Takashi, below is listing of few softlockups that I've encountered while testing your patch (MSI one).
78921 Feb 7 17:37:01 ensima-hp [ 290.184844] BUG: soft lockup - CPU#0 stuck for 11s! [kirqd:879] 78922 Feb 7 17:37:01 ensima-hp [ 290.184848] 78923 Feb 7 17:37:01 ensima-hp [ 290.184851] Pid: 879, comm: kirqd Not tainted (2.6.24 #3) 78924 Feb 7 17:37:01 ensima-hp [ 290.184854] EIP: 0060:[<c0155ed3>] EFLAGS: 00000246 CPU: 0 78925 Feb 7 17:37:01 ensima-hp [ 290.184859] EIP is at handle_IRQ_event+0x13/0x60 78926 Feb 7 17:37:01 ensima-hp [ 290.184862] EAX: 000000dc EBX: f72177a0 ECX: f7d9c000 EDX: f72177a0 78927 Feb 7 17:37:01 ensima-hp [ 290.184865] ESI: f72177a0 EDI: 000000dc EBP: 000000dc ESP: f7d9df0c 78928 Feb 7 17:37:01 ensima-hp [ 290.184868] DS: 007b ES: 007b FS: 00d8 GS: 0000 SS: 0068 78929 Feb 7 17:37:01 ensima-hp [ 290.184871] CR0: 8005003b CR2: 0807b064 CR3: 36e30000 CR4: 000006d0 78930 Feb 7 17:37:01 ensima-hp [ 290.184875] DR0: 00000000 DR1: 00000000 DR2: 00000000 DR3: 00000000 78931 Feb 7 17:37:02 ensima-hp [ 290.184878] DR6: ffff0ff0 DR7: 00000400 78932 Feb 7 17:37:02 ensima-hp [ 290.184895] [<c01573dd>] handle_edge_irq+0xad/0x130 78933 Feb 7 17:37:02 ensima-hp [ 290.184903] [<c010827b>] do_IRQ+0x3b/0x70 78934 Feb 7 17:37:02 ensima-hp [ 290.184915] [<c0105ea3>] common_interrupt+0x23/0x28 78935 Feb 7 17:37:02 ensima-hp [ 290.184929] [<c011b6f3>] balanced_irq+0x3f3/0x5b0 78936 Feb 7 17:37:02 ensima-hp [ 290.184949] [<c011b300>] balanced_irq+0x0/0x5b0 78937 Feb 7 17:37:02 ensima-hp [ 290.184969] [<c013e502>] kthread+0x42/0x70 78938 Feb 7 17:37:02 ensima-hp [ 290.184973] [<c013e4c0>] kthread+0x0/0x70 78939 Feb 7 17:37:02 ensima-hp [ 290.184977] [<c01060cf>] kernel_thread_helper+0x7/0x18 78940 Feb 7 17:37:02 ensima-hp [ 290.184987] ======================= 78941 Feb 7 17:37:13 ensima-hp [ 301.989526] BUG: soft lockup - CPU#0 stuck for 11s! [kirqd:879] 78942 Feb 7 17:37:13 ensima-hp [ 301.989529] 78943 Feb 7 17:37:13 ensima-hp [ 301.989531] Pid: 879, comm: kirqd Not tainted (2.6.24 #3) 78944 Feb 7 17:37:13 ensima-hp [ 301.989533] EIP: 0060:[<c0155ed3>] EFLAGS: 00000246 CPU: 0 78945 Feb 7 17:37:13 ensima-hp [ 301.989536] EIP is at handle_IRQ_event+0x13/0x60 78946 Feb 7 17:37:13 ensima-hp [ 301.989539] EAX: 000000dc EBX: f72177a0 ECX: f7d9c000 EDX: f72177a0 78947 Feb 7 17:37:13 ensima-hp [ 301.989541] ESI: f72177a0 EDI: 000000dc EBP: 000000dc ESP: f7d9df0c 78948 Feb 7 17:37:13 ensima-hp [ 301.989544] DS: 007b ES: 007b FS: 00d8 GS: 0000 SS: 0068 78949 Feb 7 17:37:13 ensima-hp [ 301.989547] CR0: 