Date: Thu, 26 Jan 2017 20:19:10 +0300 From: Andrew Rybchenko <arybchik@freebsd.org> To: net@FreeBSD.org Subject: ifmedia status callback is non-sleepable Message-ID: <5278f854-4f6f-2ff3-b6d3-f95e23b26ded@freebsd.org>
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Hello, I'd like to double-check that it is intended/known limitation on ifmedia status callback to be non-sleepable. The limitation is imposed by usage of the ifmedia ioctl to get status from lacp/lagg code on port creation (it holds non-sleepable rm_wlock). Backtrace of the corresponding panic: Sleeping thread (tid 100578, pid 10653) owns a non-sleepable lock KDB: stack backtrace of thread 100578: #0 0xffffffff80ae46e2 at mi_switch+0xd2 #1 0xffffffff80b31e6a at sleepq_wait+0x3a #2 0xffffffff80ae34e2 at _sx_xlock_hard+0x592 #3 0xffffffff8222fd7e at sfxge_media_status+0x2e #4 0xffffffff80be7b90 at ifmedia_ioctl+0x170 #5 0xffffffff8222c3d0 at sfxge_if_ioctl+0x1f0 #6 0xffffffff82277fbe at lagg_port_ioctl+0xde #7 0xffffffff82278f9b at lacp_linkstate+0x4b #8 0xffffffff822794c2 at lacp_port_create+0x1e2 #9 0xffffffff82276a73 at lagg_ioctl+0x1243 #10 0xffffffff80bdcbec at ifioctl+0xfbc #11 0xffffffff80b41ab4 at kern_ioctl+0x2d4 #12 0xffffffff80b41771 at sys_ioctl+0x171 #13 0xffffffff80fa16ae at amd64_syscall+0x4ce #14 0xffffffff80f8442b at Xfast_syscall+0xfb panic: sleeping thread cpuid = 23 KDB: stack backtrace: #0 0xffffffff80b24077 at kdb_backtrace+0x67 #1 0xffffffff80ad93e2 at vpanic+0x182 #2 0xffffffff80ad9253 at panic+0x43 #3 0xffffffff80b39a99 at propagate_priority+0x299 #4 0xffffffff80b3a59f at turnstile_wait+0x3ef #5 0xffffffff80ab493d at __mtx_lock_sleep+0x13d #6 0xffffffff80ad39f2 at _rm_wlock+0xb2 #7 0xffffffff82275479 at lagg_port_setlladdr+0x29 #8 0xffffffff80b363ca at taskqueue_run_locked+0x14a #9 0xffffffff80b361bf at taskqueue_run+0xbf #10 0xffffffff80a9340f at intr_event_execute_handlers+0x20f #11 0xffffffff80a93676 at ithread_loop+0xc6 #12 0xffffffff80a90055 at fork_exit+0x85 #13 0xffffffff80f8467e at fork_trampoline+0xe I think vnic driver has the problem as well since it grabs sx_lock from ifmedia status callback. Andrew.
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