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Bring in the changes to the file infrastructure for this cycle. Mostly
cleanups and some performance tweaks.
* file: remove __receive_fd()
* file: stop exposing receive_fd_user()
* fs: replace f_rcuhead with f_task_work
* file: remove pointless wrapper
* file: s/close_fd_get_file()/file_close_fd()/g
* Improve __fget_files_rcu() code generation (and thus __fget_light())
* file: massage cleanup of files that failed to open
Signed-off-by: Christian Brauner <brauner@kernel.org>
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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>
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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>
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Most of this code is basically self contained, move it out of the core
io_uring file to bring a bit more separation to the registration related
bits. This moves another ~10% of the code into register.c.
Signed-off-by: Jens Axboe <axboe@kernel.dk>
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In 8e9fad0e70b7 "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: 8e9fad0e70b7 ("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>
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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: 6ce4a93dbb5b ("io_uring/poll: use IOU_F_TWQ_LAZY_WAKE for wakeups")
Signed-off-by: Jens Axboe <axboe@kernel.dk>
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Not sure why some splice helpers return long, maybe historic reasons.
Change them all to return ssize_t to conform to the splice methods and
to the rest of the helpers.
Suggested-by: Christian Brauner <brauner@kernel.org>
Link: https://lore.kernel.org/r/20231208-horchen-helium-d3ec1535ede5@brauner/
Signed-off-by: Amir Goldstein <amir73il@gmail.com>
Link: https://lore.kernel.org/r/20231212094440.250945-2-amir73il@gmail.com
Reviewed-by: Jan Kara <jack@suse.cz>
Signed-off-by: Christian Brauner <brauner@kernel.org>
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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>
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With io_uring_types.h we see all required definitions to inline
io_uring_cmd_get_task().
Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
Reviewed-by: Ming Lei <ming.lei@redhat.com>
Link: https://lore.kernel.org/r/aa8e317f09e651a5f3e72f8c0ad3902084c1f930.1701391955.git.asml.silence@gmail.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
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Now as we can easily include io_uring_types.h, move IOU_F_TWQ_LAZY_WAKE
and inline io_uring_cmd_do_in_task_lazy().
Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
Reviewed-by: Ming Lei <ming.lei@redhat.com>
Link: https://lore.kernel.org/r/2ec9fb31dd192d1c5cf26d0a2dec5657d88a8e48.1701391955.git.asml.silence@gmail.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
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linux/io_uring.h is slowly becoming a rubbish bin where we put
anything exposed to other subsystems. For instance, the task exit
hooks and io_uring cmd infra are completely orthogonal and don't need
each other's definitions. Start cleaning it up by splitting out all
command bits into a new header file.
Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
Link: https://lore.kernel.org/r/7ec50bae6e21f371d3850796e716917fc141225a.1701391955.git.asml.silence@gmail.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
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At one point in time we had an optimisation that would not spin up a
linked timeout timer when the master request successfully completes
inline (during the first nowait execution attempt). We somehow lost it,
so this patch restores it back.
Note, that it's fine using io_arm_ltimeout() after the io_issue_sqe()
completes the request because of delayed completion, but that that adds
unwanted overhead.
Reported-by: Christian Mazakas <christian.mazakas@gmail.com>
Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
Link: https://lore.kernel.org/r/8bf69c2a4beec14c565c85c86edb871ca8b8bcc8.1701390926.git.asml.silence@gmail.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
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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>
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git://git.kernel.org/pub/scm/linux/kernel/git/vfs/vfs into for-6.8/io_uring
Merge vfs.file from the VFS tree to avoid conflicts with receive_fd() now
having 3 arguments rather than just 2.
* 'vfs.file' of git://git.kernel.org/pub/scm/linux/kernel/git/vfs/vfs:
file: remove __receive_fd()
file: stop exposing receive_fd_user()
fs: replace f_rcuhead with f_task_work
file: remove pointless wrapper
file: s/close_fd_get_file()/file_close_fd()/g
Improve __fget_files_rcu() code generation (and thus __fget_light())
file: massage cleanup of files that failed to open
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Only io_uring uses __close_fd_get_file(). All it does is hide
current->files but io_uring accesses files_struct directly right now
anyway so it's a bit pointless. Just rename pick_file() to
file_close_fd_locked() and let io_uring use it. Add a lockdep assert in
there that we expect the caller to hold file_lock while we're at it.
