Avi Kivity wrote: > On 07/02/2009 06:50 PM, Avi Kivity wrote: >> On 07/02/2009 06:37 PM, Gregory Haskins wrote: >>> (Applies to kvm.git/master:1f9050fd) >>> >>> The following is the latest attempt to fix the races in >>> irqfd/eventfd, as >>> well as restore DEASSIGN support. For more details, please read the >>> patch >>> headers. >>> >>> As always, this series has been tested against the kvm-eventfd unit >>> test >>> and everything appears to be functioning properly. You can download >>> this >>> test here: >> >> Applied, thanks. >> > > ... and unapplied. There's a refcounting mismatch in irqfd_cleanup: a > reference is taken for each irqfd, but dropped for each guest. Doh! Note that the kvm->irqfds.init boolean was supposed to make it both acquire and release the reference on a per-vm basis. Obviously, something is wrong. :) But I see later in the thread you guys have already figured out that only the last patch needs to be reverted. Ill take a look at the last patch and fix the issue once I am back in the office tomorrow. Sorry for the trouble. Kind Regards, -Greg > This causes an oops if a guest with no irqfds is created and destroyed: > > IP: [<ffffffff8105254a>] flush_workqueue+0x23/0x6e > PGD 0 > Oops: 0000 [4] SMP > CPU 1 > Modules linked in: kvm_intel kvm nfs lockd nfs_acl sco bridge stp bnep > l2cap bluetooth autofs4 sunrpc ipv6 dm_multipath uinput i5000_edac > e1000e edac_core iTCO_wdt > iTCO_vendor_support i2c_i801 i2c_core e100 mii floppy pcspkr shpchp > serio_raw ata_generic pata_acpi [last unloaded: kvm] > Pid: 2088, comm: qemu Tainted: G D > 2.6.27.19-170.2.35.fc10.x86_64 #1 TYAN Transport GT20-B5372 > RIP: 0010:[<ffffffff8105254a>] [<ffffffff8105254a>] > flush_workqueue+0x23/0x6e > RSP: 0018:ffff8801077d1b08 EFLAGS: 00010292 > RAX: ffffffff8156de08 RBX: ffff8801097e8a50 RCX: 0000000000000000 > RDX: 0000000000000000 RSI: 000000000000019f RDI: 0000000000000000 > RBP: ffff8801077d1b28 R08: 0000000000000000 R09: ffffffff81140027 > R10: ffff88012f402340 R11: ffff880125daf820 R12: ffffffff8156de10 > R13: 0000000000000000 R14: ffff88012f449cd8 R15: ffff88012f002900 > FS: 00007f9b67295950(0000) GS:ffff88012fc04980(0000) > knlGS:0000000000000000 > CS: 0010 DS: 002b ES: 002b CR0: 000000008005003b > CR2: 0000000000000020 CR3: 0000000000201000 CR4: 00000000000026e0 > DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 > DR3: 0000000000000000 DR6: 00000000ffff0ff0 DR7: 0000000000000400 > Process qemu (pid: 2088, threadinfo ffff8801077d0000, task > ffff88012984c530) > Stack: ffff8801077d1b28 ffff8801097e8a50 ffff8801097e8000 > ffff8801097e8a68 > ffff8801077d1b58 ffffffffa01c4eec 0000000800000000 ffff8801097e8000 > ffff88012f449cd8 ffff88012c80c600 ffff8801077d1b78 ffffffffa01af34b > Call Trace: > [<ffffffffa01c4eec>] kvm_irqfd_release+0x7a/0xcc [kvm] > [<ffffffffa01af34b>] kvm_vm_release+0x18/0x27 [kvm] > [<ffffffff810c14c7>] __fput+0xca/0x16d > [<ffffffff810c157f>] fput+0x15/0x17 > [<ffffffff810bea29>] filp_close+0x67/0x72 > [<ffffffff810433ec>] put_files_struct+0x74/0xc8 > [<ffffffff81043488>] exit_files+0x48/0x51 > [<ffffffff81044de9>] do_exit+0x26a/0x8a0 > [<ffffffffa01da330>] ? vmx_vcpu_put+0x9/0xb [kvm_intel] > [<ffffffff810454a1>] do_group_exit+0x82/0xaf > [<ffffffff8104eabb>] get_signal_to_deliver+0x2b0/0x2dc > [<ffffffff81010379>] ? sysret_signal+0x42/0x71 > [<ffffffff8100f45f>] do_notify_resume+0x90/0x93f > [<ffffffff81060cca>] ? do_futex+0x90/0x973 > [<ffffffffa01ad956>] ? kvm_vcpu_ioctl+0x470/0x485 [kvm] > [<ffffffff81333801>] ? trace_hardirqs_on_thunk+0x3a/0x3c > [<ffffffff810616a2>] ? sys_futex+0xf5/0x113 > [<ffffffff81010379>] ? sysret_signal+0x42/0x71 > [<ffffffff81010737>] ptregscall_common+0x67/0xb0 > > irqfd_cleanup.wq has never been initialized, but is destroyed. >
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