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* io_uring: stop SQPOLL submit on creator's deathPavel Begunkov2021-01-091-9/+53
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | When the creator of SQPOLL io_uring dies (i.e. sqo_task), we don't want its internals like ->files and ->mm to be poked by the SQPOLL task, it have never been nice and recently got racy. That can happen when the owner undergoes destruction and SQPOLL tasks tries to submit new requests in parallel, and so calls io_sq_thread_acquire*(). That patch halts SQPOLL submissions when sqo_task dies by introducing sqo_dead flag. Once set, the SQPOLL task must not do any submission, which is synchronised by uring_lock as well as the new flag. The tricky part is to make sure that disabling always happens, that means either the ring is discovered by creator's do_exit() -> cancel, or if the final close() happens before it's done by the creator. The last is guaranteed by the fact that for SQPOLL the creator task and only it holds exactly one file note, so either it pins up to do_exit() or removed by the creator on the final put in flush. (see comments in uring_flush() around file->f_count == 2). One more place that can trigger io_sq_thread_acquire_*() is __io_req_task_submit(). Shoot off requests on sqo_dead there, even though actually we don't need to. That's because cancellation of sqo_task should wait for the request before going any further. note 1: io_disable_sqo_submit() does io_ring_set_wakeup_flag() so the caller would enter the ring to get an error, but it still doesn't guarantee that the flag won't be cleared. note 2: if final __userspace__ close happens not from the creator task, the file note will pin the ring until the task dies. Fixed: b1b6b5a30dce8 ("kernel/io_uring: cancel io_uring before task works") Signed-off-by: Pavel Begunkov <asml.silence@gmail.com> Signed-off-by: Jens Axboe <axboe@kernel.dk>
* io_uring: add warn_once for io_uring_flush()Pavel Begunkov2021-01-091-4/+10
| | | | | | | | | files_cancel() should cancel all relevant requests and drop file notes, so we should never have file notes after that, including on-exit fput and flush. Add a WARN_ONCE to be sure. Signed-off-by: Pavel Begunkov <asml.silence@gmail.com> Signed-off-by: Jens Axboe <axboe@kernel.dk>
* io_uring: inline io_uring_attempt_task_drop()Pavel Begunkov2021-01-091-18/+11
| | | | | | | | A simple preparation change inlining io_uring_attempt_task_drop() into io_uring_flush(). Signed-off-by: Pavel Begunkov <asml.silence@gmail.com> Signed-off-by: Jens Axboe <axboe@kernel.dk>
* io_uring: io_rw_reissue lockdep annotationsPavel Begunkov2021-01-091-0/+2
| | | | | | | | We expect io_rw_reissue() to take place only during submission with uring_lock held. Add a lockdep annotation to check that invariant. Signed-off-by: Pavel Begunkov <asml.silence@gmail.com> Signed-off-by: Jens Axboe <axboe@kernel.dk>
* io_uring: synchronise ev_posted() with waitqueuesPavel Begunkov2021-01-071-2/+8
| | | | | | | | | | | | | | | | waitqueue_active() needs smp_mb() to be in sync with waitqueues modification, but we miss it in io_cqring_ev_posted*() apart from cq_wait() case. Take an smb_mb() out of wq_has_sleeper() making it waitqueue_active(), and place it a few lines before, so it can synchronise other waitqueue_active() as well. The patch doesn't add any additional overhead, so even if there are no problems currently, it's just safer to have it this way. Signed-off-by: Pavel Begunkov <asml.silence@gmail.com> Signed-off-by: Jens Axboe <axboe@kernel.dk>
* io_uring: dont kill fasync under completion_lockPavel Begunkov2021-01-071-5/+8
| | | | | | | | | | | | | | | | | | | | | | CPU0 CPU1 ---- ---- lock(&new->fa_lock); local_irq_disable(); lock(&ctx->completion_lock); lock(&new->fa_lock); <Interrupt> lock(&ctx->completion_lock); *** DEADLOCK *** Move kill_fasync() out of io_commit_cqring() to io_cqring_ev_posted(), so it doesn't hold completion_lock while doing it. That saves from the reported deadlock, and it's just nice to shorten the locking time and untangle nested locks (compl_lock -> wq_head::lock). Reported-by: syzbot+91ca3f25bd7f795f019c@syzkaller.appspotmail.com Signed-off-by: Pavel Begunkov <asml.silence@gmail.com> Signed-off-by: Jens Axboe <axboe@kernel.dk>
* io_uring: trigger eventfd for IOPOLLPavel Begunkov2021-01-071-2/+11
| | | | | | | | | | | | Make sure io_iopoll_complete() tries to wake up eventfd, which currently is skipped together with io_cqring_ev_posted() for non-SQPOLL IOPOLL. Add an iopoll version of io_cqring_ev_posted(), duplicates a bit of code, but they actually use different sets of wait queues may be for better. Signed-off-by: Pavel Begunkov <asml.silence@gmail.com> Signed-off-by: Jens Axboe <axboe@kernel.dk>
