wireguard-linux/fs/io_uring.c, branch jd/shorter-socket-lock

io_uring: only restore req->work for req that needs do completion

2020-04-19T19:55:27Z

When testing io_uring IORING_FEAT_FAST_POLL feature, I got below panic: BUG: kernel NULL pointer dereference, address: 0000000000000030 PGD 0 P4D 0 Oops: 0000 [#1] SMP PTI CPU: 5 PID: 2154 Comm: io_uring_echo_s Not tainted 5.6.0+ #359 Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS rel-1.11.1-0-g0551a4be2c-prebuilt.qemu-project.org 04/01/2014 RIP: 0010:io_wq_submit_work+0xf/0xa0 Code: ff ff ff be 02 00 00 00 e8 ae c9 19 00 e9 58 ff ff ff 66 0f 1f 84 00 00 00 00 00 0f 1f 44 00 00 41 54 49 89 fc 55 53 48 8b 2f <8b> 45 30 48 8d 9d 48 ff ff ff 25 01 01 00 00 83 f8 01 75 07 eb 2a RSP: 0018:ffffbef543e93d58 EFLAGS: 00010286 RAX: ffffffff84364f50 RBX: ffffa3eb50f046b8 RCX: 0000000000000000 RDX: ffffa3eb0efc1840 RSI: 0000000000000006 RDI: ffffa3eb50f046b8 RBP: 0000000000000000 R08: 00000000fffd070d R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000000 R12: ffffa3eb50f046b8 R13: ffffa3eb0efc2088 R14: ffffffff85b69be0 R15: ffffa3eb0effa4b8 FS: 00007fe9f69cc4c0(0000) GS:ffffa3eb5ef40000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 0000000000000030 CR3: 0000000020410000 CR4: 00000000000006e0 Call Trace: task_work_run+0x6d/0xa0 do_exit+0x39a/0xb80 ? get_signal+0xfe/0xbc0 do_group_exit+0x47/0xb0 get_signal+0x14b/0xbc0 ? __x64_sys_io_uring_enter+0x1b7/0x450 do_signal+0x2c/0x260 ? __x64_sys_io_uring_enter+0x228/0x450 exit_to_usermode_loop+0x87/0xf0 do_syscall_64+0x209/0x230 entry_SYSCALL_64_after_hwframe+0x49/0xb3 RIP: 0033:0x7fe9f64f8df9 Code: Bad RIP value. task_work_run calls io_wq_submit_work unexpectedly, it's obvious that struct callback_head's func member has been changed. After looking into codes, I found this issue is still due to the union definition: union { /* * Only commands that never go async can use the below fields, * obviously. Right now only IORING_OP_POLL_ADD uses them, and * async armed poll handlers for regular commands. The latter * restore the work, if needed. */ struct { struct callback_head task_work; struct hlist_node hash_node; struct async_poll *apoll; }; struct io_wq_work work; }; When task_work_run has multiple work to execute, the work that calls io_poll_remove_all() will do req->work restore for non-poll request always, but indeed if a non-poll request has been added to a new callback_head, subsequent callback will call io_async_task_func() to handle this request, that means we should not do the restore work for such non-poll request. Meanwhile in io_async_task_func(), we should drop submit ref when req has been canceled. Fix both issues. Fixes: b1f573bd15fd ("io_uring: restore req->work when canceling poll request") Signed-off-by: Xiaoguang Wang Use io_double_put_req() Signed-off-by: Jens Axboe

io_uring: don't count rqs failed after current one

2020-04-15T01:16:59Z

When checking for draining with __req_need_defer(), it tries to match how many requests were sent before a current one with number of already completed. Dropped SQEs are included in req->sequence, and they won't ever appear in CQ. To compensate for that, __req_need_defer() substracts ctx->cached_sq_dropped. However, what it should really use is number of SQEs dropped __before__ the current one. In other words, any submitted request shouldn't shouldn't affect dequeueing from the drain queue of previously submitted ones. Instead of saving proper ctx->cached_sq_dropped in each request, substract from req->sequence it at initialisation, so it includes number of properly submitted requests. note: it also changes behaviour of timeouts, but 1. it's already diverge from the description because of using SQ 2. the description is ambiguous regarding dropped SQEs Signed-off-by: Pavel Begunkov Signed-off-by: Jens Axboe

io_uring: kill already cached timeout.seq_offset

2020-04-15T01:16:57Z

req->timeout.count and req->io->timeout.seq_offset store the same value, which is sqe->off. Kill the second one Signed-off-by: Pavel Begunkov Signed-off-by: Jens Axboe

io_uring: fix cached_sq_head in io_timeout()

