Right now we punt any buffered request that ends up triggering an
-EAGAIN to an async workqueue. This works fine in terms of providing
async execution of them, but it also can create quite a lot of work
queue items. For sequentially buffered IO, it's advantageous to
serialize the issue of them. For reads, the first one will trigger a
read-ahead, and subsequent request merely end up waiting on later pages
to complete. For writes, devices usually respond better to streamed
sequential writes.
Add state to track the last buffered request we punted to a work queue,
and if the next one is sequential to the previous, attempt to get the
previous work item to handle it. We limit the number of sequential
add-ons to the a multiple (8) of the max read-ahead size of the file.
This should be a good number for both reads and wries, as it defines the
max IO size the device can do directly.
This drastically cuts down on the number of context switches we need to
handle buffered sequential IO, and a basic test case of copying a big
file with io_uring sees a 5x speedup.
Reviewed-by: Hannes Reinecke <hare@suse.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
This is basically a direct port of bfe4037e72, which implements a
one-shot poll command through aio. Description below is based on that
commit as well. However, instead of adding a POLL command and relying
on io_cancel(2) to remove it, we mimic the epoll(2) interface of
having a command to add a poll notification, IORING_OP_POLL_ADD,
and one to remove it again, IORING_OP_POLL_REMOVE.
To poll for a file descriptor the application should submit an sqe of
type IORING_OP_POLL. It will poll the fd for the events specified in the
poll_events field.
Unlike poll or epoll without EPOLLONESHOT this interface always works in
one shot mode, that is once the sqe is completed, it will have to be
resubmitted.
Reviewed-by: Hannes Reinecke <hare@suse.com>
Based-on-code-from: Christoph Hellwig <hch@lst.de>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
We'll use this for the POLL implementation. Regular requests will
NOT be using references, so initialize it to 0. Any real use of
the io_kiocb ref will initialize it to at least 2.
Reviewed-by: Hannes Reinecke <hare@suse.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
This enables an application to do IO, without ever entering the kernel.
By using the SQ ring to fill in new sqes and watching for completions
on the CQ ring, we can submit and reap IOs without doing a single system
call. The kernel side thread will poll for new submissions, and in case
of HIPRI/polled IO, it'll also poll for completions.
By default, we allow 1 second of active spinning. This can by changed
by passing in a different grace period at io_uring_register(2) time.
If the thread exceeds this idle time without having any work to do, it
will set:
sq_ring->flags |= IORING_SQ_NEED_WAKEUP.
The application will have to call io_uring_enter() to start things back
up again. If IO is kept busy, that will never be needed. Basically an
application that has this feature enabled will guard it's
io_uring_enter(2) call with:
read_barrier();
if (*sq_ring->flags & IORING_SQ_NEED_WAKEUP)
io_uring_enter(fd, 0, 0, IORING_ENTER_SQ_WAKEUP);
instead of calling it unconditionally.
It's mandatory to use fixed files with this feature. Failure to do so
will result in the application getting an -EBADF CQ entry when
submitting IO.
Reviewed-by: Hannes Reinecke <hare@suse.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
We normally have to fget/fput for each IO we do on a file. Even with
the batching we do, the cost of the atomic inc/dec of the file usage
count adds up.
This adds IORING_REGISTER_FILES, and IORING_UNREGISTER_FILES opcodes
for the io_uring_register(2) system call. The arguments passed in must
be an array of __s32 holding file descriptors, and nr_args should hold
the number of file descriptors the application wishes to pin for the
duration of the io_uring instance (or until IORING_UNREGISTER_FILES is
called).
When used, the application must set IOSQE_FIXED_FILE in the sqe->flags
member. Then, instead of setting sqe->fd to the real fd, it sets sqe->fd
to the index in the array passed in to IORING_REGISTER_FILES.
Files are automatically unregistered when the io_uring instance is torn
down. An application need only unregister if it wishes to register a new
set of fds.
Reviewed-by: Hannes Reinecke <hare@suse.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
We need this functionality for the io_uring file registration, but
we cannot rely on it since CONFIG_UNIX can be modular. Move the helpers
to a separate file, that's always builtin to the kernel if CONFIG_UNIX is
m/y.
No functional changes in this patch, just moving code around.
Reviewed-by: Hannes Reinecke <hare@suse.com>
Acked-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
If we have fixed user buffers, we can map them into the kernel when we
setup the io_uring. That avoids the need to do get_user_pages() for
each and every IO.