Link: https://lore.kernel.org/r/20231130-vfs-files-fixes-v1-2-e73ca6f4ea83@kernel.org
Reviewed-by: Jens Axboe <axboe@kernel.dk>
Reviewed-by: Jan Kara <jack@suse.cz>
Signed-off-by: Christian Brauner <brauner@kernel.org>
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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: 0091bfc81741b ("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>
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Move the buffer list 'is_ready' check below the validity check for
the buffer list for a given group.
Fixes: 5cf4f52e6d8a ("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>
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The io_mem_alloc() function returns error pointers, not NULL. Update
the check accordingly.
Fixes: b10b73c102a2 ("io_uring/kbuf: recycle freed mapped buffer ring entries")
Signed-off-by: Dan Carpenter <dan.carpenter@linaro.org>
Link: https://lore.kernel.org/r/5ed268d3-a997-4f64-bd71-47faa92101ab@moroto.mountain
Signed-off-by: Jens Axboe <axboe@kernel.dk>
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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>
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No more users of this field.
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Martin K. Petersen <martin.petersen@oracle.com>
Signed-off-by: Keith Busch <kbusch@kernel.org>
Link: https://lore.kernel.org/r/20231130215309.2923568-5-kbusch@meta.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
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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>
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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: c56e022c0a27 ("io_uring: add support for user mapped provided buffer ring")
Signed-off-by: Jens Axboe <axboe@kernel.dk>
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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: b3a4dbc89d40 ("io_uring/kbuf: Use slab for struct io_buffer objects")
Signed-off-by: Jens Axboe <axboe@kernel.dk>
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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: c392cbecd8ec ("io_uring/kbuf: defer release of mapped buffer rings")
Signed-off-by: Jens Axboe <axboe@kernel.dk>
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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: c56e022c0a27 ("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>
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The eventfd_signal_mask() helper was introduced for io_uring and similar
to eventfd_signal() it always passed 1 for @n. So don't bother with that
argument at all.
Link: https://lore.kernel.org/r/20231122-vfs-eventfd-signal-v2-3-bd549b14ce0c@kernel.org
Reviewed-by: Jan Kara <jack@suse.cz>
Reviewed-by: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Christian Brauner <brauner@kernel.org>
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In preparation for using these helpers, make them non-static and add
them to our internal header.
Signed-off-by: Jens Axboe <axboe@kernel.dk>
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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: 03d89a2de25b ("io_uring: support for user allocated memory for rings/sqes")
Signed-off-by: Jens Axboe <axboe@kernel.dk>
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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: 03d89a2de25b ("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>
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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: bd11b3a391e3 ("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>
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In order for `AT_EMPTY_PATH` to work as expected, the fact
that the user wants that behavior needs to make it to `getname_flags`
or it will return ENOENT.
Fixes: cf30da90bc3a ("io_uring: add support for IORING_OP_LINKAT")
Cc: <stable@vger.kernel.org>
Link: https://github.com/axboe/liburing/issues/995
Signed-off-by: Charles Mirabile <cmirabil@redhat.com>
Link: https://lore.kernel.org/r/20231120105545.1209530-1-cmirabil@redhat.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
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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: 7644b1a1c9a7 ("io_uring/fdinfo: lock SQ thread while retrieving thread cpu/pid")
Signed-off-by: Jens Axboe <axboe@kernel.dk>
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Introduce several new KVM uAPIs to ultimately create a guest-first memory
subsystem within KVM, a.k.a. guest_memfd. Guest-first memory allows KVM
to provide features, enhancements, and optimizations that are kludgly
or outright impossible to implement in a generic memory subsystem.
The core KVM ioctl() for guest_memfd is KVM_CREATE_GUEST_MEMFD, which
similar to the generic memfd_create(), creates an anonymous file and
returns a file descriptor that refers to it. Again like "regular"
memfd files, guest_memfd files live in RAM, have volatile storage,
and are automatically released when the last reference is dropped.
The key differences between memfd files (and every other memory subystem)
is that guest_memfd files are bound to their owning virtual machine,
cannot be mapped, read, or written by userspace, and cannot be resized.
guest_memfd files do however support PUNCH_HOLE, which can be used to
convert a guest memory area between the shared and guest-private states.
