[ppc] Default stack size on ppc64
Richard W.M. Jones
rjones at redhat.com
Wed Mar 25 22:22:09 UTC 2015
On Wed, Mar 25, 2015 at 08:03:31PM +0000, David Woodhouse wrote:
> On Wed, 2015-03-25 at 19:45 +0000, Richard W.M. Jones wrote:
> > On Wed, Mar 25, 2015 at 06:30:25PM +0000, David Woodhouse wrote:
> > > If the compiler is single-threaded, and increasing the stack ulimit
> > > fixes the problem, that implies that the default stack ulimit is less
> > > than the 8MiB-64KiB that it takes to reach the guard page...
> >
> > Just so I'm clear, is the stack supposed to grow down automatically
> > (ie. does the stack automatically use MAP_GROWSDOWN), or is OCaml
> > supposed to do something when the stack hits the guard page?
> >
> > I guess it's also possible that an OCaml stack frame is so big that it
> > skips the guard page, or that GCC does some kind of stack "filling" to
> > trigger the guard page which OCaml does not do.
>
> This is easy to trigger, right? Can you catch it in gdb and 't a a bt'
I won't bore you with the full stack trace, but the top and bottom
and some interesting registers are below.
It confirms a few things:
- Stack is overflowing because of a highly recursive function (which
does eventually bottom-out, if you give it a big enough stack).
- Compiler is single threaded.
- %r1 (at top) - %r1 (at bottom) is approximately 8 MB
- Avg. size of each stack frame is ~ 168 bytes.
Rich.
--
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Reading symbols from /home/rjones/local/bin/ocamlopt.opt...(no debugging symbols found)...done.
[?1034h(gdb) run
Starting program: /home/rjones/local/bin/ocamlopt.opt -c -g -w a -I camlp4/import -warn-error A-3 -I camlp4/config -I camlp4/boot -o camlp4/boot/camlp4boot.cmx camlp4/boot/camlp4boot.ml
Program received signal SIGSEGV, Segmentation fault.
0x00000000100587cc in .camlCSEgen__compare_1011 ()
Missing separate debuginfos, use: debuginfo-install glibc-2.18-12.fc20.ppc64p7
(gdb) t a a bt
Thread 1 (process 48132):
#0 0x00000000100587cc in .camlCSEgen__compare_1011 ()
#1 0x0000000010007b48 in .caml_apply2 ()
#2 0x0000000010263e44 in .camlMap__find_1091 ()
#3 0x0000000010058d4c in .camlCSEgen__find_equation_1124 ()
#4 0x0000000010057624 in .camlCSEgen__fun_1397 ()
#5 0x0000000010007a84 in .caml_apply3 ()
#6 0x0000000010057c5c in .camlCSEgen__fun_1397 ()
#7 0x0000000010007a84 in .caml_apply3 ()
#8 0x0000000010057c5c in .camlCSEgen__fun_1397 ()
#9 0x0000000010007a84 in .caml_apply3 ()
#10 0x000000001005799c in .camlCSEgen__fun_1397 ()
[these two stack frames are repeated over and over]
#49873 0x0000000010007a85 in .caml_apply3 ()
#49874 0x0000000010057d51 in .camlCSEgen__fun_1397 ()
#49875 0x0000000010007a85 in .caml_apply3 ()
#49876 0x0000000010057d51 in .camlCSEgen__fun_1397 ()
#49877 0x0000000010007a85 in .caml_apply3 ()
#49878 0x0000000010057315 in .camlCSEgen__fun_1406 ()
#49879 0x0000000010006a41 in .caml_send1 ()
#49880 0x0000000010059ea9 in .camlCSE__fundecl_1029 ()
#49881 0x000000001007c59d in .camlAsmgen__compile_fundecl_1050 ()
#49882 0x000000001007c895 in .camlAsmgen__compile_phrase_1053 ()
#49883 0x000000001007bbe9 in .camlAsmgen__fun_1285 ()
#49884 0x0000000010258a01 in .camlList__iter_1061 ()
#49885 0x000000001007bc2d in .camlAsmgen__fun_1290 ()
#49886 0x000000001007cc49 in .camlAsmgen__compile_implementation_1063 ()
#49887 0x0000000010082da9 in .camlOptcompile__fun_1274 ()
#49888 0x0000000010083525 in .camlOptcompile__comp_1048 ()
#49889 0x0000000010083de1 in .camlOptcompile__implementation_1040 ()
#49890 0x0000000010007cd9 in .camlOptmain__process_implementation_file_1011 ()
#49891 0x0000000010008445 in .camlOptmain__process_file_1016 ()
#49892 0x00000000100084c5 in .camlOptmain__anonymous_1022 ()
