat avg 3 msec (max 21 msec)
qd64 async discard: 76K IOPS, lat avg 845 usec (max 2.2 msec)
qd64 sync discard: 14K IOPS, lat avg 5 msec (max 25 msec)
qd64 async discard: 56K IOPS, lat avg 1153 usec (max 3.6 msec)
and synthetic null_blk testing with the same queue depth and block
size settings as above shows:
Type Trim size IOPS Lat avg (usec) Lat Max (usec)
==============================================================
sync 4k 144K 444 20314
async 4k 1353K 47 595
sync 1M 56K 1136 21031
async 1M 94K 680 760"
* tag 'for-6.12/io_uring-discard-20240913' of git://git.kernel.dk/linux:
block: implement async io_uring discard cmd
block: introduce blk_validate_byte_range()
filemap: introduce filemap_invalidate_pages
io_uring/cmd: give inline space in request to cmds
io_uring/cmd: expose iowq to cmds
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Merge tag 'for-6.12/io_uring-20240913' of git://git.kernel.dk/linux
Pull io_uring updates from Jens Axboe:
- NAPI fixes and cleanups (Pavel, Olivier)
- Add support for absolute timeouts (Pavel)
- Fixes for io-wq/sqpoll affinities (Felix)
- Efficiency improvements for dealing with huge pages (Chenliang)
- Support for a minwait mode, where the application essentially has two
timouts - one smaller one that defines the batch timeout, and the
overall large one similar to what we had before. This enables
efficient use of batching based on count + timeout, while still
working well with periods of less intensive workloads
- Use ITER_UBUF for single segment sends
- Add support for incremental buffer consumption. Right now each
operation will always consume a full buffer. With incremental
consumption, a recv/read operation only consumes the part of the
buffer that it needs to satisfy the operation
- Add support for GCOV for io_uring, to help retain a high coverage of
test to code ratio
- Fix regression with ocfs2, where an odd -EOPNOTSUPP wasn't correctly
converted to a blocking retry
- Add support for cloning registered buffers from one ring to another
- Misc cleanups (Anuj, me)
* tag 'for-6.12/io_uring-20240913' of git://git.kernel.dk/linux: (35 commits)
io_uring: add IORING_REGISTER_COPY_BUFFERS method
io_uring/register: provide helper to get io_ring_ctx from 'fd'
io_uring/rsrc: add reference count to struct io_mapped_ubuf
io_uring/rsrc: clear 'slot' entry upfront
io_uring/io-wq: inherit cpuset of cgroup in io worker
io_uring/io-wq: do not allow pinning outside of cpuset
io_uring/rw: drop -EOPNOTSUPP check in __io_complete_rw_common()
io_uring/rw: treat -EOPNOTSUPP for IOCB_NOWAIT like -EAGAIN
io_uring/sqpoll: do not allow pinning outside of cpuset
io_uring/eventfd: move refs to refcount_t
io_uring: remove unused rsrc_put_fn
io_uring: add new line after variable declaration
io_uring: add GCOV_PROFILE_URING Kconfig option
io_uring/kbuf: add support for incremental buffer consumption
io_uring/kbuf: pass in 'len' argument for buffer commit
Revert "io_uring: Require zeroed sqe->len on provided-buffers send"
io_uring/kbuf: move io_ring_head_to_buf() to kbuf.h
io_uring/kbuf: add io_kbuf_commit() helper
io_uring/kbuf: shrink nr_iovs/mode in struct buf_sel_arg
io_uring: wire up min batch wake timeout
...
