[Bug ld/31466] New: Hang when building Rust program with mmap patches

[sam at gentoo dot org]

https://sourceware.org/bugzilla/show_bug.cgi?id=31466

            Bug ID: 31466
           Summary: Hang when building Rust program with mmap patches
           Product: binutils
           Version: unspecified
            Status: NEW
          Severity: normal
          Priority: P2
         Component: ld
          Assignee: unassigned at sourceware dot org
          Reporter: sam at gentoo dot org
                CC: hjl.tools at gmail dot com
  Target Milestone: ---

Currently testing H.J's latest patchset (v5) of the mmap work [0] on top of
trunk.

So far, package builds have gone well, but when building some Rust software
earlier, I noticed ld took over 10 minutes (!).

I've attached a tarball which reproduces it, I've not tried to minimise it as
it's Rust with its gazillion static library deps (sorry).

The hanging command is:
```
/usr/bin/x86_64-pc-linux-gnu-gcc -m64
/var/tmp/portage/sys-process/procs-0.14.5/temp/rustca2ri5G/symbols.o
/var/tmp/portage/sys-process/procs-0.14.5/work/procs-0.14.5/target/release/deps/procs-bf23c8fa176eac21.procs.d1865a8196e0707d-cgu.0.rcgu.o
-Wl,--as-needed -L
/var/tmp/portage/sys-process/procs-0.14.5/work/procs-0.14.5/target/release/deps
-L /usr/lib/rust/1.75.0/lib/rustlib/x86_64-unknown-linux-gnu/lib -Wl,-Bstatic
/usr/lib/rust/1.75.0/lib/rustlib/x86_64-unknown-linux-gnu/lib/libcompiler_builtins-275fd5f39e82e176.rlib
-Wl,-Bdynamic -lc -lgcc_s -lutil -lrt -lpthread -lm -ldl -lc -Wl,--eh-frame-hdr
-Wl,-z,noexecstack -L
/usr/lib/rust/1.75.0/lib/rustlib/x86_64-unknown-linux-gnu/lib -o
/var/tmp/portage/sys-process/procs-0.14.5/work/procs-0.14.5/target/release/deps/procs-bf23c8fa176eac21
-Wl,--gc-sections -pie -Wl,-z,relro,-z,now -nodefaultlibs
```

If I append `-fuse-ld=lld`, it completes with <1s.