To utilize this feature, the application must call io_uring_register()
after having setup an io_uring instance, passing in
IORING_REGISTER_BUFFERS as the opcode. The argument must be a pointer to
an iovec array, and the nr_args should contain how many iovecs the
application wishes to map.
If successful, these buffers are now mapped into the kernel, eligible
for IO. To use these fixed buffers, the application must use the
IORING_OP_READ_FIXED and IORING_OP_WRITE_FIXED opcodes, and then
set sqe->index to the desired buffer index. sqe->addr..sqe->addr+seq->len
must point to somewhere inside the indexed buffer.
The application may register buffers throughout the lifetime of the
io_uring instance. It can call io_uring_register() with
IORING_UNREGISTER_BUFFERS as the opcode to unregister the current set of
buffers, and then register a new set. The application need not
unregister buffers explicitly before shutting down the io_uring
instance.
It's perfectly valid to setup a larger buffer, and then sometimes only
use parts of it for an IO. As long as the range is within the originally
mapped region, it will work just fine.
For now, buffers must not be file backed. If file backed buffers are
passed in, the registration will fail with -1/EOPNOTSUPP. This
restriction may be relaxed in the future.
RLIMIT_MEMLOCK is used to check how much memory we can pin. A somewhat
arbitrary 1G per buffer size is also imposed.
Reviewed-by: Hannes Reinecke <hare@suse.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
For an ITER_BVEC, we can just iterate the iov and add the pages
to the bio directly. For now, we grab a reference to those pages,
and release them normally on IO completion. This isn't really needed
for the normal case of O_DIRECT from/to a file, but some of the more
esoteric use cases (like splice(2)) will unconditionally put the
pipe buffer pages when the buffers are released. Until we can manage
that case properly, ITER_BVEC pages are treated like normal pages
in terms of reference counting.
Reviewed-by: Hannes Reinecke <hare@suse.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Similarly to how we use the state->ios_left to know how many references
to get to a file, we can use it to allocate the io_kiocb's we need in
bulk.
Reviewed-by: Hannes Reinecke <hare@suse.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Add a separate io_submit_state structure, to cache some of the things
we need for IO submission.
One such example is file reference batching. io_submit_state. We get as
many references as the number of sqes we are submitting, and drop
unused ones if we end up switching files. The assumption here is that
we're usually only dealing with one fd, and if there are multiple,
hopefuly they are at least somewhat ordered. Could trivially be extended
to cover multiple fds, if needed.
On the completion side we do the same thing, except this is trivially
done just locally in io_iopoll_reap().
Reviewed-by: Hannes Reinecke <hare@suse.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Some uses cases repeatedly get and put references to the same file, but
the only exposed interface is doing these one at the time. As each of
these entail an atomic inc or dec on a shared structure, that cost can
add up.
Add fget_many(), which works just like fget(), except it takes an
argument for how many references to get on the file. Ditto fput_many(),
which can drop an arbitrary number of references to a file.
Reviewed-by: Hannes Reinecke <hare@suse.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Add support for a polled io_uring instance. When a read or write is
submitted to a polled io_uring, the application must poll for
completions on the CQ ring through io_uring_enter(2). Polled IO may not
generate IRQ completions, hence they need to be actively found by the
application itself.
To use polling, io_uring_setup() must be used with the
IORING_SETUP_IOPOLL flag being set. It is illegal to mix and match
polled and non-polled IO on an io_uring.
Reviewed-by: Hannes Reinecke <hare@suse.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Add a new fsync opcode, which either syncs a range if one is passed,
or the whole file if the offset and length fields are both cleared
to zero. A flag is provided to use fdatasync semantics, that is only
force out metadata which is required to retrieve the file data, but
not others like metadata.
Reviewed-by: Hannes Reinecke <hare@suse.com>
Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
The submission queue (SQ) and completion queue (CQ) rings are shared
between the application and the kernel. This eliminates the need to
copy data back and forth to submit and complete IO.
IO submissions use the io_uring_sqe data structure, and completions
are generated in the form of io_uring_cqe data structures. The SQ
ring is an index into the io_uring_sqe array, which makes it possible
to submit a batch of IOs without them being contiguous in the ring.
The CQ ring is always contiguous, as completion events are inherently
unordered, and hence any io_uring_cqe entry can point back to an
arbitrary submission.