A recent commit ensured that SQPOLL cannot be setup with a CPU that
isn't in the current tasks cpuset, but it also dropped testing whether
the CPU is valid in the first place. Without that, if a task passes in
a CPU value that is too high, the following KASAN splat can get
triggered:
BUG: KASAN: stack-out-of-bounds in io_sq_offload_create+0x858/0xaa4
Read of size 8 at addr ffff800089bc7b90 by task wq-aff.t/1391
CPU: 4 UID: 1000 PID: 1391 Comm: wq-aff.t Not tainted 6.11.0-rc7-00227-g371c468f4db6 #7080
Hardware name: linux,dummy-virt (DT)
Call trace:
dump_backtrace.part.0+0xcc/0xe0
show_stack+0x14/0x1c
dump_stack_lvl+0x58/0x74
print_report+0x16c/0x4c8
kasan_report+0x9c/0xe4
__asan_report_load8_noabort+0x1c/0x24
io_sq_offload_create+0x858/0xaa4
io_uring_setup+0x1394/0x17c4
__arm64_sys_io_uring_setup+0x6c/0x180
invoke_syscall+0x6c/0x260
el0_svc_common.constprop.0+0x158/0x224
do_el0_svc+0x3c/0x5c
el0_svc+0x34/0x70
el0t_64_sync_handler+0x118/0x124
el0t_64_sync+0x168/0x16c
The buggy address belongs to stack of task wq-aff.t/1391
and is located at offset 48 in frame:
io_sq_offload_create+0x0/0xaa4
This frame has 1 object:
[32, 40) 'allowed_mask'
The buggy address belongs to the virtual mapping at
[ffff800089bc0000, ffff800089bc9000) created by:
kernel_clone+0x124/0x7e0
The buggy address belongs to the physical page:
page: refcount:1 mapcount:0 mapping:0000000000000000 index:0xffff0000d740af80 pfn:0x11740a
memcg:ffff0000c2706f02
flags: 0xbffe00000000000(node=0|zone=2|lastcpupid=0x1fff)
raw: 0bffe00000000000 0000000000000000 dead000000000122 0000000000000000
raw: ffff0000d740af80 0000000000000000 00000001ffffffff ffff0000c2706f02
page dumped because: kasan: bad access detected
Memory state around the buggy address:
ffff800089bc7a80: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
ffff800089bc7b00: 00 00 00 00 00 00 00 00 00 00 00 00 f1 f1 f1 f1
>ffff800089bc7b80: 00 f3 f3 f3 00 00 00 00 00 00 00 00 00 00 00 00
^
ffff800089bc7c00: 00 00 00 00 00 00 00 00 00 00 00 00 f1 f1 f1 f1
ffff800089bc7c80: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 f3
Reported-by: kernel test robot <oliver.sang@intel.com>
Closes: https://lore.kernel.org/oe-lkp/202409161632.cbeeca0d-lkp@intel.com
Fixes: f011c9cf04 ("io_uring/sqpoll: do not allow pinning outside of cpuset")
Tested-by: Felix Moessbauer <felix.moessbauer@siemens.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
If we change it to tracking ubuf->start + ubuf->len, then we can reduce
the size of struct io_mapped_ubuf by another 4 bytes, effectively 8
bytes, as a hole is eliminated too.
This shrinks io_mapped_ubuf to 32 bytes.
Signed-off-by: Jens Axboe <axboe@kernel.dk>
We don't really need to cache this, let's reclaim 8 bytes from struct
io_mapped_ubuf and just calculate it when we need it. The only hot path
here is io_import_fixed().
Signed-off-by: Jens Axboe <axboe@kernel.dk>
A recent commit added support for copying registered buffers from one
ring to another. But that term is a bit confusing, as no copying of
buffer data is done here. What is being done is simply cloning the
buffer registrations from one ring to another.
Rename it while we still can, so that it's more descriptive. No
functional changes in this patch.
Fixes: 7cc2a6eadc ("io_uring: add IORING_REGISTER_COPY_BUFFERS method")
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Buffers can get registered with io_uring, which allows to skip the
repeated pin_pages, unpin/unref pages for each O_DIRECT operation. This
reduces the overhead of O_DIRECT IO.
However, registrering buffers can take some time. Normally this isn't an
issue as it's done at initialization time (and hence less critical), but
for cases where rings can be created and destroyed as part of an IO
thread pool, registering the same buffers for multiple rings become a
more time sensitive proposition. As an example, let's say an application
has an IO memory pool of 500G. Initial registration takes:
Got 500 huge pages (each 1024MB)
Registered 500 pages in 409 msec
or about 0.4 seconds. If we go higher to 900 1GB huge pages being
registered:
Registered 900 pages in 738 msec
which is, as expected, a fully linear scaling.
Rather than have each ring pin/map/register the same buffer pool,
provide an io_uring_register(2) opcode to simply duplicate the buffers
that are registered with another ring. Adding the same 900GB of
registered buffers to the target ring can then be accomplished in:
Copied 900 pages in 17 usec
While timing differs a bit, this provides around a 25,000-40,000x
speedup for this use case.
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Can be done in one of two ways:
1) Regular file descriptor, just fget()
2) Registered ring, index our own table for that
In preparation for adding another register use of needing to get a ctx
from a file descriptor, abstract out this helper and use it in the main
register syscall as well.
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Currently there's a single ring owner of a mapped buffer, and hence the
reference count will always be 1 when it's torn down and freed. However,
in preparation for being able to link io_mapped_ubuf to different spots,
add a reference count to manage the lifetime of it.
Signed-off-by: Jens Axboe <axboe@kernel.dk>
No functional changes in this patch, but clearing the slot pointer
earlier will be required by a later change.
