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2021-02-04io_uring: drop mm/files between task_work_submitPavel Begunkov
Since SQPOLL task can be shared and so task_work entries can be a mix of them, we need to drop mm and files before trying to issue next request. Cc: stable@vger.kernel.org # 5.10+ Signed-off-by: Pavel Begunkov <asml.silence@gmail.com> Signed-off-by: Jens Axboe <axboe@kernel.dk>
2021-02-04io_uring: don't modify identity's files uncess identity is cowedXiaoguang Wang
Abaci Robot reported following panic: BUG: kernel NULL pointer dereference, address: 0000000000000000 PGD 800000010ef3f067 P4D 800000010ef3f067 PUD 10d9df067 PMD 0 Oops: 0002 [#1] SMP PTI CPU: 0 PID: 1869 Comm: io_wqe_worker-0 Not tainted 5.11.0-rc3+ #1 Hardware name: Red Hat KVM, BIOS 0.5.1 01/01/2011 RIP: 0010:put_files_struct+0x1b/0x120 Code: 24 18 c7 00 f4 ff ff ff e9 4d fd ff ff 66 90 0f 1f 44 00 00 41 57 41 56 49 89 fe 41 55 41 54 55 53 48 83 ec 08 e8 b5 6b db ff 41 ff 0e 74 13 48 83 c4 08 5b 5d 41 5c 41 5d 41 5e 41 5f e9 9c RSP: 0000:ffffc90002147d48 EFLAGS: 00010293 RAX: 0000000000000000 RBX: ffff88810d9a5300 RCX: 0000000000000000 RDX: ffff88810d87c280 RSI: ffffffff8144ba6b RDI: 0000000000000000 RBP: 0000000000000080 R08: 0000000000000001 R09: ffffffff81431500 R10: ffff8881001be000 R11: 0000000000000000 R12: ffff88810ac2f800 R13: ffff88810af38a00 R14: 0000000000000000 R15: ffff8881057130c0 FS: 0000000000000000(0000) GS:ffff88813bc00000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 0000000000000000 CR3: 000000010dbaa002 CR4: 00000000003706f0 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 Call Trace: __io_clean_op+0x10c/0x2a0 io_dismantle_req+0x3c7/0x600 __io_free_req+0x34/0x280 io_put_req+0x63/0xb0 io_worker_handle_work+0x60e/0x830 ? io_wqe_worker+0x135/0x520 io_wqe_worker+0x158/0x520 ? __kthread_parkme+0x96/0xc0 ? io_worker_handle_work+0x830/0x830 kthread+0x134/0x180 ? kthread_create_worker_on_cpu+0x90/0x90 ret_from_fork+0x1f/0x30 Modules linked in: CR2: 0000000000000000 ---[ end trace c358ca86af95b1e7 ]--- I guess case below can trigger above panic: there're two threads which operates different io_uring ctxs and share same sqthread identity, and later one thread exits, io_uring_cancel_task_requests() will clear task->io_uring->identity->files to be NULL in sqpoll mode, then another ctx that uses same identity will panic. Indeed we don't need to clear task->io_uring->identity->files here, io_grab_identity() should handle identity->files changes well, if task->io_uring->identity->files is not equal to current->files, io_cow_identity() should handle this changes well. Cc: stable@vger.kernel.org # 5.5+ Reported-by: Abaci Robot <abaci@linux.alibaba.com> Signed-off-by: Xiaoguang Wang <xiaoguang.wang@linux.alibaba.com> Reviewed-by: Pavel Begunkov <asml.silence@gmail.com> Signed-off-by: Jens Axboe <axboe@kernel.dk>
2021-01-28io_uring: reinforce cancel on flush during exitPavel Begunkov
What 84965ff8a84f0 ("io_uring: if we see flush on exit, cancel related tasks") really wants is to cancel all relevant REQ_F_INFLIGHT requests reliably. That can be achieved by io_uring_cancel_files(), but we'll miss it calling io_uring_cancel_task_requests(files=NULL) from io_uring_flush(), because it will go through __io_uring_cancel_task_requests(). Just always call io_uring_cancel_files() during cancel, it's good enough for now. Cc: stable@vger.kernel.org # 5.9+ Signed-off-by: Pavel Begunkov <asml.silence@gmail.com> Signed-off-by: Jens Axboe <axboe@kernel.dk>
2021-01-28io_uring: fix sqo ownership false positive warningPavel Begunkov