Two new system calls are added for this:
io_uring_setup(entries, params)
Sets up an io_uring instance for doing async IO. On success,
returns a file descriptor that the application can mmap to
gain access to the SQ ring, CQ ring, and io_uring_sqes.
io_uring_enter(fd, to_submit, min_complete, flags, sigset, sigsetsize)
Initiates IO against the rings mapped to this fd, or waits for
them to complete, or both. The behavior is controlled by the
parameters passed in. If 'to_submit' is non-zero, then we'll
try and submit new IO. If IORING_ENTER_GETEVENTS is set, the
kernel will wait for 'min_complete' events, if they aren't
already available. It's valid to set IORING_ENTER_GETEVENTS
and 'min_complete' == 0 at the same time, this allows the
kernel to return already completed events without waiting
for them. This is useful only for polling, as for IRQ
driven IO, the application can just check the CQ ring
without entering the kernel.
With this setup, it's possible to do async IO with a single system
call. Future developments will enable polled IO with this interface,
and polled submission as well. The latter will enable an application
to do IO without doing ANY system calls at all.
For IRQ driven IO, an application only needs to enter the kernel for
completions if it wants to wait for them to occur.
Each io_uring is backed by a workqueue, to support buffered async IO
as well. We will only punt to an async context if the command would
need to wait for IO on the device side. Any data that can be accessed
directly in the page cache is done inline. This avoids the slowness
issue of usual threadpools, since cached data is accessed as quickly
as a sync interface.
Sample application: http://git.kernel.dk/cgit/fio/plain/t/io_uring.c
Reviewed-by: Hannes Reinecke <hare@suse.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
mp_bvec_for_each_segment() is a bit big for the iteration, so introduce
a light-weight helper for iterating over pages, then 32bytes stack
space can be saved.
Signed-off-by: Ming Lei <ming.lei@redhat.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Introduce a fast path for single-page bvec IO, then we can avoid
to call bvec_split_segs() unnecessarily.
Signed-off-by: Ming Lei <ming.lei@redhat.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Introduce a fast path for single-page bvec IO, then blk_bvec_map_sg()
can be avoided.
Signed-off-by: Ming Lei <ming.lei@redhat.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Single-page bvec can often be seen in small BS workloads, so
introduce bvec_nth_page() for avoiding to call nth_page() unnecessarily,
which looks not cheap.
Signed-off-by: Ming Lei <ming.lei@redhat.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Store the request queue the last bio was submitted to in the iocb
private data in addition to the cookie so that we find the right block
device. Also refactor the common direct I/O bio submission code into a
nice little helper.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Modified to use bio_set_polled().
Reviewed-by: Hannes Reinecke <hare@suse.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
For the upcoming async polled IO, we can't sleep allocating requests.
If we do, then we introduce a deadlock where the submitter already
has async polled IO in-flight, but can't wait for them to complete
since polled requests must be active found and reaped.
Utilize the helper in the blockdev DIRECT_IO code.
Reviewed-by: Hannes Reinecke <hare@suse.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Just call blk_poll on the iocb cookie, we can derive the block device
from the inode trivially.
Reviewed-by: Hannes Reinecke <hare@suse.com>
Reviewed-by: Johannes Thumshirn <jthumshirn@suse.de>
Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
This new methods is used to explicitly poll for I/O completion for an
iocb. It must be called for any iocb submitted asynchronously (that
is with a non-null ki_complete) which has the IOCB_HIPRI flag set.
The method is assisted by a new ki_cookie field in struct iocb to store
the polling cookie.
Reviewed-by: Hannes Reinecke <hare@suse.com>
Reviewed-by: Johannes Thumshirn <jthumshirn@suse.de>
Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Commit 0da03cab87
("loop: Fix deadlock when calling blkdev_reread_part()") moves
blkdev_reread_part() out of the loop_ctl_mutex. However,
GENHD_FL_NO_PART_SCAN is set before __blkdev_reread_part(). As a result,
__blkdev_reread_part() will fail the check of GENHD_FL_NO_PART_SCAN and
will not rescan the loop device to delete all partitions.
Below are steps to reproduce the issue:
step1 # dd if=/dev/zero of=tmp.raw bs=1M count=100
step2 # losetup -P /dev/loop0 tmp.raw
step3 # parted /dev/loop0 mklabel gpt
step4 # parted -a none -s /dev/loop0 mkpart primary 64s 1
step5 # losetup -d /dev/loop0
Step5 will not be able to delete /dev/loop0p1 (introduced by step4) and
there is below kernel warning message:
[ 464.414043] __loop_clr_fd: partition scan of loop0 failed (rc=-22)
This patch sets GENHD_FL_NO_PART_SCAN after blkdev_reread_part().