A second KVM ioctl(), KVM_SET_MEMORY_ATTRIBUTES, allows userspace to
specify attributes for a given page of guest memory. In the long term,
it will likely be extended to allow userspace to specify per-gfn RWX
protections, including allowing memory to be writable in the guest
without it also being writable in host userspace.
The immediate and driving use case for guest_memfd are Confidential
(CoCo) VMs, specifically AMD's SEV-SNP, Intel's TDX, and KVM's own pKVM.
For such use cases, being able to map memory into KVM guests without
requiring said memory to be mapped into the host is a hard requirement.
While SEV+ and TDX prevent untrusted software from reading guest private
data by encrypting guest memory, pKVM provides confidentiality and
integrity *without* relying on memory encryption. In addition, with
SEV-SNP and especially TDX, accessing guest private memory can be fatal
to the host, i.e. KVM must be prevent host userspace from accessing
guest memory irrespective of hardware behavior.
Long term, guest_memfd may be useful for use cases beyond CoCo VMs,
for example hardening userspace against unintentional accesses to guest
memory. As mentioned earlier, KVM's ABI uses userspace VMA protections to
define the allow guest protection (with an exception granted to mapping
guest memory executable), and similarly KVM currently requires the guest
mapping size to be a strict subset of the host userspace mapping size.
Decoupling the mappings sizes would allow userspace to precisely map
only what is needed and with the required permissions, without impacting
guest performance.
A guest-first memory subsystem also provides clearer line of sight to
things like a dedicated memory pool (for slice-of-hardware VMs) and
elimination of "struct page" (for offload setups where userspace _never_
needs to DMA from or into guest memory).
guest_memfd is the result of 3+ years of development and exploration;
taking on memory management responsibilities in KVM was not the first,
second, or even third choice for supporting CoCo VMs. But after many
failed attempts to avoid KVM-specific backing memory, and looking at
where things ended up, it is quite clear that of all approaches tried,
guest_memfd is the simplest, most robust, and most extensible, and the
right thing to do for KVM and the kernel at-large.
The "development cycle" for this version is going to be very short;
ideally, next week I will merge it as is in kvm/next, taking this through
the KVM tree for 6.8 immediately after the end of the merge window.
The series is still based on 6.6 (plus KVM changes for 6.7) so it
will require a small fixup for changes to get_file_rcu() introduced in
6.7 by commit 0ede61d8589c ("file: convert to SLAB_TYPESAFE_BY_RCU").
The fixup will be done as part of the merge commit, and most of the text
above will become the commit message for the merge.
Pending post-merge work includes:
- hugepage support
- looking into using the restrictedmem framework for guest memory
- introducing a testing mechanism to poison memory, possibly using
the same memory attributes introduced here
- SNP and TDX support
There are two non-KVM patches buried in the middle of this series:
fs: Rename anon_inode_getfile_secure() and anon_inode_getfd_secure()
mm: Add AS_UNMOVABLE to mark mapping as completely unmovable
The first is small and mostly suggested-by Christian Brauner; the second
a bit less so but it was written by an mm person (Vlastimil Babka).
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The call to the inode_init_security_anon() LSM hook is not the sole
reason to use anon_inode_getfile_secure() or anon_inode_getfd_secure().
For example, the functions also allow one to create a file with non-zero
size, without needing a full-blown filesystem. In this case, you don't
need a "secure" version, just unique inodes; the current name of the
functions is confusing and does not explain well the difference with
the more "standard" anon_inode_getfile() and anon_inode_getfd().
Of course, there is another side of the coin; neither io_uring nor
userfaultfd strictly speaking need distinct inodes, and it is not
that clear anymore that anon_inode_create_get{file,fd}() allow the LSM
to intercept and block the inode's creation. If one was so inclined,
anon_inode_getfile_secure() and anon_inode_getfd_secure() could be kept,
using the shared inode or a new one depending on CONFIG_SECURITY.
However, this is probably overkill, and potentially a cause of bugs in
different configurations. Therefore, just add a comment to io_uring
and userfaultfd explaining the choice of the function.
While at it, remove the export for what is now anon_inode_create_getfd().
There is no in-tree module that uses it, and the old name is gone anyway.