* io_uring: Fix return value from alloc_fixed_file_ref_nodeMatthew Wilcox (Oracle)2021-01-061-6/+6
| | | | | | | | | | | | alloc_fixed_file_ref_node() currently returns an ERR_PTR on failure. io_sqe_files_unregister() expects it to return NULL and since it can only return -ENOMEM, it makes more sense to change alloc_fixed_file_ref_node() to behave that way. Fixes: 1ffc54220c44 ("io_uring: fix io_sqe_files_unregister() hangs") Reported-by: Dan Carpenter <dan.carpenter@oracle.com> Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org> Signed-off-by: Jens Axboe <axboe@kernel.dk>
* io_uring: Delete useless variable ‘id’ in io_prep_async_workYe Bin2021-01-051-2/+0
| | | | | | | | | | | Fix follow warning: fs/io_uring.c:1523:22: warning: variable ‘id’ set but not used [-Wunused-but-set-variable] struct io_identity *id; ^~ Reported-by: Hulk Robot <hulkci@huawei.com> Signed-off-by: Ye Bin <yebin10@huawei.com> Signed-off-by: Jens Axboe <axboe@kernel.dk>
* io_uring: cancel more aggressively in exit_workPavel Begunkov2021-01-041-4/+9
| | | | | | | | | While io_ring_exit_work() is running new requests of all sorts may be issued, so it should do a bit more to cancel them, otherwise they may just get stuck. e.g. in io-wq, in poll lists, etc. Signed-off-by: Pavel Begunkov <asml.silence@gmail.com> Signed-off-by: Jens Axboe <axboe@kernel.dk>
* io_uring: drop file refs after task cancelPavel Begunkov2021-01-041-9/+16
| | | | | | | | | io_uring fds marked O_CLOEXEC and we explicitly cancel all requests before going through exec, so we don't want to leave task's file references to not our anymore io_uring instances. Signed-off-by: Pavel Begunkov <asml.silence@gmail.com> Signed-off-by: Jens Axboe <axboe@kernel.dk>
* io_uring: patch up IOPOLL overflow_flush syncPavel Begunkov2021-01-041-37/+41
| | | | | | | | | | | | | IOPOLL skips completion locking but keeps it under uring_lock, thus io_cqring_overflow_flush() and so io_cqring_events() need additional locking with uring_lock in some cases for IOPOLL. Remove __io_cqring_overflow_flush() from io_cqring_events(), introduce a wrapper around flush doing needed synchronisation and call it by hand. Cc: stable@vger.kernel.org # 5.5+ Signed-off-by: Pavel Begunkov <asml.silence@gmail.com> Signed-off-by: Jens Axboe <axboe@kernel.dk>
* io_uring: synchronise IOPOLL on task_submit failPavel Begunkov2021-01-041-6/+7
| | | | | | | | | io_req_task_submit() might be called for IOPOLL, do the fail path under uring_lock to comply with IOPOLL synchronisation based solely on it. Cc: stable@vger.kernel.org # 5.5+ Signed-off-by: Pavel Begunkov <asml.silence@gmail.com> Signed-off-by: Jens Axboe <axboe@kernel.dk>
* io_uring: fix io_sqe_files_unregister() hangsPavel Begunkov2020-12-311-2/+22
| | | | | | | | | | | io_sqe_files_unregister() uninterruptibly waits for enqueued ref nodes, however requests keeping them may never complete, e.g. because of some userspace dependency. Make sure it's interruptible otherwise it would hang forever. Cc: stable@vger.kernel.org # 5.6+ Signed-off-by: Pavel Begunkov <asml.silence@gmail.com> Signed-off-by: Jens Axboe <axboe@kernel.dk>
* io_uring: add a helper for setting a ref nodePavel Begunkov2020-12-311-10/+12
| | | | | | | | | Setting a new reference node to a file data is not trivial, don't repeat it, add and use a helper. Cc: stable@vger.kernel.org # 5.6+ Signed-off-by: Pavel Begunkov <asml.silence@gmail.com> Signed-off-by: Jens Axboe <axboe@kernel.dk>
* io_uring: don't assume mm is constant across submitsJens Axboe2020-12-291-7/+7
| | | | | | | | | | | | | | If we COW the identity, we assume that ->mm never changes. But this isn't true of multiple processes end up sharing the ring. Hence treat id->mm like like any other process compontent when it comes to the identity mapping. This is pretty trivial, just moving the existing grab into io_grab_identity(), and including a check for the match. Cc: stable@vger.kernel.org # 5.10 Fixes: 1e6fa5216a0e ("io_uring: COW io_identity on mismatch") Reported-by: Christian Brauner <christian.brauner@ubuntu.com>: Tested-by: Christian Brauner <christian.brauner@ubuntu.com>: Signed-off-by: Jens Axboe <axboe@kernel.dk>
* io_uring: hold uring_lock while completing failed polled io in ↵Xiaoguang Wang2020-12-231-10/+19
