page fault in ata-queue.c:93

With GENERIC HEAD from May 5 04:56 UTC I got:

Fatal trap 12: page fault while in kernel mode
cpuid = 0; apic id = 00
fault virtual address   = 0xc172e035
fault code              = supervisor read, page not present
instruction pointer     = 0x20:0xc04d048d
stack pointer           = 0x28:0xcc9cbc68
frame pointer           = 0x28:0xcc9cbc70
code segment            = base 0x0, limit 0xfffff, type 0x1b
                        = DPL 0, pres 1, def32 1, gran 1
processor eflags        = interrupt enabled, resume, IOPL = 0
current process         = 4 (g_down)
[thread pid 4 tid 100040 ]
Stopped at      ata_queue_request+0x1b1:        testb   $0x4,0x35(%ebx)
db> hr~~~GDB: no debug ports present

(kgdb) l *0xc04d048d
0xc04d048d is in ata_queue_request (../../../dev/ata/ata-queue.c:93).
88              ATA_DEBUG_RQ(request, "queued");
89              ata_start(ch->dev);
90          }
91
92          /* if this is a requeued request callback/sleep we're done */
93          if (request->flags & ATA_R_REQUEUE)
94              return;
95
96          /* if this is not a callback wait until request is completed */
97          if (!request->callback) {

The system froze during typing "where".
-- 
Peter Holm