If anybody actually needs the symbol, they can ask or they can just use
anon_inode_create_getfile(), which will be exported very soon for use
in KVM.
Suggested-by: Christian Brauner <brauner@kernel.org>
Reviewed-by: Christian Brauner <brauner@kernel.org>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
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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: fc68fcda0491 ("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>
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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: fc68fcda0491 ("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>
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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>
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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>
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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>
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io_uring does non-blocking connection attempts, which can yield some
unexpected results if a connect request is re-attempted by an an
application. This is equivalent to the following sync syscall sequence:
sock = socket(AF_INET, SOCK_STREAM | SOCK_NONBLOCK, IPPROTO_TCP);
connect(sock, &addr, sizeof(addr);
ret == -1 and errno == EINPROGRESS expected here. Now poll for POLLOUT
on sock, and when that returns, we expect the socket to be connected.
But if we follow that procedure with:
connect(sock, &addr, sizeof(addr));
you'd expect ret == -1 and errno == EISCONN here, but you actually get
ret == 0. If we attempt the connection one more time, then we get EISCON
as expected.
io_uring used to do this, but turns out that bluetooth fails with EBADFD
if you attempt to re-connect. Also looks like EISCONN _could_ occur with
this sequence.
Retain the ->in_progress logic, but work-around a potential EISCONN or
EBADFD error and only in those cases look at the sock_error(). This
should work in general and avoid the odd sequence of a repeated connect
request returning success when the socket is already connected.
This is all a side effect of the socket state being in a CONNECTING
state when we get EINPROGRESS, and only a re-connect or other related
operation will turn that into CONNECTED.
Cc: stable@vger.kernel.org
Fixes: 3fb1bd688172 ("io_uring/net: handle -EINPROGRESS correct for IORING_OP_CONNECT")
Link: https://github.com/axboe/liburing/issues/980
Signed-off-by: Jens Axboe <axboe@kernel.dk>
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The new read multishot method doesn't need to allocate async data ever,
as it doesn't do vectored IO and it must only be used with provided
buffers. While it doesn't have ->prep_async() set, it also sets
->async_size to 0, which is different from any other read/write type we
otherwise support.
If it's used on a file type that isn't pollable, we do try and allocate
this async data, and then try and use that data. But since we passed in
a size of 0 for the data, we get a NULL back on data allocation. We then
proceed to dereference that to copy state, and that obviously won't end
well.
Add a check in io_setup_async_rw() for this condition, and avoid copying
state. Also add a check for whether or not buffer selection is specified
in prep while at it.
Fixes: fc68fcda0491 ("io_uring/rw: add support for IORING_OP_READ_MULTISHOT")
Link: https://bugzilla.kernel.org/show_bug.cgi?id=218101
Signed-off-by: Jens Axboe <axboe@kernel.dk>
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Pull io_uring futex support from Jens Axboe:
"This adds support for using futexes through io_uring - first futex
wake and wait, and then the vectored variant of waiting, futex waitv.
For both wait/wake/waitv, we support the bitset variant, as the
'normal' variants can be easily implemented on top of that.
PI and requeue are not supported through io_uring, just the above
mentioned parts. This may change in the future, but in the spirit of
keeping this small (and based on what people have been asking for),
this is what we currently have.
Wake support is pretty straight forward, most of the thought has gone
into the wait side to avoid needing to offload wait operations to a
blocking context. Instead, we rely on the usual callbacks to retry and
post a completion event, when appropriate.
As far as I can recall, the first request for futex support with
io_uring came from Andres Freund, working on postgres. His aio rework
of postgres was one of the early adopters of io_uring, and futex
support was a natural extension for that. This is relevant from both a
usability point of view, as well as for effiency and performance. In
Andres's words, for the former:
Futex wait support in io_uring makes it a lot easier to avoid
deadlocks in concurrent programs that have their own buffer pool:
Obviously pages in the application buffer pool have to be locked
during IO. If the initiator of IO A needs to wait for a held lock
B, the holder of lock B might wait for the IO A to complete. The
ability to wait for a lock and IO completions at the same time
provides an efficient way to avoid such deadlocks
and in terms of effiency, even without unlocking the full potential
yet, Andres says:
Futex wake support in io_uring is useful because it allows for more
efficient directed wakeups. For some "locks" postgres has queues
implemented in userspace, with wakeup logic that cannot easily be
implemented with FUTEX_WAKE_BITSET on a single "futex word"
(imagine waiting for journal flushes to have completed up to a
certain point).