| | | | | | | | | | | | | | | | | | | | | | | io_wq_submit_work() io_iopoll_complete() does not hold completion_lock to complete polled io, so in io_wq_submit_work(), we can not call io_req_complete() directly, to complete polled io, otherwise there maybe concurrent access to cqring, defer_list, etc, which is not safe. Commit dad1b1242fd5 ("io_uring: always let io_iopoll_complete() complete polled io") has fixed this issue, but Pavel reported that IOPOLL apart from rw can do buf reg/unreg requests( IORING_OP_PROVIDE_BUFFERS or IORING_OP_REMOVE_BUFFERS), so the fix is not good. Given that io_iopoll_complete() is always called under uring_lock, so here for polled io, we can also get uring_lock to fix this issue. Fixes: dad1b1242fd5 ("io_uring: always let io_iopoll_complete() complete polled io") Cc: <stable@vger.kernel.org> # 5.5+ Signed-off-by: Xiaoguang Wang <xiaoguang.wang@linux.alibaba.com> Reviewed-by: Pavel Begunkov <asml.silence@gmail.com> [axboe: don't deref 'req' after completing it'] Signed-off-by: Jens Axboe <axboe@kernel.dk>
* io_uring: fix double io_uring freePavel Begunkov2020-12-231-32/+39
| | | | | | | | | | | Once we created a file for current context during setup, we should not call io_ring_ctx_wait_and_kill() directly as it'll be done by fput(file) Cc: stable@vger.kernel.org # 5.10 Reported-by: syzbot+c9937dfb2303a5f18640@syzkaller.appspotmail.com Signed-off-by: Pavel Begunkov <asml.silence@gmail.com> [axboe: fix unused 'ret' for !CONFIG_UNIX] Signed-off-by: Jens Axboe <axboe@kernel.dk>
* io_uring: fix ignoring xa_store errorsPavel Begunkov2020-12-211-3/+7
| | | | | | | | | xa_store() may fail, check the result. Cc: stable@vger.kernel.org # 5.10 Fixes: 0f2122045b946 ("io_uring: don't rely on weak ->files references") Signed-off-by: Pavel Begunkov <asml.silence@gmail.com> Signed-off-by: Jens Axboe <axboe@kernel.dk>
* io_uring: end waiting before task cancel attemptsPavel Begunkov2020-12-201-1/+1
| | | | | | | | | Get rid of TASK_UNINTERRUPTIBLE and waiting with finish_wait before going for next iteration in __io_uring_task_cancel(), because __io_uring_files_cancel() doesn't expect that sheduling is disallowed. Signed-off-by: Pavel Begunkov <asml.silence@gmail.com> Signed-off-by: Jens Axboe <axboe@kernel.dk>
* io_uring: always progress task_work on task cancelPavel Begunkov2020-12-201-1/+1
| | | | | | | | Might happen that __io_uring_cancel_task_requests() cancels nothing but there are task_works pending. We need to always run them. Signed-off-by: Pavel Begunkov <asml.silence@gmail.com> Signed-off-by: Jens Axboe <axboe@kernel.dk>
* io_uring: make ctx cancel on exit targeted to actual ctxJens Axboe2020-12-201-1/+8
| | | | | | | | | | Before IORING_SETUP_ATTACH_WQ, we could just cancel everything on the io-wq when exiting. But that's not the case if they are shared, so cancel for the specific ctx instead. Cc: stable@vger.kernel.org Fixes: 24369c2e3bb0 ("io_uring: add io-wq workqueue sharing") Signed-off-by: Jens Axboe <axboe@kernel.dk>
* io_uring: fix 0-iov read buffer selectPavel Begunkov2020-12-191-3/+1
| | | | | | | | | Doing vectored buf-select read with 0 iovec passed is meaningless and utterly broken, forbid it. Cc: <stable@vger.kernel.org> # 5.7+ Signed-off-by: Pavel Begunkov <asml.silence@gmail.com> Signed-off-by: Jens Axboe <axboe@kernel.dk>
* io_uring: close a small race gap for files cancelPavel Begunkov2020-12-181-4/+4
| | | | | | | | | | | | | | | | | The purpose of io_uring_cancel_files() is to wait for all requests matching ->files to go/be cancelled. We should first drop files of a request in io_req_drop_files() and only then make it undiscoverable for io_uring_cancel_files. First drop, then delete from list. It's ok to leave req->id->files dangling, because it's not dereferenced by cancellation code, only compared against. It would potentially go to sleep and be awaken by following in io_req_drop_files() wake_up(). Fixes: 0f2122045b946 ("io_uring: don't rely on weak ->files references") Cc: <stable@vger.kernel.org> # 5.5+ Signed-off-by: Pavel Begunkov <asml.silence@gmail.com> Signed-off-by: Jens Axboe <axboe@kernel.dk>
* io_uring: limit {io|sq}poll submit locking scopePavel Begunkov2020-12-171-3/+6
| | | | | | | | | We don't need to take uring_lock for SQPOLL|IOPOLL to do io_cqring_overflow_flush() when cq_overflow_list is empty, remove it from the hot path. Signed-off-by: Pavel Begunkov <asml.silence@gmail.com> Signed-off-by: Jens Axboe <axboe@kernel.dk>
* io_uring: inline io_cqring_mark_overflow()Pavel Begunkov2020-12-171-13/+9
| | | | | | | | | There is only one user of it and the name is misleading, get rid of it by inlining. By the way make overflow_flush's return value deduction simpler. Signed-off-by: Pavel Begunkov <asml.silence@gmail.com> Signed-off-by: Jens Axboe <axboe@kernel.dk>
* io_uring: consolidate CQ nr events calculationPavel Begunkov2020-12-171-9/+8
