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commit c4068bf898ddaef791049a366828d9b84b467bda upstream.
The smart syzbot has found a reproducer for the following issue:
==================================================================
BUG: KASAN: use-after-free in instrument_atomic_write include/linux/instrumented.h:71 [inline]
BUG: KASAN: use-after-free in atomic_inc include/asm-generic/atomic-instrumented.h:240 [inline]
BUG: KASAN: use-after-free in io_wqe_inc_running fs/io-wq.c:301 [inline]
BUG: KASAN: use-after-free in io_wq_worker_running+0xde/0x110 fs/io-wq.c:613
Write of size 4 at addr ffff8882183db08c by task io_wqe_worker-0/7771
CPU: 0 PID: 7771 Comm: io_wqe_worker-0 Not tainted 5.9.0-rc4-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Call Trace:
__dump_stack lib/dump_stack.c:77 [inline]
dump_stack+0x198/0x1fd lib/dump_stack.c:118
print_address_description.constprop.0.cold+0xae/0x497 mm/kasan/report.c:383
__kasan_report mm/kasan/report.c:513 [inline]
kasan_report.cold+0x1f/0x37 mm/kasan/report.c:530
check_memory_region_inline mm/kasan/generic.c:186 [inline]
check_memory_region+0x13d/0x180 mm/kasan/generic.c:192
instrument_atomic_write include/linux/instrumented.h:71 [inline]
atomic_inc include/asm-generic/atomic-instrumented.h:240 [inline]
io_wqe_inc_running fs/io-wq.c:301 [inline]
io_wq_worker_running+0xde/0x110 fs/io-wq.c:613
schedule_timeout+0x148/0x250 kernel/time/timer.c:1879
io_wqe_worker+0x517/0x10e0 fs/io-wq.c:580
kthread+0x3b5/0x4a0 kernel/kthread.c:292
ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:294
Allocated by task 7768:
kasan_save_stack+0x1b/0x40 mm/kasan/common.c:48
kasan_set_track mm/kasan/common.c:56 [inline]
__kasan_kmalloc.constprop.0+0xbf/0xd0 mm/kasan/common.c:461
kmem_cache_alloc_node_trace+0x17b/0x3f0 mm/slab.c:3594
kmalloc_node include/linux/slab.h:572 [inline]
kzalloc_node include/linux/slab.h:677 [inline]
io_wq_create+0x57b/0xa10 fs/io-wq.c:1064
io_init_wq_offload fs/io_uring.c:7432 [inline]
io_sq_offload_start fs/io_uring.c:7504 [inline]
io_uring_create fs/io_uring.c:8625 [inline]
io_uring_setup+0x1836/0x28e0 fs/io_uring.c:8694
do_syscall_64+0x2d/0x70 arch/x86/entry/common.c:46
entry_SYSCALL_64_after_hwframe+0x44/0xa9
Freed by task 21:
kasan_save_stack+0x1b/0x40 mm/kasan/common.c:48
kasan_set_track+0x1c/0x30 mm/kasan/common.c:56
kasan_set_free_info+0x1b/0x30 mm/kasan/generic.c:355
__kasan_slab_free+0xd8/0x120 mm/kasan/common.c:422
__cache_free mm/slab.c:3418 [inline]
kfree+0x10e/0x2b0 mm/slab.c:3756
__io_wq_destroy fs/io-wq.c:1138 [inline]
io_wq_destroy+0x2af/0x460 fs/io-wq.c:1146
io_finish_async fs/io_uring.c:6836 [inline]
io_ring_ctx_free fs/io_uring.c:7870 [inline]
io_ring_exit_work+0x1e4/0x6d0 fs/io_uring.c:7954
process_one_work+0x94c/0x1670 kernel/workqueue.c:2269
worker_thread+0x64c/0x1120 kernel/workqueue.c:2415
kthread+0x3b5/0x4a0 kernel/kthread.c:292
ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:294
The buggy address belongs to the object at ffff8882183db000
which belongs to the cache kmalloc-1k of size 1024
The buggy address is located 140 bytes inside of
1024-byte region [ffff8882183db000, ffff8882183db400)
The buggy address belongs to the page:
page:000000009bada22b refcount:1 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x2183db
flags: 0x57ffe0000000200(slab)
raw: 057ffe0000000200 ffffea0008604c48 ffffea00086a8648 ffff8880aa040700
raw: 0000000000000000 ffff8882183db000 0000000100000002 0000000000000000
page dumped because: kasan: bad access detected
Memory state around the buggy address:
ffff8882183daf80: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
ffff8882183db000: fa fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
>ffff8882183db080: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
^
ffff8882183db100: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
ffff8882183db180: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
==================================================================
which is down to the comment below,
/* all workers gone, wq exit can proceed */
if (!nr_workers && refcount_dec_and_test(&wqe->wq->refs))
complete(&wqe->wq->done);
because there might be multiple cases of wqe in a wq and we would wait
for every worker in every wqe to go home before releasing wq's resources
on destroying.
