Filesystem wedges caused by r251446

Hi

I've been experiencing process wedges writing files.  It occurs
reliably under "heavy" IO activity, perhaps with large files but
I'm not entirely sure what the trigger is.  The symptom is that
during an installworld, it reliably hangs the install process on
/usr/bin/clang (sometimes it hangs earlier at the mtree on /usr)

The problem leaves the filesystem in a state where it cannot be
cleanly unmounted.  A binary search pins the offending commit on
r251446.

The major differences between the working system and the broken one
are, CPU, RAM and arch (i386/amd64) they are otherwise identical
Dell R200 servers.

Working:
CPU: Intel(R) Core(TM)2 Duo CPU     E4600  _at_ 2.40GHz (2400.14-MHz 686-class CPU)
RAM:	2G
Arch:	i386

Broken:
CPU: Intel(R) Core(TM)2 Duo CPU     E7300  _at_ 2.66GHz (2666.82-MHz K8-class CPU)
RAM: 	4G
Arch:	amd64

The compiler, gcc, clang (trunk or release) has no effect.

Working CPU:
FreeBSD 10.0-CURRENT #6 r252384: Sun Jun 30 08:36:31 SAST 2013
    ianf_at_fw2:/usr/obj/usr/src/sys/FIREWALL i386
FreeBSD clang version 3.3 (tags/RELEASE_33/final 183502) 20130610
CPU: Intel(R) Core(TM)2 Duo CPU     E4600  _at_ 2.40GHz (2400.14-MHz 686-class CPU)
  Origin = "GenuineIntel"  Id = 0x6fd  Family = 0x6  Model = 0xf  Stepping = 13
  Features=0xbfebfbff<FPU,VME,DE,PSE,TSC,MSR,PAE,MCE,CX8,APIC,SEP,MTRR,PGE,MCA,C
MOV,PAT,PSE36,CLFLUSH,DTS,ACPI,MMX,FXSR,SSE,SSE2,SS,HTT,TM,PBE>
  Features2=0xe39d<SSE3,DTES64,MON,DS_CPL,EST,TM2,SSSE3,CX16,xTPR,PDCM>
  AMD Features=0x20100000<NX,LM>
  AMD Features2=0x1<LAHF>
  TSC: P-state invariant, performance statistics
real memory  = 2147483648 (2048 MB)
avail memory = 2076581888 (1980 MB)


Broken on:
FreeBSD 10.0-CURRENT #19 r251445: Thu Jul  4 08:39:21 SAST 2013
    ianf_at_fw1:/usr/obj/usr/src/sys/FIREWALL amd64
FreeBSD clang version 3.3 (trunk 178860) 20130405
CPU: Intel(R) Core(TM)2 Duo CPU     E7300  _at_ 2.66GHz (2666.82-MHz K8-class CPU)
  Origin = "GenuineIntel"  Id = 0x10676  Family = 0x6  Model = 0x17  Stepping = 6
  Features=0xbfebfbff<FPU,VME,DE,PSE,TSC,MSR,PAE,MCE,CX8,APIC,SEP,MTRR,PGE,MCA,CMOV,PAT,PSE36,CLFLUSH,DTS,ACPI,MMX,FXSR,SSE,SSE2,SS,HTT,TM,PBE>
  Features2=0x8e39d<SSE3,DTES64,MON,DS_CPL,EST,TM2,SSSE3,CX16,xTPR,PDCM,SSE4.1>
  AMD Features=0x20100800<SYSCALL,NX,LM>
  AMD Features2=0x1<LAHF>
  TSC: P-state invariant, performance statistics
real memory  = 4294967296 (4096 MB)
avail memory = 3970727936 (3786 MB)

Ian

-- 
Ian Freislich