[parisc-linux] 2.6.11-rc3-pa3 smp "Segmentation fault" but not up

[parisc-linux] 2.6.11-rc3-pa3 smp "Segmentation fault" but not up

[Joel Soete]

[-- Attachment #1: Type: text/plain, Size: 1678 bytes --]

Hi all,

To stress a bit kernel I launch my usual loop test on the n4k (2way, 4Gb ram):
# while true ; do readprofile -r ; make $OPTB clean ; make $OPTB oldconfig; make -j2 $OPTB vmlinux 2>&1 | tee -a /var/logs/k-loop; 
readprofile >> /var/logs/prof-loop.doc ; done

With previous kernel it makes panic kernel hazardiously from 1 to more 200 occurences. With this 2.6.11-rc3-pa3 after about 49 runs 
some "Segmentation fault" occures:
make[3]: *** [drivers/pci/probe.o] Segmentation fault
make[3]: *** [drivers/block/ioctl.o] Segmentation fault
make[2]: *** [arch/parisc/math-emu/fpudispatch.o] Segmentation fault
make[2]: *** [arch/parisc/math-emu/driver.o] Segmentation fault
make[2]: *** [arch/parisc/math-emu/driver.o] Segmentation fault
make[2]: *** [arch/parisc/math-emu/frnd.o] Segmentation fault
make[2]: *** [arch/parisc/math-emu/driver.o] Segmentation fault
make[2]: *** [arch/parisc/math-emu/denormal.o] Segmentation fault
make[2]: *** [arch/parisc/math-emu/frnd.o] Segmentation fault
make[3]: *** [drivers/md/raid0.o] Segmentation fault
make[2]: *** [arch/parisc/math-emu/driver.o] Segmentation fault
make[2]: *** [arch/parisc/math-emu/driver.o] Segmentation fault
make[2]: *** [arch/parisc/math-emu/frnd.o] Segmentation fault
make[2]: *** [arch/parisc/math-emu/frnd.o] Segmentation fault

for some child's shell (I attached dmesg because very long).

I so stop this loop to reboot with same kernel but up build and relaunch the loop.
After about 12h it already runs 80 times without any segmantation fault.

Any idea?

Thanks,
     Joel

PS: this last was build with gcc-3.3-hppa64 and binutils-hppa64 while previous was build with hppa64-gcc-3.0 and same binutils

[-- Attachment #2: PageFault.doc --]
[-- Type: application/msword, Size: 28529 bytes --]

[-- Attachment #3: Type: text/plain, Size: 169 bytes --]

_______________________________________________
parisc-linux mailing list
parisc-linux@lists.parisc-linux.org
http://lists.parisc-linux.org/mailman/listinfo/parisc-linux

Re: [parisc-linux] 2.6.11-rc3-pa3 smp "Segmentation fault" but not up

[Matthew Wilcox]

On Sat, Jan 15, 2005 at 02:02:00PM +0000, Joel Soete wrote:
> With previous kernel it makes panic kernel hazardiously from 1 to more 200 
> occurences. With this 2.6.11-rc3-pa3 after about 49 runs some "Segmentation 
> fault" occures:
> make[3]: *** [drivers/pci/probe.o] Segmentation fault
> 
> for some child's shell (I attached dmesg because very long).
> 
> I so stop this loop to reboot with same kernel but up build and relaunch 
> the loop.
> After about 12h it already runs 80 times without any segmantation fault.
> 
> Any idea?

I suspect the new clear_user_page code.  Could you try backing that out
and rerunning your test?

-- 
"Next the statesmen will invent cheap lies, putting the blame upon 
the nation that is attacked, and every man will be glad of those
conscience-soothing falsities, and will diligently study them, and refuse
to examine any refutations of them; and thus he will by and by convince 
himself that the war is just, and will thank God for the better sleep 
he enjoys after this process of grotesque self-deception." -- Mark Twain
_______________________________________________
parisc-linux mailing list
parisc-linux@lists.parisc-linux.org
http://lists.parisc-linux.org/mailman/listinfo/parisc-linux

Re: [parisc-linux] 2.6.11-rc3-pa3 smp "Segmentation fault" but not up

[Joel Soete]

Hello Grant,

Sorry for delay but the n stand in the office and join it from home i need to use vpn connection which deasable my local lan (and 
also my pop3 access to my isp :-( and obviously irc)

Grant Grundler wrote:
> On Sat, Jan 15, 2005 at 10:11:54PM +0000, Joel Soete wrote:
> 
>>this patch:
>><http://cvs.parisc-linux.org/linux-2.6/arch/parisc/kernel/pacache.S?r1=1.9&r2=1.10> ?
> 
> 
> I don't think willy is refering to any particular issue.
> 
> 
>>Well in doubt I revert all changes since:
>><http://cvs.parisc-linux.org/*checkout*/linux-2.6/arch/parisc/kernel/pacache.S?rev=1.9.20.2>
>>
>>Btw what do you suspect that Grant (and I) could have missed (just divid by 
>>2 the number of loop thanks to dword insn)?
> 
> 
> No - I mangled that. The code you submitted was correct in this regard.
Agree (but what could we imagine on a system which only have one atomic insn iirc?)

