[ Upstream commit 2b35b8b43e ]
We know the request is either being removed, or already in the process of
being removed through task_work, so we can delete it from our waitid list
upfront. This is important for remove all conditions, as we otherwise
will find it multiple times and prevent cancelation progress.
Remove the dead check in cancelation as well for the hash_node being
empty or not. We already have a waitid reference check for ownership,
so we don't need to check the list too.
Cc: stable@vger.kernel.org
Fixes: f31ecf671d ("io_uring: add IORING_OP_WAITID support")
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Sasha Levin <sashal@kernel.org>
[ Upstream commit 30dab608c3 ]
We know the request is either being removed, or already in the process of
being removed through task_work, so we can delete it from our futex list
upfront. This is important for remove all conditions, as we otherwise
will find it multiple times and prevent cancelation progress.
Cc: stable@vger.kernel.org
Fixes: 194bb58c60 ("io_uring: add support for futex wake and wait")
Fixes: 8f350194d5 ("io_uring: add support for vectored futex waits")
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Sasha Levin <sashal@kernel.org>
[ Upstream commit cef59d1ea7 ]
We make a few cancellation judgements based on ctx->rings, so let's
zero it afer deallocation for IORING_SETUP_NO_MMAP just like it's
done with the mmap case. Likely, it's not a real problem, but zeroing
is safer and better tested.
Cc: stable@vger.kernel.org
Fixes: 03d89a2de2 ("io_uring: support for user allocated memory for rings/sqes")
Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
Link: https://lore.kernel.org/r/9ff6cdf91429b8a51699c210e1f6af6ea3f8bdcf.1710255382.git.asml.silence@gmail.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Sasha Levin <sashal@kernel.org>
[ Upstream commit 0a3737db84 ]
If read multishot is being invoked from the poll retry handler, then we
should return IOU_ISSUE_SKIP_COMPLETE rather than -EAGAIN. If not, then
a CQE will be posted with -EAGAIN rather than triggering the retry when
the file is flagged as readable again.
Cc: stable@vger.kernel.org
Reported-by: Sargun Dhillon <sargun@meta.com>
Fixes: fc68fcda04 ("io_uring/rw: add support for IORING_OP_READ_MULTISHOT")
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Sasha Levin <sashal@kernel.org>
[ Upstream commit 3a96378e22 ]
When checking for concurrent CQE posting, we're not only interested in
requests running from the poll handler but also strayed requests ended
up in normal io-wq execution. We're disallowing multishots in general
from io-wq, not only when they came in a certain way.
Cc: stable@vger.kernel.org
Fixes: 17add5cea2 ("io_uring: force multishot CQEs into task context")
Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
Link: https://lore.kernel.org/r/d8c5b36a39258036f93301cd60d3cd295e40653d.1709905727.git.asml.silence@gmail.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Sasha Levin <sashal@kernel.org>
[ Upstream commit deaef31bc1 ]
If we loop for multishot receive on the initial attempt, and then abort
later on to wait for more, we miss a case where we should be copying the
io_async_msghdr from the stack to stable storage. This leads to the next
retry potentially failing, if the application had the msghdr on the
stack.
Cc: stable@vger.kernel.org
Fixes: 9bb66906f2 ("io_uring: support multishot in recvmsg")
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Sasha Levin <sashal@kernel.org>
[ Upstream commit 1a8ec63b2b ]
With multiple poll entries __io_queue_proc() might be running in
parallel with poll handlers and possibly task_work, we should not be
carelessly modifying req->flags there. io_poll_double_prepare() handles
a similar case with locking but it's much easier to move it into
__io_arm_poll_handler().
Cc: stable@vger.kernel.org
Fixes: 595e52284d ("io_uring/poll: don't enable lazy wake for POLLEXCLUSIVE")
Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
Link: https://lore.kernel.org/r/455cc49e38cf32026fa1b49670be8c162c2cb583.1709834755.git.asml.silence@gmail.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Sasha Levin <sashal@kernel.org>
[ Upstream commit 5e3afe580a ]
Taking the ctx lock is not enough to use the deferred request completion
infrastructure, it'll get queued into the list but no one would expect
it there, so it will sit there until next io_submit_flush_completions().
It's hard to care about the cancellation path, so complete it via tw.