WARNING: CPU: 0 PID: 21359 at fs/io_uring.c:9042 io_uring_cancel_task_requests+0xe55/0x10c0 fs/io_uring.c:9042 Call Trace: io_uring_flush+0x47b/0x6e0 fs/io_uring.c:9227 filp_close+0xb4/0x170 fs/open.c:1295 close_files fs/file.c:403 [inline] put_files_struct fs/file.c:418 [inline] put_files_struct+0x1cc/0x350 fs/file.c:415 exit_files+0x7e/0xa0 fs/file.c:435 do_exit+0xc22/0x2ae0 kernel/exit.c:820 do_group_exit+0x125/0x310 kernel/exit.c:922 get_signal+0x427/0x20f0 kernel/signal.c:2773 arch_do_signal_or_restart+0x2a8/0x1eb0 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+0x148/0x250 kernel/entry/common.c:201 __syscall_exit_to_user_mode_work kernel/entry/common.c:291 [inline] syscall_exit_to_user_mode+0x19/0x50 kernel/entry/common.c:302 entry_SYSCALL_64_after_hwframe+0x44/0xa9 Now io_uring_cancel_task_requests() can be called not through file notes but directly, remove a WARN_ONCE() there that give us false positives. That check is not very important and we catch it in other places. Fixes: 84965ff8a84f0 ("io_uring: if we see flush on exit, cancel related tasks") Cc: stable@vger.kernel.org # 5.9+ Reported-by: syzbot+3e3d9bd0c6ce9efbc3ef@syzkaller.appspotmail.com Signed-off-by: Pavel Begunkov <asml.silence@gmail.com> Signed-off-by: Jens Axboe <axboe@kernel.dk>
2021-01-28io_uring: fix list corruption for splice file_getPavel Begunkov
kernel BUG at lib/list_debug.c:29! Call Trace: __list_add include/linux/list.h:67 [inline] list_add include/linux/list.h:86 [inline] io_file_get+0x8cc/0xdb0 fs/io_uring.c:6466 __io_splice_prep+0x1bc/0x530 fs/io_uring.c:3866 io_splice_prep fs/io_uring.c:3920 [inline] io_req_prep+0x3546/0x4e80 fs/io_uring.c:6081 io_queue_sqe+0x609/0x10d0 fs/io_uring.c:6628 io_submit_sqe fs/io_uring.c:6705 [inline] io_submit_sqes+0x1495/0x2720 fs/io_uring.c:6953 __do_sys_io_uring_enter+0x107d/0x1f30 fs/io_uring.c:9353 do_syscall_64+0x2d/0x70 arch/x86/entry/common.c:46 entry_SYSCALL_64_after_hwframe+0x44/0xa9 io_file_get() may be called from splice, and so REQ_F_INFLIGHT may already be set. Fixes: 02a13674fa0e8 ("io_uring: account io_uring internal files as REQ_F_INFLIGHT") Cc: stable@vger.kernel.org # 5.9+ Reported-by: syzbot+6879187cf57845801267@syzkaller.appspotmail.com Signed-off-by: Pavel Begunkov <asml.silence@gmail.com> Signed-off-by: Jens Axboe <axboe@kernel.dk>
2021-01-27io_uring: fix flush cqring overflow list while TASK_INTERRUPTIBLEHao Xu
Abaci reported the follow warning: [ 27.073425] do not call blocking ops when !TASK_RUNNING; state=1 set at [] prepare_to_wait_exclusive+0x3a/0xc0 [ 27.075805] WARNING: CPU: 0 PID: 951 at kernel/sched/core.c:7853 __might_sleep+0x80/0xa0 [ 27.077604] Modules linked in: [ 27.078379] CPU: 0 PID: 951 Comm: a.out Not tainted 5.11.0-rc3+ #1 [ 27.079637] Hardware name: Red Hat KVM, BIOS 0.5.1 01/01/2011 [ 27.080852] RIP: 0010:__might_sleep+0x80/0xa0 [ 27.081835] Code: 65 48 8b 04 25 80 71 01 00 48 8b 90 c0 15 00 00 48 8b 70 18 48 c7 c7 08 39 95 82 c6 05 f9 5f de 08 01 48 89 d1 e8 00 c6 fa ff 0b eb bf 41 0f b6 f5 48 c7 c7 40 23 c9 82 e8 f3 48 ec 00 eb a7 [ 27.084521] RSP: 0018:ffffc90000fe3ce8 EFLAGS: 00010286 [ 27.085350] RAX: 0000000000000000 RBX: ffffffff82956083 RCX: 0000000000000000 [ 27.086348] RDX: ffff8881057a0000 RSI: ffffffff8118cc9e RDI: ffff88813bc28570 [ 27.087598] RBP: 00000000000003a7 R08: 0000000000000001 R09: 0000000000000001 [ 27.088819] R10: ffffc90000fe3e00 R11: 00000000fffef9f0 R12: 0000000000000000 [ 27.089819] R13: 0000000000000000 R14: ffff88810576eb80 R15: ffff88810576e800 [ 27.091058] FS: 00007f7b144cf740(0000) GS:ffff88813bc00000(0000) knlGS:0000000000000000 [ 27.092775] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 [ 27.093796] CR2: 00000000022da7b8 CR3: 000000010b928002 CR4: 00000000003706f0 [ 27.094778] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 [ 27.095780] DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 [ 27.097011] Call Trace: [ 27.097685] __mutex_lock+0x5d/0xa30 [ 27.098565] ? prepare_to_wait_exclusive+0x71/0xc0 [ 27.099412] ? io_cqring_overflow_flush.part.101+0x6d/0x70 [ 27.100441] ? lockdep_hardirqs_on_prepare+0xe9/0x1c0 [ 27.101537] ? _raw_spin_unlock_irqrestore+0x2d/0x40 [ 27.102656] ? trace_hardirqs_on+0x46/0x110 [ 27.103459] ? io_cqring_overflow_flush.part.101+0x6d/0x70 [ 27.104317] io_cqring_overflow_flush.part.101+0x6d/0x70 [ 27.105113] io_cqring_wait+0x36e/0x4d0 [ 27.105770] ? find_held_lock+0x28/0xb0 [ 27.106370] ? io_uring_remove_task_files+0xa0/0xa0 [ 27.107076] __x64_sys_io_uring_enter+0x4fb/0x640 [ 27.107801] ? rcu_read_lock_sched_held+0x59/0xa0 [ 27.108562] ? lockdep_hardirqs_on_prepare+0xe9/0x1c0 [ 27.109684] ? syscall_enter_from_user_mode+0x26/0x70 [ 27.110731] do_syscall_64+0x2d/0x40 [ 27.111296] entry_SYSCALL_64_after_hwframe+0x44/0xa9 [ 27.112056] RIP: 0033:0x7f7b13dc8239 [ 27.112663] Code: 01 00 48 81 c4 80 00 00 00 e9 f1 fe ff ff 0f 1f 00 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 3d 01 f0 ff ff 73 01 c3 48 8b 0d 27 ec 2c 00 f7 d8 64 89 01 48 [ 27.115113] RSP: 002b:00007ffd6d7f5c88 EFLAGS: 00000286 ORIG_RAX: 00000000000001aa [ 27.116562] RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 00007f7b13dc8239 [ 27.117961] RDX: 000000000000478e RSI: 0000000000000000 RDI: 0000000000000003 [ 27.118925] RBP: 00007ffd6d7f5cb0 R08: 0000000020000040 R09: 0000000000000008 [ 27.119773] R10: 0000000000000001 R11: 0000000000000286 R12: 0000000000400480 [ 27.120614] R13: 00007ffd6d7f5d90 R14: 0000000000000000 R15: 0000000000000000 [ 27.121490] irq event stamp: 5635 [ 27.121946] hardirqs last enabled at (5643): [] console_unlock+0x5c4/0x740 [ 27.123476] hardirqs last disabled at (5652): [] console_unlock+0x4e7/0x740 [ 27.125192] softirqs last enabled at (5272): [] __do_softirq+0x3c5/0x5aa [ 27.126430] softirqs last disabled at (5267): [] asm_call_irq_on_stack+0xf/0x20 [ 27.127634] ---[ end trace 289d7e28fa60f928 ]--- This is caused by calling io_cqring_overflow_flush() which may sleep after calling prepare_to_wait_exclusive() which set task state to TASK_INTERRUPTIBLE Reported-by: Abaci <abaci@linux.alibaba.com> Fixes: 6c503150ae33 ("io_uring: patch up IOPOLL overflow_flush sync") Reviewed-by: Pavel Begunkov <asml.silence@gmail.com> Signed-off-by: Hao Xu <haoxu@linux.alibaba.com> Signed-off-by: Jens Axboe <axboe@kernel.dk>
2021-01-26io_uring: fix wqe->lock/completion_lock deadlockPavel Begunkov
Joseph reports following deadlock: CPU0: ... io_kill_linked_timeout // &ctx->completion_lock io_commit_cqring __io_queue_deferred __io_queue_async_work io_wq_enqueue io_wqe_enqueue // &wqe->lock CPU1: ... __io_uring_files_cancel io_wq_cancel_cb io_wqe_cancel_pending_work // &wqe->lock io_cancel_task_cb // &ctx->completion_lock Only __io_queue_deferred() calls queue_async_work() while holding ctx->completion_lock, enqueue drained requests via io_req_task_queue() instead. Cc: stable@vger.kernel.org # 5.9+ Reported-by: Joseph Qi <joseph.qi@linux.alibaba.com> Tested-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>
2021-01-26io_uring: fix cancellation taking mutex while TASK_UNINTERRUPTIBLEPavel Begunkov
do not call blocking ops when !TASK_RUNNING; state=2 set at [<00000000ced9dbfc>] prepare_to_wait+0x1f4/0x3b0 kernel/sched/wait.c:262 WARNING: CPU: 1 PID: 19888 at kernel/sched/core.c:7853 __might_sleep+0xed/0x100 kernel/sched/core.c:7848 RIP: 0010:__might_sleep+0xed/0x100 kernel/sched/core.c:7848 Call Trace: __mutex_lock_common+0xc4/0x2ef0 kernel/locking/mutex.c:935 __mutex_lock kernel/locking/mutex.c:1103 [inline] mutex_lock_nested+0x1a/0x20 kernel/locking/mutex.c:1118 io_wq_submit_work+0x39a/0x720 fs/io_uring.c:6411 io_run_cancel fs/io-wq.c:856 [inline] io_wqe_cancel_pending_work fs/io-wq.c:990 [inline] io_wq_cancel_cb+0x614/0xcb0 fs/io-wq.c:1027 io_uring_cancel_files fs/io_uring.c:8874 [inline] io_uring_cancel_task_requests fs/io_uring.c:8952 [inline] __io_uring_files_cancel+0x115d/0x19e0 