Fixes: 0da03cab87 ("loop: Fix deadlock when calling blkdev_reread_part()")
Signed-off-by: Dongli Zhang <dongli.zhang@oracle.com>
Reviewed-by: Jan Kara <jack@suse.cz>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Do not print warn message when the partition scan returns 0.
Fixes: d57f3374ba ("loop: Move special partition reread handling in loop_clr_fd()")
Signed-off-by: Dongli Zhang <dongli.zhang@oracle.com>
Reviewed-by: Jan Kara <jack@suse.cz>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Block bounce needs to allocate new page for doing IO, and the
new page has to be updated to bvec table.
Commit 6dc4f100c switches __blk_queue_bounce() to use the new
bio_for_each_segment_all() interface. Unfortunately the new
bio_for_each_segment_all() can't be used to update bvec table.
This patch fixes this issue by retrieving bvec from the table
directly, then the new allocated page can be updated to the bio.
This way is safe because the cloned bio is single page bvec.
Fixes: 6dc4f100c ("block: allow bio_for_each_segment_all() to iterate over multi-page bvec")
Cc: Christoph Hellwig <hch@lst.de>
Cc: Omar Sandoval <osandov@fb.com>
Signed-off-by: Ming Lei <ming.lei@redhat.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Pull NVMe changes for 5.1 from Christoph
* 'nvme-5.1' of git://git.infradead.org/nvme: (22 commits)
nvme-rdma: use nr_phys_segments when map rq to sgl
nvmet: convert to SPDX identifiers
nvmet-rdma: convert to SPDX identifiers
nvme-loop: convert to SPDX identifiers
nvmet-fcloop: convert to SPDX identifiers
nvmet-fc: convert to SPDX identifiers
nvme: convert to SPDX identifiers
nvme-pci: convert to SPDX identifiers
nvme-lightnvm: convert to SPDX identifiers
nvme-rdma: convert to SPDX identifiers
nvme-fc: convert to SPDX identifiers
nvme-fabrics: convert to SPDX identifiers
nvme-tcp.h: fix SPDX header
nvme_ioctl.h: remove duplicate GPL boilerplate
nvme: return error from nvme_alloc_ns()
nvme: avoid that deleting a controller triggers a circular locking complaint
nvme: introduce a helper function for controller deletion
nvme: unexport nvme_delete_ctrl_sync()
nvme-pci: check kstrtoint() return value in queue_count_set()
nvme-fabrics: document the poll function argument
...
Use blk_rq_nr_phys_segments() instead of blk_rq_payload_bytes() to check
if a command contains data to be mapped. This fixes the case where
a struct request contains LBAs, but it has no payload, such as
Write Zeroes support.
Fixes: 6e02318eae ("nvme: add support for the Write Zeroes command")
Reported-by: Ming Lei <tom.leiming@gmail.com>
Signed-off-by: Chaitanya Kulkarni <chaitanya.kulkarni@wdc.com>
Tested-by: Ming Lei <tom.leiming@gmail.com>
Signed-off-by: Christoph Hellwig <hch@lst.de>
Update license to use SPDX-License-Identifier instead of verbose license
text.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Sagi Grimberg <sagi@grimberg.me>
Update license to use SPDX-License-Identifier instead of verbose license
text.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Sagi Grimberg <sagi@grimberg.me>
Update license to use SPDX-License-Identifier instead of verbose license
text.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Sagi Grimberg <sagi@grimberg.me>
Update license to use SPDX-License-Identifier instead of verbose license
text.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Sagi Grimberg <sagi@grimberg.me>
Update license to use SPDX-License-Identifier instead of verbose license
text.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Sagi Grimberg <sagi@grimberg.me>
Update license to use SPDX-License-Identifier instead of verbose license
text.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Sagi Grimberg <sagi@grimberg.me>
Update license to use SPDX-License-Identifier instead of verbose license
text.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Sagi Grimberg <sagi@grimberg.me>
Update license to use SPDX-License-Identifier instead of verbose license
text.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Sagi Grimberg <sagi@grimberg.me>
Update license to use SPDX-License-Identifier instead of verbose license
text.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Sagi Grimberg <sagi@grimberg.me>
Update license to use SPDX-License-Identifier instead of verbose license
text.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Sagi Grimberg <sagi@grimberg.me>
Update license to use SPDX-License-Identifier instead of verbose license
text.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Sagi Grimberg <sagi@grimberg.me>
We already have a ЅPDX header, so no need to duplicate the information.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Sagi Grimberg <sagi@grimberg.me>
nvme_alloc_ns() might fail, so we should be returning an error code.
