[Bug gdb/27526] New: Attaching to threaded process on glibc 2.33: libthread_db fails to initialize with "generic error"

[Bug gdb/27526] New: Attaching to threaded process on glibc 2.33: libthread_db fails to initialize with "generic error"

[simark at simark dot ca]

https://sourceware.org/bugzilla/show_bug.cgi?id=27526

            Bug ID: 27526
           Summary: Attaching to threaded process on glibc 2.33:
                    libthread_db fails to initialize with "generic error"
           Product: gdb
           Version: HEAD
            Status: NEW
          Severity: normal
          Priority: P2
         Component: gdb
          Assignee: unassigned at sourceware dot org
          Reporter: simark at simark dot ca
  Target Milestone: ---

As reported here:

  https://sourceware.org/pipermail/gdb/2021-February/049208.html

On a Linux system with glibc 2.33, attaching to a threaded program gives:

$ pidof gnome-calculator 
1476833
(gdb) attach 1476833
Attaching to process 1476833
[New LWP 1476834]
[New LWP 1476835]
[New LWP 1476836]
LOOKUP nptl_version in libpthread.so.0
LOOKUP nptl_version in libpthread.so.0
LOOKUP _rtld_global in ld-linux-x86-64.so.2
LOOKUP _dl_stack_user in (null)
Error while reading shared library symbols for /usr/lib/libpthread.so.0:
Cannot find user-level thread for LWP 1476836: generic error
0x00007fdb0288b6ed in __GI___poll (fds=0x5581bab7b100, nfds=3, timeout=-1) at
../sysdeps/unix/sysv/linux/poll.c:29
29      ../sysdeps/unix/sysv/linux/poll.c: No such file or directory.
(gdb) 

The "LOOKUP" lines come from a print I added in ps_pglobal_lookup to see which
symbols libthread_db asks GDB to look up.

The lookup for _dl_stack_user is new with glibc 2.33, I don't see it with glibc
2.31 (I don't have a system with glibc 2.32 handy).  We fail to find a symbol
with this name, which fails the loading/initialization of libthread_db.

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[Bug gdb/27526] Attaching to threaded process on glibc 2.33: libthread_db fails to initialize with "generic error"

[simark at simark dot ca]

https://sourceware.org/bugzilla/show_bug.cgi?id=27526

--- Comment #1 from Simon Marchi <simark at simark dot ca> ---
The stack trace where the lookup for _dl_stack_user happens:

#0  ps_pglobal_lookup (ph=0x60c000037fe8, obj=0x0, name=0x7fffde34e6bd
"_dl_stack_user", sym_addr=0x6170000477c8) at
/home/simark/src/binutils-gdb/gdb/proc-service.c:102
#1  0x00007fffde34c7cc in td_mod_lookup (ps=<optimized out>, mod=mod@entry=0x0,
idx=idx@entry=54, sym_addr=sym_addr@entry=0x6170000477c8) at
td_symbol_list.c:48
#2  0x00007fffde34b131 in __td_ta_stack_user (ta=ta@entry=0x617000047580,
plist=plist@entry=0x7fffffffb000) at td_thr_validate.c:32
#3  0x00007fffde349b8c in td_ta_map_lwp2thr (ta_arg=0x617000047580,
lwpid=1476836, th=0x7fffffffb0a0) at td_ta_map_lwp2thr.c:190
#4  0x000055555d54fbc2 in thread_from_lwp (stopped=0x61700003a700, ptid=...) at
/home/simark/src/binutils-gdb/gdb/linux-thread-db.c:415
#5  0x000055555d554b6b in try_thread_db_load_1 (info=0x60c000037fc0) at
/home/simark/src/binutils-gdb/gdb/linux-thread-db.c:912
#6  0x000055555d555837 in try_thread_db_load (library=0x555560734260
"libthread_db.so.1", check_auto_load_safe=false) at
/home/simark/src/binutils-gdb/gdb/linux-thread-db.c:1014
#7  0x000055555d55689c in try_thread_db_load_from_sdir () at
/home/simark/src/binutils-gdb/gdb/linux-thread-db.c:1091
#8  0x000055555d557450 in thread_db_load_search () at
/home/simark/src/binutils-gdb/gdb/linux-thread-db.c:1146
#9  0x000055555d557d90 in thread_db_load () at
/home/simark/src/binutils-gdb/gdb/linux-thread-db.c:1203
#10 0x000055555d557e72 in check_for_thread_db () at
/home/simark/src/binutils-gdb/gdb/linux-thread-db.c:1246
#11 0x000055555d557fdf in thread_db_new_objfile (objfile=0x614000007040) at
/home/simark/src/binutils-gdb/gdb/linux-thread-db.c:1275
...

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[Bug gdb/27526] Attaching to threaded process on glibc 2.33: libthread_db fails to initialize with "generic error"

[fweimer at redhat dot com]

https://sourceware.org/bugzilla/show_bug.cgi?id=27526

Florian Weimer <fweimer at redhat dot com> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |fweimer at redhat dot com

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[Bug gdb/27526] Attaching to threaded process on glibc 2.33: libthread_db fails to initialize with "generic error"

[vries at gcc dot gnu.org]

https://sourceware.org/bugzilla/show_bug.cgi?id=27526

Tom de Vries <vries at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |vries at gcc dot gnu.org

--- Comment #2 from Tom de Vries <vries at gcc dot gnu.org> ---
Looks like a duplicate of PR25674.