fs/io_uring.c:9038 io_uring_files_cancel include/linux/io_uring.h:51 [inline] do_exit+0x2e6/0x2490 kernel/exit.c:780 do_group_exit+0x168/0x2d0 kernel/exit.c:922 get_signal+0x16b5/0x2030 kernel/signal.c:2770 arch_do_signal_or_restart+0x8e/0x6a0 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:201 __syscall_exit_to_user_mode_work kernel/entry/common.c:291 [inline] syscall_exit_to_user_mode+0x48/0x190 kernel/entry/common.c:302 entry_SYSCALL_64_after_hwframe+0x44/0xa9 Rewrite io_uring_cancel_files() to mimic __io_uring_task_cancel()'s counting scheme, so it does all the heavy work before setting TASK_UNINTERRUPTIBLE. Cc: stable@vger.kernel.org # 5.9+ Reported-by: syzbot+f655445043a26a7cfab8@syzkaller.appspotmail.com Signed-off-by: Pavel Begunkov <asml.silence@gmail.com> [axboe: fix inverted task check] Signed-off-by: Jens Axboe <axboe@kernel.dk>
2021-01-26io_uring: fix __io_uring_files_cancel() with TASK_UNINTERRUPTIBLEPavel Begunkov
If the tctx inflight number haven't changed because of cancellation, __io_uring_task_cancel() will continue leaving the task in TASK_UNINTERRUPTIBLE state, that's not expected by __io_uring_files_cancel(). Ensure we always call finish_wait() before retrying. Cc: stable@vger.kernel.org # 5.9+ Signed-off-by: Pavel Begunkov <asml.silence@gmail.com> Signed-off-by: Jens Axboe <axboe@kernel.dk>
2021-01-24io_uring: only call io_cqring_ev_posted() if events were postedJens Axboe
This normally doesn't cause any extra harm, but it does mean that we'll increment the eventfd notification count, if one has been registered with the ring. This can confuse applications, when they see more notifications on the eventfd side than are available in the ring. Do the nice thing and only increment this count, if we actually posted (or even overflowed) events. Reported-and-tested-by: Dan Melnic <dmm@fb.com> Signed-off-by: Jens Axboe <axboe@kernel.dk>
2021-01-24io_uring: if we see flush on exit, cancel related tasksJens Axboe
Ensure we match tasks that belong to a dead or dying task as well, as we need to reap those in addition to those belonging to the exiting task. Cc: stable@vger.kernel.org # 5.9+ Reported-by: Josef Grieb <josef.grieb@gmail.com> Signed-off-by: Jens Axboe <axboe@kernel.dk>
2021-01-24io_uring: account io_uring internal files as REQ_F_INFLIGHTJens Axboe
We need to actively cancel anything that introduces a potential circular loop, where io_uring holds a reference to itself. If the file in question is an io_uring file, then add the request to the inflight list. Cc: stable@vger.kernel.org # 5.9+ Signed-off-by: Jens Axboe <axboe@kernel.dk>
2021-01-24io_uring: fix sleeping under spin in __io_clean_opPavel Begunkov
[ 27.629441] BUG: sleeping function called from invalid context at fs/file.c:402 [ 27.631317] in_atomic(): 1, irqs_disabled(): 1, non_block: 0, pid: 1012, name: io_wqe_worker-0 [ 27.633220] 1 lock held by io_wqe_worker-0/1012: [ 27.634286] #0: ffff888105e26c98 (&ctx->completion_lock) {....}-{2:2}, at: __io_req_complete.part.102+0x30/0x70 [ 27.649249] Call Trace: [ 27.649874] dump_stack+0xac/0xe3 [ 27.650666] ___might_sleep+0x284/0x2c0 [ 27.651566] put_files_struct+0xb8/0x120 [ 27.652481] __io_clean_op+0x10c/0x2a0 [ 27.653362] __io_cqring_fill_event+0x2c1/0x350 [ 27.654399] __io_req_complete.part.102+0x41/0x70 [ 27.655464] io_openat2+0x151/0x300 [ 27.656297] io_issue_sqe+0x6c/0x14e0 [ 27.660991] io_wq_submit_work+0x7f/0x240 [ 27.662890] io_worker_handle_work+0x501/0x8a0 [ 27.664836] io_wqe_worker+0x158/0x520 [ 27.667726] kthread+0x134/0x180 [ 27.669641] ret_from_fork+0x1f/0x30 Instead of cleaning files on overflow, return back overflow cancellation into io_uring_cancel_files(). Previously it was racy to clean REQ_F_OVERFLOW flag, but we got rid of it, and can do it through repetitive attempts targeting all matching requests. Reported-by: Abaci <abaci@linux.alibaba.com> Reported-by: Joseph Qi <joseph.qi@linux.alibaba.com> Cc: Xiaoguang Wang <xiaoguang.wang@linux.alibaba.com> Signed-off-by: Pavel Begunkov <asml.silence@gmail.com> Signed-off-by: Jens Axboe <axboe@kernel.dk>
