- 02 Apr, 2021 1 commit
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Jens Axboe authored
It's non-obvious how retry is done for block backed files, when it happens off the kiocb done path. It also makes it tricky to deal with the iov_iter handling. Just mark the req as needing a reissue, and handling it from the submission path instead. This makes it directly obvious that we're not re-importing the iovec from userspace past the submit point, and it means that we can just reuse our usual -EAGAIN retry path from the read/write handling. At some point in the future, we'll gain the ability to always reliably return -EAGAIN through the stack. A previous attempt on the block side didn't pan out and got reverted, hence the need to check for this information out-of-band right now. Signed-off-by:Jens Axboe <axboe@kernel.dk>
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- 01 Apr, 2021 3 commits
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Pavel Begunkov authored
iov_iter_revert() is done in completion handlers that happensf before read/write returns -EIOCBQUEUED, no need to repeat reverting afterwards. Moreover, even though it may appear being just a no-op, it's actually races with 1) user forging a new iovec of a different size 2) reissue, that is done via io-wq continues completely asynchronously. Fixes: 3e6a0d3c ("io_uring: fix -EAGAIN retry with IOPOLL") Signed-off-by:
Pavel Begunkov <asml.silence@gmail.com> Signed-off-by:
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Pavel Begunkov authored
task_pid may be large enough to not fit into the left space of TASK_COMM_LEN-sized buffers and overflow in sprintf. We not so care about uniqueness, so replace it with safer snprintf(). Reported-by:
Alexey Dobriyan <adobriyan@gmail.com> Signed-off-by:
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Jens Axboe authored
S_ISBLK is marked as unbounded work for async preparation, because it doesn't match S_ISREG. That is incorrect, as any read/write to a block device is also a bounded operation. Fix it up and ensure that S_ISBLK isn't marked unbounded. Signed-off-by:
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- 30 Mar, 2021 1 commit
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Jens Axboe authored
Don't call into get_signal() with the sqd mutex held, it'll fail if we're freezing the task and we'll get complaints on locks still being held: ==================================== WARNING: iou-sqp-8386/8387 still has locks held! 5.12.0-rc4-syzkaller #0 Not tainted ------------------------------------ 1 lock held by iou-sqp-8386/8387: #0: ffff88801e1d2470 (&sqd->lock){+.+.}-{3:3}, at: io_sq_thread+0x24c/0x13a0 fs/io_uring.c:6731 stack backtrace: CPU: 1 PID: 8387 Comm: iou-sqp-8386 Not tainted 5.12.0-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:79 [inline] dump_stack+0x141/0x1d7 lib/dump_stack.c:120 try_to_freeze include/linux/freezer.h:66 [inline] get_signal+0x171a/0x2150 kernel/signal.c:2576 io_sq_thread+0x8d2/0x13a0 fs/io_uring.c:6748 Fold the get_signal() case in with the parking checks, as we need to drop the lock in both cases, and since we need to be checking for parking when juggling the lock anyway. Reported-by: syzbot+796d767eb376810256f5@syzkaller.appspotmail.com Fixes: dbe1bdbb ("io_uring: handle signals for IO threads like a normal thread") Signed-off-by:
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- 29 Mar, 2021 2 commits
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Pavel Begunkov authored
general protection fault, probably for non-canonical address 0xdffffc0000000018: 0000 [#1] KASAN: null-ptr-deref in range [0x00000000000000c0-0x00000000000000c7] RIP: 0010:io_commit_cqring+0x37f/0xc10 fs/io_uring.c:1318 Call Trace: io_kill_timeouts+0x2b5/0x320 fs/io_uring.c:8606 io_ring_ctx_wait_and_kill+0x1da/0x400 fs/io_uring.c:8629 io_uring_create fs/io_uring.c:9572 [inline] io_uring_setup+0x10da/0x2ae0 fs/io_uring.c:9599 do_syscall_64+0x2d/0x70 arch/x86/entry/common.c:46 entry_SYSCALL_64_after_hwframe+0x44/0xae It can get into wait_and_kill() before setting up ctx->rings, and hence io_commit_cqring() fails. Mimic poll cancel and do it only when we completed events, there can't be any requests if it failed before initialising rings. Fixes: 80c4cbdb ("io_uring: do post-completion chore on t-out cancel") Reported-by: syzbot+0e905eb8228070c457a0@syzkaller.appspotmail.com Signed-off-by:
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Pavel Begunkov authored