8005003b CR2: 0807b064 CR3: 36e30000 CR4: 000006d0 78950 Feb 7 17:37:13 ensima-hp [ 301.989550] DR0: 00000000 DR1: 00000000 DR2: 00000000 DR3: 00000000 78951 Feb 7 17:37:14 ensima-hp [ 301.989552] DR6: ffff0ff0 DR7: 00000400 78952 Feb 7 17:37:14 ensima-hp [ 301.989560] [<c01573dd>] handle_edge_irq+0xad/0x130 78953 Feb 7 17:37:14 ensima-hp [ 301.989581] [<c010827b>] do_IRQ+0x3b/0x70 78954 Feb 7 17:37:14 ensima-hp [ 301.989592] [<c0105ea3>] common_interrupt+0x23/0x28 78955 Feb 7 17:37:14 ensima-hp [ 301.989606] [<c011b6f3>] balanced_irq+0x3f3/0x5b0 78956 Feb 7 17:37:14 ensima-hp [ 301.989639] [<c011b300>] balanced_irq+0x0/0x5b0 78957 Feb 7 17:37:14 ensima-hp [ 301.989644] [<c013e502>] kthread+0x42/0x70 78958 Feb 7 17:37:14 ensima-hp [ 301.989646] [<c013e4c0>] kthread+0x0/0x70 78959 Feb 7 17:37:14 ensima-hp [ 301.989651] [<c01060cf>] kernel_thread_helper+0x7/0x18 78960 Feb 7 17:37:14 ensima-hp [ 301.989659] ======================= 78961 Feb 7 17:37:25 ensima-hp [ 313.794211] BUG: soft lockup - CPU#0 stuck for 11s! [kirqd:879] 78962 Feb 7 17:37:25 ensima-hp [ 313.794214] 78963 Feb 7 17:37:25 ensima-hp [ 313.794216] Pid: 879, comm: kirqd Not tainted (2.6.24 #3) 78964 Feb 7 17:37:25 ensima-hp [ 313.794218] EIP: 0060:[<c03a6117>] EFLAGS: 00000282 CPU: 0 78965 Feb 7 17:37:25 ensima-hp [ 313.794222] EIP is at _read_unlock_irqrestore+0x7/0x30 78966 Feb 7 17:37:25 ensima-hp [ 313.794226] EAX: 00000282 EBX: f6ee4800 ECX: f7d9c000 EDX: 00000282 78967 Feb 7 17:37:25 ensima-hp [ 313.794229] ESI: f71d1380 EDI: 000004c8 EBP: f6ee4800 ESP: f7d9deac 78968 Feb 7 17:37:25 ensima-hp [ 313.794231] DS: 007b ES: 007b FS: 00d8 GS: 0000 SS: 0068 78969 Feb 7 17:37:25 ensima-hp [ 313.794237] CR0: 8005003b CR2: 0807b064 CR3: 36e30000 CR4: 000006d0 78970 Feb 7 17:37:25 ensima-hp [ 313.794257] DR0: 00000000 DR1: 00000000 DR2: 00000000 DR3: 00000000 78971 Feb 7 17:37:25 ensima-hp [ 313.794272] DR6: ffff0ff0 DR7: 00000400 78972 Feb 7 17:37:26 ensima-hp [ 313.794275] [<f955ffed>] snd_pcm_period_elapsed+0x7d/0x2f0 [snd_pcm] 78973 Feb 7 17:37:26 ensima-hp [ 313.794298] [<c027c993>] pci_bus_write_config_word+0x63/0x80 78974 Feb 7 17:37:26 ensima-hp [ 313.794323] [<f956efd9>] azx_interrupt+0x79/0x100 [snd_hda_intel] 78975 Feb 7 17:37:26 ensima-hp [ 313.794344] [<c0155ef0>] handle_IRQ_event+0x30/0x60 78976 Feb 7 17:37:26 ensima-hp [ 313.794351] [<c01573dd>] handle_edge_irq+0xad/0x130 78977 Feb 7 17:37:26 ensima-hp [ 313.794357] [<c010827b>] do_IRQ+0x3b/0x70 78978 Feb 7 17:37:26 ensima-hp [ 313.794366] [<c0105ea3>] common_interrupt+0x23/0x28 