Signed-off-by: Hannes Reinecke <hare@suse.com>
Reviewed-by: Sagi Grimberg <sagi@grimberg.me>
Signed-off-by: Christoph Hellwig <hch@lst.de>
This patch does not change any functionality but makes the next patch
in this series easier to read.
Signed-off-by: Bart Van Assche <bvanassche@acm.org>
Reviewed-by: Sagi Grimberg <sagi@grimberg.me>
Signed-off-by: Christoph Hellwig <hch@lst.de>
Since nvme_delete_ctrl_sync() is not called from any other kernel module,
unexport it.
Signed-off-by: Bart Van Assche <bvanassche@acm.org>
Reviewed-by: Sagi Grimberg <sagi@grimberg.me>
Reviewed-by: Chaitanya Kulkarni <chaitanya.kulkarni@wdc.com>
Signed-off-by: Christoph Hellwig <hch@lst.de>
This patch avoids that the compiler complains about 'ret' being set
but not being used when building with W=1.
Fixes: 3b6592f70a ("nvme: utilize two queue maps, one for reads and one for writes") # v5.0-rc1
Signed-off-by: Bart Van Assche <bvanassche@acm.org>
Reviewed-by: Sagi Grimberg <sagi@grimberg.me>
Reviewed-by: Chaitanya Kulkarni <chaitanya.kulkarni@wdc.com>
Signed-off-by: Christoph Hellwig <hch@lst.de>
This patch avoids that the kernel-doc tool reports a warning when
building with W=1.
Fixes: 26c682274e ("nvme-fabrics: allow nvmf_connect_io_queue to poll") # v5.0-rc1
Signed-off-by: Bart Van Assche <bvanassche@acm.org>
Reviewed-by: Sagi Grimberg <sagi@grimberg.me>
Reviewed-by: Chaitanya Kulkarni <chaitanya.kulkarni@wdc.com>
Signed-off-by: Christoph Hellwig <hch@lst.de>
Implement a simple round-robin I/O policy for multipathing. Path
selection is done in two rounds, first iterating across all optimized
paths, and if that doesn't return any valid paths, iterate over all
optimized and non-optimized paths. If no paths are found, use the
existing algorithm. Also add a sysfs attribute 'iopolicy' to switch
between the current NUMA-aware I/O policy and the 'round-robin' I/O
policy.
Signed-off-by: Hannes Reinecke <hare@suse.com>
Signed-off-by: Christoph Hellwig <hch@lst.de>
rq->bio can be NULL sometimes, such as flush request, so don't
read bio->bi_seg_front_size until this 'bio' is checked as valid.
Cc: Bart Van Assche <bvanassche@acm.org>
Reported-by: Bart Van Assche <bvanassche@acm.org>
Fixes: dcebd75592 ("block: use bio_for_each_bvec() to compute multi-page bvec count")
Signed-off-by: Ming Lei <ming.lei@redhat.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
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Merge tag 'v5.0-rc6' into for-5.1/block
Pull in 5.0-rc6 to avoid a dumb merge conflict with fs/iomap.c.
This is needed since io_uring is now based on the block branch,
to avoid a conflict between the multi-page bvecs and the bits
of io_uring that touch the core block parts.
* tag 'v5.0-rc6': (525 commits)
Linux 5.0-rc6
x86/mm: Make set_pmd_at() paravirt aware
MAINTAINERS: Update the ocores i2c bus driver maintainer, etc
blk-mq: remove duplicated definition of blk_mq_freeze_queue
Blk-iolatency: warn on negative inflight IO counter
blk-iolatency: fix IO hang due to negative inflight counter
MAINTAINERS: unify reference to xen-devel list
x86/mm/cpa: Fix set_mce_nospec()
futex: Handle early deadlock return correctly
futex: Fix barrier comment
net: dsa: b53: Fix for failure when irq is not defined in dt
blktrace: Show requests without sector
mips: cm: reprime error cause
mips: loongson64: remove unreachable(), fix loongson_poweroff().
sit: check if IPv6 enabled before calling ip6_err_gen_icmpv6_unreach()
geneve: should not call rt6_lookup() when ipv6 was disabled
KVM: nVMX: unconditionally cancel preemption timer in free_nested (CVE-2019-7221)
KVM: x86: work around leak of uninitialized stack contents (CVE-2019-7222)
kvm: fix kvm_ioctl_create_device() reference counting (CVE-2019-6974)
signal: Better detection of synchronous signals
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