Thus a "lock release" sometimes need to wake up many processes in a
row. A quick-and-dirty conversion to doing these wakeups via
io_uring lead to a 3% throughput increase, with 12% fewer context
switches, albeit in a fairly extreme workload"
* tag 'io_uring-futex-2023-10-30' of git://git.kernel.dk/linux:
io_uring: add support for vectored futex waits
futex: make the vectored futex operations available
futex: make futex_parse_waitv() available as a helper
futex: add wake_data to struct futex_q
io_uring: add support for futex wake and wait
futex: abstract out a __futex_wake_mark() helper
futex: factor out the futex wake handling
futex: move FUTEX2_VALID_MASK to futex.h
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Pull io_uring {get,set}sockopt support from Jens Axboe:
"This adds support for using getsockopt and setsockopt via io_uring.
The main use cases for this is to enable use of direct descriptors,
rather than first instantiating a normal file descriptor, doing the
option tweaking needed, then turning it into a direct descriptor. With
this support, we can avoid needing a regular file descriptor
completely.
The net and bpf bits have been signed off on their side"
* tag 'for-6.7/io_uring-sockopt-2023-10-30' of git://git.kernel.dk/linux:
selftests/bpf/sockopt: Add io_uring support
io_uring/cmd: Introduce SOCKET_URING_OP_SETSOCKOPT
io_uring/cmd: Introduce SOCKET_URING_OP_GETSOCKOPT
io_uring/cmd: return -EOPNOTSUPP if net is disabled
selftests/net: Extract uring helpers to be reusable
tools headers: Grab copy of io_uring.h
io_uring/cmd: Pass compat mode in issue_flags
net/socket: Break down __sys_getsockopt
net/socket: Break down __sys_setsockopt
bpf: Add sockptr support for setsockopt
bpf: Add sockptr support for getsockopt
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Pull io_uring updates from Jens Axboe:
"This contains the core io_uring updates, of which there are not many,
and adds support for using WAITID through io_uring and hence not
needing to block on these kinds of events.
Outside of that, tweaks to the legacy provided buffer handling and
some cleanups related to cancelations for uring_cmd support"
* tag 'for-6.7/io_uring-2023-10-30' of git://git.kernel.dk/linux:
io_uring/poll: use IOU_F_TWQ_LAZY_WAKE for wakeups
io_uring/kbuf: Use slab for struct io_buffer objects
io_uring/kbuf: Allow the full buffer id space for provided buffers
io_uring/kbuf: Fix check of BID wrapping in provided buffers
io_uring/rsrc: cleanup io_pin_pages()
io_uring: cancelable uring_cmd
io_uring: retain top 8bits of uring_cmd flags for kernel internal use
io_uring: add IORING_OP_WAITID support
exit: add internal include file with helpers
exit: add kernel_waitid_prepare() helper
exit: move core of do_wait() into helper
exit: abstract out should_wake helper for child_wait_callback()
io_uring/rw: add support for IORING_OP_READ_MULTISHOT
io_uring/rw: mark readv/writev as vectored in the opcode definition
io_uring/rw: split io_read() into a helper
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Pull misc vfs updates from Christian Brauner:
"This contains the usual miscellaneous features, cleanups, and fixes
for vfs and individual fses.
Features:
- Rename and export helpers that get write access to a mount. They
are used in overlayfs to get write access to the upper mount.
- Print the pretty name of the root device on boot failure. This
helps in scenarios where we would usually only print
"unknown-block(1,2)".
- Add an internal SB_I_NOUMASK flag. This is another part in the
endless POSIX ACL saga in a way.
When POSIX ACLs are enabled via SB_POSIXACL the vfs cannot strip
the umask because if the relevant inode has POSIX ACLs set it might
take the umask from there. But if the inode doesn't have any POSIX
ACLs set then we apply the umask in the filesytem itself. So we end
up with:
(1) no SB_POSIXACL -> strip umask in vfs
(2) SB_POSIXACL -> strip umask in filesystem
The umask semantics associated with SB_POSIXACL allowed filesystems
that don't even support POSIX ACLs at all to raise SB_POSIXACL
purely to avoid umask stripping. That specifically means NFS v4 and
Overlayfs. NFS v4 does it because it delegates this to the server
and Overlayfs because it needs to delegate umask stripping to the
upper filesystem, i.e., the filesystem used as the writable layer.