Fixes: ef7dfac51d ("io_uring/poll: serialize poll linked timer start with poll removal")
Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
Link: https://lore.kernel.org/r/c446740bc16858f8a2a8dcdce899812f21d15f23.1710514702.git.asml.silence@gmail.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Sasha Levin <sashal@kernel.org>
[ Upstream commit 67d1189d10 ]
Looking at the error path of __io_uaddr_map, if we fail after pinning
the pages for any reasons, ret will be set to -EINVAL and the error
handler won't properly release the pinned pages.
I didn't manage to trigger it without forcing a failure, but it can
happen in real life when memory is heavily fragmented.
Signed-off-by: Gabriel Krisman Bertazi <krisman@suse.de>
Fixes: 223ef47431 ("io_uring: don't allow IORING_SETUP_NO_MMAP rings on highmem pages")
Link: https://lore.kernel.org/r/20240313213912.1920-1-krisman@suse.de
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Sasha Levin <sashal@kernel.org>
[ Upstream commit 6f0974eccb ]
This kind of state is per-syscall, and since we're doing the waiting off
entering the io_uring_enter(2) syscall, there's no way that iowait can
already be set for this case. Simplify it by setting it if we need to,
and always clearing it to 0 when done.
Fixes: 7b72d661f1 ("io_uring: gate iowait schedule on having pending requests")
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Sasha Levin <sashal@kernel.org>
[ Upstream commit 86bcacc957 ]
The namelen is of type int. It shouldn't be made size_t which is
unsigned. The signed number is needed for error checking before use.
Fixes: c55978024d ("io_uring/net: move receive multishot out of the generic msghdr path")
Signed-off-by: Muhammad Usama Anjum <usama.anjum@collabora.com>
Link: https://lore.kernel.org/r/20240301144349.2807544-1-usama.anjum@collabora.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Sasha Levin <sashal@kernel.org>
[ Upstream commit 8ede3db506 ]
The "controllen" variable is type size_t (unsigned long). Casting it
to int could lead to an integer underflow.
The check_add_overflow() function considers the type of the destination
which is type int. If we add two positive values and the result cannot
fit in an integer then that's counted as an overflow.
However, if we cast "controllen" to an int and it turns negative, then
negative values *can* fit into an int type so there is no overflow.
Good: 100 + (unsigned long)-4 = 96 <-- overflow
Bad: 100 + (int)-4 = 96 <-- no overflow
I deleted the cast of the sizeof() as well. That's not a bug but the
cast is unnecessary.
Fixes: 9b0fc3c054 ("io_uring: fix types in io_recvmsg_multishot_overflow")
Signed-off-by: Dan Carpenter <dan.carpenter@linaro.org>
Link: https://lore.kernel.org/r/138bd2e2-ede8-4bcc-aa7b-f3d9de167a37@moroto.mountain
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Sasha Levin <sashal@kernel.org>
[ Upstream commit c55978024d ]
Move the actual user_msghdr / compat_msghdr into the send and receive
sides, respectively, so we can move the uaddr receive handling into its
own handler, and ditto the multishot with buffer selection logic.
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Stable-dep-of: 8ede3db506 ("io_uring/net: fix overflow check in io_recvmsg_mshot_prep()")
Signed-off-by: Sasha Levin <sashal@kernel.org>
[ Upstream commit 52307ac4f2 ]
For recvmsg, we roll our own since we support buffer selections. This
isn't the case for sendmsg right now, but in preparation for doing so,
make the recvmsg copy helpers generic so we can call them from the
sendmsg side as well.
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Stable-dep-of: 8ede3db506 ("io_uring/net: fix overflow check in io_recvmsg_mshot_prep()")
Signed-off-by: Sasha Levin <sashal@kernel.org>
[ Upstream commit 9fe3eaea4a ]
If we have a ton of notifications coming in, we can be looping in here
for a long time. This can be problematic for various reasons, mostly
because we can starve userspace. If the application is waiting on N
events, then only re-run if we need more events.
Fixes: c0e0d6ba25 ("io_uring: add IORING_SETUP_DEFER_TASKRUN")
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Sasha Levin <sashal@kernel.org>
[ Upstream commit 592b480543 ]
A previous commit added looping around handling traditional task_work
as an optimization, and while that may seem like a good idea, it's also
possible to run into application starvation doing so. If the task_work
generation is bursty, we can get very deep task_work queues, and we can
end up looping in here for a very long time.