| | | | | | | | | Add a helper which calculates number of events in CQ. Handcoded version of it in io_cqring_overflow_flush() is not the clearest thing, so it makes it slightly more readable. Signed-off-by: Pavel Begunkov <asml.silence@gmail.com> Signed-off-by: Jens Axboe <axboe@kernel.dk>
* io_uring: remove racy overflow list fast checksPavel Begunkov2020-12-171-4/+1
| | | | | | | | | | | list_empty_careful() is not racy only if some conditions are met, i.e. no re-adds after del_init. io_cqring_overflow_flush() does list_move(), so it's actually racy. Remove those checks, we have ->cq_check_overflow for the fast path. Signed-off-by: Pavel Begunkov <asml.silence@gmail.com> Signed-off-by: Jens Axboe <axboe@kernel.dk>
* io_uring: cancel reqs shouldn't kill overflow listPavel Begunkov2020-12-171-4/+2
| | | | | | | | | | | | | | | | | | | io_uring_cancel_task_requests() doesn't imply that the ring is going away, it may continue to work well after that. The problem is that it sets ->cq_overflow_flushed effectively disabling the CQ overflow feature Split setting cq_overflow_flushed from flush, and do the first one only on exit. It's ok in terms of cancellations because there is a io_uring->in_idle check in __io_cqring_fill_event(). It also fixes a race with setting ->cq_overflow_flushed in io_uring_cancel_task_requests, whuch's is not atomic and a part of a bitmask with other flags. Though, the only other flag that's not set during init is drain_next, so it's not as bad for sane architectures. Signed-off-by: Pavel Begunkov <asml.silence@gmail.com> Fixes: 0f2122045b946 ("io_uring: don't rely on weak ->files references") Signed-off-by: Jens Axboe <axboe@kernel.dk>
* io_uring: hold mmap_sem for mm->locked_vm manipulationJens Axboe2020-12-171-4/+10
| | | | | | | | | The kernel doesn't seem to have clear rules around this, but various spots are using the mmap_sem to serialize access to modifying the locked_vm count. Play it safe and lock the mm for write when accounting or unaccounting locked memory. Signed-off-by: Jens Axboe <axboe@kernel.dk>
* io_uring: break links on shutdown failureJens Axboe2020-12-161-0/+2
| | | | | | | | Ensure that the return value of __sys_shutdown_sock() is used to potentially break links to the request, if we fail. Fixes: 36f4fa6886a8 ("io_uring: add support for shutdown(2)") Signed-off-by: Jens Axboe <axboe@kernel.dk>
* Merge tag 'for-5.11/block-2020-12-14' of git://git.kernel.dk/linux-blockLinus Torvalds2020-12-161-6/+4
|\ | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Pull block updates from Jens Axboe: "Another series of killing more code than what is being added, again thanks to Christoph's relentless cleanups and tech debt tackling. This contains: - blk-iocost improvements (Baolin Wang) - part0 iostat fix (Jeffle Xu) - Disable iopoll for split bios (Jeffle Xu) - block tracepoint cleanups (Christoph Hellwig) - Merging of struct block_device and hd_struct (Christoph Hellwig) - Rework/cleanup of how block device sizes are updated (Christoph Hellwig) - Simplification of gendisk lookup and removal of block device aliasing (Christoph Hellwig) - Block device ioctl cleanups (Christoph Hellwig) - Removal of bdget()/blkdev_get() as exported API (Christoph Hellwig) - Disk change rework, avoid ->revalidate_disk() (Christoph Hellwig) - sbitmap improvements (Pavel Begunkov) - Hybrid polling fix (Pavel Begunkov) - bvec iteration improvements (Pavel Begunkov) - Zone revalidation fixes (Damien Le Moal) - blk-throttle limit fix (Yu Kuai) - Various little fixes" * tag 'for-5.11/block-2020-12-14' of git://git.kernel.dk/linux-block: (126 commits) blk-mq: fix msec comment from micro to milli seconds blk-mq: update arg in comment of blk_mq_map_queue blk-mq: add helper allocating tagset->tags Revert "block: Fix a lockdep complaint triggered by request queue flushing" nvme-loop: use blk_mq_hctx_set_fq_lock_class to set loop's lock class blk-mq: add new API of blk_mq_hctx_set_fq_lock_class block: disable iopoll for split bio block: Improve blk_revalidate_disk_zones() checks sbitmap: simplify wrap check sbitmap: replace CAS with atomic and sbitmap: remove swap_lock sbitmap: optimise sbitmap_deferred_clear() blk-mq: skip hybrid polling if iopoll doesn't spin blk-iocost: Factor out the base vrate change into a separate function blk-iocost: Factor out the active iocgs' state check into a separate function blk-iocost: Move the usage ratio calculation to the correct place blk-iocost: Remove unnecessary advance declaration blk-iocost: Fix some typos in comments blktrace: fix up a kerneldoc comment block: remove the request_queue to argument request based tracepoints ...