2020-04-15T01:16:55Z

io_timeout() can be executed asynchronously by a worker and without holding ctx->uring_lock 1. using ctx->cached_sq_head there is racy there 2. it should count events from a moment of timeout's submission, but not execution Use req->sequence. Signed-off-by: Pavel Begunkov Signed-off-by: Jens Axboe

io_uring: only post events in io_poll_remove_all() if we completed some

2020-04-13T23:05:14Z

syzbot reports this crash: BUG: unable to handle page fault for address: ffffffffffffffe8 PGD f96e17067 P4D f96e17067 PUD f96e19067 PMD 0 Oops: 0000 [#1] SMP DEBUG_PAGEALLOC KASAN PTI CPU: 55 PID: 211750 Comm: trinity-c127 Tainted: G B L 5.7.0-rc1-next-20200413 #4 Hardware name: HP ProLiant DL380 Gen9/ProLiant DL380 Gen9, BIOS P89 04/12/2017 RIP: 0010:__wake_up_common+0x98/0x290 el/sched/wait.c:87 Code: 40 4d 8d 78 e8 49 8d 7f 18 49 39 fd 0f 84 80 00 00 00 e8 6b bd 2b 00 49 8b 5f 18 45 31 e4 48 83 eb 18 4c 89 ff e8 08 bc 2b 00 <45> 8b 37 41 f6 c6 04 75 71 49 8d 7f 10 e8 46 bd 2b 00 49 8b 47 10 RSP: 0018:ffffc9000adbfaf0 EFLAGS: 00010046 RAX: 0000000000000000 RBX: ffffffffffffffe8 RCX: ffffffffaa9636b8 RDX: 0000000000000003 RSI: dffffc0000000000 RDI: ffffffffffffffe8 RBP: ffffc9000adbfb40 R08: fffffbfff582c5fd R09: fffffbfff582c5fd R10: ffffffffac162fe3 R11: fffffbfff582c5fc R12: 0000000000000000 R13: ffff888ef82b0960 R14: ffffc9000adbfb80 R15: ffffffffffffffe8 FS: 00007fdcba4c4740(0000) GS:ffff889033780000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: ffffffffffffffe8 CR3: 0000000f776a0004 CR4: 00000000001606e0 Call Trace: __wake_up_common_lock+0xea/0x150 ommon_lock at kernel/sched/wait.c:124 ? __wake_up_common+0x290/0x290 ? lockdep_hardirqs_on+0x16/0x2c0 __wake_up+0x13/0x20 io_cqring_ev_posted+0x75/0xe0 v_posted at fs/io_uring.c:1160 io_ring_ctx_wait_and_kill+0x1c0/0x2f0 l at fs/io_uring.c:7305 io_uring_create+0xa8d/0x13b0 ? io_req_defer_prep+0x990/0x990 ? __kasan_check_write+0x14/0x20 io_uring_setup+0xb8/0x130 ? io_uring_create+0x13b0/0x13b0 ? check_flags.part.28+0x220/0x220 ? lockdep_hardirqs_on+0x16/0x2c0 __x64_sys_io_uring_setup+0x31/0x40 do_syscall_64+0xcc/0xaf0 ? syscall_return_slowpath+0x580/0x580 ? lockdep_hardirqs_off+0x1f/0x140 ? entry_SYSCALL_64_after_hwframe+0x3e/0xb3 ? trace_hardirqs_off_caller+0x3a/0x150 ? trace_hardirqs_off_thunk+0x1a/0x1c entry_SYSCALL_64_after_hwframe+0x49/0xb3 RIP: 0033:0x7fdcb9dd76ed Code: 00 c3 66 2e 0f 1f 84 00 00 00 00 00 90 f3 0f 1e fa 