One immediately observable problem with that is handling network traffic
using provided buffers, where flooding incoming traffic and looping
task_work handling will very quickly lead to buffer starvation as we
keep running task_work rather than returning to the application so it
can handle the associated CQEs and also provide buffers back.
Fixes: 3a0c037b0e ("io_uring: batch task_work")
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Sasha Levin <sashal@kernel.org>
Commit 6e5e6d2749 upstream.
This is dead code after we dropped support for passing io_uring fds
over SCM_RIGHTS, get rid of it.
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Sasha Levin <sashal@kernel.org>
Commit a4104821ad upstream.
Since we no longer allow sending io_uring fds over SCM_RIGHTS, move to
using io_is_uring_fops() to detect whether this is a io_uring fd or not.
With that done, kill off io_uring_get_socket() as nobody calls it
anymore.
This is in preparation to yanking out the rest of the core related to
unix gc with io_uring.
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Sasha Levin <sashal@kernel.org>
commit a37ee9e117 upstream.
If we hit CQ ring overflow when attempting to post a multishot accept
completion, we don't properly save the result or return code. This
results in losing the accepted fd value.
Instead, we return the result from the poll operation that triggered
the accept retry. This is generally POLLIN|POLLPRI|POLLRDNORM|POLLRDBAND
which is 0xc3, or 195, which looks like a valid file descriptor, but it
really has no connection to that.
Handle this like we do for other multishot completions - assign the
result, and return IOU_STOP_MULTISHOT to cancel any further completions
from this request when overflow is hit. This preserves the result, as we
should, and tells the application that the request needs to be re-armed.
Cc: stable@vger.kernel.org
Fixes: 515e269612 ("io_uring: revert "io_uring fix multishot accept ordering"")
Link: https://github.com/axboe/liburing/issues/1062
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Commit 76b367a2d8 upstream.
If we have multiple clients and some/all are flooding the receives to
such an extent that we can retry a LOT handling multishot receives, then
we can be starving some clients and hence serving traffic in an
imbalanced fashion.
Limit multishot retry attempts to some arbitrary value, whose only
purpose serves to ensure that we don't keep serving a single connection
for way too long. We default to 32 retries, which should be more than
enough to provide fairness, yet not so small that we'll spend too much
time requeuing rather than handling traffic.
Cc: stable@vger.kernel.org
Depends-on: 704ea888d6 ("io_uring/poll: add requeue return code from poll multishot handling")
Depends-on: 1e5d765a82f ("io_uring/net: un-indent mshot retry path in io_recv_finish()")
Depends-on: e84b01a880 ("io_uring/poll: move poll execution helpers higher up")
Fixes: b3fdea6ecb ("io_uring: multishot recv")
Fixes: 9bb66906f2 ("io_uring: support multishot in recvmsg")
Link: https://github.com/axboe/liburing/issues/1043
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Commit 704ea888d6 upstream.
Since our poll handling is edge triggered, multishot handlers retry
internally until they know that no more data is available. In
preparation for limiting these retries, add an internal return code,
IOU_REQUEUE, which can be used to inform the poll backend about the
handler wanting to retry, but that this should happen through a normal
task_work requeue rather than keep hammering on the issue side for this
one request.
No functional changes in this patch, nobody is using this return code
just yet.
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
commit c79f52f065 upstream.
io_read_mshot() always relies on poll triggering retries, and this works
fine as long as we do a retry per size of the buffer being read. The
buffer size is given by the size of the buffer(s) in the given buffer
group ID.
But if we're reading less than what is available, then we don't always
get to read everything that is available. For example, if the buffers
available are 32 bytes and we have 64 bytes to read, then we'll
correctly read the first 32 bytes and then wait for another poll trigger
before we attempt the next read. This next poll trigger may never
happen, in which case we just sit forever and never make progress, or it
may trigger at some point in the future, and now we're just delivering
the available data much later than we should have.
io_read_mshot() could do retries itself, but that is wasteful as we'll
be going through all of __io_read() again, and most likely in vain.
Rather than do that, bump our poll reference count and have
io_poll_check_events() do one more loop and check with vfs_poll() if we
have more data to read. If we do, io_read_mshot() will get invoked again
directly and we'll read the next chunk.
io_poll_multishot_retry() must only get called from inside
io_poll_issue(), which is our multishot retry handler, as we know we
already "own" the request at this point.