Signed-off-by: Jens Axboe <axboe@kernel.dk>
When an io_uring request needs blocking context we offload it to the
io_uring's thread pool called io-wq. We can get there off ->uring_cmd
by returning -EAGAIN, but there is no straightforward way of doing that
from an asynchronous callback. Add a helper that would transfer a
command to a blocking context.
Note, we do an extra hop via task_work before io_queue_iowq(), that's a
limitation of io_uring infra we have that can likely be lifted later
if that would ever become a problem.
Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
Link: https://lore.kernel.org/r/f735f807d7c8ba50c9452c69dfe5d3e9e535037b.1726072086.git.asml.silence@gmail.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
* for-6.12/io_uring: (31 commits)
io_uring/io-wq: inherit cpuset of cgroup in io worker
io_uring/io-wq: do not allow pinning outside of cpuset
io_uring/rw: drop -EOPNOTSUPP check in __io_complete_rw_common()
io_uring/rw: treat -EOPNOTSUPP for IOCB_NOWAIT like -EAGAIN
io_uring/sqpoll: do not allow pinning outside of cpuset
io_uring/eventfd: move refs to refcount_t
io_uring: remove unused rsrc_put_fn
io_uring: add new line after variable declaration
io_uring: add GCOV_PROFILE_URING Kconfig option
io_uring/kbuf: add support for incremental buffer consumption
io_uring/kbuf: pass in 'len' argument for buffer commit
Revert "io_uring: Require zeroed sqe->len on provided-buffers send"
io_uring/kbuf: move io_ring_head_to_buf() to kbuf.h
io_uring/kbuf: add io_kbuf_commit() helper
io_uring/kbuf: shrink nr_iovs/mode in struct buf_sel_arg
io_uring: wire up min batch wake timeout
io_uring: add support for batch wait timeout
io_uring: implement our own schedule timeout handling
io_uring: move schedule wait logic into helper
io_uring: encapsulate extraneous wait flags into a separate struct
...
The io worker threads are userland threads that just never exit to the
userland. By that, they are also assigned to a cgroup (the group of the
creating task).
When creating a new io worker, this worker should inherit the cpuset
of the cgroup.
Fixes: da64d6db3b ("io_uring: One wqe per wq")
Signed-off-by: Felix Moessbauer <felix.moessbauer@siemens.com>
Link: https://lore.kernel.org/r/20240910171157.166423-3-felix.moessbauer@siemens.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
The io worker threads are userland threads that just never exit to the
userland. By that, they are also assigned to a cgroup (the group of the
creating task).
When changing the affinity of the io_wq thread via syscall, we must only
allow cpumasks within the limits defined by the cpuset controller of the
cgroup (if enabled).
Fixes: da64d6db3b ("io_uring: One wqe per wq")
Signed-off-by: Felix Moessbauer <felix.moessbauer@siemens.com>
Link: https://lore.kernel.org/r/20240910171157.166423-2-felix.moessbauer@siemens.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
A recent change ensured that the necessary -EOPNOTSUPP -> -EAGAIN
transformation happens inline on both the reader and writer side,
and hence there's no need to check for both of these anymore on
the completion handler side.
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Some file systems, ocfs2 in this case, will return -EOPNOTSUPP for
an IOCB_NOWAIT read/write attempt. While this can be argued to be
correct, the usual return value for something that requires blocking
issue is -EAGAIN.
A refactoring io_uring commit dropped calling kiocb_done() for
negative return values, which is otherwise where we already do that
transformation. To ensure we catch it in both spots, check it in
__io_read() itself as well.
Reported-by: Robert Sander <r.sander@heinlein-support.de>
Link: https://fosstodon.org/@gurubert@mastodon.gurubert.de/113112431889638440
Cc: stable@vger.kernel.org
Fixes: a08d195b58 ("io_uring/rw: split io_read() into a helper")
Signed-off-by: Jens Axboe <axboe@kernel.dk>
The submit queue polling threads are userland threads that just never
exit to the userland. When creating the thread with IORING_SETUP_SQ_AFF,
the affinity of the poller thread is set to the cpu specified in
sq_thread_cpu. However, this CPU can be outside of the cpuset defined
by the cgroup cpuset controller. This violates the rules defined by the
cpuset controller and is a potential issue for realtime applications.
In b7ed6d8ffd6 we fixed the default affinity of the poller thread, in
case no explicit pinning is required by inheriting the one of the
creating task. In case of explicit pinning, the check is more
complicated, as also a cpu outside of the parent cpumask is allowed.
We implemented this by using cpuset_cpus_allowed (that has support for
cgroup cpusets) and testing if the requested cpu is in the set.