Always try to do cancellation in __io_uring_task_cancel() at least once, so it actually goes and cleans its sqpoll tasks (i.e. via io_sqpoll_cancel_sync()), otherwise sqpoll task may submit new requests after cancellation and it's racy for many reasons. Fixes: 521d6a73 ("io_uring: cancel sqpoll via task_work") Signed-off-by:
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- 27 Mar, 2021 11 commits
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Colin Ian King authored
There is an assignment to io that is never read after the assignment, the assignment is redundant and can be removed. Signed-off-by:
Colin Ian King <colin.king@canonical.com> Signed-off-by:
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Pavel Begunkov authored
As tasks always wait and kill their io-wq on exec/exit, files are of no more concern to us, so we don't need to specifically cancel them by hand in those cases. Moreover we should not, because io_match_task() looks at req->task->files now, which is always true and so leads to extra cancellations, that wasn't a case before per-task io-wq. Signed-off-by:
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Pavel Begunkov authored
Don't account usual timeouts (i.e. not linked) as REQ_F_INFLIGHT but keep behaviour prior to dd59a3d5 ("io_uring: reliably cancel linked timeouts"). Signed-off-by:
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Pavel Begunkov authored
Don't forget about io_commit_cqring() + io_cqring_ev_posted() after exit/exec cancelling timeouts. Both functions declared only after io_kill_timeouts(), so to avoid tons of forward declarations move it down. Signed-off-by:
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Pavel Begunkov authored
When we cancel a timeout we should emit a sensible return code, like -ECANCELED but not 0, otherwise it may trick users. Signed-off-by:
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Jens Axboe authored
This reverts commit 4db4b1a0. The IO threads allow and handle SIGSTOP now, so don't special case them anymore in task_set_jobctl_pending(). Signed-off-by:
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Jens Axboe authored
This reverts commit 15b2219f. Before IO threads accepted signals, the freezer using take signals to wake up an IO thread would cause them to loop without any way to clear the pending signal. That is no longer the case, so stop special casing PF_IO_WORKER in the freezer. Signed-off-by:
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Jens Axboe authored
This reverts commit 6fb8f43c. The IO threads do allow signals now, including SIGSTOP, and we can allow ptrace attach. Attaching won't reveal anything interesting for the IO threads, but it will allow eg gdb to attach to a task with io_urings and IO threads without complaining. And once attached, it will allow the usual introspection into regular threads. Signed-off-by:
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Jens Axboe authored
This reverts commit 5be28c8f. IO threads now take signals just fine, so there's no reason to limit them specifically. Revert the change that prevented that from happening. Signed-off-by:
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Jens Axboe authored
This is racy - move the blocking into when the task is created and we're marking it as PF_IO_WORKER anyway. The IO threads are now prepared to handle signals like SIGSTOP as well, so clear that from the mask to allow proper stopping of IO threads. Acked-by:
"Eric W. Biederman" <ebiederm@xmission.com> Reported-by:
Oleg Nesterov <oleg@redhat.com> Signed-off-by:
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Jens Axboe authored
We go through various hoops to disallow signals for the IO threads, but there's really no reason why we cannot just allow them. The IO threads never return to userspace like a normal thread, and hence don't go through normal signal processing. Instead, just check for a pending signal as part of the work loop, and call get_signal() to handle it for us if anything is pending. With that, we can support receiving signals, including special ones like SIGSTOP. Acked-by:
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- 26 Mar, 2021 1 commit
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Jens Axboe authored