2021-01-22io_uring: fix short read retries for non-reg filesPavel Begunkov
Sockets and other non-regular files may actually expect short reads to happen, don't retry reads for them. Because non-reg files don't set FMODE_BUF_RASYNC and so it won't do second/retry do_read, we can filter out those cases after first do_read() attempt with ret>0. Cc: stable@vger.kernel.org # 5.9+ Suggested-by: Jens Axboe <axboe@kernel.dk> Signed-off-by: Pavel Begunkov <asml.silence@gmail.com> Signed-off-by: Jens Axboe <axboe@kernel.dk>
2021-01-22io_uring: fix SQPOLL IORING_OP_CLOSE cancelation stateJens Axboe
IORING_OP_CLOSE is special in terms of cancelation, since it has an intermediate state where we've removed the file descriptor but hasn't closed the file yet. For that reason, it's currently marked with IO_WQ_WORK_NO_CANCEL to prevent cancelation. This ensures that the op is always run even if canceled, to prevent leaving us with a live file but an fd that is gone. However, with SQPOLL, since a cancel request doesn't carry any resources on behalf of the request being canceled, if we cancel before any of the close op has been run, we can end up with io-wq not having the ->files assigned. This can result in the following oops reported by Joseph: BUG: kernel NULL pointer dereference, address: 00000000000000d8 PGD 800000010b76f067 P4D 800000010b76f067 PUD 10b462067 PMD 0 Oops: 0000 [#1] SMP PTI CPU: 1 PID: 1788 Comm: io_uring-sq Not tainted 5.11.0-rc4 #1 Hardware name: Red Hat KVM, BIOS 0.5.1 01/01/2011 RIP: 0010:__lock_acquire+0x19d/0x18c0 Code: 00 00 8b 1d fd 56 dd 08 85 db 0f 85 43 05 00 00 48 c7 c6 98 7b 95 82 48 c7 c7 57 96 93 82 e8 9a bc f5 ff 0f 0b e9 2b 05 00 00 <48> 81 3f c0 ca 67 8a b8 00 00 00 00 41 0f 45 c0 89 04 24 e9 81 fe RSP: 0018:ffffc90001933828 EFLAGS: 00010002 RAX: 0000000000000001 RBX: 0000000000000001 RCX: 0000000000000000 RDX: 0000000000000000 RSI: 0000000000000000 RDI: 00000000000000d8 RBP: 0000000000000246 R08: 0000000000000001 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000000 R12: 0000000000000000 R13: 0000000000000000 R14: ffff888106e8a140 R15: 00000000000000d8 FS: 0000000000000000(0000) GS:ffff88813bd00000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 00000000000000d8 CR3: 0000000106efa004 CR4: 00000000003706e0 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 Call Trace: lock_acquire+0x31a/0x440 ? close_fd_get_file+0x39/0x160 ? __lock_acquire+0x647/0x18c0 _raw_spin_lock+0x2c/0x40 ? close_fd_get_file+0x39/0x160 close_fd_get_file+0x39/0x160 io_issue_sqe+0x1334/0x14e0 ? lock_acquire+0x31a/0x440 ? __io_free_req+0xcf/0x2e0 ? __io_free_req+0x175/0x2e0 ? find_held_lock+0x28/0xb0 ? io_wq_submit_work+0x7f/0x240 io_wq_submit_work+0x7f/0x240 io_wq_cancel_cb+0x161/0x580 ? io_wqe_wake_worker+0x114/0x360 ? io_uring_get_socket+0x40/0x40 io_async_find_and_cancel+0x3b/0x140 io_issue_sqe+0xbe1/0x14e0 ? __lock_acquire+0x647/0x18c0 ? __io_queue_sqe+0x10b/0x5f0 __io_queue_sqe+0x10b/0x5f0 ? io_req_prep+0xdb/0x1150 ? mark_held_locks+0x6d/0xb0 ? mark_held_locks+0x6d/0xb0 ? io_queue_sqe+0x235/0x4b0 io_queue_sqe+0x235/0x4b0 io_submit_sqes+0xd7e/0x12a0 ? _raw_spin_unlock_irq+0x24/0x30 ? io_sq_thread+0x3ae/0x940 io_sq_thread+0x207/0x940 ? do_wait_intr_irq+0xc0/0xc0 ? __ia32_sys_io_uring_enter+0x650/0x650 kthread+0x134/0x180 ? kthread_create_worker_on_cpu+0x90/0x90 ret_from_fork+0x1f/0x30 Fix this by moving the IO_WQ_WORK_NO_CANCEL until _after_ we've modified the fdtable. Canceling before this point is totally fine, and running it in the io-wq context _after_ that point is also fine. For 5.12, we'll handle this internally and get rid of the no-cancel flag, as IORING_OP_CLOSE is the only user of it. Cc: stable@vger.kernel.org Fixes: b5dba59e0cf7 ("io_uring: add support for IORING_OP_CLOSE") Reported-by: "Abaci <abaci@linux.alibaba.com>" Reviewed-and-tested-by: Joseph Qi <joseph.qi@linux.alibaba.com> Signed-off-by: Jens Axboe <axboe@kernel.dk>