78979 Feb 7 17:37:26 ensima-hp [ 313.794377] [<c011b6f3>] balanced_irq+0x3f3/0x5b0 78980 Feb 7 17:37:26 ensima-hp [ 313.794393] [<c011b300>] balanced_irq+0x0/0x5b0 78981 Feb 7 17:37:26 ensima-hp [ 313.794398] [<c013e502>] kthread+0x42/0x70 78982 Feb 7 17:37:26 ensima-hp [ 313.794401] [<c013e4c0>] kthread+0x0/0x70 78983 Feb 7 17:37:26 ensima-hp [ 313.794405] [<c01060cf>] kernel_thread_helper+0x7/0x18 78984 Feb 7 17:37:27 ensima-hp [ 313.794414] ======================= 78985 Feb 7 17:37:37 ensima-hp [ 325.598892] BUG: soft lockup - CPU#0 stuck for 11s! [kirqd:879] 78986 Feb 7 17:37:37 ensima-hp [ 325.598895] 78987 Feb 7 17:37:37 ensima-hp [ 325.598897] Pid: 879, comm: kirqd Not tainted (2.6.24 #3) 78988 Feb 7 17:37:37 ensima-hp [ 325.598899] EIP: 0060:[<c03a6117>] EFLAGS: 00000282 CPU: 0 78989 Feb 7 17:37:37 ensima-hp [ 325.598902] EIP is at _read_unlock_irqrestore+0x7/0x30 78990 Feb 7 17:37:37 ensima-hp [ 325.598907] EAX: 00000282 EBX: f6ee4800 ECX: f7d9c000 EDX: 00000282 78991 Feb 7 17:37:37 ensima-hp [ 325.598910] ESI: f71d1380 EDI: 000004c8 EBP: f6ee4800 ESP: f7d9deac 78992 Feb 7 17:37:37 ensima-hp [ 325.598913] DS: 007b ES: 007b FS: 00d8 GS: 0000 SS: 0068 78993 Feb 7 17:37:37 ensima-hp [ 325.598924] CR0: 8005003b CR2: 0807b064 CR3: 36e30000 CR4: 000006d0 78994 Feb 7 17:37:37 ensima-hp [ 325.598928] DR0: 00000000 DR1: 00000000 DR2: 00000000 DR3: 00000000 78995 Feb 7 17:37:37 ensima-hp [ 325.598942] DR6: ffff0ff0 DR7: 00000400 78996 Feb 7 17:37:37 ensima-hp [ 325.598946] [<f955ffed>] snd_pcm_period_elapsed+0x7d/0x2f0 [snd_pcm] 78997 Feb 7 17:37:37 ensima-hp [ 325.598964] [<c027c993>] pci_bus_write_config_word+0x63/0x80 78998 Feb 7 17:37:37 ensima-hp [ 325.598983] [<f956efd9>] azx_interrupt+0x79/0x100 [snd_hda_intel] 78999 Feb 7 17:37:38 ensima-hp [ 325.599003] [<c0155ef0>] handle_IRQ_event+0x30/0x60 79000 Feb 7 17:37:38 ensima-hp [ 325.599010] [<c01573dd>] handle_edge_irq+0xad/0x130 79001 Feb 7 17:37:38 ensima-hp [ 325.599016] [<c010827b>] do_IRQ+0x3b/0x70 79002 Feb 7 17:37:38 ensima-hp [ 325.599025] [<c0105ea3>] common_interrupt+0x23/0x28 79003 Feb 7 17:37:38 ensima-hp [ 325.599036] [<c011b6f3>] balanced_irq+0x3f3/0x5b0 79004 Feb 7 17:37:38 ensima-hp [ 325.599052] [<c011b300>] balanced_irq+0x0/0x5b0 79005 Feb 7 17:37:38 ensima-hp [ 325.599057] [<c013e502>] kthread+0x42/0x70 79006 Feb 7 17:37:38 ensima-hp [ 325.599060] [<c013e4c0>] kthread+0x0/0x70 79007 Feb 7 17:37:38 ensima-hp [ 325.599064] [<c01060cf>] kernel_thread_helper+0x7/0x18 79008 Feb 7 17:37:38 ensima-hp [ 325.599073] =======================