kmemleak shows that there is a memory leak in io_uring read operation,
where a buffer is allocated at iovec import, but never de-allocated.
The memory is allocated at io_async_rw->free_iovec, but, then
io_async_rw is kfreed, taking the allocated memory with it. I saw this
happening when the read operation fails with -11 (EAGAIN).
This is the kmemleak splat.
unreferenced object 0xffff8881da591c00 (size 256):
...
backtrace (crc 7a15bdee):
[<00000000256f2de4>] __kmalloc+0x2d6/0x410
[<000000007a9f5fc7>] iovec_from_user.part.0+0xc6/0x160
[<00000000cecdf83a>] __import_iovec+0x50/0x220
[<00000000d1d586a2>] __io_import_iovec+0x13d/0x220
[<0000000054ee9bd2>] io_prep_rw+0x186/0x340
[<00000000a9c0372d>] io_prep_rwv+0x31/0x120
[<000000001d1170b9>] io_prep_readv+0xe/0x30
[<0000000070b8eb67>] io_submit_sqes+0x1bd/0x780
[<00000000812496d4>] __do_sys_io_uring_enter+0x3ed/0x5b0
[<0000000081499602>] do_syscall_64+0x5d/0x170
[<00000000de1c5a4d>] entry_SYSCALL_64_after_hwframe+0x76/0x7e
This occurs because the async data cleanup functions are not set for
read/write operations. As a result, the potentially allocated iovec in
the rw async data is not freed before the async data is released,
leading to a memory leak.
With this following patch, kmemleak does not show the leaked memory
anymore, and all liburing tests pass.
Fixes: a9165b83c1 ("io_uring/rw: always setup io_async_rw for read/write requests")
Signed-off-by: Breno Leitao <leitao@debian.org>
Link: https://lore.kernel.org/r/20240530142340.1248216-1-leitao@debian.org
Signed-off-by: Jens Axboe <axboe@kernel.dk>
It's pretty trivial to wire up provided buffer support for the send
side, just like how it's done the receive side. This enables setting up
a buffer ring that an application can use to push pending sends to,
and then have a send pick a buffer from that ring.
One of the challenges with async IO and networking sends is that you
can get into reordering conditions if you have more than one inflight
at the same time. Consider the following scenario where everything is
fine:
1) App queues sendA for socket1
2) App queues sendB for socket1
3) App does io_uring_submit()
4) sendA is issued, completes successfully, posts CQE
5) sendB is issued, completes successfully, posts CQE
All is fine. Requests are always issued in-order, and both complete
inline as most sends do.
However, if we're flooding socket1 with sends, the following could
also result from the same sequence:
1) App queues sendA for socket1
2) App queues sendB for socket1
3) App does io_uring_submit()
4) sendA is issued, socket1 is full, poll is armed for retry
5) Space frees up in socket1, this triggers sendA retry via task_work
6) sendB is issued, completes successfully, posts CQE
7) sendA is retried, completes successfully, posts CQE
Now we've sent sendB before sendA, which can make things unhappy. If
both sendA and sendB had been using provided buffers, then it would look
as follows instead:
1) App queues dataA for sendA, queues sendA for socket1
2) App queues dataB for sendB queues sendB for socket1
3) App does io_uring_submit()
4) sendA is issued, socket1 is full, poll is armed for retry
5) Space frees up in socket1, this triggers sendA retry via task_work
6) sendB is issued, picks first buffer (dataA), completes successfully,
posts CQE (which says "I sent dataA")
7) sendA is retried, picks first buffer (dataB), completes successfully,
posts CQE (which says "I sent dataB")
Now we've sent the data in order, and everybody is happy.
It's worth noting that this also opens the door for supporting multishot
sends, as provided buffers would be a prerequisite for that. Those can
trigger either when new buffers are added to the outgoing ring, or (if
stalled due to lack of space) when space frees up in the socket.
Signed-off-by: Jens Axboe <axboe@kernel.dk>
It's now unused, drop the code related to it. This includes the
io_issue_defs->manual alloc field.