To that end, rework wq's refcount by making it independent of the tracking
of workers because after all they are two different things, and keeping
it balanced when workers come and go. Note the manager kthread, like
other workers, now holds a grab to wq during its lifetime.
Finally to help destroy wq, check IO_WQ_BIT_EXIT upon creating worker
and do nothing for exiting wq.
Cc: stable@vger.kernel.org # v5.5+
Reported-by: syzbot+45fa0a195b941764e0f0@syzkaller.appspotmail.com
Reported-by: syzbot+9af99580130003da82b1@syzkaller.appspotmail.com
Cc: Pavel Begunkov <asml.silence@gmail.com>
Signed-off-by: Hillf Danton <hdanton@sina.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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commit 95da84659226d75698a1ab958be0af21d9cc2a9c upstream.
During a context switch the scheduler invokes wq_worker_sleeping() with
disabled preemption. Disabling preemption is needed because it protects
access to `worker->sleeping'. As an optimisation it avoids invoking
schedule() within the schedule path as part of possible wake up (thus
preempt_enable_no_resched() afterwards).
The io-wq has been added to the mix in the same section with disabled
preemption. This breaks on PREEMPT_RT because io_wq_worker_sleeping()
acquires a spinlock_t. Also within the schedule() the spinlock_t must be
acquired after tsk_is_pi_blocked() otherwise it will block on the
sleeping lock again while scheduling out.
While playing with `io_uring-bench' I didn't notice a significant
latency spike after converting io_wqe::lock to a raw_spinlock_t. The
latency was more or less the same.
In order to keep the spinlock_t it would have to be moved after the
tsk_is_pi_blocked() check which would introduce a branch instruction
into the hot path.
The lock is used to maintain the `work_list' and wakes one task up at
most.
Should io_wqe_cancel_pending_work() cause latency spikes, while
searching for a specific item, then it would need to drop the lock
during iterations.
revert_creds() is also invoked under the lock. According to debug
cred::non_rcu is 0. Otherwise it should be moved outside of the locked
section because put_cred_rcu()->free_uid() acquires a sleeping lock.
Convert io_wqe::lock to a raw_spinlock_t.c
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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commit 9b8284921513fc1ea57d87777283a59b05862f03 upstream.
If we don't get and assign the namespace for the async work, then certain
paths just don't work properly (like /dev/stdin, /proc/mounts, etc).
Anything that references the current namespace of the given task should
be assigned for async work on behalf of that task.
Cc: stable@vger.kernel.org # v5.5+
Reported-by: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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commit 204361a77f4018627addd4a06877448f088ddfc0 upstream.
Don't forget to update wqe->hash_tail after cancelling a pending work
item, if it was hashed.
Cc: stable@vger.kernel.org # 5.7+
Reported-by: Dmitry Shulyak <yashulyak@gmail.com>
Fixes: 86f3cd1b589a1 ("io-wq: handle hashed writes in chains")
Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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If a process is going away, io_uring_flush() will cancel only 1
request with a matching pid. Cancel all of them
Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
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This adds support for cancelling all io-wq works matching a predicate.
