Re: kernel page fault with nfs

Tobias C. Berner wrote:
> Now that I posted it, 32767 should of course be 2^15=32768. Let me
> recheck if it still
> hangs with the correct value.
> 
> On Monday 20 October 2014 09.15:39 Tobias C. Berner wrote:
> > Hi Marcelo
> > 
> > Yes, I'm using readahead:
> > The mountoptions are
> > "readahead=4,soft,intr,rw,tcp,wsize=32767,rsize=32767,late"
> > 
If you type "nfsstat -m", you will see what is actually getting used.
(I suspect the above rsize/wsize got clipped to 32256 or something like
 that. I think it clips it to a multiple of 512.)

If rsize/wsize are not a power of 2, there are issues, although I've never
been able to see why it is broken. Maybe it should clip it to the power of
2 below the value, since it causes unexplained problems otherwise.

rick

> > 
> > mfg Tobias
> > 
> > On Monday 20 October 2014 10.41:30 Marcelo Araujo wrote:
> > > Hello Tobias,
> > > 
> > > Could you show how you are mount the NFS share?
> > > Are you using 'readahead' option?
> > > 
> > > Best Regards,
> > > 
> > > 2014-10-19 17:40 GMT+08:00 Tobias C. Berner <tcberner_at_gmail.com>:
> > > > both are at 1100038.
> > > > 
> > > > On Sunday 19 October 2014 11.12:36 Marcelo Araujo wrote:
> > > > > It is still strange, could you do what Allan said and send us
> > > > > the
> > > > > result
> > > > 
> > > > in
> > > > 
> > > > > case you are not sure you have world and kernel in the same
> > > > > revision!
> > > > > 
> > > > > On Oct 19, 2014 6:48 AM, "Tobias C. Berner"
> > > > > <tcberner_at_gmail.com> wrote:
> > > > > >  Hi
> > > > > > 
> > > > > > World ist from october 16, installed world and kernel then.
> > > > > > 
> > > > > > Kernel was later rebuilt with debug-options.
> > > > > > 
> > > > > > 
> > > > > > 
> > > > > > 
> > > > > > 
> > > > > > Is the following more sensible?
> > > > > > 
> > > > > > 
> ##################################################
> > > > > > 
> > > > > > # kgdb NOXON/kernel.debug vmcore.1
> > > > > > 
> > > > > > Fatal trap 12: page fault while in kernel mode
> > > > > > 
> > > > > > cpuid = 5; apic id = 05
> > > > > > 
> > > > > > fault virtual address = 0xfffffe07d1744000
> > > > > > 
> > > > > > fault code = supervisor write data, page not present
> > > > > > 
> > > > > > instruction pointer = 0x20:0xffffffff80d4d58a
> > > > > > 
> > > > > > stack pointer = 0x28:0xfffffe086057f240
> > > > > > 
> > > > > > frame pointer = 0x28:0xfffffe086057f2f0
> > > > > > 
> > > > > > code segment = base 0x0, limit 0xfffff, type 0x1b
> > > > > > 
> > > > > > = DPL 0, pres 1, long 1, def32 0, gran 1
> > > > > > 
> > > > > > processor eflags = interrupt enabled, resume, IOPL = 0
> > > > > > 
> > > > > > current process = 6524 (python2.7)
> > > > > > 
> > > > > > 
> > > > > > 
> > > > > > 
> > > > > > 
> > > > > > (kgdb) bt
> > > > > > 
> > > > > > #0 doadump (textdump=1) at pcpu.h:219
> > > > > > 
> > > > > > #1 0xffffffff80926b6d in kern_reboot (howto=260) at
> > > > > > /usr/src/sys/kern/kern_shutdown.c:447
> > > > > > 
> > > > > > #2 0xffffffff809270c0 in panic (fmt=<value optimized out>)
> > > > > > at
> > > > > > /usr/src/sys/kern/kern_shutdown.c:746
> > > > > > 
> > > > > > #3 0xffffffff8035f167 in db_panic (addr=<value optimized
> > > > > > out>,
> > > > > > have_addr=2, count=0, modif=0x0) at
> > > > > > /usr/src/sys/ddb/db_command.c:473
> > > > > > 
> > > > > > #4 0xffffffff8035ed7d in db_command (cmd_table=0x0) at
> > > > > > /usr/src/sys/ddb/db_command.c:440
> > > > > > 
> > > > > > #5 0xffffffff8035eaf4 in db_command_loop () at
> > > > > > /usr/src/sys/ddb/db_command.c:493
> > > > > > 
> > > > > > #6 0xffffffff80361600 in db_trap (type=<value optimized
> > > > > > out>,
> > > > > > code=0)
> > > > 
> > > > at
> > > > 
> > > > > > /usr/src/sys/ddb/db_main.c:251
> > > > > > 
> > > > > > #7 0xffffffff80966f01 in kdb_trap (type=12, code=0,
> > > > > > tf=<value
> > > > > > optimized
> > > > > > out>) at /usr/src/sys/kern/subr_kdb.c:654
> > > > > > 
> > > > > > #8 0xffffffff80d4fa7c in trap_fatal
> > > > > > (frame=0xfffffe086057f190,
> > > > 
> > > > eva=<value
> > > > 
> > > > > > optimized out>) at /usr/src/sys/amd64/amd64/trap.c:861
> > > > > > 
> > > > > > #9 0xffffffff80d4fe0c in trap_pfault
> > > > > > (frame=0xfffffe086057f190,
> > > > > > usermode=<value optimized out>) at
> > > > > > /usr/src/sys/amd64/amd64/trap.c:677
> > > > > > 
> > > > > > #10 0xffffffff80d4f42e in trap (frame=0xfffffe086057f190)
> > > > > > at
> > > > > > /usr/src/sys/amd64/amd64/trap.c:426
> > > > > > 
> > > > > > #11 0xffffffff80d33972 in calltrap () at
> > > > > > /usr/src/sys/amd64/amd64/exception.S:231
> > > > > > 
> > > > > > #12 0xffffffff80d4d58a in bzero () at
> > > > > > /usr/src/sys/amd64/amd64/support.S:53
> > > > > > 
> > > > > > #13 0xffffffff80830463 in ncl_doio (vp=0xfffff801e7f99938,
> > > > > > bp=0xfffffe07c5a168e8, cr=<value optimized out>, td=<value
> > > > > > optimized
> > > > 
> > > > out>,
> > > > 
> > > > > > called_from_strategy=<value optimized out>)
> > > > > > 
> > > > > > at /usr/src/sys/fs/nfsclient/nfs_clbio.c:1648
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