| * block: remove i_bdevChristoph Hellwig2020-12-011-6/+4
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Switch the block device lookup interfaces to directly work with a dev_t so that struct block_device references are only acquired by the blkdev_get variants (and the blk-cgroup special case). This means that we now don't need an extra reference in the inode and can generally simplify handling of struct block_device to keep the lookups contained in the core block layer code. Signed-off-by: Christoph Hellwig <hch@lst.de> Reviewed-by: Jan Kara <jack@suse.cz> Reviewed-by: Hannes Reinecke <hare@suse.de> Acked-by: Tejun Heo <tj@kernel.org> Acked-by: Coly Li <colyli@suse.de> [bcache] Signed-off-by: Jens Axboe <axboe@kernel.dk>
* | Merge tag 'for-5.11/io_uring-2020-12-14' of git://git.kernel.dk/linux-blockLinus Torvalds2020-12-161-557/+770
|\ \ | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Pull io_uring updates from Jens Axboe: "Fairly light set of changes this time around, and mostly some bits that were pushed out to 5.11 instead of 5.10, fixes/cleanups, and a few features. In particular: - Cleanups around iovec import (David Laight, Pavel) - Add timeout support for io_uring_enter(2), which enables us to clean up liburing and avoid a timeout sqe submission in the completion path. The big win here is that it allows setups that split SQ and CQ handling into separate threads to avoid locking, as the CQ side will no longer submit when timeouts are needed when waiting for events (Hao Xu) - Add support for socket shutdown, and renameat/unlinkat. - SQPOLL cleanups and improvements (Xiaoguang Wang) - Allow SQPOLL setups for CAP_SYS_NICE, and enable regular (non-fixed) files to be used. - Cancelation improvements (Pavel) - Fixed file reference improvements (Pavel) - IOPOLL related race fixes (Pavel) - Lots of other little fixes and cleanups (mostly Pavel)" * tag 'for-5.11/io_uring-2020-12-14' of git://git.kernel.dk/linux-block: (43 commits) io_uring: fix io_cqring_events()'s noflush io_uring: fix racy IOPOLL flush overflow io_uring: fix racy IOPOLL completions io_uring: always let io_iopoll_complete() complete polled io io_uring: add timeout update io_uring: restructure io_timeout_cancel() io_uring: fix files cancellation io_uring: use bottom half safe lock for fixed file data io_uring: fix miscounting ios_left io_uring: change submit file state invariant io_uring: check kthread stopped flag when sq thread is unparked io_uring: share fixed_file_refs b/w multiple rsrcs io_uring: replace inflight_wait with tctx->wait io_uring: don't take fs for recvmsg/sendmsg io_uring: only wake up sq thread while current task is in io worker context io_uring: don't acquire uring_lock twice io_uring: initialize 'timeout' properly in io_sq_thread() io_uring: refactor io_sq_thread() handling io_uring: always batch cancel in *cancel_files() io_uring: pass files into kill timeouts/poll ...
| * | io_uring: fix io_cqring_events()'s noflushPavel Begunkov2020-12-091-1/+1
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Checking !list_empty(&ctx->cq_overflow_list) around noflush in io_cqring_events() is racy, because if it fails but a request overflowed just after that, io_cqring_overflow_flush() still will be called. Remove the second check, it shouldn't be a problem for performance, because there is cq_check_overflow bit check just above. Cc: <stable@vger.kernel.org> # 5.5+ Signed-off-by: Pavel Begunkov <asml.silence@gmail.com> Signed-off-by: Jens Axboe <axboe@kernel.dk>
| * | io_uring: fix racy IOPOLL flush overflowPavel Begunkov2020-12-091-4/+6
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | It's not safe to call io_cqring_overflow_flush() for IOPOLL mode without hodling uring_lock, because it does synchronisation differently. Make sure we have it. As for io_ring_exit_work(), we don't even need it there because io_ring_ctx_wait_and_kill() already set force flag making all overflowed requests to be dropped. Cc: <stable@vger.kernel.org> # 5.5+ Signed-off-by: Pavel Begunkov <asml.silence@gmail.com> Signed-off-by: Jens Axboe <axboe@kernel.dk>
| * | io_uring: fix racy IOPOLL completionsPavel Begunkov2020-12-091-5/+18
| | | | | | | | | | | | | | | | | | | | | | | | | | | IOPOLL allows buffer remove/provide requests, but they doesn't synchronise by rules of IOPOLL, namely it have to hold uring_lock. Cc: <stable@vger.kernel.org> # 5.7+ Signed-off-by: Pavel Begunkov <asml.silence@gmail.com> Signed-off-by: Jens Axboe <axboe@kernel.dk>