This went so far that SB_POSIXACL is raised eve on kernels that
don't even have POSIX ACL support at all.
Stop this blatant abuse and add SB_I_NOUMASK which is an internal
superblock flag that filesystems can raise to opt out of umask
handling. That should really only be the two mentioned above. It's
not that we want any filesystems to do this. Ideally we have all
umask handling always in the vfs.
- Make overlayfs use SB_I_NOUMASK too.
- Now that we have SB_I_NOUMASK, stop checking for SB_POSIXACL in
IS_POSIXACL() if the kernel doesn't have support for it. This is a
very old patch but it's only possible to do this now with the wider
cleanup that was done.
- Follow-up work on fake path handling from last cycle. Citing mostly
from Amir:
When overlayfs was first merged, overlayfs files of regular files
and directories, the ones that are installed in file table, had a
"fake" path, namely, f_path is the overlayfs path and f_inode is
the "real" inode on the underlying filesystem.
In v6.5, we took another small step by introducing of the
backing_file container and the file_real_path() helper. This change
allowed vfs and filesystem code to get the "real" path of an
overlayfs backing file. With this change, we were able to make
fsnotify work correctly and report events on the "real" filesystem
objects that were accessed via overlayfs.
This method works fine, but it still leaves the vfs vulnerable to
new code that is not aware of files with fake path. A recent
example is commit db1d1e8b9867 ("IMA: use vfs_getattr_nosec to get
the i_version"). This commit uses direct referencing to f_path in
IMA code that otherwise uses file_inode() and file_dentry() to
reference the filesystem objects that it is measuring.
This contains work to switch things around: instead of having
filesystem code opt-in to get the "real" path, have generic code
opt-in for the "fake" path in the few places that it is needed.
Is it far more likely that new filesystems code that does not use
the file_dentry() and file_real_path() helpers will end up causing
crashes or averting LSM/audit rules if we keep the "fake" path
exposed by default.
This change already makes file_dentry() moot, but for now we did
not change this helper just added a WARN_ON() in ovl_d_real() to
catch if we have made any wrong assumptions.
After the dust settles on this change, we can make file_dentry() a
plain accessor and we can drop the inode argument to ->d_real().
- Switch struct file to SLAB_TYPESAFE_BY_RCU. This looks like a small
change but it really isn't and I would like to see everyone on
their tippie toes for any possible bugs from this work.
Essentially we've been doing most of what SLAB_TYPESAFE_BY_RCU for
files since a very long time because of the nasty interactions
between the SCM_RIGHTS file descriptor garbage collection. So
extending it makes a lot of sense but it is a subtle change. There
are almost no places that fiddle with file rcu semantics directly
and the ones that did mess around with struct file internal under
rcu have been made to stop doing that because it really was always
dodgy.
I forgot to put in the link tag for this change and the discussion
in the commit so adding it into the merge message:
https://lore.kernel.org/r/20230926162228.68666-1-mjguzik@gmail.com
Cleanups:
- Various smaller pipe cleanups including the removal of a spin lock
that was only used to protect against writes without pipe_lock()
from O_NOTIFICATION_PIPE aka watch queues. As that was never
implemented remove the additional locking from pipe_write().
- Annotate struct watch_filter with the new __counted_by attribute.
- Clarify do_unlinkat() cleanup so that it doesn't look like an extra
iput() is done that would cause issues.
- Simplify file cleanup when the file has never been opened.
- Use module helper instead of open-coding it.
- Predict error unlikely for stale retry.
- Use WRITE_ONCE() for mount expiry field instead of just commenting
that one hopes the compiler doesn't get smart.
Fixes:
- Fix readahead on block devices.
- Fix writeback when layztime is enabled and inodes whose timestamp
is the only thing that changed reside on wb->b_dirty_time. This
caused excessively large zombie memory cgroup when lazytime was
enabled as such inodes weren't handled fast enough.