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 <48> 3d 01 f0 ff ff 73 01 c3 48 8b 0d 6b 57 2c 00 f7 d8 64 89 01 48 RSP: 002b:00007ffe7fd4e4f8 EFLAGS: 00000246 ORIG_RAX: 00000000000001a9 RAX: ffffffffffffffda RBX: 00000000000001a9 RCX: 00007fdcb9dd76ed RDX: fffffffffffffffc RSI: 0000000000000000 RDI: 0000000000005d54 RBP: 00000000000001a9 R08: 0000000e31d3caa7 R09: 0082400004004000 R10: ffffffffffffffff R11: 0000000000000246 R12: 0000000000000002 R13: 00007fdcb842e058 R14: 00007fdcba4c46c0 R15: 00007fdcb842e000 Modules linked in: bridge stp llc nfnetlink cn brd vfat fat ext4 crc16 mbcache jbd2 loop kvm_intel kvm irqbypass intel_cstate intel_uncore dax_pmem intel_rapl_perf dax_pmem_core ip_tables x_tables xfs sd_mod tg3 firmware_class libphy hpsa scsi_transport_sas dm_mirror dm_region_hash dm_log dm_mod [last unloaded: binfmt_misc] CR2: ffffffffffffffe8 ---[ end trace f9502383d57e0e22 ]--- RIP: 0010:__wake_up_common+0x98/0x290 Code: 40 4d 8d 78 e8 49 8d 7f 18 49 39 fd 0f 84 80 00 00 00 e8 6b bd 2b 00 49 8b 5f 18 45 31 e4 48 83 eb 18 4c 89 ff e8 08 bc 2b 00 <45> 8b 37 41 f6 c6 04 75 71 49 8d 7f 10 e8 46 bd 2b 00 49 8b 47 10 RSP: 0018:ffffc9000adbfaf0 EFLAGS: 00010046 RAX: 0000000000000000 RBX: ffffffffffffffe8 RCX: ffffffffaa9636b8 RDX: 0000000000000003 RSI: dffffc0000000000 RDI: ffffffffffffffe8 RBP: ffffc9000adbfb40 R08: fffffbfff582c5fd R09: fffffbfff582c5fd R10: ffffffffac162fe3 R11: fffffbfff582c5fc R12: 0000000000000000 R13: ffff888ef82b0960 R14: ffffc9000adbfb80 R15: ffffffffffffffe8 FS: 00007fdcba4c4740(0000) GS:ffff889033780000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: ffffffffffffffe8 CR3: 0000000f776a0004 CR4: 00000000001606e0 Kernel panic - not syncing: Fatal exception Kernel Offset: 0x29800000 from 0xffffffff81000000 (relocation range: 0xffffffff80000000-0xffffffffbfffffff) ---[ end Kernel panic - not syncing: Fatal exception ]— which is due to error injection (or allocation failure) preventing the rings from being setup. On shutdown, we attempt to remove any pending requests, and for poll request, we call io_cqring_ev_posted() when we've killed poll requests. However, since the rings aren't setup, we won't find any poll requests. Make the calling of io_cqring_ev_posted() dependent on actually having completed requests. This fixes this setup corner case, and removes spurious calls if we remove poll requests and don't find any. Reported-by: Qian Cai Signed-off-by: Jens Axboe