| * | io_uring: always let io_iopoll_complete() complete polled ioXiaoguang Wang2020-12-091-2/+13
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Abaci Fuzz reported a double-free or invalid-free BUG in io_commit_cqring(): [ 95.504842] BUG: KASAN: double-free or invalid-free in io_commit_cqring+0x3ec/0x8e0 [ 95.505921] [ 95.506225] CPU: 0 PID: 4037 Comm: io_wqe_worker-0 Tainted: G B W 5.10.0-rc5+ #1 [ 95.507434] Hardware name: Red Hat KVM, BIOS 0.5.1 01/01/2011 [ 95.508248] Call Trace: [ 95.508683] dump_stack+0x107/0x163 [ 95.509323] ? io_commit_cqring+0x3ec/0x8e0 [ 95.509982] print_address_description.constprop.0+0x3e/0x60 [ 95.510814] ? vprintk_func+0x98/0x140 [ 95.511399] ? io_commit_cqring+0x3ec/0x8e0 [ 95.512036] ? io_commit_cqring+0x3ec/0x8e0 [ 95.512733] kasan_report_invalid_free+0x51/0x80 [ 95.513431] ? io_commit_cqring+0x3ec/0x8e0 [ 95.514047] __kasan_slab_free+0x141/0x160 [ 95.514699] kfree+0xd1/0x390 [ 95.515182] io_commit_cqring+0x3ec/0x8e0 [ 95.515799] __io_req_complete.part.0+0x64/0x90 [ 95.516483] io_wq_submit_work+0x1fa/0x260 [ 95.517117] io_worker_handle_work+0xeac/0x1c00 [ 95.517828] io_wqe_worker+0xc94/0x11a0 [ 95.518438] ? io_worker_handle_work+0x1c00/0x1c00 [ 95.519151] ? __kthread_parkme+0x11d/0x1d0 [ 95.519806] ? io_worker_handle_work+0x1c00/0x1c00 [ 95.520512] ? io_worker_handle_work+0x1c00/0x1c00 [ 95.521211] kthread+0x396/0x470 [ 95.521727] ? _raw_spin_unlock_irq+0x24/0x30 [ 95.522380] ? kthread_mod_delayed_work+0x180/0x180 [ 95.523108] ret_from_fork+0x22/0x30 [ 95.523684] [ 95.523985] Allocated by task 4035: [ 95.524543] kasan_save_stack+0x1b/0x40 [ 95.525136] __kasan_kmalloc.constprop.0+0xc2/0xd0 [ 95.525882] kmem_cache_alloc_trace+0x17b/0x310 [ 95.533930] io_queue_sqe+0x225/0xcb0 [ 95.534505] io_submit_sqes+0x1768/0x25f0 [ 95.535164] __x64_sys_io_uring_enter+0x89e/0xd10 [ 95.535900] do_syscall_64+0x33/0x40 [ 95.536465] entry_SYSCALL_64_after_hwframe+0x44/0xa9 [ 95.537199] [ 95.537505] Freed by task 4035: [ 95.538003] kasan_save_stack+0x1b/0x40 [ 95.538599] kasan_set_track+0x1c/0x30 [ 95.539177] kasan_set_free_info+0x1b/0x30 [ 95.539798] __kasan_slab_free+0x112/0x160 [ 95.540427] kfree+0xd1/0x390 [ 95.540910] io_commit_cqring+0x3ec/0x8e0 [ 95.541516] io_iopoll_complete+0x914/0x1390 [ 95.542150] io_do_iopoll+0x580/0x700 [ 95.542724] io_iopoll_try_reap_events.part.0+0x108/0x200 [ 95.543512] io_ring_ctx_wait_and_kill+0x118/0x340 [ 95.544206] io_uring_release+0x43/0x50 [ 95.544791] __fput+0x28d/0x940 [ 95.545291] task_work_run+0xea/0x1b0 [ 95.545873] do_exit+0xb6a/0x2c60 [ 95.546400] do_group_exit+0x12a/0x320 [ 95.546967] __x64_sys_exit_group+0x3f/0x50 [ 95.547605] do_syscall_64+0x33/0x40 [ 95.548155] entry_SYSCALL_64_after_hwframe+0x44/0xa9 The reason is that once we got a non EAGAIN error in io_wq_submit_work(), we'll complete req by calling io_req_complete(), which will hold completion_lock to call io_commit_cqring(), but for polled io, io_iopoll_complete() won't hold completion_lock to call io_commit_cqring(), then there maybe concurrent access to ctx->defer_list, double free may happen. To fix this bug, we always let io_iopoll_complete() complete polled io. Cc: <stable@vger.kernel.org> # 5.5+ Reported-by: Abaci Fuzz <abaci@linux.alibaba.com> Signed-off-by: Xiaoguang Wang <xiaoguang.wang@linux.alibaba.com> Reviewed-by: Pavel Begunkov <asml.silence@gmail.com> Reviewed-by: Joseph Qi <joseph.qi@linux.alibaba.com> Signed-off-by: Pavel Begunkov <asml.silence@gmail.com> Signed-off-by: Jens Axboe <axboe@kernel.dk>
| * | io_uring: add timeout updatePavel Begunkov2020-12-091-4/+50
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Support timeout updates through IORING_OP_TIMEOUT_REMOVE with passed in IORING_TIMEOUT_UPDATE. Updates doesn't support offset timeout mode. Oirignal timeout.off will be ignored as well. Signed-off-by: Pavel Begunkov <asml.silence@gmail.com> [axboe: remove now unused 'ret' variable] Signed-off-by: Jens Axboe <axboe@kernel.dk>
| * | io_uring: restructure io_timeout_cancel()Pavel Begunkov2020-12-091-19/+23
| | | | | | | | | | | | | | | | | | | | | | | | Add io_timeout_extract() helper, which searches and disarms timeouts, but doesn't complete them. No functional changes. Signed-off-by: Pavel Begunkov <asml.silence@gmail.com> Signed-off-by: Jens Axboe <axboe@kernel.dk>
| * | io_uring: fix files cancellationPavel Begunkov2020-12-091-4/+4