While in there, and since ->async_size is now being used a bit more
frequently and in the issue path, move it to io_issue_defs[].
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Basic conversion ensuring async_data is allocated off the prep path. Adds
a basic alloc cache as well, as passthrough IO can be quite high in rate.
Tested-by: Anuj Gupta <anuj20.g@samsung.com>
Reviewed-by: Anuj Gupta <anuj20.g@samsung.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
While doing that, get rid of io_async_connect and just use the generic
io_async_msghdr. Both of them have a struct sockaddr_storage in there,
and while io_async_msghdr is bigger, if the same type can be used then
the netmsg_cache can get reused for connect as well.
Signed-off-by: Jens Axboe <axboe@kernel.dk>
read/write requests try to put everything on the stack, and then alloc
and copy if a retry is needed. This necessitates a bunch of nasty code
that deals with intermediate state.
Get rid of this, and have the prep side setup everything that is needed
upfront, which greatly simplifies the opcode handlers.
This includes adding an alloc cache for io_async_rw, to make it cheap
to handle.
In terms of cost, this should be basically free and transparent. For
the worst case of {READ,WRITE}_FIXED which didn't need it before,
performance is unaffected in the normal peak workload that is being
used to test that. Still runs at 122M IOPS.
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Move the io_async_msghdr out of the issue path and into prep handling,
e it's now done unconditionally and hence does not need to be part
of the issue path. This means any usage of io_sendrecv_prep_async() and
io_sendmsg_prep_async(), and hence the forced async setup path is now
unified with the normal prep setup.
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Move the io_async_msghdr out of the issue path and into prep handling,
since it's now done unconditionally and hence does not need to be part
of the issue path. This reduces the footprint of the multishot fast
path of multiple invocations of ->issue() per prep, and also means that
using ->prep_async() can be dropped for recvmsg asthis is now done via
setup on the prep side.
Signed-off-by: Jens Axboe <axboe@kernel.dk>
No functional changes in this patch, just in preparation for carrying
more state than what is available now, if necessary.
Signed-off-by: Jens Axboe <axboe@kernel.dk>
No functional changes in this patch, just in preparation for carrying
more state then what is being done now, if necessary. While unifying
some of this code, add a generic send setup prep handler that they can
both use.
This gets rid of some manual msghdr and sockaddr on the stack, and makes
it look a bit more like the sendmsg/recvmsg variants. Going forward, more
can get unified on top.
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Adds support for doing truncate through io_uring, eliminating
the need for applications to roll their own thread pool or offload
mechanism to be able to do non-blocking truncates.
Signed-off-by: Tony Solomonik <tony.solomonik@gmail.com>
Link: https://lore.kernel.org/r/20240202121724.17461-3-tony.solomonik@gmail.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
We need to correct some aspects of the IORING_OP_FIXED_FD_INSTALL
command to take into account the security implications of making an
io_uring-private file descriptor generally accessible to a userspace
task.
The first change in this patch is to enable auditing of the FD_INSTALL
operation as installing a file descriptor into a task's file descriptor
table is a security relevant operation and something that admins/users
may want to audit.
The second change is to disable the io_uring credential override
functionality, also known as io_uring "personalities", in the
FD_INSTALL command. The credential override in FD_INSTALL is
particularly problematic as it affects the credentials used in the
security_file_receive() LSM hook. If a task were to request a
credential override via REQ_F_CREDS on a FD_INSTALL operation, the LSM
would incorrectly check to see if the overridden credentials of the
io_uring were able to "receive" the file as opposed to the task's
credentials. After discussions upstream, it's difficult to imagine a
use case where we would want to allow a credential override on a
FD_INSTALL operation so we are simply going to block REQ_F_CREDS on
IORING_OP_FIXED_FD_INSTALL operations.