Fixes: 37d1e2e364 ("io_uring: move SQPOLL thread io-wq forked worker")
Cc: stable@vger.kernel.org # 6.1+
Signed-off-by: Felix Moessbauer <felix.moessbauer@siemens.com>
Link: https://lore.kernel.org/r/20240909150036.55921-1-felix.moessbauer@siemens.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
atomic_t for the struct io_ev_fd references and there are no issues with
it. While the ref getting and putting for the eventfd code is somewhat
performance critical for cases where eventfd signaling is used (news
flash, you should not...), it probably doesn't warrant using an atomic_t
for this. Let's just move to it to refcount_t to get the added
protection of over/underflows.
Link: https://lore.kernel.org/lkml/202409082039.hnsaIJ3X-lkp@intel.com/
Reported-by: kernel test robot <lkp@intel.com>
Closes: https://lore.kernel.org/oe-kbuild-all/202409082039.hnsaIJ3X-lkp@intel.com/
Signed-off-by: Jens Axboe <axboe@kernel.dk>
If GCOV is enabled and this option is set, it enables code coverage
profiling of the io_uring subsystem. Only use this for test purposes,
as it will impact the runtime performance.
Signed-off-by: Jens Axboe <axboe@kernel.dk>
io_provided_buffers_select() returns 0 to indicate success, but it should
be returning 1 to indicate that 1 vec was mapped. This causes peeking
to fail with classic provided buffers, and while that's not a use case
that anyone should use, it should still work correctly.
The end result is that no buffer will be selected, and hence a completion
with '0' as the result will be posted, without a buffer attached.
Fixes: 35c8711c8f ("io_uring/kbuf: add helpers for getting/peeking multiple buffers")
Signed-off-by: Jens Axboe <axboe@kernel.dk>
For buffer registration (or updates), a userspace iovec is copied in
and updated. If the application is within a compat syscall, then the
iovec type is compat_iovec rather than iovec. However, the type used
in __io_sqe_buffers_update() and io_sqe_buffers_register() is always
struct iovec, and hence the source is incremented by the size of a
non-compat iovec in the loop. This misses every other iovec in the
source, and will run into garbage half way through the copies and
return -EFAULT to the application.
Maintain the source address separately and assign to our user vec
pointer, so that copies always happen from the right source address.
While in there, correct a bad placement of __user which triggered
the following sparse warning prior to this fix:
io_uring/rsrc.c:981:33: warning: cast removes address space '__user' of expression
io_uring/rsrc.c:981:30: warning: incorrect type in assignment (different address spaces)
io_uring/rsrc.c:981:30: expected struct iovec const [noderef] __user *uvec
io_uring/rsrc.c:981:30: got struct iovec *[noderef] __user
Fixes: f4eaf8eda8 ("io_uring/rsrc: Drop io_copy_iov in favor of iovec API")
Reviewed-by: Gabriel Krisman Bertazi <krisman@suse.de>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
By default, any recv/read operation that uses provided buffers will
consume at least 1 buffer fully (and maybe more, in case of bundles).
This adds support for incremental consumption, meaning that an
application may add large buffers, and each read/recv will just consume
the part of the buffer that it needs.
For example, let's say an application registers 1MB buffers in a
provided buffer ring, for streaming receives. If it gets a short recv,
then the full 1MB buffer will be consumed and passed back to the
application. With incremental consumption, only the part that was
actually used is consumed, and the buffer remains the current one.
This means that both the application and the kernel needs to keep track
of what the current receive point is. Each recv will still pass back a
buffer ID and the size consumed, the only difference is that before the
next receive would always be the next buffer in the ring. Now the same
buffer ID may return multiple receives, each at an offset into that
buffer from where the previous receive left off. Example:
Application registers a provided buffer ring, and adds two 32K buffers
to the ring.
Buffer1 address: 0x1000000 (buffer ID 0)
Buffer2 address: 0x2000000 (buffer ID 1)
A recv completion is received with the following values:
cqe->res 0x1000 (4k bytes received)
cqe->flags 0x11 (CQE_F_BUFFER|CQE_F_BUF_MORE set, buffer ID 0)
and the application now knows that 4096b of data is available at
0x1000000, the start of that buffer, and that more data from this buffer
will be coming. Now the next receive comes in:
cqe->res 0x2010 (8k bytes received)
cqe->flags 0x11 (CQE_F_BUFFER|CQE_F_BUF_MORE set, buffer ID 0)
which tells the application that 8k is available where the last
completion left off, at 0x1001000. Next completion is:
cqe->res 0x5000 (20k bytes received)
cqe->flags 0x1 (CQE_F_BUFFER set, buffer ID 0)
and the application now knows that 20k of data is available at
0x1003000, which is where the previous receive ended. CQE_F_BUF_MORE
isn't set, as no more data is available in this buffer ID. The next
completion is then:
cqe->res 0x1000 (4k bytes received)
cqe->flags 0x10001 (CQE_F_BUFFER|CQE_F_BUF_MORE set, buffer ID 1)
which tells the application that buffer ID 1 is now the current one,
hence there's 4k of valid data at 0x2000000. 0x2001000 will be the next
receive point for this buffer ID.
