Date: Sat, 20 Oct 2018 18:56:05 +0200 From: Peter Holm <peter@holm.cc> To: current@freebsd.org Subject: Page fault in midi/sequencer.c Message-ID: <20181020165604.GA4946@x2.osted.lan>
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I can trigger this on 13.0-CURRENT r339445 with a non-root test program: Calling uiomove() with the following non-sleepable locks held: exclusive sleep mutex seqflq (seqflq) r = 0 (0xfffff80003860c08) locked @ dev/sound/midi/sequencer.c:952 stack backtrace: #0 0xffffffff80bfe263 at witness_debugger+0x73 #1 0xffffffff80bff1b8 at witness_warn+0x448 #2 0xffffffff80bf6a91 at uiomove_faultflag+0x71 #3 0xffffffff809439e6 at mseq_write+0x4c6 #4 0xffffffff80a4f725 at devfs_write_f+0x185 #5 0xffffffff80c02a87 at dofilewrite+0x97 #6 0xffffffff80c0287f at kern_pwritev+0x5f #7 0xffffffff80c0277d at sys_pwrite+0x8d #8 0xffffffff81070af7 at amd64_syscall+0x2a7 #9 0xffffffff8104a4ad at fast_syscall_common+0x101 Kernel page fault with the following non-sleepable locks held: exclusive sleep mutex seqflq (seqflq) r = 0 (0xfffff80003860c08) locked @ dev/sound/midi/sequencer.c:952 stack backtrace: #0 0xffffffff80bfe263 at witness_debugger+0x73 #1 0xffffffff80bff1b8 at witness_warn+0x448 #2 0xffffffff810700d3 at trap_pfault+0x53 #3 0xffffffff8106f70a at trap+0x2ba #4 0xffffffff81049bc5 at calltrap+0x8 #5 0xffffffff80bf6b42 at uiomove_faultflag+0x122 #6 0xffffffff809439e6 at mseq_write+0x4c6 #7 0xffffffff80a4f725 at devfs_write_f+0x185 #8 0xffffffff80c02a87 at dofilewrite+0x97 #9 0xffffffff80c0287f at kern_pwritev+0x5f #10 0xffffffff80c0277d at sys_pwrite+0x8d #11 0xffffffff81070af7 at amd64_syscall+0x2a7 #12 0xffffffff8104a4ad at fast_syscall_common+0x101 Fatal trap 12: page fault while in kernel mode cpuid = 4; apic id = 04 fault virtual address = 0x20ea6b fault code = supervisor read data, page not present instruction pointer = 0x20:0xffffffff8106d32d stack pointer = 0x28:0xfffffe00a844a660 frame pointer = 0x28:0xfffffe00a844a660 code segment = base 0x0, limit 0xfffff, type 0x1b = DPL 0, pres 1, long 1, def32 0, gran 1 processor eflags = interrupt enabled, resume, IOPL = 0 current process = 2356 (xxx) [ thread pid 2356 tid 100278 ] Stopped at copyin_nosmap_erms+0xdd: movl (%rsi),%edx db> -- Peter
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