It isn't used yet, so no change in observable behaviour.
Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
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Go all over all pending lists and cancel works there, and only then
try to match running requests. No functional changes here, just a
preparation for bulk cancellation.
Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
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Pull io_uring fixes from Jens Axboe:
"A few late stragglers in here. In particular:
- Validate full range for provided buffers (Bijan)
- Fix bad use of kfree() in buffer registration failure (Denis)
- Don't allow close of ring itself, it's not fully safe. Making it
fully safe would require making the system call more expensive,
which isn't worth it.
- Buffer selection fix
- Regression fix for O_NONBLOCK retry
- Make IORING_OP_ACCEPT honor O_NONBLOCK (Jiufei)
- Restrict opcode handling for SQ/IOPOLL (Pavel)
- io-wq work handling cleanups and improvements (Pavel, Xiaoguang)
- IOPOLL race fix (Xiaoguang)"
* tag 'io_uring-5.8-2020-06-11' of git://git.kernel.dk/linux-block:
io_uring: fix io_kiocb.flags modification race in IOPOLL mode
io_uring: check file O_NONBLOCK state for accept
io_uring: avoid unnecessary io_wq_work copy for fast poll feature
io_uring: avoid whole io_wq_work copy for requests completed inline
io_uring: allow O_NONBLOCK async retry
io_wq: add per-wq work handler instead of per work
io_uring: don't arm a timeout through work.func
io_uring: remove custom ->func handlers
io_uring: don't derive close state from ->func
io_uring: use kvfree() in io_sqe_buffer_register()
io_uring: validate the full range of provided buffers for access
io_uring: re-set iov base/len for buffer select retry
io_uring: move send/recv IOPOLL check into prep
io_uring: deduplicate io_openat{,2}_prep()
io_uring: do build_open_how() only once
io_uring: fix {SQ,IO}POLL with unsupported opcodes
io_uring: disallow close of ring itself
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Some architectures like arm64 and s390 require USER_DS to be set for
kernel threads to access user address space, which is the whole purpose of
kthread_use_mm, but other like x86 don't. That has lead to a huge mess
where some callers are fixed up once they are tested on said
architectures, while others linger around and yet other like io_uring try
to do "clever" optimizations for what usually is just a trivial asignment
to a member in the thread_struct for most architectures.
Make kthread_use_mm set USER_DS, and kthread_unuse_mm restore to the
previous value instead.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Tested-by: Jens Axboe <axboe@kernel.dk>
Reviewed-by: Jens Axboe <axboe@kernel.dk>
Acked-by: Michael S. Tsirkin <mst@redhat.com>
Cc: Alex Deucher <alexander.deucher@amd.com>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: Felipe Balbi <balbi@kernel.org>
Cc: Felix Kuehling <Felix.Kuehling@amd.com>
Cc: Jason Wang <jasowang@redhat.com>
Cc: Zhenyu Wang <zhenyuw@linux.intel.com>
Cc: Zhi Wang <zhi.a.wang@intel.com>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Link: http://lkml.kernel.org/r/20200404094101.672954-7-hch@lst.de
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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Switch the function documentation to kerneldoc comments, and add
WARN_ON_ONCE asserts that the calling thread is a kernel thread and does
not have ->mm set (or has ->mm set in the case of unuse_mm).
Also give the functions a kthread_ prefix to better document the use case.