Cc: stable@vger.kernel.org
Link: https://github.com/axboe/liburing/issues/1041
Fixes: fc68fcda04 ("io_uring/rw: add support for IORING_OP_READ_MULTISHOT")
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
commit 91e5d765a8 upstream.
In preparation for putting some retry logic in there, have the done
path just skip straight to the end rather than have too much nesting
in here.
No functional changes in this patch.
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
commit e84b01a880 upstream.
In preparation for calling __io_poll_execute() higher up, move the
functions to avoid forward declarations.
No functional changes in this patch.
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
commit 72bd80252f upstream.
If we use IORING_OP_RECV with provided buffers and pass in '0' as the
length of the request, the length is retrieved from the selected buffer.
If MSG_WAITALL is also set and we get a short receive, then we may hit
the retry path which decrements sr->len and increments the buffer for
a retry. However, the length is still zero at this point, which means
that sr->len now becomes huge and import_ubuf() will cap it to
MAX_RW_COUNT and subsequently return -EFAULT for the range as a whole.
Fix this by always assigning sr->len once the buffer has been selected.
Cc: stable@vger.kernel.org
Fixes: 7ba89d2af1 ("io_uring: ensure recv and recvmsg handle MSG_WAITALL correctly")
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
[ Upstream commit dc12d1799c ]
The UINT_MAX work item counting bias in io_req_local_work_add() in case
of !IOU_F_TWQ_LAZY_WAKE works in a sense that we will not miss a wake up,
however it's still eerie. In particular, if we add a lazy work item
after a non-lazy one, we'll increment it and get nr_tw==0, and
subsequent adds may try to unnecessarily wake up the task, which is
though not so likely to happen in real workloads.
Half the bias, it's still large enough to be larger than any valid
->cq_wait_nr, which is limited by IORING_MAX_CQ_ENTRIES, but further
have a good enough of space before it overflows.
Fixes: 8751d15426 ("io_uring: reduce scheduling due to tw")
Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
Link: https://lore.kernel.org/r/108b971e958deaf7048342930c341ba90f75d806.1705438669.git.asml.silence@gmail.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Sasha Levin <sashal@kernel.org>
commit 6ff1407e24 upstream.
A previous commit added an earlier break condition here, which is fine if
we're using non-local task_work as it'll be run on return to userspace.
However, if DEFER_TASKRUN is used, then we could be leaving local
task_work that is ready to process in the ctx list until next time that
we enter the kernel to wait for events.
Move the break condition to _after_ we have run task_work.
Cc: stable@vger.kernel.org
Fixes: 846072f16e ("io_uring: mimimise io_cqring_wait_schedule")
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
commit 0a535eddbe upstream.
If IOSQE_ASYNC is set and we fail importing an iovec for a readv or
writev request, then we leave ->bytes_done uninitialized and hence the
eventual failure CQE posted can potentially have a random res value
rather than the expected -EINVAL.
Setup ->bytes_done before potentially failing, so we have a consistent
value if we fail the request early.
Cc: stable@vger.kernel.org
Reported-by: xingwei lee <xrivendell7@gmail.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
commit 9b43ef3d52 upstream.
IOPOLL request should never return IOU_OK, so the following iopoll
queueing check in io_issue_sqe() after getting IOU_OK doesn't make any
sense as would never turn true. Let's optimise on that and return a bit
earlier. It's also much more resilient to potential bugs from
mischieving iopoll implementations.
Cc: <stable@vger.kernel.org>
Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
Link: https://lore.kernel.org/r/2f8690e2fa5213a2ff292fac29a7143c036cdd60.1701390926.git.asml.silence@gmail.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
In 8e9fad0e70 "io_uring: Add io_uring command support for sockets"
you've got an include of asm-generic/ioctls.h done in io_uring/uring_cmd.c.
That had been done for the sake of this chunk -
+ ret = prot->ioctl(sk, SIOCINQ, &arg);
+ if (ret)
+ return ret;
+ return arg;
+ case SOCKET_URING_OP_SIOCOUTQ:
+ ret = prot->ioctl(sk, SIOCOUTQ, &arg);
SIOC{IN,OUT}Q are defined to symbols (FIONREAD and TIOCOUTQ) that come from
ioctls.h, all right, but the values vary by the architecture.