After running for 3 minutes, attaching gdb gives:
```
0x00007f26fd2ed2e3 in bfd_getl64 (p=0x7f26fa3f1530) at
/usr/src/debug/sys-devel/binutils-9999/binutils/bfd/libbfd.c:913
913     }
(gdb) bt
#0  0x00007f26fd2ed2e3 in bfd_getl64 (p=0x7f26fa3f1530) at
/usr/src/debug/sys-devel/binutils-9999/binutils/bfd/libbfd.c:913
#1  0x00007f26fd310ca7 in bfd_elf64_swap_reloca_in
(abfd=abfd@entry=0x55f06a8871e0, s=s@entry=0x7f26fa3f1528 "\f\033\020",
dst=dst@entry=0x55f079aab3c8)
    at /usr/src/debug/sys-devel/binutils-9999/binutils/bfd/elfcode.h:445
#2  0x00007f26fd33702d in elf_link_read_relocs_from_section
(abfd=abfd@entry=0x55f06a8871e0, sec=sec@entry=0x55f0717bf2c8,
shdr=0x55f0717bfa78, external_relocs_addr=<optimized out>,
    external_relocs_size=<optimized out>, internal_relocs=<optimized out>) at
/usr/src/debug/sys-devel/binutils-9999/binutils/bfd/elflink.c:2708
#3  0x00007f26fd3373bc in _bfd_elf_link_info_read_relocs (abfd=0x55f06a8871e0,
info=<optimized out>, o=0x55f0717bf2c8, external_relocs=<optimized out>,
internal_relocs=0x55f0799a8c90,
    keep_memory=<optimized out>) at
/usr/src/debug/sys-devel/binutils-9999/binutils/bfd/elflink.c:2832
#4  0x00007f26fd352b0f in init_reloc_cookie_rels (cookie=0x7ffe635e0ff0,
info=0x55f068a4fec0 <link_info>, abfd=<optimized out>, sec=0x55f0717bf2c8)
    at /usr/src/debug/sys-devel/binutils-9999/binutils/bfd/elflink.c:13668
#5  init_reloc_cookie_for_section (cookie=cookie@entry=0x7ffe635e0ff0,
info=info@entry=0x55f068a4fec0 <link_info>, sec=sec@entry=0x55f0717bf2c8)
    at /usr/src/debug/sys-devel/binutils-9999/binutils/bfd/elflink.c:13700
#6  0x00007f26fd35307c in _bfd_elf_gc_mark (info=info@entry=0x55f068a4fec0
<link_info>, sec=sec@entry=0x55f06dcb2158,
    gc_mark_hook=gc_mark_hook@entry=0x7f26fd3110e0 <_bfd_x86_elf_gc_mark_hook>)
at /usr/src/debug/sys-devel/binutils-9999/binutils/bfd/elflink.c:13929
#7  0x00007f26fd352dc6 in _bfd_elf_gc_mark_reloc
(info=info@entry=0x55f068a4fec0 <link_info>, sec=sec@entry=0x55f06dcb0c28,
    gc_mark_hook=gc_mark_hook@entry=0x7f26fd3110e0 <_bfd_x86_elf_gc_mark_hook>,
cookie=cookie@entry=0x7ffe635e10d0)
    at /usr/src/debug/sys-devel/binutils-9999/binutils/bfd/elflink.c:13872
#8  0x00007f26fd35300a in _bfd_elf_gc_mark (info=info@entry=0x55f068a4fec0
<link_info>, sec=sec@entry=0x55f06dcb0c28,
    gc_mark_hook=gc_mark_hook@entry=0x7f26fd3110e0 <_bfd_x86_elf_gc_mark_hook>)
at /usr/src/debug/sys-devel/binutils-9999/binutils/bfd/elflink.c:13916
#9  0x00007f26fd352dc6 in _bfd_elf_gc_mark_reloc
(info=info@entry=0x55f068a4fec0 <link_info>, sec=sec@entry=0x55f06dcb09c8,
    gc_mark_hook=gc_mark_hook@entry=0x7f26fd3110e0 <_bfd_x86_elf_gc_mark_hook>,
cookie=cookie@entry=0x7ffe635e11b0)
    at /usr/src/debug/sys-devel/binutils-9999/binutils/bfd/elflink.c:13872
#10 0x00007f26fd35300a in _bfd_elf_gc_mark (info=info@entry=0x55f068a4fec0
<link_info>, sec=sec@entry=0x55f06dcb09c8,
    gc_mark_hook=gc_mark_hook@entry=0x7f26fd3110e0 <_bfd_x86_elf_gc_mark_hook>)
at /usr/src/debug/sys-devel/binutils-9999/binutils/bfd/elflink.c:13916
#11 0x00007f26fd352dc6 in _bfd_elf_gc_mark_reloc
(info=info@entry=0x55f068a4fec0 <link_info>, sec=sec@entry=0x55f06dcfe618,
    gc_mark_hook=gc_mark_hook@entry=0x7f26fd3110e0 <_bfd_x86_elf_gc_mark_hook>,
cookie=cookie@entry=0x7ffe635e1290)
    at /usr/src/debug/sys-devel/binutils-9999/binutils/bfd/elflink.c:13872
#12 0x00007f26fd35300a in _bfd_elf_gc_mark (info=info@entry=0x55f068a4fec0
<link_info>, sec=sec@entry=0x55f06dcfe618,
    gc_mark_hook=gc_mark_hook@entry=0x7f26fd3110e0 <_bfd_x86_elf_gc_mark_hook>)
at /usr/src/debug/sys-devel/binutils-9999/binutils/bfd/elflink.c:13916
#13 0x00007f26fd352dc6 in _bfd_elf_gc_mark_reloc
(info=info@entry=0x55f068a4fec0 <link_info>, sec=sec@entry=0x55f06dcfe4e8,
    gc_mark_hook=gc_mark_hook@entry=0x7f26fd3110e0 <_bfd_x86_elf_gc_mark_hook>,
cookie=cookie@entry=0x7ffe635e1370)
    at /usr/src/debug/sys-devel/binutils-9999/binutils/bfd/elflink.c:13872
#14 0x00007f26fd35300a in _bfd_elf_gc_mark (info=info@entry=0x55f068a4fec0
<link_info>, sec=sec@entry=0x55f06dcfe4e8,
    gc_mark_hook=gc_mark_hook@entry=0x7f26fd3110e0 <_bfd_x86_elf_gc_mark_hook>)
at /usr/src/debug/sys-devel/binutils-9999/binutils/bfd/elflink.c:13916
#15 0x00007f26fd352dc6 in _bfd_elf_gc_mark_reloc
(info=info@entry=0x55f068a4fec0 <link_info>, sec=sec@entry=0x55f06b1b7618,
    gc_mark_hook=gc_mark_hook@entry=0x7f26fd3110e0 <_bfd_x86_elf_gc_mark_hook>,
cookie=cookie@entry=0x7ffe635e1450)