[hch@lst.de: fix a comment typo, cover the newly merged use_mm/unuse_mm caller in vfio]
Link: http://lkml.kernel.org/r/20200416053158.586887-3-hch@lst.de
[sfr@canb.auug.org.au: powerpc/vas: fix up for {un}use_mm() rename]
Link: http://lkml.kernel.org/r/20200422163935.5aa93ba5@canb.auug.org.au
Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Stephen Rothwell <sfr@canb.auug.org.au>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Tested-by: Jens Axboe <axboe@kernel.dk>
Reviewed-by: Jens Axboe <axboe@kernel.dk>
Acked-by: Felix Kuehling <Felix.Kuehling@amd.com>
Acked-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> [usb]
Acked-by: Haren Myneni <haren@linux.ibm.com>
Cc: Alex Deucher <alexander.deucher@amd.com>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: Felipe Balbi <balbi@kernel.org>
Cc: Jason Wang <jasowang@redhat.com>
Cc: "Michael S. Tsirkin" <mst@redhat.com>
Cc: Zhenyu Wang <zhenyuw@linux.intel.com>
Cc: Zhi Wang <zhi.a.wang@intel.com>
Link: http://lkml.kernel.org/r/20200404094101.672954-6-hch@lst.de
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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Patch series "improve use_mm / unuse_mm", v2.
This series improves the use_mm / unuse_mm interface by better documenting
the assumptions, and my taking the set_fs manipulations spread over the
callers into the core API.
This patch (of 3):
Use the proper API instead.
Link: http://lkml.kernel.org/r/20200404094101.672954-1-hch@lst.de
These helpers are only for use with kernel threads, and I will tie them
more into the kthread infrastructure going forward. Also move the
prototypes to kthread.h - mmu_context.h was a little weird to start with
as it otherwise contains very low-level MM bits.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Tested-by: Jens Axboe <axboe@kernel.dk>
Reviewed-by: Jens Axboe <axboe@kernel.dk>
Acked-by: Felix Kuehling <Felix.Kuehling@amd.com>
Cc: Alex Deucher <alexander.deucher@amd.com>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: Felipe Balbi <balbi@kernel.org>
Cc: Jason Wang <jasowang@redhat.com>
Cc: "Michael S. Tsirkin" <mst@redhat.com>
Cc: Zhenyu Wang <zhenyuw@linux.intel.com>
Cc: Zhi Wang <zhi.a.wang@intel.com>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Link: http://lkml.kernel.org/r/20200404094101.672954-1-hch@lst.de
Link: http://lkml.kernel.org/r/20200416053158.586887-1-hch@lst.de
Link: http://lkml.kernel.org/r/20200404094101.672954-5-hch@lst.de
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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io_uring is the only user of io-wq, and now it uses only io-wq callback
for all its requests, namely io_wq_submit_work(). Instead of storing
work->runner callback in each instance of io_wq_work, keep it in io-wq
itself.
pros:
- reduces io_wq_work size
- more robust -- ->func won't be invalidated with mem{cpy,set}(req)
- helps other work
Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
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If the original task is (or has) exited, then the task work will not get
queued properly. Allow for using the io-wq manager task to queue this
work for execution, and ensure that the io-wq manager notices and runs
this work if woken up (or exiting).
Reported-by: Dan Melnic <dmm@fb.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
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We always punt async buffered writes to an io-wq helper, as the core
kernel does not have IOCB_NOWAIT support for that. Most buffered async
writes complete very quickly, as it's just a copy operation. This means
that doing multiple locking roundtrips on the shared wqe lock for each
buffered write is wasteful. Additionally, buffered writes are hashed
work items, which means that any buffered write to a given file is
serialized.
Keep identicaly hashed work items contiguously in @wqe->work_list, and
track a tail for each hash bucket. On dequeue of a hashed item, splice
all of the same hash in one go using the tracked tail. Until the batch
is done, the caller doesn't have to synchronize with the wqe or worker
locks again.
Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
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After io_assign_current_work() of a linked work, it can be decided to
offloaded to another thread so doing io_wqe_enqueue(). However, until
next io_assign_current_work() it can be cancelled, that isn't handled.
Don't assign it, if it's not going to be executed.
Fixes: 60cf46ae6054 ("io-wq: hash dependent work")
Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
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Enable io-wq hashing stuff for dependent works simply by re-enqueueing
such requests.
Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
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It's a preparation patch removing io_wq_enqueue_hashed(), which
now should be done by io_wq_hash_work() + io_wq_enqueue().