FIONREAD is
0x467F on mips
0x4004667F on alpha, powerpc and sparc
0x8004667F on sh and xtensa
0x541B everywhere else
TIOCOUTQ is
0x7472 on mips
0x40047473 on alpha, powerpc and sparc
0x80047473 on sh and xtensa
0x5411 everywhere else
->ioctl() expects the same values it would've gotten from userland; all
places where we compare with SIOC{IN,OUT}Q are using asm/ioctls.h, so
they pick the correct values. io_uring_cmd_sock(), OTOH, ends up
passing the default ones.
Fixes: 8e9fad0e70 ("io_uring: Add io_uring command support for sockets")
Cc: <stable@vger.kernel.org>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Link: https://lore.kernel.org/r/20231214213408.GT1674809@ZenIV
Signed-off-by: Jens Axboe <axboe@kernel.dk>
There are a few quirks around using lazy wake for poll unconditionally,
and one of them is related the EPOLLEXCLUSIVE. Those may trigger
exclusive wakeups, which wake a limited number of entries in the wait
queue. If that wake number is less than the number of entries someone is
waiting for (and that someone is also using DEFER_TASKRUN), then we can
get stuck waiting for more entries while we should be processing the ones
we already got.
If we're doing exclusive poll waits, flag the request as not being
compatible with lazy wakeups.
Reported-by: Pavel Begunkov <asml.silence@gmail.com>
Fixes: 6ce4a93dbb ("io_uring/poll: use IOU_F_TWQ_LAZY_WAKE for wakeups")
Signed-off-by: Jens Axboe <axboe@kernel.dk>
File reference cycles have caused lots of problems for io_uring
in the past, and it still doesn't work exactly right and races with
unix_stream_read_generic(). The safest fix would be to completely
disallow sending io_uring files via sockets via SCM_RIGHT, so there
are no possible cycles invloving registered files and thus rendering
SCM accounting on the io_uring side unnecessary.
Cc: <stable@vger.kernel.org>
Fixes: 0091bfc817 ("io_uring/af_unix: defer registered files gc to io_uring release")
Reported-and-suggested-by: Jann Horn <jannh@google.com>
Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
Link: https://lore.kernel.org/r/c716c88321939156909cfa1bd8b0faaf1c804103.1701868795.git.asml.silence@gmail.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Move the buffer list 'is_ready' check below the validity check for
the buffer list for a given group.
Fixes: 5cf4f52e6d ("io_uring: free io_buffer_list entries via RCU")
Reported-by: Dan Carpenter <dan.carpenter@linaro.org>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Callers of mutex_unlock() have to make sure that the mutex stays alive
for the whole duration of the function call. For io_uring that means
that the following pattern is not valid unless we ensure that the
context outlives the mutex_unlock() call.
mutex_lock(&ctx->uring_lock);
req_put(req); // typically via io_req_task_submit()
mutex_unlock(&ctx->uring_lock);
Most contexts are fine: io-wq pins requests, syscalls hold the file,
task works are taking ctx references and so on. However, the task work
fallback path doesn't follow the rule.
Cc: <stable@vger.kernel.org>
Fixes: 04fc6c802d ("io_uring: save ctx put/get for task_work submit")
Reported-by: Jann Horn <jannh@google.com>
Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
Link: https://lore.kernel.org/io-uring/CAG48ez3xSoYb+45f1RLtktROJrpiDQ1otNvdR+YLQf7m+Krj5Q@mail.gmail.com/
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Normally within a syscall it's fine to use fdget/fdput for grabbing a
file from the file table, and it's fine within io_uring as well. We do
that via io_uring_enter(2), io_uring_register(2), and then also for
cancel which is invoked from the latter. io_uring cannot close its own
file descriptors as that is explicitly rejected, and for the cancel
side of things, the file itself is just used as a lookup cookie.
However, it is more prudent to ensure that full references are always
grabbed. For anything threaded, either explicitly in the application
itself or through use of the io-wq worker threads, this is what happens
anyway. Generalize it and use fget/fput throughout.
Also see the below link for more details.