2021-01-16io_uring: fix skipping disabling sqo on execPavel Begunkov
If there are no requests at the time __io_uring_task_cancel() is called, tctx_inflight() returns zero and and it terminates not getting a chance to go through __io_uring_files_cancel() and do io_disable_sqo_submit(). And we absolutely want them disabled by the time cancellation ends. Reported-by: Jens Axboe <axboe@kernel.dk> Signed-off-by: Pavel Begunkov <asml.silence@gmail.com> Fixes: d9d05217cb69 ("io_uring: stop SQPOLL submit on creator's death") Signed-off-by: Jens Axboe <axboe@kernel.dk>
2021-01-16io_uring: fix uring_flush in exit_files() warningPavel Begunkov
WARNING: CPU: 1 PID: 11100 at fs/io_uring.c:9096 io_uring_flush+0x326/0x3a0 fs/io_uring.c:9096 RIP: 0010:io_uring_flush+0x326/0x3a0 fs/io_uring.c:9096 Call Trace: filp_close+0xb4/0x170 fs/open.c:1280 close_files fs/file.c:401 [inline] put_files_struct fs/file.c:416 [inline] put_files_struct+0x1cc/0x350 fs/file.c:413 exit_files+0x7e/0xa0 fs/file.c:433 do_exit+0xc22/0x2ae0 kernel/exit.c:820 do_group_exit+0x125/0x310 kernel/exit.c:922 get_signal+0x3e9/0x20a0 kernel/signal.c:2770 arch_do_signal_or_restart+0x2a8/0x1eb0 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+0x148/0x250 kernel/entry/common.c:201 __syscall_exit_to_user_mode_work kernel/entry/common.c:291 [inline] syscall_exit_to_user_mode+0x19/0x50 kernel/entry/common.c:302 entry_SYSCALL_64_after_hwframe+0x44/0xa9 An SQPOLL ring creator task may have gotten rid of its file note during exit and called io_disable_sqo_submit(), but the io_uring is still left referenced through fdtable, which will be put during close_files() and cause a false positive warning. First split the warning into two for more clarity when is hit, and the add sqo_dead check to handle the described case. Reported-by: syzbot+a32b546d58dde07875a1@syzkaller.appspotmail.com Signed-off-by: Pavel Begunkov <asml.silence@gmail.com> Signed-off-by: Jens Axboe <axboe@kernel.dk>
2021-01-16io_uring: fix false positive sqo warning on flushPavel Begunkov
WARNING: CPU: 1 PID: 9094 at fs/io_uring.c:8884 io_disable_sqo_submit+0x106/0x130 fs/io_uring.c:8884 Call Trace: io_uring_flush+0x28b/0x3a0 fs/io_uring.c:9099 filp_close+0xb4/0x170 fs/open.c:1280 close_fd+0x5c/0x80 fs/file.c:626 __do_sys_close fs/open.c:1299 [inline] __se_sys_close fs/open.c:1297 [inline] __x64_sys_close+0x2f/0xa0 fs/open.c:1297 do_syscall_64+0x2d/0x70 arch/x86/entry/common.c:46 entry_SYSCALL_64_after_hwframe+0x44/0xa9 io_uring's final close() may be triggered by any task not only the creator. It's well handled by io_uring_flush() including SQPOLL case, though a warning in io_disable_sqo_submit() will fallaciously fire by moving this warning out to the only call site that matters. Reported-by: syzbot+2f5d1785dc624932da78@syzkaller.appspotmail.com Signed-off-by: Pavel Begunkov <asml.silence@gmail.com> Signed-off-by: Jens Axboe <axboe@kernel.dk>
2021-01-16io_uring: iopoll requests should also wake task ->in_idle stateJens Axboe
If we're freeing/finishing iopoll requests, ensure we check if the task is in idling in terms of cancelation. Otherwise we could end up waiting forever in __io_uring_task_cancel() if the task has active iopoll requests that need cancelation. Cc: stable@vger.kernel.org # 5.9+ Signed-off-by: Jens Axboe <axboe@kernel.dk>
2021-01-15io_uring: ensure finish_wait() is always called in __io_uring_task_cancel()Jens Axboe
