[Pvfs2-developers] Copy commands segfault on 2.4 kernels

[Phil Carns]

Hi Bart,

 From your strace output, my guess is that cp is running into trouble 
with the value of one of the fstat() fields, but its hard to say which one.

Are you able to reproduce this reliably?  Could you run the strace again 
with the -v option to see if it gives a full listing of what values were 
in the stat structs it got before crashing?

-Phil

Bart Taylor wrote:
> Hey guys,
> 
> I am running into a problem with a system copy command segfaulting on 
> 2.4 kernels. Specifically, I am seeing this show up on RHEL3 machines 
> running a patched version of PVFS 2.6. Machines running Linux 2.6 
> kernels do not experience this problem.  I believe we may have mentioned 
> this recently but hoped it would be fixed by some updates pulled into 
> dcache. That, apparently, is not the case.
> 
> The segfault is extremely consistent; it happens every time a cp is 
> executed with a PVFS2 file system as the target.  The target file is 
> always created with a size of zero, so at least part of the command is 
> completing. 'dd' commands execute normally.
> 
> The setup is simple:  1 server node (RHEL4 2.6 kernel) with the default 
> interactive genconfig output, and 1 client with a 2.4 kernel.  Mount the 
> file system, execute a copy onto the file system. 
> 
> Here is the conf file contents:
> 
> <Defaults>
>         UnexpectedRequests 50
>         EventLogging none
>         LogStamp datetime
>         BMIModules bmi_tcp
>         FlowModules flowproto_multiqueue
>         PerfUpdateInterval 1000
>         ServerJobBMITimeoutSecs 30
>         ServerJobFlowTimeoutSecs 30
>         ClientJobBMITimeoutSecs 300
>         ClientJobFlowTimeoutSecs 300
>         ClientRetryLimit 5
>         ClientRetryDelayMilliSecs 2000
>         TCPBindSpecific yes
> </Defaults>
> 
> <Aliases>
>         Alias node1 tcp://node1:3334
> </Aliases>
> 
> <Filesystem>
>         Name pvfs2-fs
>         ID 1227216139
>         RootHandle 1048576
>         <MetaHandleRanges>
>                 Range node1 4-2147483650
>         </MetaHandleRanges>
>         <DataHandleRanges>
>                 Range node1 2147483651-4294967297
>         </DataHandleRanges>
>         <StorageHints>
>                 TroveSyncMeta no
>                 TroveSyncData no
>                 CoalescingHighWatermark infinity
>                 CoalescingLowWatermark 0
>                 TroveSyncMetaTimerSecs 5
>                 DBCacheSizeBytes 1073741824
>         </StorageHints>
> </Filesystem>
> 
> And here is the last bit of an strace on a copy command:
> 
> [root at node1 root]# strace cp test.file /mnt/pvfs2/
> .....
> brk(0)                                  = 0x95ce000
> open("/usr/lib/locale/locale-archive", O_RDONLY|O_LARGEFILE) = 3
> fstat64(3, {st_mode=S_IFREG|0644, st_size=32148976, ...}) = 0
> mmap2(NULL, 2097152, PROT_READ, MAP_PRIVATE, 3, 0) = 0xb73f4000
> close(3)                                = 0
> geteuid32()                             = 0
> lstat64("/mnt/pvfs2/", {st_mode=S_IFDIR|S_ISVTX|0777, st_size=4096, 
> ...}) = 0
> stat64("/mnt/pvfs2/", {st_mode=S_IFDIR|S_ISVTX|0777, st_size=4096, ...}) = 0
> stat64("test.file", {st_mode=S_IFREG|0644, st_size=5, ...}) = 0
> stat64("/mnt/pvfs2/test.file", {st_mode=S_IFREG|0644, st_size=0, ...}) = 0
> open("test.file", O_RDONLY|O_LARGEFILE) = 3
> fstat64(3, {st_mode=S_IFREG|0644, st_size=5, ...}) = 0
> open("/mnt/pvfs2/test.file", O_WRONLY|O_TRUNC|O_LARGEFILE) = 4
> fstat64(4, {st_mode=S_IFREG|0644, st_size=0, ...}) = 0
> fstat64(3, {st_mode=S_IFREG|0644, st_size=5, ...}) = 0
> --- SIGSEGV (Segmentation fault) @ 0 (0) ---
> +++ killed by SIGSEGV +++
> 
> 
> There is nothing in the client or server logs without turning on 
> additional logging.
> 
> Are there any suggestions on what might be causing this? Can I provide 
> any additional information that will be helpful for debugging?
> 
> Bart.
> 
> 
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