On Sunday August 3, [EMAIL PROTECTED] wrote: > > I can trigger it reliably with a 2.6.26 client. I've also triggered it > with 496d6c32d4d057cb44272d9bd587ff97d023ee92 reverted on the server. > > It's harder to trigger with 2.6.27-rc1+ but I managed to get an Oops > on the fourth build after three successful builds on the NFS4 mount. > > One of the Oopses I got with 2.6.26 had a slightly different call trace: > > Unable to handle kernel paging request for instruction fetch > Faulting instruction address: 0x00000000
So we have called a function pointer which was NULL. There a lots of function pointers in use in this code. There is the 'acceptable' function. There is ->fh_to_dentry and ->fh_to_parent. And various inode operations line ->lookup, but that is a bit further away. > NIP [00000000] 0x0 > LR [c0159bb0] exportfs_decode_fh+0xa8/0x200 I guess this is where the call came from. exportfs_decode_fh is never passed NULL for 'acceptable'. Only ever 'nfsd_acceptable'. ->fh_to_parent is tested for NULL before being called, and ->fh_to_dentry is called very early in exportfs_decode_fh, where as the bad call is 0xa8 in to the function. Is it possible that ->fh_to_parent is being changed immediately after being tested for NULL and before being dereferenced. That seems unlikely. What filesystem is being exported here? Can you get an assembly version of exportfs_decode_fh, so we can check what is happening at 0xa8 (and 0x4c). Either "disassemble exportfs_decode_fh" in gdb, or make fs/exportfs/expfs.i (I think). NeilBrown > Call Trace: > [c1f79d50] [c0159b54] exportfs_decode_fh+0x4c/0x200 (unreliable) > [c1f79e80] [c015d568] fh_verify+0x2e8/0x578 > [c1f79ed0] [c016b1ec] nfsd4_putfh+0x60/0x78 > [c1f79ef0] [c016afd0] nfsd4_proc_compound+0x1e4/0x34c > [c1f79f30] [c015a060] nfsd_dispatch+0xfc/0x220 > [c1f79f50] [c0400c70] svc_process+0x3e4/0x6e8 > [c1f79f90] [c015a8bc] nfsd+0x1c4/0x294 > [c1f79fd0] [c0049e48] kthread+0x5c/0x9c > [c1f79ff0] [c00125c0] kernel_thread+0x44/0x60 _______________________________________________ Linuxppc-dev mailing list Linuxppc-dev@ozlabs.org https://ozlabs.org/mailman/listinfo/linuxppc-dev