If we enter with requests pending and performm cancelations, we'll have a different inflight count before and after calling prepare_to_wait(). This causes the loop to restart. If we actually ended up canceling everything, or everything completed in-between, then we'll break out of the loop without calling finish_wait() on the waitqueue. This can trigger a warning on exit_signals(), as we leave the task state in TASK_UNINTERRUPTIBLE. Put a finish_wait() after the loop to catch that case. Cc: stable@vger.kernel.org # 5.9+ Signed-off-by: Jens Axboe <axboe@kernel.dk>
2021-01-15io_uring: flush timeouts that should already have expiredMarcelo Diop-Gonzalez
Right now io_flush_timeouts() checks if the current number of events is equal to ->timeout.target_seq, but this will miss some timeouts if there have been more than 1 event added since the last time they were flushed (possible in io_submit_flush_completions(), for example). Fix it by recording the last sequence at which timeouts were flushed so that the number of events seen can be compared to the number of events needed without overflow. Signed-off-by: Marcelo Diop-Gonzalez <marcelo827@gmail.com> Reviewed-by: Pavel Begunkov <asml.silence@gmail.com> Signed-off-by: Jens Axboe <axboe@kernel.dk>
2021-01-13io_uring: do sqo disable on install_fd errorPavel Begunkov
WARNING: CPU: 0 PID: 8494 at fs/io_uring.c:8717 io_ring_ctx_wait_and_kill+0x4f2/0x600 fs/io_uring.c:8717 Call Trace: io_uring_release+0x3e/0x50 fs/io_uring.c:8759 __fput+0x283/0x920 fs/file_table.c:280 task_work_run+0xdd/0x190 kernel/task_work.c:140 tracehook_notify_resume include/linux/tracehook.h:189 [inline] exit_to_user_mode_loop kernel/entry/common.c:174 [inline] exit_to_user_mode_prepare+0x249/0x250 kernel/entry/common.c:201 __syscall_exit_to_user_mode_work kernel/entry/common.c:291 [inline] syscall_exit_to_user_mode+0x19/0x50 kernel/entry/common.c:302 entry_SYSCALL_64_after_hwframe+0x44/0xa9 failed io_uring_install_fd() is a special case, we don't do io_ring_ctx_wait_and_kill() directly but defer it to fput, though still need to io_disable_sqo_submit() before. note: it doesn't fix any real problem, just a warning. That's because sqring won't be available to the userspace in this case and so SQPOLL won't submit anything. Reported-by: syzbot+9c9c35374c0ecac06516@syzkaller.appspotmail.com Fixes: d9d05217cb69 ("io_uring: stop SQPOLL submit on creator's death") Signed-off-by: Pavel Begunkov <asml.silence@gmail.com> Signed-off-by: Jens Axboe <axboe@kernel.dk>
2021-01-13io_uring: fix null-deref in io_disable_sqo_submitPavel Begunkov
general protection fault, probably for non-canonical address 0xdffffc0000000022: 0000 [#1] KASAN: null-ptr-deref in range [0x0000000000000110-0x0000000000000117] RIP: 0010:io_ring_set_wakeup_flag fs/io_uring.c:6929 [inline] RIP: 0010:io_disable_sqo_submit+0xdb/0x130 fs/io_uring.c:8891 Call Trace: io_uring_create fs/io_uring.c:9711 [inline] io_uring_setup+0x12b1/0x38e0 fs/io_uring.c:9739 do_syscall_64+0x2d/0x70 arch/x86/entry/common.c:46 entry_SYSCALL_64_after_hwframe+0x44/0xa9 io_disable_sqo_submit() might be called before user rings were allocated, don't do io_ring_set_wakeup_flag() in those cases. Reported-by: syzbot+ab412638aeb652ded540@syzkaller.appspotmail.com Fixes: d9d05217cb69 ("io_uring: stop SQPOLL submit on creator's death") Signed-off-by: Pavel Begunkov <asml.silence@gmail.com> Signed-off-by: Jens Axboe <axboe@kernel.dk>
2021-01-11io_uring: don't take files/mm for a dead taskPavel Begunkov
In rare cases a task may be exiting while io_ring_exit_work() trying to cancel/wait its requests. It's ok for __io_sq_thread_acquire_mm() because of SQPOLL check, but is not for __io_sq_thread_acquire_files(). Play safe and fail for both of them. Cc: stable@vger.kernel.org # 5.5+ Signed-off-by: Pavel Begunkov <asml.silence@gmail.com> Signed-off-by: Jens Axboe <axboe@kernel.dk>
