On 1/18/25 2:42 AM, lizetao wrote: > Hi, > >> -----Original Message----- >> From: Jens Axboe <axboe@xxxxxxxxx> >> Sent: Thursday, January 16, 2025 10:51 PM >> To: lizetao <lizetao1@xxxxxxxxxx>; Pavel Begunkov <asml.silence@xxxxxxxxx> >> Cc: io-uring@xxxxxxxxxxxxxxx >> Subject: Re: [PATCH] test/defer: fix deadlock when io_uring_submit fail >> >> On 1/15/25 6:10 AM, lizetao wrote: >>> While performing fault injection testing, a bug report was triggered: >>> >>> FAULT_INJECTION: forcing a failure. >>> name fail_usercopy, interval 1, probability 0, space 0, times 0 >>> CPU: 12 UID: 0 PID: 18795 Comm: defer.t Tainted: G O >> 6.13.0-rc6-gf2a0a37b174b #17 >>> Tainted: [O]=OOT_MODULE >>> Hardware name: linux,dummy-virt (DT) >>> Call trace: >>> show_stack+0x20/0x38 (C) >>> dump_stack_lvl+0x78/0x90 >>> dump_stack+0x1c/0x28 >>> should_fail_ex+0x544/0x648 >>> should_fail+0x14/0x20 >>> should_fail_usercopy+0x1c/0x28 >>> get_timespec64+0x7c/0x258 >>> __io_timeout_prep+0x31c/0x798 >>> io_link_timeout_prep+0x1c/0x30 >>> io_submit_sqes+0x59c/0x1d50 >>> __arm64_sys_io_uring_enter+0x8dc/0xfa0 >>> invoke_syscall+0x74/0x270 >>> el0_svc_common.constprop.0+0xb4/0x240 >>> do_el0_svc+0x48/0x68 >>> el0_svc+0x38/0x78 >>> el0t_64_sync_handler+0xc8/0xd0 >>> el0t_64_sync+0x198/0x1a0 >>> >>> The deadlock stack is as follows: >>> >>> io_cqring_wait+0xa64/0x1060 >>> __arm64_sys_io_uring_enter+0x46c/0xfa0 >>> invoke_syscall+0x74/0x270 >>> el0_svc_common.constprop.0+0xb4/0x240 >>> do_el0_svc+0x48/0x68 >>> el0_svc+0x38/0x78 >>> el0t_64_sync_handler+0xc8/0xd0 >>> el0t_64_sync+0x198/0x1a0 >>> >>> This is because after the submission fails, the defer.t testcase is still waiting to >> submit the failed request, resulting in an eventual deadlock. >>> Solve the problem by telling wait_cqes the number of requests to wait for. >> >> I suspect this would be fixed by setting IORING_SETUP_SUBMIT_ALL for ring init, >> something probably all/most tests should set. > > > I tested it and found that IORING_SETUP_SUBMIT_ALL can indeed solve > this problem. Should I just modify this problem or add > IORING_SETUP_SUBMIT_ALL to the general path to solve most possible > problems? I think just fix up this one. We really should have all the tests use t_create_ring*() first, and those helpers should just set SUBMIT_ALL. But that's a separate change. -- Jens Axboe