io_uring: io_async_task_func() should check and honor cancelation

2020-04-13T17:22:52Z

If the request has been marked as canceled, don't try and issue it. Instead just fill a canceled event and finish the request. Signed-off-by: Jens Axboe

io_uring: check for need to re-wait in polled async handling

2020-04-13T17:09:12Z

We added this for just the regular poll requests in commit a6ba632d2c24 ("io_uring: retry poll if we got woken with non-matching mask"), we should do the same for the poll handler used pollable async requests. Move the re-wait check and arm into a helper, and call it from io_async_task_func() as well. Signed-off-by: Jens Axboe

io_uring: correct O_NONBLOCK check for splice punt

2020-04-13T03:16:01Z

The splice file punt check uses file->f_mode to check for O_NONBLOCK, but it should be checking file->f_flags. This leads to punting even for files that have O_NONBLOCK set, which isn't necessary. This equates to checking for FMODE_PATH, which will never be set on the fd in question. Fixes: 7d67af2c0134 ("io_uring: add splice(2) support") Signed-off-by: Jens Axboe

io_uring: restore req->work when canceling poll request

2020-04-12T14:46:50Z

When running liburing test case 'accept', I got below warning: RED: Invalid credentials RED: At include/linux/cred.h:285 RED: Specified credentials: 00000000d02474a0 RED: ->magic=4b, put_addr=000000005b4f46e9 RED: ->usage=-1699227648, subscr=-25693 RED: ->*uid = { 256,-25693,-25693,65534 } RED: ->*gid = { 0,-1925859360,-1789740800,-1827028688 } RED: ->security is 00000000258c136e eneral protection fault, probably for non-canonical address 0xdead4ead00000000: 0000 [#1] SMP PTI PU: 21 PID: 2037 Comm: accept Not tainted 5.6.0+ #318 ardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS rel-1.11.1-0-g0551a4be2c-prebuilt.qemu-project.org 04/01/2014 IP: 0010:dump_invalid_creds+0x16f/0x184 ode: 48 8b 83 88 00 00 00 48 3d ff 0f 00 00 76 29 48 89 c2 81 e2 00 ff ff ff 48 81 fa 00 6b 6b 6b 74 17 5b 48 c7 c7 4b b1 10 8e 5d <8b> 50 04 41 5c 8b 30 41 5d e9 67 e3 04 00 5b 5d 41 5c 41 5d c3 0f SP: 0018:ffffacc1039dfb38 EFLAGS: 00010087 AX: dead4ead00000000 RBX: ffff9ba39319c100 RCX: 0000000000000007 DX: 0000000000000000 RSI: 0000000000000000 RDI: ffffffff8e10b14b BP: ffffffff8e108476 R08: 0000000000000000 R09: 0000000000000001 10: 0000000000000000 R11: ffffacc1039df9e5 R12: 000000009552b900 13: 000000009319c130 R14: ffff9ba39319c100 R15: 0000000000000246 S: 00007f96b2bfc4c0(0000) GS:ffff9ba39f340000(0000) knlGS:0000000000000000 S: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 R2: 0000000000401870 CR3: 00000007db7a4000 CR4: 00000000000006e0 all Trace: __invalid_creds+0x48/0x4a __io_req_aux_free+0x2e8/0x3b0 ? io_poll_remove_one+0x2a/0x1d0 __io_free_req+0x18/0x200 io_free_req+0x31/0x350 io_poll_remove_one+0x17f/0x1d0 io_poll_cancel.isra.80+0x6c/0x80 io_async_find_and_cancel+0x111/0x120 io_issue_sqe+0x181/0x10e0 ? __lock_acquire+0x552/0xae0 ? lock_acquire+0x8e/0x310 ? fs_reclaim_acquire.part.97+0x5/0x30 __io_queue_sqe.part.100+0xc4/0x580 ? io_submit_sqes+0x751/0xbd0 ? rcu_read_lock_sched_held+0x32/0x40 io_submit_sqes+0x9ba/0xbd0 ? __x64_sys_io_uring_enter+0x2b2/0x460 ? __x64_sys_io_uring_enter+0xaf/0x460 ? find_held_lock+0x2d/0x90 ? __x64_sys_io_uring_enter+0x111/0x460 __x64_sys_io_uring_enter+0x2d7/0x460 do_syscall_64+0x5a/0x230 entry_SYSCALL_64_after_hwframe+0x49/0xb3 After looking into codes, it turns out that this issue is because we didn't restore the req->work, which is changed in io_arm_poll_handler(), req->work is a union with below struct: struct { struct callback_head task_work; struct hlist_node hash_node; struct async_poll *apoll; }; If we forget to restore, members in struct io_wq_work would be invalid, restore the req->work to fix this issue. Signed-off-by: Xiaoguang Wang Get rid of not needed 'need_restore' variable. Signed-off-by: Jens Axboe

io_uring: move all request init code in one place

2020-04-12T14:46:50Z

Requests initialisation is scattered across several functions, namely io_init_req(), io_submit_sqes(), io_submit_sqe(). Put it in io_init_req() for better data locality and code clarity. Signed-off-by: Pavel Begunkov Signed-off-by: Jens Axboe