Also, set hash value for dependant works, and do it as late as possible,
because req->file can be unavailable before. This hash will be ignored
by io-wq.
Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
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This little tweak restores the behaviour that was before the recent
io_worker_handle_work() optimisation patches. It makes the function do
cond_resched() and flush_signals() only if there is an actual work to
execute.
Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
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Deduplicate cancellation parts, as many of them looks the same, as do
e.g.
- io_wqe_cancel_cb_work() and io_wqe_cancel_work()
- io_wq_worker_cancel() and io_work_cancel()
Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
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First it changes io-wq interfaces. It replaces {get,put}_work() with
free_work(), which guaranteed to be called exactly once. It also enforces
free_work() callback to be non-NULL.
io_uring follows the changes and instead of putting a submission reference
in io_put_req_async_completion(), it will be done in io_free_work(). As
removes io_get_work() with corresponding refcount_inc(), the ref balance
is maintained.
Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
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When executing non-linked hashed work, io_worker_handle_work()
will lock-unlock wqe->lock to update hash, and then immediately
lock-unlock to get next work. Optimise this case and do
lock/unlock only once.
Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
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There are 2 optimisations:
- Now, io_worker_handler_work() do io_assign_current_work() twice per
request, and each one adds lock/unlock(worker->lock) pair. The first is
to reset worker->cur_work to NULL, and the second to set a real work
shortly after. If there is a dependant work, set it immediately, that
effectively removes the extra NULL'ing.
- And there is no use in taking wqe->lock for linked works, as they are
not hashed now. Optimise it out.
Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
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This is a preparation patch, it adds some helpers and makes
the next patches cleaner.
- extract io_impersonate_work() and io_assign_current_work()
- replace @next label with nested do-while
- move put_work() right after NULL'ing cur_work.
Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
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@hash_map is unsigned long, but BIT_ULL() is used for manipulations.
BIT() is a better match as it returns exactly unsigned long value.
Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
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IO_WQ_WORK_CB is used only for linked timeouts, which will be armed
before the work setup (i.e. mm, override creds, etc). The setup
shouldn't take long, so it's ok to arm it a bit later and get rid
of IO_WQ_WORK_CB.
Make io-wq call work->func() only once, callbacks will handle the rest.
i.e. the linked timeout handler will do the actual issue. And as a
bonus, it removes an extra indirect call.
Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
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IO_WQ_WORK_HAS_MM is set but never used, remove it.
Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
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io_wq_flush() is buggy, during cancelation of a flush, the associated
work may be passed to the caller's (i.e. io_uring) @match callback. That
callback is expecting it to be embedded in struct io_kiocb. Cancelation
of internal work probably doesn't make a lot of sense to begin with.
As the flush helper is no longer used, just delete it and the associated
work flag.
Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
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To cancel a work, io-wq sets IO_WQ_WORK_CANCEL and executes the
callback. However, IO_WQ_WORK_NO_CANCEL works will just execute and may
return next work, which will be ignored and lost.
Cancel the whole link.
Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
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Andres reports that buffered IO seems to suck up more cycles than we
would like, and he narrowed it down to the fact that the io-wq workers
will briefly spin for more work on completion of a work item. This was
a win on the networking side, but apparently some other cases take a
hit because of it. Remove the optimization to avoid burning more CPU
than we have to for disk IO.