- Convert BUG_ON() to WARN_ON_ONCE() in open_last_lookups()"
* tag 'vfs-6.7.misc' of gitolite.kernel.org:pub/scm/linux/kernel/git/vfs/vfs: (26 commits)
file, i915: fix file reference for mmap_singleton()
vfs: Convert BUG_ON to WARN_ON_ONCE in open_last_lookups
writeback, cgroup: switch inodes with dirty timestamps to release dying cgwbs
chardev: Simplify usage of try_module_get()
ovl: rely on SB_I_NOUMASK
fs: fix umask on NFS with CONFIG_FS_POSIX_ACL=n
fs: store real path instead of fake path in backing file f_path
fs: create helper file_user_path() for user displayed mapped file path
fs: get mnt_writers count for an open backing file's real path
vfs: stop counting on gcc not messing with mnt_expiry_mark if not asked
vfs: predict the error in retry_estale as unlikely
backing file: free directly
vfs: fix readahead(2) on block devices
io_uring: use files_lookup_fd_locked()
file: convert to SLAB_TYPESAFE_BY_RCU
vfs: shave work on failed file open
fs: simplify misleading code to remove ambiguity regarding ihold()/iput()
watch_queue: Annotate struct watch_filter with __counted_by
fs/pipe: use spinlock in pipe_read() only if there is a watch_queue
fs/pipe: remove unnecessary spinlock from pipe_write()
...
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Pull misc filesystem fixes from Al Viro:
"Assorted fixes all over the place: literally nothing in common, could
have been three separate pull requests.
All are simple regression fixes, but not for anything from this cycle"
* tag 'pull-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs:
ceph_wait_on_conflict_unlink(): grab reference before dropping ->d_lock
io_uring: kiocb_done() should *not* trust ->ki_pos if ->{read,write}_iter() failed
sparc32: fix a braino in fault handling in csum_and_copy_..._user()
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failed
->ki_pos value is unreliable in such cases. For an obvious example,
consider O_DSYNC write - we feed the data to page cache and start IO,
then we make sure it's completed. Update of ->ki_pos is dealt with
by the first part; failure in the second ends up with negative value
returned _and_ ->ki_pos left advanced as if sync had been successful.
In the same situation write(2) does not advance the file position
at all.
Reviewed-by: Christian Brauner <brauner@kernel.org>
Reviewed-by: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
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If an application does O_DIRECT writes with io_uring and the file system
supports IOCB_DIO_CALLER_COMP, then completions of the dio write side is
done from the task_work that will post the completion event for said
write as well.
Whenever a dio write is done against a file, the inode i_dio_count is
elevated. This enables other callers to use inode_dio_wait() to wait for
previous writes to complete. If we defer the full dio completion to
task_work, we are dependent on that task_work being run before the
inode i_dio_count can be decremented.
If the same task that issues io_uring dio writes with
IOCB_DIO_CALLER_COMP performs a synchronous system call that calls
inode_dio_wait(), then we can deadlock as we're blocked sleeping on
the event to become true, but not processing the completions that will
result in the inode i_dio_count being decremented.
Until we can guarantee that this is the case, then disable the deferred
caller completions.
Fixes: 099ada2c8726 ("io_uring/rw: add write support for IOCB_DIO_CALLER_COMP")
Reported-by: Andres Freund <andres@anarazel.de>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
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We could race with SQ thread exit, and if we do, we'll hit a NULL pointer
dereference when the thread is cleared. Grab the SQPOLL data lock before
attempting to get the task cpu and pid for fdinfo, this ensures we have a
stable view of it.
Cc: stable@vger.kernel.org
Link: https://bugzilla.kernel.org/show_bug.cgi?id=218032
Reviewed-by: Gabriel Krisman Bertazi <krisman@suse.de>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
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Add initial support for SOCKET_URING_OP_SETSOCKOPT. This new command is
similar to setsockopt. This implementation leverages the function
do_sock_setsockopt(), which is shared with the setsockopt() system call
path.
Important to say that userspace needs to keep the pointer's memory alive
until the operation is completed. I.e, the memory could not be
deallocated before the CQE is returned to userspace.
Signed-off-by: Breno Leitao <leitao@debian.org>
Reviewed-by: Gabriel Krisman Bertazi <krisman@suse.de>
Link: https://lore.kernel.org/r/20231016134750.1381153-11-leitao@debian.org
Signed-off-by: Jens Axboe <axboe@kernel.dk>
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