2021-01-11io_uring: drop mm and files after task_work_runPavel Begunkov
__io_req_task_submit() run by task_work can set mm and files, but io_sq_thread() in some cases, and because __io_sq_thread_acquire_mm() and __io_sq_thread_acquire_files() do a simple current->mm/files check it may end up submitting IO with mm/files of another task. We also need to drop it after in the end to drop potentially grabbed references to them. Cc: stable@vger.kernel.org # 5.9+ Signed-off-by: Pavel Begunkov <asml.silence@gmail.com> Signed-off-by: Jens Axboe <axboe@kernel.dk>
2021-01-09io_uring: stop SQPOLL submit on creator's deathPavel Begunkov
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>
2021-01-09io_uring: add warn_once for io_uring_flush()Pavel Begunkov
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>
2021-01-09io_uring: inline io_uring_attempt_task_drop()Pavel Begunkov
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>
2021-01-09io_uring: io_rw_reissue lockdep annotationsPavel Begunkov
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>
2021-01-07io_uring: synchronise ev_posted() with waitqueuesPavel Begunkov
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>
2021-01-07io_uring: dont kill fasync under completion_lockPavel Begunkov
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>
2021-01-07io_uring: trigger eventfd for IOPOLLPavel Begunkov
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>
2021-01-06io_uring: Fix return value from alloc_fixed_file_ref_nodeMatthew Wilcox (Oracle)
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>
2021-01-05io_uring: Delete useless variable ‘id’ in io_prep_async_workYe Bin
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>
2021-01-04io_uring: cancel more aggressively in exit_workPavel Begunkov
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>
2021-01-04io_uring: drop file refs after task cancelPavel Begunkov
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>
2021-01-04io_uring: patch up IOPOLL overflow_flush syncPavel Begunkov
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>
2021-01-04io_uring: synchronise IOPOLL on task_submit failPavel Begunkov
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>
2020-12-30io_uring: fix io_sqe_files_unregister() hangsPavel Begunkov
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>
2020-12-30io_uring: add a helper for setting a ref nodePavel Begunkov
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>
2020-12-29io_uring: don't assume mm is constant across submitsJens Axboe
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>
2020-12-22io_uring: hold uring_lock while completing failed polled io in ↵Xiaoguang Wang
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>
2020-12-22io_uring: fix double io_uring freePavel Begunkov
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>
2020-12-21io_uring: fix ignoring xa_store errorsPavel Begunkov
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>
2020-12-20io_uring: end waiting before task cancel attemptsPavel Begunkov
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>
2020-12-20io_uring: always progress task_work on task cancelPavel Begunkov
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>
2020-12-20io_uring: make ctx cancel on exit targeted to actual ctxJens Axboe
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>
2020-12-19io_uring: fix 0-iov read buffer selectPavel Begunkov
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>
2020-12-18io_uring: close a small race gap for files cancelPavel Begunkov
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>
2020-12-17io_uring: limit {io|sq}poll submit locking scopePavel Begunkov
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>
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