Reported-by: Andres Freund <andres@anarazel.de>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
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Glauber reports a crash on init on a box he has:
RIP: 0010:__alloc_pages_nodemask+0x132/0x340
Code: 18 01 75 04 41 80 ce 80 89 e8 48 8b 54 24 08 8b 74 24 1c c1 e8 0c 48 8b 3c 24 83 e0 01 88 44 24 20 48 85 d2 0f 85 74 01 00 00 <3b> 77 08 0f 82 6b 01 00 00 48 89 7c 24 10 89 ea 48 8b 07 b9 00 02
RSP: 0018:ffffb8be4d0b7c28 EFLAGS: 00010246
RAX: 0000000000000000 RBX: 0000000000000000 RCX: 000000000000e8e8
RDX: 0000000000000000 RSI: 0000000000000002 RDI: 0000000000002080
RBP: 0000000000012cc0 R08: 0000000000000000 R09: 0000000000000002
R10: 0000000000000dc0 R11: ffff995c60400100 R12: 0000000000000000
R13: 0000000000012cc0 R14: 0000000000000001 R15: ffff995c60db00f0
FS: 00007f4d115ca900(0000) GS:ffff995c60d80000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000000000002088 CR3: 00000017cca66002 CR4: 00000000007606e0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
PKRU: 55555554
Call Trace:
alloc_slab_page+0x46/0x320
new_slab+0x9d/0x4e0
___slab_alloc+0x507/0x6a0
? io_wq_create+0xb4/0x2a0
__slab_alloc+0x1c/0x30
kmem_cache_alloc_node_trace+0xa6/0x260
io_wq_create+0xb4/0x2a0
io_uring_setup+0x97f/0xaa0
? io_remove_personalities+0x30/0x30
? io_poll_trigger_evfd+0x30/0x30
do_syscall_64+0x5b/0x1c0
entry_SYSCALL_64_after_hwframe+0x44/0xa9
RIP: 0033:0x7f4d116cb1ed
which is due to the 'wqe' and 'worker' allocation being node affine.
But it isn't valid to call the node affine allocation if the node isn't
online.
Setup structures for even offline nodes, as usual, but skip them in
terms of thread setup to not waste resources. If the node isn't online,
just alloc memory with NUMA_NO_NODE.
Reported-by: Glauber Costa <glauber@scylladb.com>
Tested-by: Glauber Costa <glauber@scylladb.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
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|
Add a helper that allows the caller to cancel work based on what mm
it belongs to. This allows io_uring to cancel work from a given
task or thread when it exits.
Signed-off-by: Jens Axboe <axboe@kernel.dk>
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|
We want to use the cancel functionality for canceling based on not
just the work itself. Instead of matching on the work address
manually, allow a match handler to tell us if we found the right work
item or not.
No functional changes in this patch.
Signed-off-by: Jens Axboe <axboe@kernel.dk>
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Some work items need this for relative path lookup, make it available
like the other inherited credentials/mm/etc.
Cc: stable@vger.kernel.org # 5.3+
Signed-off-by: Jens Axboe <axboe@kernel.dk>
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We're not consistent in how the file table is grabbed and assigned if we
have a command linked that requires the use of it.
Add ->file_table to the io_op_defs[] array, and use that to determine
when to grab the table instead of having the handlers set it if they
need to defer. This also means we can kill the IO_WQ_WORK_NEEDS_FILES
flag. We always initialize work->files, so io-wq can just check for
that.
Signed-off-by: Jens Axboe <axboe@kernel.dk>
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Export a helper to attach to an existing io-wq, rather than setting up
a new one. This is doable now that we have reference counted io_wq's.
Reported-by: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
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We currently setup the io_wq with a static set of mm and creds. Even for
a single-use io-wq per io_uring, this is suboptimal as we have may have
multiple enters of the ring. For sharing the io-wq backend, it doesn't
work at all.
Switch to passing in the creds and mm when the work item is setup. This
means that async work is no longer deferred to the io_uring mm and creds,
it is done with the current mm and creds.
Flag this behavior with IORING_FEAT_CUR_PERSONALITY, so applications know
they can rely on the current personality (mm and creds) being the same
for direct issue and async issue.
Reviewed-by: Stefan Metzmacher <metze@samba.org>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
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In preparation for sharing an io-wq across different users, add a
reference count that manages destruction of it.
Reviewed-by: Pavel Begunkov <asml.silence@gmail.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
|
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io-wq assumes that work will complete fast (and not block), so it
doesn't create a new worker when work is enqueued, if we already have
at least one worker running. This is done on the assumption that if work
is running, then it will complete fast.