> I fixed the off-by-2x bug in the next commit:
> http://cvs.parisc-linux.org/linux-2.6/arch/parisc/kernel/pacache.S?r1=1.10&r2=1.11
> 
> My suspicion is the prefetching might be causing problems since it's going
> past the end of the page. The kernel tmp alias pages might be causing problems
> since we don't flush past the end of those. (Or something like that).
> 
sorry I didn't have yet understand all details of prefetching

> Can you remove only the prefetching in that algorithm?
> 
Yes, I did and already run one occurence of the loop without pb, .. so we have to be patient to see if first mentioned pb (failures 
after some loop occurence: about 50 last time) :-)

> 
>>But already strange results:
> 
> ...
> 
>>and after those first 11 failed it seems to continue??
> 
> 
> Do you mean after restarting the make the build completed?

No, just let continue the loop (that doesn't make sense to me but in fact I already encounter this case with 2.6.10-paXX but don't 
have time to report it).

Is nicol also encounter the same pb (just in case of small diff in hw config)?

Thanks,
	Joel
_______________________________________________
parisc-linux mailing list
parisc-linux@lists.parisc-linux.org
http://lists.parisc-linux.org/mailman/listinfo/parisc-linux

Same pb on b2k 64bit + 2.6.11-rc2-pa0 [Was: [parisc-linux] 2.6.11-rc3-pa3 smp "Segmentation fault" but not up]

[Joel Soete]

Hello Grant,
> 
[...]
> > My suspicion is the prefetching might be causing problems since it's
going
> > past the end of the page. The kernel tmp alias pages might be causing=

problems
> > since we don't flush past the end of those. (Or something like that).=

> > 
> sorry I didn't have yet understand all details of prefetching
> 
> > Can you remove only the prefetching in that algorithm?
> > 
> Yes, I did and already run one occurence of the loop without pb, .. so
we
> have to be patient to see if first mentioned pb (failures 
> after some loop occurence: about 50 last time) :-)
> 
mmm, I was ongoing to forget why the n was looping on a kernel's build wh=
en
the b2k panic due to the same pb with lastest 2.6.11-rc2-pa0 (+workaround=
):
patst005 login: Backtrace:
 [<000000001017cd00>] do_wp_page+0x250/0x950
 [<000000001017ee14>] handle_mm_fault+0x1b4/0x1e0
 [<0000000010110ec4>] do_page_fault+0x2bc/0x360
 [<000000001011299c>] handle_interruption+0x34c/0x748
 [<0000000010107094>] intr_check_sig+0x0/0xc


Kernel Fault: Code=3D15 regs=3D000000001d68c540 (Addr=3D0000000020000000)=

      
     YZrvWESTHLNXBCVMcbcbcbcbOGFRQPDI
PSW: 00001000000001001110011100001111 Not tainted
r00-03  0000000000000000 0000000000000000 000000001017cd00 0000000010a0df=
c8
r04-07  00000000105e2020 000000001d874000 0000000010983960 000000000007e2=
b0
r08-11  000000001d71cad0 000000001e7e9c00 000000000ffffb25 000000001d4043=
f0
r12-15  0000000010983960 000000001d8dc000 0000000000000001 000000000006a4=
04
r16-19  000000001d432740 000000000006a404 000000000006b404 00000000000000=
00
r20-23  0000000000000000 0000000000000000 0000000000000000 00000000000000=
00
r24-27  00000000000000d2 0000000020000000 000000001d875000 00000000105e20=
20
r28-31  0000000010983960 000000001d68c510 000000001d68c540 00000000000000=
20
sr0-3   0000000000429800 0000000000000000 0000000000000000 00000000004298=
00
sr4-7   0000000000000000 0000000000000000 0000000000000000 00000000000000=
00

IASQ: 0000000000000000 0000000000000000 IAOQ: 00000000101012c4 0000000010=
1012c8
 IIR: 0f2010d3    ISR: 0000000000000000  IOR: 0000000020000000
 CPU:        0   CR30: 000000001d68c000 CR31: 00000000105a0000
 ORIG_R28: 00000000103e3e68
 IAOQ[0]: copy_user_page_asm+0xa4/0xb0
 IAOQ[1]: copy_user_page_asm+0xa8/0xb0
 RP(r2): do_wp_page+0x250/0x950
Kernel panic - not syncing: Kernel Fault

I so applied the same work around:
--- arch/parisc/kernel/pacache.S.Orig   2005-01-25 13:44:26.000000000 +01=
00
+++ arch/parisc/kernel/pacache.S        2005-01-25 13:44:55.000000000 +01=
00
@@ -306,13 +306,18 @@
 
        ldd             0(%r25), %r19           /* bundle 1 */
        ldi             32, %r1                 /* PAGE_SIZE/128 =3D=3D 3=
2 */
+
+#if    0       /* Comment out prefetching awaiting better fix */
        ldw             64(%r25), %r0           /* prefetch 1 cacheline a=
head
*/
        ldw             128(%r25), %r0          /* prefetch 2 */
+#endif
 
 1:     ldd             8(%r25), %r20
+#if    0       /* Comment out prefetching awaiting better fix */
        ldw             192(%r25), %r0          /* prefetch 3 */
        ldw             256(%r25), %r0          /* prefetch 4 */
        nop     /* pad to preserve alignment */
+#endif
 
        ldd             16(%r25), %r21          /* bundle 2 */
        ldd             24(%r25), %r22
=3D=3D=3D=3D=3D=3D=3D=3D=3D><=3D=3D=3D=3D=3D=3D=3D=3D=3D

which help too

(I ran the build kernel loop on the smp n4k during a week: 612 runs amoun=
g
111 failed because of various page_fault :-)

Thanks,
Joel


_______________________________________________
parisc-linux mailing list
parisc-linux@lists.parisc-linux.org
http://lists.parisc-linux.org/mailman/listinfo/parisc-linux