Link: https://lore.kernel.org/io-uring/CAG48ez1htVSO3TqmrF8QcX2WFuYTRM-VZ_N10i-VZgbtg=NNqw@mail.gmail.com/
Suggested-by: Jann Horn <jannh@google.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
mmap_lock nests under uring_lock out of necessity, as we may be doing
user copies with uring_lock held. However, for mmap of provided buffer
rings, we attempt to grab uring_lock with mmap_lock already held from
do_mmap(). This makes lockdep, rightfully, complain:
WARNING: possible circular locking dependency detected
6.7.0-rc1-00009-gff3337ebaf94-dirty #4438 Not tainted
------------------------------------------------------
buf-ring.t/442 is trying to acquire lock:
ffff00020e1480a8 (&ctx->uring_lock){+.+.}-{3:3}, at: io_uring_validate_mmap_request.isra.0+0x4c/0x140
but task is already holding lock:
ffff0000dc226190 (&mm->mmap_lock){++++}-{3:3}, at: vm_mmap_pgoff+0x124/0x264
which lock already depends on the new lock.
the existing dependency chain (in reverse order) is:
-> #1 (&mm->mmap_lock){++++}-{3:3}:
__might_fault+0x90/0xbc
io_register_pbuf_ring+0x94/0x488
__arm64_sys_io_uring_register+0x8dc/0x1318
invoke_syscall+0x5c/0x17c
el0_svc_common.constprop.0+0x108/0x130
do_el0_svc+0x2c/0x38
el0_svc+0x4c/0x94
el0t_64_sync_handler+0x118/0x124
el0t_64_sync+0x168/0x16c
-> #0 (&ctx->uring_lock){+.+.}-{3:3}:
__lock_acquire+0x19a0/0x2d14
lock_acquire+0x2e0/0x44c
__mutex_lock+0x118/0x564
mutex_lock_nested+0x20/0x28
io_uring_validate_mmap_request.isra.0+0x4c/0x140
io_uring_mmu_get_unmapped_area+0x3c/0x98
get_unmapped_area+0xa4/0x158
do_mmap+0xec/0x5b4
vm_mmap_pgoff+0x158/0x264
ksys_mmap_pgoff+0x1d4/0x254
__arm64_sys_mmap+0x80/0x9c
invoke_syscall+0x5c/0x17c
el0_svc_common.constprop.0+0x108/0x130
do_el0_svc+0x2c/0x38
el0_svc+0x4c/0x94
el0t_64_sync_handler+0x118/0x124
el0t_64_sync+0x168/0x16c
From that mmap(2) path, we really just need to ensure that the buffer
list doesn't go away from underneath us. For the lower indexed entries,
they never go away until the ring is freed and we can always sanely
reference those as long as the caller has a file reference. For the
higher indexed ones in our xarray, we just need to ensure that the
buffer list remains valid while we return the address of it.
Free the higher indexed io_buffer_list entries via RCU. With that we can
avoid needing ->uring_lock inside mmap(2), and simply hold the RCU read
lock around the buffer list lookup and address check.
To ensure that the arrayed lookup either returns a valid fully formulated
entry via RCU lookup, add an 'is_ready' flag that we access with store
and release memory ordering. This isn't needed for the xarray lookups,
but doesn't hurt either. Since this isn't a fast path, retain it across
both types. Similarly, for the allocated array inside the ctx, ensure
we use the proper load/acquire as setup could in theory be running in
parallel with mmap.
While in there, add a few lockdep checks for documentation purposes.
Cc: stable@vger.kernel.org
Fixes: c56e022c0a ("io_uring: add support for user mapped provided buffer ring")
Signed-off-by: Jens Axboe <axboe@kernel.dk>
We used to just use our page list for final teardown, which would ensure
that we got all the buffers, even the ones that were not on the normal
cached list. But while moving to slab for the io_buffers, we know only
prune this list, not the deferred locked list that we have. This can
cause a leak of memory, if the workload ends up using the intermediate
locked list.
Fix this by always pruning both lists when tearing down.
Fixes: b3a4dbc89d ("io_uring/kbuf: Use slab for struct io_buffer objects")
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Right now we stash any potentially mmap'ed provided ring buffer range
for freeing at release time, regardless of when they get unregistered.
Since we're keeping track of these ranges anyway, keep track of their
registration state as well, and use that to recycle ranges when
appropriate rather than always allocate new ones.
The lookup is a basic scan of entries, checking for the best matching
free entry.
Fixes: c392cbecd8 ("io_uring/kbuf: defer release of mapped buffer rings")
Signed-off-by: Jens Axboe <axboe@kernel.dk>
If a provided buffer ring is setup with IOU_PBUF_RING_MMAP, then the
kernel allocates the memory for it and the application is expected to
mmap(2) this memory. However, io_uring uses remap_pfn_range() for this
operation, so we cannot rely on normal munmap/release on freeing them
for us.