Right now we're never calling get_signal() from PF_IO_WORKER threads, but in preparation for doing so, don't handle a fatal signal for them. The workers have state they need to cleanup when exiting, so just return instead of calling do_exit() on their behalf. The threads themselves will detect a fatal signal and do proper shutdown. Signed-off-by:
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- 25 Mar, 2021 2 commits
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Pavel Begunkov authored
Arguably we want CQEs of linked requests be in a strict order of submission as it always was. Now if init of a request fails its CQE may be posted before all prior linked requests including the head of the link. Fix it by failing it last. Fixes: de59bc10 ("io_uring: fail links more in io_submit_sqe()") Signed-off-by:
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Jens Axboe authored
syzbot reports that it's triggering the warning condition on having pending work on shutdown: WARNING: CPU: 1 PID: 12346 at fs/io-wq.c:1061 io_wq_destroy fs/io-wq.c:1061 [inline] WARNING: CPU: 1 PID: 12346 at fs/io-wq.c:1061 io_wq_put+0x153/0x260 fs/io-wq.c:1072 Modules linked in: CPU: 1 PID: 12346 Comm: syz-executor.5 Not tainted 5.12.0-rc2-syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 RIP: 0010:io_wq_destroy fs/io-wq.c:1061 [inline] RIP: 0010:io_wq_put+0x153/0x260 fs/io-wq.c:1072 Code: 8d e8 71 90 ea 01 49 89 c4 41 83 fc 40 7d 4f e8 33 4d 97 ff 42 80 7c 2d 00 00 0f 85 77 ff ff ff e9 7a ff ff ff e8 1d 4d 97 ff <0f> 0b eb b9 8d 6b ff 89 ee 09 de bf ff ff ff ff e8 18 51 97 ff 09 RSP: 0018:ffffc90001ebfb08 EFLAGS: 00010293 RAX: ffffffff81e16083 RBX: ffff888019038040 RCX: ffff88801e86b780 RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000040 RBP: 1ffff1100b2f8a80 R08: ffffffff81e15fce R09: ffffed100b2f8a82 R10: ffffed100b2f8a82 R11: 0000000000000000 R12: 0000000000000000 R13: dffffc0000000000 R14: ffff8880597c5400 R15: ffff888019038000 FS: 00007f8dcd89c700(0000) GS:ffff8880b9c00000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 000055e9a054e160 CR3: 000000001dfb8000 CR4: 00000000001506f0 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 Call Trace: io_uring_clean_tctx+0x1b7/0x210 fs/io_uring.c:8802 __io_uring_files_cancel+0x13c/0x170 fs/io_uring.c:8820 io_uring_files_cancel include/linux/io_uring.h:47 [inline] do_exit+0x258/0x2340 kernel/exit.c:780 do_group_exit+0x168/0x2d0 kernel/exit.c:922 get_signal+0x1734/0x1ef0 kernel/signal.c:2773 arch_do_signal_or_restart+0x3c/0x610 arch/x86/kernel/signal.c:811 handle_signal_work kernel/entry/common.c:147 [inline] exit_to_user_mode_loop kernel/entry/common.c:171 [inline] exit_to_user_mode_prepare+0xac/0x1e0 kernel/entry/common.c:208 __syscall_exit_to_user_mode_work kernel/entry/common.c:290 [inline] syscall_exit_to_user_mode+0x48/0x180 kernel/entry/common.c:301 entry_SYSCALL_64_after_hwframe+0x44/0xae RIP: 0033:0x465f69 which shouldn't happen, but seems to be possible due to a race on whether or not the io-wq manager sees a fatal signal first, or whether the io-wq workers do. If we race with queueing work and then send a fatal signal to the owning task, and the io-wq worker sees that before the manager sets IO_WQ_BIT_EXIT, then it's possible to have the worker exit and leave work behind. Just turn the WARN_ON_ONCE() into a cancelation condition instead. Reported-by: syzbot+77a738a6bc947bf639ca@syzkaller.appspotmail.com Signed-off-by:
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- 24 Mar, 2021 1 commit
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Pavel Begunkov authored
WARNING: CPU: 1 PID: 27907 at fs/io_uring.c:7147 io_sq_thread_park+0xb5/0xd0 fs/io_uring.c:7147 CPU: 1 PID: 27907 Comm: iou-sqp-27905 Not tainted 5.12.0-rc4-syzkaller #0 RIP: 0010:io_sq_thread_park+0xb5/0xd0 fs/io_uring.c:7147 Call Trace: io_ring_ctx_wait_and_kill+0x214/0x700 fs/io_uring.c:8619 io_uring_release+0x3e/0x50 fs/io_uring.c:8646 __fput+0x288/0x920 fs/file_table.c:280 task_work_run+0xdd/0x1a0 kernel/task_work.c:140 io_run_task_work fs/io_uring.c:2238 [inline] io_run_task_work fs/io_uring.c:2228 [inline] io_uring_try_cancel_requests+0x8ec/0xc60 fs/io_uring.c:8770 io_uring_cancel_sqpoll+0x1cf/0x290 fs/io_uring.c:8974 io_sqpoll_cancel_cb+0x87/0xb0 fs/io_uring.c:8907 io_run_task_work_head+0x58/0xb0 fs/io_uring.c:1961 io_sq_thread+0x3e2/0x18d0 fs/io_uring.c:6763 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:294 May happen that last ctx ref is killed in io_uring_cancel_sqpoll(), so fput callback (i.e. io_uring_release()) is enqueued through task_work, and run by same cancellation. As it's deeply nested we can't do parking or taking sqd->lock there, because its state is unclear. So avoid ctx ejection from sqd list from io_ring_ctx_wait_and_kill() and do it in a clear context in io_ring_exit_work(). Fixes: f6d54255 ("io_uring: halt SQO submission on ctx exit") Reported-by: syzbot+e3a3f84f5cecf61f0583@syzkaller.appspotmail.com Signed-off-by:
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- 22 Mar, 2021 3 commits
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Pavel Begunkov authored
io_provide_buffers_prep()'s "p->len * p->nbufs" to sign extension problems. Not a huge problem as it's only used for access_ok() and increases the checked length, but better to keep typing right. Reported-by:
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Pavel Begunkov authored
Don't miss to call kiocb_end_write() from __io_complete_rw() on reissue. Shouldn't be much of a problem as the function actually does some work only for ISREG, and NONBLOCK won't be reissued. Signed-off-by:
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Pavel Begunkov authored
Request's io-wq work is hashed in io_prep_async_link(), so as trace_io_uring_queue_async_work() looks at it should follow after prep has been done. Signed-off-by:
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- 21 Mar, 2021 5 commits
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Jens Axboe authored
Linus correctly points out that this is both unnecessary and generates much worse code on some archs as going from current to thread_info is actually backwards - and obviously just wasteful, since the thread_info is what we care about. Since io_uring only operates on current for these operations, just use test_thread_flag() instead. For io-wq, we can further simplify and use tracehook_notify_signal() to handle the TIF_NOTIFY_SIGNAL work and clear the flag. The latter isn't an actual bug right now, but it may very well be in the future if we place other work items under TIF_NOTIFY_SIGNAL. Reported-by:
Linus Torvalds <torvalds@linux-foundation.org> Link: https://lore.kernel.org/io-uring/CAHk-=wgYhNck33YHKZ14mFB5MzTTk8gqXHcfj=RWTAXKwgQJgg@mail.gmail.com/Signed-off-by:
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Stefan Metzmacher authored
Without that it's not safe to use them in a linked combination with others. Now combinations like IORING_OP_SENDMSG followed by IORING_OP_SPLICE should be possible. We already handle short reads and writes for the following opcodes: - IORING_OP_READV - IORING_OP_READ_FIXED - IORING_OP_READ - IORING_OP_WRITEV - IORING_OP_WRITE_FIXED - IORING_OP_WRITE - IORING_OP_SPLICE - IORING_OP_TEE Now we have it for these as well: - IORING_OP_SENDMSG - IORING_OP_SEND - IORING_OP_RECVMSG - IORING_OP_RECV For IORING_OP_RECVMSG we also check for the MSG_TRUNC and MSG_CTRUNC flags in order to call req_set_fail_links(). There might be applications arround depending on the behavior that even short send[msg]()/recv[msg]() retuns continue an IOSQE_IO_LINK chain. It's very unlikely that such applications pass in MSG_WAITALL, which is only defined in 'man 2 recvmsg', but not in 'man 2 sendmsg'. It's expected that the low level sock_sendmsg() call just ignores MSG_WAITALL, as MSG_ZEROCOPY is also ignored without explicitly set SO_ZEROCOPY. We also expect the caller to know about the implicit truncation to MAX_RW_COUNT, which we don't detect. cc: netdev@vger.kernel.org Link: https://lore.kernel.org/r/c4e1a4cc0d905314f4d5dc567e65a7b09621aab3.1615908477.git.metze@samba.orgSigned-off-by:
Stefan Metzmacher <metze@samba.org> Signed-off-by:
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Jens Axboe authored
Mark the current task as running if we need to run task_work from the io-wq threads as part of work handling. If that is the case, then return as such so that the caller can appropriately loop back and reset if it was part of a going-to-sleep flush. Fixes: 3bfe6106 ("io-wq: fork worker threads from original task") Signed-off-by:
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Eric W. Biederman authored
Just like we don't allow normal signals to IO threads, don't deliver a STOP to a task that has PF_IO_WORKER set. The IO threads don't take signals in general, and have no means of flushing out a stop either. Longer term, we may want to look into allowing stop of these threads, as it relates to eg process freezing. For now, this prevents a spin issue if a SIGSTOP is delivered to the parent task. Reported-by:
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Jens Axboe authored
They don't take signals individually, and even if they share signals with the parent task, don't allow them to be delivered through the worker thread. Linux does allow this kind of behavior for regular threads, but it's really a compatability thing that we need not care about for the IO threads. Reported-by:
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- 18 Mar, 2021 4 commits
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Pavel Begunkov authored
Attaching to already dead/dying SQPOLL task is disallowed in io_sq_offload_create(), but cleanup is hand coded by calling io_put_sq_data()/etc., that miss to put ctx->sq_creds. Defer everything to error-path io_sq_thread_finish(), adding ctx->sqd_list in the error case as well as finish will handle it. Signed-off-by:
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Stefan Metzmacher authored
Signed-off-by:
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Stefan Metzmacher authored
Link: https://lore.kernel.org/r/8c1d14f3748105f4caeda01716d47af2fa41d11c.1615809009.git.metze@samba.orgSigned-off-by:
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Stefan Metzmacher authored
We never want to generate any SIGPIPE, -EPIPE only is much better. Signed-off-by:
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- 15 Mar, 2021 6 commits
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Pavel Begunkov authored
Running sqpoll cancellations via task_work_run() is a bad idea because it depends on other task works to be run, but those may be locked in currently running task_work_run() because of how it's (splicing the list in batches). Enqueue and run them through a separate callback head, namely struct io_sq_data::park_task_work. As a nice bonus we now precisely control where it's run, that's much safer than guessing where it can happen as it was before. Reported-by:
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Pavel Begunkov authored
We already have helpers to run/add callback_head but taking ctx and working with ctx->exit_task_work. Extract generic versions of them implemented in terms of struct callback_head, it will be used later. Signed-off-by:
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Pavel Begunkov authored
If io_sq_thread_park() of one task got rescheduled right after set_bit(), before it gets back to mutex_lock() there can happen park()/unpark() by another task with SQPOLL locking again and continuing running never seeing that first set_bit(SHOULD_PARK), so won't even try to put the mutex down for parking. It will get parked eventually when SQPOLL drops the lock for reschedule, but may be problematic and will get in the way of further fixes. Account number of tasks waiting for parking with a new atomic variable park_pending and adjust SHOULD_PARK accordingly. It doesn't entirely replaces SHOULD_PARK bit with this atomic var because it's convenient to have it as a bit in the state and will help to do optimisations later. Signed-off-by:
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Pavel Begunkov authored
io_sq_thread_finish() is called in io_ring_ctx_free(), so SQPOLL task is potentially running submitting new requests. It's not a disaster because of using a "try" variant of percpu_ref_get, but is far from nice. Remove ctx from the sqd ctx list earlier, before cancellation loop, so SQPOLL can't find it and so won't submit new requests. Signed-off-by:
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Pavel Begunkov authored
The only user of read-locking of sqd->rw_lock is sq_thread itself, which is by definition alone, so we don't really need rw_semaphore, but mutex will do. Replace it with a mutex, and kill read-to-write upgrading and extra task_work handling in io_sq_thread(). Signed-off-by:
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Pavel Begunkov authored
If io_req_complete_post() put not a final ref, we can't rely on the request's ctx ref, and so ctx may potentially be freed while complete_post() is in io_cqring_ev_posted()/etc. In that case get an additional ctx reference, and put it in the end, so protecting following io_cqring_ev_posted(). And also prolong ctx lifetime until spin_unlock happens, as we do with mutexes, so added percpu_ref_get() doesn't race with ctx free. Signed-off-by:
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