Fixes: dc18b89ab1 ("io_uring/openclose: add support for IORING_OP_FIXED_FD_INSTALL")
Signed-off-by: Paul Moore <paul@paul-moore.com>
Link: https://lore.kernel.org/r/20240123215501.289566-2-paul@paul-moore.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
io_uring can currently open/close regular files or fixed/direct
descriptors. Or you can instantiate a fixed descriptor from a regular
one, and then close the regular descriptor. But you currently can't turn
a purely fixed/direct descriptor into a regular file descriptor.
IORING_OP_FIXED_FD_INSTALL adds support for installing a direct
descriptor into the normal file table, just like receiving a file
descriptor or opening a new file would do. This is all nicely abstracted
into receive_fd(), and hence adding support for this is truly trivial.
Since direct descriptors are only usable within io_uring itself, it can
be useful to turn them into real file descriptors if they ever need to
be accessed via normal syscalls. This can either be a transitory thing,
or just a permanent transition for a given direct descriptor.
By default, new fds are installed with O_CLOEXEC set. The application
can disable O_CLOEXEC by setting IORING_FIXED_FD_NO_CLOEXEC in the
sqe->install_fd_flags member.
Suggested-by: Christian Brauner <brauner@kernel.org>
Reviewed-by: Christian Brauner <brauner@kernel.org>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Rather than sprinkle opcode checks in the generic read/write prep handler,
have a separate prep handler for the vectored readv/writev operation.
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Rather than sprinkle opcode checks in the generic read/write prep handler,
have a separate prep handler for the vectored readv/writev operation.
Signed-off-by: Jens Axboe <axboe@kernel.dk>
This adds support for IORING_OP_FUTEX_WAITV, which allows registering a
notification for a number of futexes at once. If one of the futexes are
woken, then the request will complete with the index of the futex that got
woken as the result. This is identical to what the normal vectored futex
waitv operation does.
Use like IORING_OP_FUTEX_WAIT, except sqe->addr must now contain a
pointer to a struct futex_waitv array, and sqe->off must now contain the
number of elements in that array. As flags are passed in the futex_vector
array, and likewise for the value and futex address(es), sqe->addr2
and sqe->addr3 are also reserved for IORING_OP_FUTEX_WAITV.
For cancelations, FUTEX_WAITV does not rely on the futex_unqueue()
return value as we're dealing with multiple futexes. Instead, a separate
per io_uring request atomic is used to claim ownership of the request.
Waiting on N futexes could be done with IORING_OP_FUTEX_WAIT as well,
but that punts a lot of the work to the application:
1) Application would need to submit N IORING_OP_FUTEX_WAIT requests,
rather than just a single IORING_OP_FUTEX_WAITV.
2) When one futex is woken, application would need to cancel the
remaining N-1 requests that didn't trigger.
While this is of course doable, having a single vectored futex wait
makes for much simpler application code.
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Add support for FUTEX_WAKE/WAIT primitives.
IORING_OP_FUTEX_WAKE is mix of FUTEX_WAKE and FUTEX_WAKE_BITSET, as
it does support passing in a bitset.
Similary, IORING_OP_FUTEX_WAIT is a mix of FUTEX_WAIT and
FUTEX_WAIT_BITSET.
For both of them, they are using the futex2 interface.
FUTEX_WAKE is straight forward, as those can always be done directly from
the io_uring submission without needing async handling. For FUTEX_WAIT,
things are a bit more complicated. If the futex isn't ready, then we
rely on a callback via futex_queue->wake() when someone wakes up the
futex. From that calback, we queue up task_work with the original task,
which will post a CQE and wake it, if necessary.
Cancelations are supported, both from the application point-of-view,
but also to be able to cancel pending waits if the ring exits before
all events have occurred. The return value of futex_unqueue() is used
to gate who wins the potential race between cancelation and futex
wakeups. Whomever gets a 'ret == 1' return from that claims ownership
of the io_uring futex request.
This is just the barebones wait/wake support. PI or REQUEUE support is
not added at this point, unclear if we might look into that later.
Likewise, explicit timeouts are not supported either. It is expected
that users that need timeouts would do so via the usual io_uring
mechanism to do that using linked timeouts.