#49893 0x0000000010283ec5 in .camlArg__parse_argv_dynamic_1078 ()
#49894 0x0000000010284161 in .camlArg__parse_1140 ()
#49895 0x00000000100092bd in .camlOptmain__main_1474 ()
#49896 0x000000001000a785 in .camlOptmain__entry ()
#49897 0x0000000010003439 in caml_startup.code_begin ()
#49898 0x00000000102b633d in .caml_start_program ()
#49899 0x00000000102b6a30 in .caml_main ()
#49900 0x000000001029da60 in .main ()
(gdb) info registers
r0 0x10007b48 268467016
r1 0x3fffff800030 70368735789104
r2 0x1048c4e0 273204448
r3 0x3fffb7fa8fc0 70367535861696
r4 0x3fffb7fa9810 70367535863824
r5 0x103a5f34 272260916
r6 0x5 5
r7 0x3fffb7d0f750 70367533135696
r8 0x1 1
r9 0x3fffb7fa8fd8 70367535861720
r10 0xc00 3072
r11 0x10007b18 268466968
r12 0x0 0
r13 0x803935c3e0 550715638752
r14 0x100587c4 268797892
r15 0x3fffb7fa8fc0 70367535861696
r16 0x800 2048
r17 0x1005737c 268792700
r18 0xc00 3072
r19 0x9 9
r20 0x3fffb7fa9268 70367535862376
r21 0x3fffb7fa9158 70367535862104
r22 0x3fffb7fa9120 70367535862048
r23 0x13 19
r24 0x13 19
r25 0x4c 76
r26 0x9 9
r27 0x3fffa63f3f18 70367238373144
r28 0x3fffb7fa9048 70367535861832
r29 0x3fffff8001e0 70368735789536
r30 0x3fffb7dd1000 70367533928448
r31 0x3fffb7fa8fb8 70367535861688
pc 0x100587cc 0x100587cc <.camlCSEgen__compare_1011+8>
msr 0x900000000000d032 10376293541461676082
cr 0x22000824 570427428
lr 0x10007b48 0x10007b48 <.caml_apply2+48>
ctr 0x100587c4 268797892
xer 0x20000000 536870912
orig_r3 0x10007b44 268467012
trap 0x300 768
(gdb) frame 49878
#49878 0x0000000010057315 in .camlCSEgen__fun_1406 ()
(gdb) info registers
r0 0x10007b48 268467016
r1 0x3fffffffdbd0 70368744168400
r2 0x1048c4e0 273204448
r3 0x3fffb7fa8fc0 70367535861696
r4 0x3fffb7fa9810 70367535863824
r5 0x103a5f34 272260916
r6 0x5 5
r7 0x3fffb7d0f750 70367533135696
r8 0x1 1
r9 0x3fffb7fa8fd8 70367535861720
r10 0xc00 3072
r11 0x10007b18 268466968
r12 0x0 0
r13 0x803935c3e0 550715638752
r14 0x100587c4 268797892
r15 0x3fffb7fa8fc0 70367535861696
r16 0x800 2048
r17 0x1005737c 268792700
r18 0xc00 3072
r19 0x9 9
r20 0x3fffb7fa9268 70367535862376
r21 0x3fffb7fa9158 70367535862104
r22 0x3fffb7fa9120 70367535862048
r23 0x13 19
r24 0x13 19
r25 0x4c 76
r26 0x9 9
r27 0x3fffa63f3f18 70367238373144
r28 0x3fffb7fa9048 70367535861832
r29 0x3fffff8001e0 70368735789536
r30 0x3fffb7dd1000 70367533928448
r31 0x3fffb7fa8fb8 70367535861688
pc 0x10057315 0x10057315 <.camlCSEgen__fun_1406+69>
msr 0x900000000000d032 10376293541461676082
cr 0x22000824 570427428
lr 0x10057315 0x10057315 <.camlCSEgen__fun_1406+69>
ctr 0x100587c4 268797892
xer 0x20000000 536870912
orig_r3 0x10007b44 268467012
trap 0x300 768
(gdb) frame 49900
#49900 0x000000001029da60 in .main ()
(gdb) info registers
r0 0x10007b48 268467016
r1 0x3fffffffed10 70368744172816
r2 0x1048c4e0 273204448
r3 0x3fffb7fa8fc0 70367535861696
r4 0x3fffb7fa9810 70367535863824
r5 0x103a5f34 272260916
r6 0x5 5
r7 0x3fffb7d0f750 70367533135696
r8 0x1 1
r9 0x3fffb7fa8fd8 70367535861720
r10 0xc00 3072
r11 0x10007b18 268466968
r12 0x0 0
r13 0x803935c3e0 550715638752
r14 0x100587c4 268797892
r15 0x3fffb7fa8fc0 70367535861696
r16 0x800 2048
r17 0x1005737c 268792700
r18 0xc00 3072
r19 0x9 9
r20 0x3fffb7fa9268 70367535862376
r21 0x3fffb7fa9158 70367535862104
r22 0x3fffb7fa9120 70367535862048
r23 0x0 0
r24 0x0 0
r25 0x0 0
r26 0x0 0
r27 0x803934fe00 550715588096
r28 0x8039350d18 550715591960
r29 0x803934f930 550715586864
r30 0x0 0
r31 0x0 0
pc 0x1029da60 0x1029da60 <.main+20>
msr 0x900000000000d032 10376293541461676082
cr 0x22000824 570427428
lr 0x1029da60 0x1029da60 <.main+20>
ctr 0x100587c4 268797892
xer 0x20000000 536870912
orig_r3 0x10007b44 268467012
trap 0x300 768
(gdb) quit
A debugging session is active.
Inferior 1 [process 48132] will be killed.
Quit anyway? (y or n)
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