On Sun, Jan 31, 2021 at 2:59 PM Denis Fondras <open...@ledeuns.net> wrote:
> I am using XCP-ng with the latest OpenBSD snapshot. > > Whenever I make an hardware change in networking on the VM (connect or > disconnect an interface, change associated network), the VM panics : > > openbsd# panic: grant table reference 5912 is held by domain 0: frame > 0x1f1a4 flags 0x19 > Stopped at db_enter+0x10: popq %rbp > TID PID UID PRFLAGS PFLAGS CPU COMMAND > *349758 65579 0 0x14000 0x200 0 xenwatch > db_enter() at db_enter+0x10 > panic(ffffffff81da7541) at panic+0x12a > xen_bus_dmamap_unload(ffffffff820ede50,ffff8000000e9380) at > xen_bus_dmamap_unload+0x138 > xnf_tx_ring_destroy(ffff800000162000) at xnf_tx_ring_destroy+0x104 > xnf_detach(ffff800000162000,0) at xnf_detach+0x55 > config_detach(ffff800000162000,0) at config_detach+0x140 > xen_hotplug(ffff80000012e200) at xen_hotplug+0x181 > taskq_thread(ffff8000000dde00) at taskq_thread+0x66 > end trace frame: 0x0, count: 7 > https://www.openbsd.org/ddb.html describes the minimum info required in > bug reports. Insufficient info makes it difficult to find and fix bugs. > ddb> > > If I apply the following patch, it obviously does not panic and seems to > work > correctly : > > Hi Denis, This is not a real fix unfortunately, you're just ignoring the issue. Somehow the grant table reference is not released when we perform the detach. You can try increasing amount of iterations to 10000 (or more) for example and see if this is a timing issue. Cheers, Mike > Index: xen.c > =================================================================== > RCS file: /cvs/src/sys/dev/pv/xen.c,v > retrieving revision 1.97 > diff -u -p -r1.97 xen.c > --- xen.c 29 Jun 2020 06:50:52 -0000 1.97 > +++ xen.c 31 Jan 2021 13:13:07 -0000 > @@ -1204,7 +1204,7 @@ xen_grant_table_remove(struct xen_softc > loop = 0; > while (atomic_cas_uint(ptr, flags, GTF_invalid) != flags) { > if (loop++ > 10) { > - panic("grant table reference %u is held " > + printf("grant table reference %u is held " > "by domain %d: frame %#x flags %#x", > ref + ge->ge_start, ge->ge_table[ref].domid, > ge->ge_table[ref].frame, > ge->ge_table[ref].flags); > > Can someone give me a clue on what _atomic_cas_uint() is ? > > Thank you in advance. > > Denis > > OpenBSD 6.8-current (GENERIC) #9: Sun Jan 31 14:08:42 CET 2021 > r...@openbsd.lab.ledeuns.net:/sys/arch/amd64/compile/GENERIC > real mem = 1052770304 (1004MB) > avail mem = 1005694976 (959MB) > random: good seed from bootblocks > mpath0 at root > scsibus0 at mpath0: 256 targets > mainbus0 at root > bios0 at mainbus0: SMBIOS rev. 2.4 @ 0xeb01f (11 entries) > bios0: vendor Xen version "4.13" date 01/21/2021 > bios0: Xen HVM domU > acpi0 at bios0: ACPI 4.0 > acpi0: sleep states S5 > acpi0: tables DSDT FACP APIC HPET WAET > acpi0: wakeup devices > acpitimer0 at acpi0: 3579545 Hz, 32 bits > acpimadt0 at acpi0 addr 0xfee00000: PC-AT compat > ioapic0 at mainbus0: apid 1 pa 0xfec00000, version 11, 48 pins, remapped > cpu0 at mainbus0: apid 0 (boot processor) > cpu0: Intel(R) Xeon(R) CPU E5-2407 v2 @ 2.40GHz, 2394.83 MHz, 06-3e-04 > cpu0: > FPU,VME,DE,PSE,TSC,MSR,PAE,MCE,CX8,APIC,SEP,MTRR,PGE,MCA,CMOV,PAT,PSE36,CFLUSH,ACPI,MMX,FXSR,SSE,SSE2,SS,SSE3,PCLMUL,SSSE3,CX16,PCID,SSE4.1,SSE4.2,x2APIC,POPCNT,DEADLINE,AES,XSAVE,AVX,F16C,RDRAND,HV,NXE,PAGE1GB,RDTSCP,LONG,LAHF,FSGSBASE,SMEP,ERMS,MD_CLEAR,IBRS,IBPB,STIBP,L1DF,SSBD,XSAVEOPT,MELTDOWN > cpu0: 256KB 64b/line 8-way L2 cache > cpu0: smt 0, core 0, package 0 > mtrr: Pentium Pro MTRR support, 8 var ranges, 88 fixed ranges > cpu0: apic clock running at 100MHz > acpihpet0 at acpi0: 62500000 Hz > acpiprt0 at acpi0: bus 0 (PCI0) > acpipci0 at acpi0 PCI0 > acpicmos0 at acpi0 > "ACPI0007" at acpi0 not configured > acpicpu0 at acpi0: C1(@1 halt!) > cpu0: using VERW MDS workaround (except on vmm entry) > pvbus0 at mainbus0: Hyper-V 0.0, Xen 4.13 > xen0 at pvbus0: features 0x2705, 64 grant table frames, event channel 2 > xbf0 at xen0 backend 0 channel 6: disk > scsibus1 at xbf0: 1 targets > sd0 at scsibus1 targ 0 lun 0: <Xen, phy xvda 768, 0000> > sd0: 10240MB, 512 bytes/sector, 20971520 sectors > xbf1 at xen0 backend 0 channel 7: cdrom > xbf1: timed out waiting for backend to connect > xnf0 at xen0 backend 0 channel 7: address 76:88:23:28:25:f4 > xnf1 at xen0 backend 0 channel 8: address 62:36:ed:68:46:3c > xnf2 at xen0 backend 0 channel 9: address be:04:e2:f3:7d:75 > pci0 at mainbus0 bus 0 > pchb0 at pci0 dev 0 function 0 "Intel 82441FX" rev 0x02 > pcib0 at pci0 dev 1 function 0 "Intel 82371SB ISA" rev 0x00 > pciide0 at pci0 dev 1 function 1 "Intel 82371SB IDE" rev 0x00: DMA, > channel 0 wired to compatibility, channel 1 wired to compatibility > pciide0: channel 0 disabled (no drives) > atapiscsi0 at pciide0 channel 1 drive 1 > scsibus2 at atapiscsi0: 2 targets > cd0 at scsibus2 targ 0 lun 0: <QEMU, QEMU DVD-ROM, 0.10> removable > cd0(pciide0:1:1): using PIO mode 4, DMA mode 2 > uhci0 at pci0 dev 1 function 2 "Intel 82371SB USB" rev 0x01: apic 1 int 23 > piixpm0 at pci0 dev 1 function 3 "Intel 82371AB Power" rev 0x01: SMBus > disabled > vga1 at pci0 dev 2 function 0 "Cirrus Logic CL-GD5446" rev 0x00 > wsdisplay0 at vga1 mux 1: console (80x25, vt100 emulation) > wsdisplay0: screen 1-5 added (80x25, vt100 emulation) > xspd0 at pci0 dev 3 function 0 "XenSource Platform Device" rev 0x01 > isa0 at pcib0 > isadma0 at isa0 > fdc0 at isa0 port 0x3f0/6 irq 6 drq 2 > com0 at isa0 port 0x3f8/8 irq 4: ns16550a, 16 byte fifo > pckbc0 at isa0 port 0x60/5 irq 1 irq 12 > pckbd0 at pckbc0 (kbd slot) > wskbd0 at pckbd0: console keyboard, using wsdisplay0 > pms0 at pckbc0 (aux slot) > wsmouse0 at pms0 mux 0 > pcppi0 at isa0 port 0x61 > spkr0 at pcppi0 > lpt0 at isa0 port 0x378/4 irq 7 > usb0 at uhci0: USB revision 1.0 > uhub0 at usb0 configuration 1 interface 0 "Intel UHCI root hub" rev > 1.00/1.00 addr 1 > uhidev0 at uhub0 port 2 configuration 1 interface 0 "QEMU 0.10.2 QEMU USB > Tablet" rev 1.00/0.00 addr 2 > uhidev0: iclass 3/1 > ums0 at uhidev0: 3 buttons, Z dir > wsmouse1 at ums0 mux 0 > vscsi0 at root > scsibus3 at vscsi0: 256 targets > softraid0 at root > scsibus4 at softraid0: 256 targets > root on sd0a (bd7a4058a4c9a3e2.a) swap on sd0b dump on sd0b > fd0 at fdc0 drive 1: density unknown > xbf2 at xen0 backend 0 channel 10: disk > scsibus5 at xbf2: 1 targets > sd1 at scsibus5 targ 0 lun 0: <Xen, phy xvdb 832, 0000> > sd1: 4096MB, 512 bytes/sector, 8388608 sectors > WARNING: R/W mount of / denied. Filesystem is not clean - run fsck > grant table reference 6678 is held by domain 0: frame 0x1b178 flags > 0x19sd1 detached > scsibus5 detached > xbf2 detached > >