Add an option to force io-wq to fork a new worker for work queued. This
is signaled by setting IO_WQ_WORK_CONCURRENT on the work item. For that
case, io-wq will create a new worker, even though workers are already
running.
Signed-off-by: Jens Axboe <axboe@kernel.dk>
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Not all work can be cancelled, some of it we may need to guarantee
that it runs to completion. Allow the caller to set IO_WQ_WORK_NO_CANCEL
on work that must not be cancelled. Note that the caller work function
must also check for IO_WQ_WORK_NO_CANCEL on work that is marked
IO_WQ_WORK_CANCEL.
Signed-off-by: Jens Axboe <axboe@kernel.dk>
|
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If we require mm and user context, mark the request for cancellation
if we fail to acquire the desired mm.
Signed-off-by: Jens Axboe <axboe@kernel.dk>
|
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Reschedule the current IO worker to cut the risk that it is becoming
a cpu hog.
Signed-off-by: Hillf Danton <hdanton@sina.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
|
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Commit e61df66c69b1 ("io-wq: ensure free/busy list browsing see all
items") added a list for io workers in addition to the free and busy
lists, not only making worker walk cleaner, but leaving the busy list
unused. Let's remove it.
Signed-off-by: Hillf Danton <hdanton@sina.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
|
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- Fix a few typos found while reading the code.
- Fix stale io_get_sqring comment referencing s->sqe, the 's' parameter
was renamed to 'req', but the comment still holds.
Signed-off-by: Brian Gianforcaro <b.gianfo@gmail.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
|
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To avoid going to sleep only to get woken shortly thereafter, spin
briefly for new work upon completion of work.
Signed-off-by: Jens Axboe <axboe@kernel.dk>
|
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We only have one cases of using the waitqueue to wake the worker, the
rest are using wake_up_process(). Since we can save some cycles not
fiddling with the waitqueue io_wqe_worker(), switch the work activation
to task wakeup and get rid of the now unused wait_queue_head_t in
struct io_worker.
Signed-off-by: Jens Axboe <axboe@kernel.dk>
|
|
syzbot reports:
kasan: CONFIG_KASAN_INLINE enabled
kasan: GPF could be caused by NULL-ptr deref or user memory access
general protection fault: 0000 [#1] PREEMPT SMP KASAN
CPU: 0 PID: 9217 Comm: io_uring-sq Not tainted 5.4.0-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS
Google 01/01/2011
RIP: 0010:creds_are_invalid kernel/cred.c:792 [inline]
RIP: 0010:__validate_creds include/linux/cred.h:187 [inline]
RIP: 0010:override_creds+0x9f/0x170 kernel/cred.c:550
Code: ac 25 00 81 fb 64 65 73 43 0f 85 a3 37 00 00 e8 17 ab 25 00 49 8d 7c
24 10 48 b8 00 00 00 00 00 fc ff df 48 89 fa 48 c1 ea 03 <0f> b6 04 02 84
c0 74 08 3c 03 0f 8e 96 00 00 00 41 8b 5c 24 10 bf
RSP: 0018:ffff88809c45fda0 EFLAGS: 00010202
RAX: dffffc0000000000 RBX: 0000000043736564 RCX: ffffffff814f3318
RDX: 0000000000000002 RSI: ffffffff814f3329 RDI: 0000000000000010
RBP: ffff88809c45fdb8 R08: ffff8880a3aac240 R09: ffffed1014755849
R10: ffffed1014755848 R11: ffff8880a3aac247 R12: 0000000000000000
R13: ffff888098ab1600 R14: 0000000000000000 R15: 0000000000000000
FS: 0000000000000000(0000) GS:ffff8880ae800000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007ffd51c40664 CR3: 0000000092641000 CR4: 00000000001406f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
io_sq_thread+0x1c7/0xa20 fs/io_uring.c:3274
kthread+0x361/0x430 kernel/kthread.c:255
ret_from_fork+0x24/0x30 arch/x86/entry/entry_64.S:352