The SQE format is as follows:
`addr` Address of futex
`fd` futex2(2) FUTEX2_* flags
`futex_flags` io_uring specific command flags. None valid now.
`addr2` Value of futex
`addr3` Mask to wake/wait
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
This adds support for an async version of waitid(2), in a fully async
version. If an event isn't immediately available, wait for a callback
to trigger a retry.
The format of the sqe is as follows:
sqe->len The 'which', the idtype being queried/waited for.
sqe->fd The 'pid' (or id) being waited for.
sqe->file_index The 'options' being set.
sqe->addr2 A pointer to siginfo_t, if any, being filled in.
buf_index, add3, and waitid_flags are reserved/unused for now.
waitid_flags will be used for options for this request type. One
interesting use case may be to add multi-shot support, so that the
request stays armed and posts a notification every time a monitored
process state change occurs.
Note that this does not support rusage, on Arnd's recommendation.
See the waitid(2) man page for details on the arguments.
Signed-off-by: Jens Axboe <axboe@kernel.dk>
This behaves like IORING_OP_READ, except:
1) It only supports pollable files (eg pipes, sockets, etc). Note that
for sockets, you probably want to use recv/recvmsg with multishot
instead.
2) It supports multishot mode, meaning it will repeatedly trigger a
read and fill a buffer when data is available. This allows similar
use to recv/recvmsg but on non-sockets, where a single request will
repeatedly post a CQE whenever data is read from it.
3) Because of #2, it must be used with provided buffers. This is
uniformly true across any request type that supports multishot and
transfers data, with the reason being that it's obviously not
possible to pass in a single buffer for the data, as multiple reads
may very well trigger before an application has a chance to process
previous CQEs and the data passed from them.
Reviewed-by: Gabriel Krisman Bertazi <krisman@suse.de>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
This is cleaner than gating on the opcode type, particularly as more
read/write type opcodes may be added.
Then we can use that for the data import, and for __io_read() on
whether or not we need to copy state.
Reviewed-by: Gabriel Krisman Bertazi <krisman@suse.de>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Currently uring CMD operation relies on having large SQEs, but future
operations might want to use normal SQE.
The io_uring_cmd currently only saves the payload (cmd) part of the SQE,
but, for commands that use normal SQE size, it might be necessary to
access the initial SQE fields outside of the payload/cmd block. So,
saves the whole SQE other than just the pdu.
This changes slightly how the io_uring_cmd works, since the cmd
structures and callbacks are not opaque to io_uring anymore. I.e, the
callbacks can look at the SQE entries, not only, in the cmd structure.
The main advantage is that we don't need to create custom structures for
simple commands.
Creates io_uring_sqe_cmd() that returns the cmd private data as a null
pointer and avoids casting in the callee side.
Also, make most of ublk_drv's sqe->cmd priv structure into const, and use
io_uring_sqe_cmd() to get the private structure, removing the unwanted
cast. (There is one case where the cast is still needed since the
header->{len,addr} is updated in the private structure)
Suggested-by: Pavel Begunkov <asml.silence@gmail.com>
Signed-off-by: Breno Leitao <leitao@debian.org>
Reviewed-by: Keith Busch <kbusch@kernel.org>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Pavel Begunkov <asml.silence@gmail.com>
Link: https://lore.kernel.org/r/20230504121856.904491-3-leitao@debian.org
Signed-off-by: Jens Axboe <axboe@kernel.dk>
fadvise and madvise both provide hints for caching or access pattern for
file and memory respectively. Skip them.
Fixes: 5bd2182d58 ("audit,io_uring,io-wq: add some basic audit support to io_uring")
Signed-off-by: Richard Guy Briggs <rgb@redhat.com>
Link: https://lore.kernel.org/r/b5dfdcd541115c86dbc774aa9dd502c964849c5f.1675282642.git.rgb@redhat.com
Acked-by: Paul Moore <paul@paul-moore.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
This patch removes some "cold" fields from `struct io_issue_def`.