    at /usr/src/debug/sys-devel/binutils-9999/binutils/bfd/elflink.c:13872
#16 0x00007f26fd35300a in _bfd_elf_gc_mark (info=info@entry=0x55f068a4fec0
<link_info>, sec=sec@entry=0x55f06b1b7618,
    gc_mark_hook=gc_mark_hook@entry=0x7f26fd3110e0 <_bfd_x86_elf_gc_mark_hook>)
at /usr/src/debug/sys-devel/binutils-9999/binutils/bfd/elflink.c:13916
#17 0x00007f26fd352dc6 in _bfd_elf_gc_mark_reloc
(info=info@entry=0x55f068a4fec0 <link_info>, sec=sec@entry=0x55f06b1c5078,
    gc_mark_hook=gc_mark_hook@entry=0x7f26fd3110e0 <_bfd_x86_elf_gc_mark_hook>,
cookie=cookie@entry=0x7ffe635e1530)
    at /usr/src/debug/sys-devel/binutils-9999/binutils/bfd/elflink.c:13872
#18 0x00007f26fd35300a in _bfd_elf_gc_mark (info=info@entry=0x55f068a4fec0
<link_info>, sec=sec@entry=0x55f06b1c5078,
    gc_mark_hook=gc_mark_hook@entry=0x7f26fd3110e0 <_bfd_x86_elf_gc_mark_hook>)
at /usr/src/debug/sys-devel/binutils-9999/binutils/bfd/elflink.c:13916
#19 0x00007f26fd352dc6 in _bfd_elf_gc_mark_reloc
(info=info@entry=0x55f068a4fec0 <link_info>, sec=sec@entry=0x55f06b1cecf8,
    gc_mark_hook=gc_mark_hook@entry=0x7f26fd3110e0 <_bfd_x86_elf_gc_mark_hook>,
cookie=cookie@entry=0x7ffe635e1610)
    at /usr/src/debug/sys-devel/binutils-9999/binutils/bfd/elflink.c:13872
--Type <RET> for more, q to quit, c to continue without paging--
#20 0x00007f26fd35300a in _bfd_elf_gc_mark (info=info@entry=0x55f068a4fec0
<link_info>, sec=sec@entry=0x55f06b1cecf8,
    gc_mark_hook=gc_mark_hook@entry=0x7f26fd3110e0 <_bfd_x86_elf_gc_mark_hook>)
at /usr/src/debug/sys-devel/binutils-9999/binutils/bfd/elflink.c:13916
#21 0x00007f26fd352dc6 in _bfd_elf_gc_mark_reloc
(info=info@entry=0x55f068a4fec0 <link_info>, sec=sec@entry=0x55f06b1ce378,
    gc_mark_hook=gc_mark_hook@entry=0x7f26fd3110e0 <_bfd_x86_elf_gc_mark_hook>,
cookie=cookie@entry=0x7ffe635e16f0)
    at /usr/src/debug/sys-devel/binutils-9999/binutils/bfd/elflink.c:13872
#22 0x00007f26fd35300a in _bfd_elf_gc_mark (info=info@entry=0x55f068a4fec0
<link_info>, sec=sec@entry=0x55f06b1ce378,
    gc_mark_hook=gc_mark_hook@entry=0x7f26fd3110e0 <_bfd_x86_elf_gc_mark_hook>)
at /usr/src/debug/sys-devel/binutils-9999/binutils/bfd/elflink.c:13916
#23 0x00007f26fd352dc6 in _bfd_elf_gc_mark_reloc
(info=info@entry=0x55f068a4fec0 <link_info>, sec=sec@entry=0x55f06b1ce118,
    gc_mark_hook=gc_mark_hook@entry=0x7f26fd3110e0 <_bfd_x86_elf_gc_mark_hook>,
cookie=cookie@entry=0x7ffe635e17d0)
    at /usr/src/debug/sys-devel/binutils-9999/binutils/bfd/elflink.c:13872
#24 0x00007f26fd35300a in _bfd_elf_gc_mark (info=info@entry=0x55f068a4fec0
<link_info>, sec=sec@entry=0x55f06b1ce118,
    gc_mark_hook=gc_mark_hook@entry=0x7f26fd3110e0 <_bfd_x86_elf_gc_mark_hook>)
at /usr/src/debug/sys-devel/binutils-9999/binutils/bfd/elflink.c:13916
#25 0x00007f26fd352dc6 in _bfd_elf_gc_mark_reloc
(info=info@entry=0x55f068a4fec0 <link_info>, sec=sec@entry=0x55f06b340fc8,
    gc_mark_hook=gc_mark_hook@entry=0x7f26fd3110e0 <_bfd_x86_elf_gc_mark_hook>,
cookie=cookie@entry=0x7ffe635e18b0)
    at /usr/src/debug/sys-devel/binutils-9999/binutils/bfd/elflink.c:13872
#26 0x00007f26fd35300a in _bfd_elf_gc_mark (info=info@entry=0x55f068a4fec0
<link_info>, sec=sec@entry=0x55f06b340fc8,
    gc_mark_hook=gc_mark_hook@entry=0x7f26fd3110e0 <_bfd_x86_elf_gc_mark_hook>)
at /usr/src/debug/sys-devel/binutils-9999/binutils/bfd/elflink.c:13916
#27 0x00007f26fd352dc6 in _bfd_elf_gc_mark_reloc
(info=info@entry=0x55f068a4fec0 <link_info>, sec=sec@entry=0x55f06a860a28,
    gc_mark_hook=gc_mark_hook@entry=0x7f26fd3110e0 <_bfd_x86_elf_gc_mark_hook>,
cookie=cookie@entry=0x7ffe635e1990)
    at /usr/src/debug/sys-devel/binutils-9999/binutils/bfd/elflink.c:13872
#28 0x00007f26fd35300a in _bfd_elf_gc_mark (info=info@entry=0x55f068a4fec0
<link_info>, sec=sec@entry=0x55f06a860a28,
    gc_mark_hook=gc_mark_hook@entry=0x7f26fd3110e0 <_bfd_x86_elf_gc_mark_hook>)
at /usr/src/debug/sys-devel/binutils-9999/binutils/bfd/elflink.c:13916
#29 0x00007f26fd356b55 in bfd_elf_gc_sections (abfd=0x55f06a84b8a0,
info=0x55f068a4fec0 <link_info>) at
/usr/src/debug/sys-devel/binutils-9999/binutils/bfd/elflink.c:14483
#30 0x000055f0687cbb66 in lang_gc_sections () at
/usr/src/debug/sys-devel/binutils-9999/binutils/ld/ldlang.c:7756
#31 lang_process () at
/usr/src/debug/sys-devel/binutils-9999/binutils/ld/ldlang.c:8346
#32 0x000055f0688e6676 in main (argc=51, argv=<optimized out>) at
/usr/src/debug/sys-devel/binutils-9999/binutils/ld/ldmain.c:511
```