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | io_uring_cancel_files()'s task check condition mistakenly got flipped. 1. There can't be a request in the inflight list without IO_WQ_WORK_FILES, kill this check to keep the whole condition simpler. 2. Also, don't call the function for files==NULL to not do such a check, all that staff is already handled well by its counter part, __io_uring_cancel_task_requests(). With that just flip the task check. Also, it iowq-cancels all request of current task there, don't forget to set right ->files into struct io_task_cancel. Fixes: c1973b38bf639 ("io_uring: cancel only requests of current task") Reported-by: syzbot+c0d52d0b3c0c3ffb9525@syzkaller.appspotmail.com Signed-off-by: Pavel Begunkov <asml.silence@gmail.com> Signed-off-by: Jens Axboe <axboe@kernel.dk>
| * | io_uring: use bottom half safe lock for fixed file dataJens Axboe2020-12-091-8/+8
| | | | | | | | | | | | | | | | | | | | | | | | | | | io_file_data_ref_zero() can be invoked from soft-irq from the RCU core, hence we need to ensure that the file_data lock is bottom half safe. Use the _bh() variants when grabbing this lock. Reported-by: syzbot+1f4ba1e5520762c523c6@syzkaller.appspotmail.com Signed-off-by: Jens Axboe <axboe@kernel.dk>
| * | io_uring: fix miscounting ios_leftPavel Begunkov2020-12-091-12/+9
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | io_req_init() doesn't decrement state->ios_left if a request doesn't need ->file, it just returns before that on if(!needs_file). That's not really a problem but may cause overhead for an additional fput(). Also inline and kill io_req_set_file() as it's of no use anymore. Signed-off-by: Pavel Begunkov <asml.silence@gmail.com> Signed-off-by: Jens Axboe <axboe@kernel.dk>
| * | io_uring: change submit file state invariantPavel Begunkov2020-12-091-11/+10
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Keep submit state invariant of whether there are file refs left based on state->nr_refs instead of (state->file==NULL), and always check against the first one. It's easier to track and allows to remove 1 if. It also automatically leaves struct submit_state in a consistent state after io_submit_state_end(), that's not used yet but nice. btw rename has_refs to file_refs for more clarity. Signed-off-by: Pavel Begunkov <asml.silence@gmail.com> Signed-off-by: Jens Axboe <axboe@kernel.dk>
| * | io_uring: check kthread stopped flag when sq thread is unparkedXiaoguang Wang2020-12-091-1/+9
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | syzbot reports following issue: INFO: task syz-executor.2:12399 can't die for more than 143 seconds. task:syz-executor.2 state:D stack:28744 pid:12399 ppid: 8504 flags:0x00004004 Call Trace: context_switch kernel/sched/core.c:3773 [inline] __schedule+0x893/0x2170 kernel/sched/core.c:4522 schedule+0xcf/0x270 kernel/sched/core.c:4600 schedule_timeout+0x1d8/0x250 kernel/time/timer.c:1847 do_wait_for_common kernel/sched/completion.c:85 [inline] __wait_for_common kernel/sched/completion.c:106 [inline] wait_for_common kernel/sched/completion.c:117 [inline] wait_for_completion+0x163/0x260 kernel/sched/completion.c:138 kthread_stop+0x17a/0x720 kernel/kthread.c:596 io_put_sq_data fs/io_uring.c:7193 [inline] io_sq_thread_stop+0x452/0x570 fs/io_uring.c:7290 io_finish_async fs/io_uring.c:7297 [inline] io_sq_offload_create fs/io_uring.c:8015 [inline] io_uring_create fs/io_uring.c:9433 [inline] io_uring_setup+0x19b7/0x3730 fs/io_uring.c:9507 do_syscall_64+0x2d/0x70 arch/x86/entry/common.c:46 entry_SYSCALL_64_after_hwframe+0x44/0xa9 RIP: 0033:0x45deb9 Code: Unable to access opcode bytes at RIP 0x45de8f. RSP: 002b:00007f174e51ac78 EFLAGS: 00000246 ORIG_RAX: 00000000000001a9 RAX: ffffffffffffffda RBX: 0000000000008640 RCX: 000000000045deb9 RDX: 0000000000000000 RSI: 0000000020000140 RDI: 00000000000050e5 RBP: 000000000118bf58 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 000000000118bf2c R13: 00007ffed9ca723f R14: 00007f174e51b9c0 R15: 000000000118bf2c INFO: task syz-executor.2:12399 blocked for more than 143 seconds. Not tainted 5.10.0-rc3-next-20201110-syzkaller #0 "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. Currently we don't have a reproducer yet, but seems that there is a race in current codes: => io_put_sq_data ctx_list is empty now. | ==> kthread_park(sqd->thread); | | T1: sq thread is parked now. ==> kthread_stop(sqd->thread); | KTHREAD_SHOULD_STOP is set now.