The plan is to keep only highly used fields into `struct io_issue_def`, so,
it may be hot in the cache. The hot fields are basically all the bitfields
and the callback functions for .issue and .prep.
The other less frequently used fields are now located in a secondary and
cold struct, called `io_cold_def`.
This is the size for the structs:
Before: io_issue_def = 56 bytes
After: io_issue_def = 24 bytes; io_cold_def = 40 bytes
Signed-off-by: Breno Leitao <leitao@debian.org>
Reviewed-by: Pavel Begunkov <asml.silence@gmail.com>
Link: https://lore.kernel.org/r/20230112144411.2624698-2-leitao@debian.org
Signed-off-by: Jens Axboe <axboe@kernel.dk>
The current io_op_def struct is becoming huge and the name is a bit
generic.
The goal of this patch is to rename this struct to `io_issue_def`. This
struct will contain the hot functions associated with the issue code
path.
For now, this patch only renames the structure, and an upcoming patch
will break up the structure in two, moving the non-issue fields to a
secondary struct.
Signed-off-by: Breno Leitao <leitao@debian.org>
Reviewed-by: Pavel Begunkov <asml.silence@gmail.com>
Link: https://lore.kernel.org/r/20230112144411.2624698-1-leitao@debian.org
Signed-off-by: Jens Axboe <axboe@kernel.dk>
The msg variants of sending aren't audited separately, so we should not
be setting audit_skip for the zerocopy sendmsg variant either.
Fixes: 493108d95f ("io_uring/net: zerocopy sendmsg")
Reported-by: Paul Moore <paul@paul-moore.com>
Reviewed-by: Paul Moore <paul@paul-moore.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Put this up in the same way as iopoll is done for regular read/write IO.
Make place for storing a cookie into struct io_uring_cmd on submission.
Perform the completion using the ->uring_cmd_iopoll handler.
Signed-off-by: Kanchan Joshi <joshi.k@samsung.com>
Signed-off-by: Pankaj Raghav <p.raghav@samsung.com>
Link: https://lore.kernel.org/r/20220823161443.49436-3-joshi.k@samsung.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Following user feedback, this patch simplifies zerocopy send API. One of
the main complaints is that the current API is difficult with the
userspace managing notification slots, and then send retries with error
handling make it even worse.
Instead of keeping notification slots change it to the per-request
notifications model, which posts both completion and notification CQEs
for each request when any data has been sent, and only one CQE if it
fails. All notification CQEs will have IORING_CQE_F_NOTIF set and
IORING_CQE_F_MORE in completion CQEs indicates whether to wait a
notification or not.
IOSQE_CQE_SKIP_SUCCESS is disallowed with zerocopy sends for now.
This is less flexible, but greatly simplifies the user API and also the
kernel implementation. We reuse notif helpers in this patch, but in the
future there won't be need for keeping two requests.
Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
Link: https://lore.kernel.org/r/95287640ab98fc9417370afb16e310677c63e6ce.1662027856.git.asml.silence@gmail.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
We usually copy all bits that a request needs from the userspace for
async execution, so the userspace can keep them on the stack. However,
send zerocopy violates this pattern for addresses and may reloads it
e.g. from io-wq. Save the address if any in ->async_data as usual.
Reported-by: Stefan Metzmacher <metze@samba.org>
Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
Link: https://lore.kernel.org/r/d7512d7aa9abcd36e9afe1a4d292a24cb2d157e5.1661342812.git.asml.silence@gmail.com
[axboe: fold in incremental fix]
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Add a new io_uring opcode IORING_OP_SENDZC. The main distinction from
IORING_OP_SEND is that the user should specify a notification slot
index in sqe::notification_idx and the buffers are safe to reuse only
when the used notification is flushed and completes.
Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
Link: https://lore.kernel.org/r/a80387c6a68ce9cf99b3b6ef6f71068468761fb7.1657643355.git.asml.silence@gmail.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
We already have the declarations in opdef.h, move the rest into its own
file rather than in the main io_uring.c file.
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Breno Leitao