When a buffer will be reused by future CQE completions,
IORING_CQE_BUF_MORE will be set in cqe->flags. This tells the application
that the kernel isn't done with the buffer yet, and that it should expect
more completions for this buffer ID. Will only be set by provided buffer
rings setup with IOU_PBUF_RING INC, as that's the only type of buffer
that will see multiple consecutive completions for the same buffer ID.
For any other provided buffer type, any completion that passes back
a buffer to the application is final.
Once a buffer has been fully consumed, the buffer ring head is
incremented and the next receive will indicate the next buffer ID in the
CQE cflags.
On the send side, the application can manage how much data is sent from
an existing buffer by setting sqe->len to the desired send length.
An application can request incremental consumption by setting
IOU_PBUF_RING_INC in the provided buffer ring registration. Outside of
that, any provided buffer ring setup and buffer additions is done like
before, no changes there. The only change is in how an application may
see multiple completions for the same buffer ID, hence needing to know
where the next receive will happen.
Note that like existing provided buffer rings, this should not be used
with IOSQE_ASYNC, as both really require the ring to remain locked over
the duration of the buffer selection and the operation completion. It
will consume a buffer otherwise regardless of the size of the IO done.
Signed-off-by: Jens Axboe <axboe@kernel.dk>
In preparation for needing the consumed length, pass in the length being
completed. Unused right now, but will be used when it is possible to
partially consume a buffer.
Signed-off-by: Jens Axboe <axboe@kernel.dk>
This reverts commit 79996b45f7.
Revert the change that restricts a send provided buffer to be zero, so
it will always consume the whole buffer. This is strictly needed for
partial consumption, as the send may very well be a subset of the
current buffer. In fact, that's the intended use case.
For non-incremental provided buffer rings, an application should set
sqe->len carefully to avoid the potential issue described in the
reverted commit. It is recommended that '0' still be set for len for
that case, if the application is set on maintaining more than 1 send
inflight for the same socket. This is somewhat of a nonsensical thing
to do.
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Committing the selected ring buffer is currently done in three different
spots, combine it into a helper and just call that.
Signed-off-by: Jens Axboe <axboe@kernel.dk>
nr_iovs is capped at 1024, and mode only has a few low values. We can
safely make them u16, in preparation for adding a few more members.
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Expose min_wait_usec in io_uring_getevents_arg, replacing the pad member
that is currently in there. The value is in usecs, which is explained in
the name as well.
Note that if min_wait_usec and a normal timeout is used in conjunction,
the normal timeout is still relative to the base time. For example, if
min_wait_usec is set to 100 and the normal timeout is 1000, the max
total time waited is still 1000. This also means that if the normal
timeout is shorter than min_wait_usec, then only the min_wait_usec will
take effect.
See previous commit for an explanation of how this works.
IORING_FEAT_MIN_TIMEOUT is added as a feature flag for this, as
applications doing submit_and_wait_timeout() style operations will
generally not see the -EINVAL from the wait side as they return the
number of IOs submitted. Only if no IOs are submitted will the -EINVAL
bubble back up to the application.
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Waiting for events with io_uring has two knobs that can be set:
1) The number of events to wake for
2) The timeout associated with the event
Waiting will abort when either of those conditions are met, as expected.
This adds support for a third event, which is associated with the number
of events to wait for. Applications generally like to handle batches of
completions, and right now they'd set a number of events to wait for and
the timeout for that. If no events have been received but the timeout
triggers, control is returned to the application and it can wait again.
However, if the application doesn't have anything to do until events are
reaped, then it's possible to make this waiting more efficient.
For example, the application may have a latency time of 50 usecs and
wanting to handle a batch of 8 requests at the time. If it uses 50 usecs
as the timeout, then it'll be doing 20K context switches per second even
if nothing is happening.
This introduces the notion of min batch wait time. If the min batch wait
time expires, then we'll return to userspace if we have any events at all.
If none are available, the general wait time is applied. Any request
arriving after the min batch wait time will cause waiting to stop and
return control to the application.
Signed-off-by: Jens Axboe <axboe@kernel.dk>