Stash an io_buf_free entry away for each of these, if any, and provide
a helper to free them post ->release().
Cc: stable@vger.kernel.org
Fixes: c56e022c0a ("io_uring: add support for user mapped provided buffer ring")
Reported-by: Jann Horn <jannh@google.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
This flag only applies to the SQ and CQ rings, it's perfectly valid
to use a mmap approach for the provided ring buffers. Move the
check into where it belongs.
Cc: stable@vger.kernel.org
Fixes: 03d89a2de2 ("io_uring: support for user allocated memory for rings/sqes")
Signed-off-by: Jens Axboe <axboe@kernel.dk>
io_sqes_map() is used rather than io_mem_alloc(), if the application
passes in memory for mapping rather than have the kernel allocate it and
then mmap(2) the ranges. This then calls __io_uaddr_map() to perform the
page mapping and pinning, which checks if we end up with the same pages,
if more than one page is mapped. But this check is incorrect and only
checks if the first and last pages are the same, where it really should
be checking if the mapped pages are contigous. This allows mapping a
single normal page, or a huge page range.
Down the line we can add support for remapping pages to be virtually
contigous, which is really all that io_uring cares about.
Cc: stable@vger.kernel.org
Fixes: 03d89a2de2 ("io_uring: support for user allocated memory for rings/sqes")
Reported-by: Jann Horn <jannh@google.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
If the offset equals the bv_len of the first registered bvec, then the
request does not include any of that first bvec. Skip it so that drivers
don't have to deal with a zero length bvec, which was observed to break
NVMe's PRP list creation.
Cc: stable@vger.kernel.org
Fixes: bd11b3a391 ("io_uring: don't use iov_iter_advance() for fixed buffers")
Signed-off-by: Keith Busch <kbusch@kernel.org>
Link: https://lore.kernel.org/r/20231120221831.2646460-1-kbusch@meta.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
A previous commit added a trylock for getting the SQPOLL thread info via
fdinfo, but this introduced a regression where we often fail to get it if
the thread is busy. For that case, we end up not printing the current CPU
and PID info.
Rather than rely on this lock, just print the pid we already stored in
the io_sq_data struct, and ensure we update the current CPU every time
we've slept or potentially rescheduled. The latter won't potentially be
100% accurate, but that wasn't the case before either as the task can
get migrated at any time unless it has been pinned at creation time.
We retain keeping the io_sq_data dereference inside the ctx->uring_lock,
as it has always been, as destruction of the thread and data happen below
that. We could make this RCU safe, but there's little point in doing that.
With this, we always print the last valid information we had, rather than
have spurious outputs with missing information.
Fixes: 7644b1a1c9 ("io_uring/fdinfo: lock SQ thread while retrieving thread cpu/pid")
Signed-off-by: Jens Axboe <axboe@kernel.dk>
When doing a multishot read, the code path reuses the old read
paths. However this breaks an assumption built into those paths,
namely that struct io_rw::len is available for reuse by __io_import_iovec.
For multishot this results in len being set for the first receive
call, and then subsequent calls are clamped to that buffer length
incorrectly.
Instead keep len as zero after recycling buffers, to reuse the full
buffer size of the next selected buffer.
Fixes: fc68fcda04 ("io_uring/rw: add support for IORING_OP_READ_MULTISHOT")
Signed-off-by: Dylan Yudaken <dyudaken@gmail.com>
Link: https://lore.kernel.org/r/20231106203909.197089-4-dyudaken@gmail.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
For addr: this field is not used, since buffer select is forced.
But by forcing it to be zero it leaves open future uses of the field.
len is actually usable, you could imagine that you want to receive
multishot up to a certain length.
However right now this is not how it is implemented, and it seems
safer to force this to be zero.
Fixes: fc68fcda04 ("io_uring/rw: add support for IORING_OP_READ_MULTISHOT")
Signed-off-by: Dylan Yudaken <dyudaken@gmail.com>
Link: https://lore.kernel.org/r/20231106203909.197089-3-dyudaken@gmail.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
It can be useful to know if io_kbuf_recycle did actually recycle the
buffer on the request, or if it left the request alone.
Signed-off-by: Dylan Yudaken <dyudaken@gmail.com>
Link: https://lore.kernel.org/r/20231106203909.197089-2-dyudaken@gmail.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Jens Axboe