Modules linked in:
---[ end trace f2e1a4307fbe2245 ]---
RIP: 0010:creds_are_invalid kernel/cred.c:792 [inline]
RIP: 0010:__validate_creds include/linux/cred.h:187 [inline]
RIP: 0010:override_creds+0x9f/0x170 kernel/cred.c:550
Code: ac 25 00 81 fb 64 65 73 43 0f 85 a3 37 00 00 e8 17 ab 25 00 49 8d 7c
24 10 48 b8 00 00 00 00 00 fc ff df 48 89 fa 48 c1 ea 03 <0f> b6 04 02 84
c0 74 08 3c 03 0f 8e 96 00 00 00 41 8b 5c 24 10 bf
RSP: 0018:ffff88809c45fda0 EFLAGS: 00010202
RAX: dffffc0000000000 RBX: 0000000043736564 RCX: ffffffff814f3318
RDX: 0000000000000002 RSI: ffffffff814f3329 RDI: 0000000000000010
RBP: ffff88809c45fdb8 R08: ffff8880a3aac240 R09: ffffed1014755849
R10: ffffed1014755848 R11: ffff8880a3aac247 R12: 0000000000000000
R13: ffff888098ab1600 R14: 0000000000000000 R15: 0000000000000000
FS: 0000000000000000(0000) GS:ffff8880ae800000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007ffd51c40664 CR3: 0000000092641000 CR4: 00000000001406f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
which is caused by slab fault injection triggering a failure in
prepare_creds(). We don't actually need to create a copy of the creds
as we're not modifying it, we just need a reference on the current task
creds. This avoids the failure case as well, and propagates the const
throughout the stack.
Fixes: 181e448d8709 ("io_uring: async workers should inherit the user creds")
Reported-by: syzbot+5320383e16029ba057ff@syzkaller.appspotmail.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
|
|
Currently we're using 40 bytes for the io_wq_work structure, and 16 of
those is the doubly link list node. We don't need doubly linked lists,
we always add to tail to keep things ordered, and any other use case
is list traversal with deletion. For the deletion case, we can easily
support any node deletion by keeping track of the previous entry.
This shrinks io_wq_work to 32 bytes, and subsequently io_kiock from
io_uring to 216 to 208 bytes.
Signed-off-by: Jens Axboe <axboe@kernel.dk>
|
|
There are several things that can go wrong in the current code on NUMA
systems, especially if not all nodes are online all the time:
- If the identifiers of the online nodes do not form a single contiguous
block starting at zero, wq->wqes will be too small, and OOB memory
accesses will occur e.g. in the loop in io_wq_create().
- If a node comes online between the call to num_online_nodes() and the
for_each_node() loop in io_wq_create(), an OOB write will occur.
- If a node comes online between io_wq_create() and io_wq_enqueue(), a
lookup is performed for an element that doesn't exist, and an OOB read
will probably occur.
Fix it by:
- using nr_node_ids instead of num_online_nodes() for the allocation size;
nr_node_ids is calculated by setup_nr_node_ids() to be bigger than the
highest node ID that could possibly come online at some point, even if
those nodes' identifiers are not a contiguous block
- creating workers for all possible CPUs, not just all online ones
This is basically what the normal workqueue code also does, as far as I can
tell.
Signed-off-by: Jann Horn <jannh@google.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
|
|
These allocations are single-element allocations, so don't use the array
allocation wrapper for them.
Signed-off-by: Jann Horn <jannh@google.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
|
|
If we don't inherit the original task creds, then we can confuse users
like fuse that pass creds in the request header. See link below on
identical aio issue.
Link: https://lore.kernel.org/linux-fsdevel/26f0d78e-99ca-2f1b-78b9-433088053a61@scylladb.com/T/#u
Signed-off-by: Jens Axboe <axboe@kernel.dk>
|
Hillf Danton
Sebastian Andrzej Siewior
Jens Axboe
Pavel Begunkov
Linus Torvalds
Christoph Hellwig
Brian Gianforcaro
Jann Horn