perf report says:
```
    51.41%  ld              
libbfd-2.42.50.20240308.gentoo-sys-devel-binutils-mt.so  [.]
bfd_elf64_swap_symbol_in
    11.99%  ld              
libbfd-2.42.50.20240308.gentoo-sys-devel-binutils-mt.so  [.]
bfd_elf_get_elf_syms
     5.85%  ld              
libbfd-2.42.50.20240308.gentoo-sys-devel-binutils-mt.so  [.]
bfd_elf64_swap_reloca_in
     4.44%  ld               [kernel.kallsyms]                                 
      [k] clear_page_rep
     2.94%  ld              
libbfd-2.42.50.20240308.gentoo-sys-devel-binutils-mt.so  [.] bfd_getl32
     2.89%  ld              
libbfd-2.42.50.20240308.gentoo-sys-devel-binutils-mt.so  [.] bfd_getl64
     1.71%  ld              
libbfd-2.42.50.20240308.gentoo-sys-devel-binutils-mt.so  [.]
elf_link_read_relocs_from_section
     1.22%  ld               [kernel.kallsyms]                                 
      [k] page_remove_rmap
     1.21%  ld               [kernel.kallsyms]                                 
      [k] __rmqueue_pcplist
     0.92%  ld              
libbfd-2.42.50.20240308.gentoo-sys-devel-binutils-mt.so  [.] bfd_getl16
     0.89%  ld               [kernel.kallsyms]                                 
      [k] stackleak_erase
     0.74%  ld               [kernel.kallsyms]                                 
      [k] __free_one_page
     0.58%  ld               [kernel.kallsyms]                                 
      [k] free_unref_page_prepare
     0.56%  ld               [kernel.kallsyms]                                 
      [k] native_irq_return_iret
     0.47%  ld               [kernel.kallsyms]                                 
      [k] __handle_mm_fault
[...]
```

[0]
https://inbox.sourceware.org/binutils/20240308152443.13534-1-hjl.tools@gmail.com/T/#t

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