| ===> kthread_unpark(k); | | T2: sq thread is now unparkd, run again. | | T3: sq thread is now preempted out. | ===> wake_up_process(k); | | | T4: Since sqd ctx_list is empty, needs_sched will be true, | then sq thread sets task state to TASK_INTERRUPTIBLE, | and schedule, now sq thread will never be waken up. ===> wait_for_completion | I have artificially used mdelay() to simulate above race, will get same stack like this syzbot report, but to be honest, I'm not sure this code race triggers syzbot report. To fix this possible code race, when sq thread is unparked, need to check whether sq thread has been stopped. Reported-by: syzbot+03beeb595f074db9cfd1@syzkaller.appspotmail.com Signed-off-by: Xiaoguang Wang <xiaoguang.wang@linux.alibaba.com> Signed-off-by: Jens Axboe <axboe@kernel.dk>
| * | io_uring: share fixed_file_refs b/w multiple rsrcsPavel Begunkov2020-12-091-8/+15
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Double fixed files for splice/tee are done in a nasty way, it takes 2 ref_node refs, and during the second time it blindly overrides req->fixed_file_refs hoping that it haven't changed. That works because all that is done under iouring_lock in a single go but is error-prone. Bind everything explicitly to a single ref_node and take only one ref, with current ref_node ordering it's guaranteed to keep all files valid awhile the request is inflight. That's mainly a cleanup + preparation for generic resource handling, but also saves pcpu_ref get/put for splice/tee with 2 fixed files. Signed-off-by: Pavel Begunkov <asml.silence@gmail.com> Signed-off-by: Jens Axboe <axboe@kernel.dk>
| * | io_uring: replace inflight_wait with tctx->waitPavel Begunkov2020-12-091-7/+6
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | As tasks now cancel only theirs requests, and inflight_wait is awaited only in io_uring_cancel_files(), which should be called with ->in_idle set, instead of keeping a separate inflight_wait use tctx->wait. That will add some spurious wakeups but actually is safer from point of not hanging the task. e.g. task1 | IRQ | *start* io_complete_rw_common(link) | link: req1 -> req2 -> req3(with files) *cancel_files() | io_wq_cancel(), etc. | | put_req(link), adds to io-wq req2 schedule() | So, task1 will never try to cancel req2 or req3. If req2 is long-standing (e.g. read(empty_pipe)), this may hang. Signed-off-by: Pavel Begunkov <asml.silence@gmail.com> Signed-off-by: Jens Axboe <axboe@kernel.dk>
| * | io_uring: don't take fs for recvmsg/sendmsgPavel Begunkov2020-12-091-4/+2
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | We don't even allow not plain data msg_control, which is disallowed in __sys_{send,revb}msg_sock(). So no need in fs for IORING_OP_SENDMSG and IORING_OP_RECVMSG. fs->lock is less contanged not as much as before, but there are cases that can be, e.g. IOSQE_ASYNC. Signed-off-by: Pavel Begunkov <asml.silence@gmail.com> Signed-off-by: Jens Axboe <axboe@kernel.dk>
| * | io_uring: only wake up sq thread while current task is in io worker contextXiaoguang Wang2020-12-091-3/+8
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | If IORING_SETUP_SQPOLL is enabled, sqes are either handled in sq thread task context or in io worker task context. If current task context is sq thread, we don't need to check whether should wake up sq thread. io_iopoll_req_issued() calls wq_has_sleeper(), which has smp_mb() memory barrier, before this patch, perf shows obvious overhead: Samples: 481K of event 'cycles', Event count (approx.): 299807382878 Overhead Comma Shared Object Symbol 3.69% :9630 [kernel.vmlinux] [k] io_issue_sqe With this patch, perf shows: Samples: 482K of event 'cycles', Event count (approx.): 299929547283 Overhead Comma Shared Object Symbol 0.70% :4015 [kernel.vmlinux] [k] io_issue_sqe It shows some obvious improvements. Signed-off-by: Xiaoguang Wang <xiaoguang.wang@linux.alibaba.com> Signed-off-by: Jens Axboe <axboe@kernel.dk>
| * | io_uring: don't acquire uring_lock twiceXiaoguang Wang2020-12-091-11/+7
| | | | | | | | | | | | | | | | | | | | | | | | Both IOPOLL and sqes handling need to acquire uring_lock, combine them together, then we just need to acquire uring_lock once. Signed-off-by: Xiaoguang Wang <xiaoguang.wang@linux.alibaba.com> Signed-off-by: Jens Axboe <axboe@kernel.dk>
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