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[Bug gdb/27526] Attaching to threaded process on glibc 2.33: libthread_db fails to initialize with "generic error"

[simark at simark dot ca]

https://sourceware.org/bugzilla/show_bug.cgi?id=27526

--- Comment #3 from Simon Marchi <simark at simark dot ca> ---
(In reply to Tom de Vries from comment #2)
> Looks like a duplicate of PR25674.

Even though it's the same error message ("Generic error", not very
descriptive), I don't think it's the same root cause.  PR25674 looks like a
race condition when attaching, this one is caused by a change in glibc.

See: https://sourceware.org/pipermail/gdb-patches/2021-March/176787.html

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[Bug gdb/27526] Attaching to threaded process on glibc 2.33: libthread_db fails to initialize with "generic error"

[crvisqr at gmail dot com]

https://sourceware.org/bugzilla/show_bug.cgi?id=27526

crvi <crvisqr at gmail dot com> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |crvisqr at gmail dot com

--- Comment #4 from crvi <crvisqr at gmail dot com> ---
Same here in fedora rawhide with glibc-2.33 and gdb-10.1-15.fc35.

Any suggested workarounds ?

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[Bug gdb/27526] Attaching to threaded process on glibc 2.33: libthread_db fails to initialize with "generic error"

[simark at simark dot ca]

https://sourceware.org/bugzilla/show_bug.cgi?id=27526

Simon Marchi <simark at simark dot ca> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
   Target Milestone|---                         |11.1

--- Comment #5 from Simon Marchi <simark at simark dot ca> ---
(In reply to crvi from comment #4)
> Same here in fedora rawhide with glibc-2.33 and gdb-10.1-15.fc35.
> 
> Any suggested workarounds ?


I don't see a workaround for this, we'll need a proper fix in GDB.  I'm marking
this bug with the 11.1 target milestone, I don't think we'll want to release
GDB 11 without a fix for this.

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[Bug gdb/27526] Attaching to threaded process on glibc 2.33: libthread_db fails to initialize with "generic error"

[vries at gcc dot gnu.org]

https://sourceware.org/bugzilla/show_bug.cgi?id=27526

--- Comment #6 from Tom de Vries <vries at gcc dot gnu.org> ---
Patch posted:
https://sourceware.org/pipermail/gdb-patches/2021-March/177369.html

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[Bug gdb/27526] Attaching to threaded process on glibc 2.33: libthread_db fails to initialize with "generic error"

[simark at simark dot ca]

https://sourceware.org/bugzilla/show_bug.cgi?id=27526

Simon Marchi <simark at simark dot ca> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
   Target Milestone|11.1                        |10.2

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[Bug gdb/27526] Attaching to threaded process on glibc 2.33: libthread_db fails to initialize with "generic error"

[vries at gcc dot gnu.org]

https://sourceware.org/bugzilla/show_bug.cgi?id=27526

--- Comment #7 from Tom de Vries <vries at gcc dot gnu.org> ---
It seems there's a glibc PR27744 - "Support different libpthread/ld.so load
orders in libthread_db" with a commit that should fix this on the glibc side.

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[Bug gdb/27526] Attaching to threaded process on glibc 2.33: libthread_db fails to initialize with "generic error"

[vries at gcc dot gnu.org]

https://sourceware.org/bugzilla/show_bug.cgi?id=27526

Tom de Vries <vries at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
           See Also|                            |https://sourceware.org/bugz
                   |                            |illa/show_bug.cgi?id=27744

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[Bug gdb/27526] Attaching to threaded process on glibc 2.33: libthread_db fails to initialize with "generic error"

[simark at simark dot ca]

https://sourceware.org/bugzilla/show_bug.cgi?id=27526

--- Comment #8 from Simon Marchi <simark at simark dot ca> ---
I posted a v2 here:

https://sourceware.org/pipermail/gdb-patches/2021-May/178485.html

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[Bug gdb/27526] Attaching to threaded process on glibc 2.33: libthread_db fails to initialize with "generic error"

[brobecker at gnat dot com]

https://sourceware.org/bugzilla/show_bug.cgi?id=27526

Joel Brobecker <brobecker at gnat dot com> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
   Target Milestone|10.2                        |11.1
                 CC|                            |brobecker at gnat dot com

--- Comment #9 from Joel Brobecker <brobecker at gnat dot com> ---
Important fix to have for our next release.

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[Bug gdb/27526] Attaching to threaded process on glibc 2.33: libthread_db fails to initialize with "generic error"

[brobecker at gnat dot com]

https://sourceware.org/bugzilla/show_bug.cgi?id=27526

--- Comment #10 from Joel Brobecker <brobecker at gnat dot com> ---
Hello,

Now that https://sourceware.org/pipermail/gdb-patches/2021-June/179786.html has
been pushed to master, do we have anything left to do for this PR, or can we
close?

Thank you!

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[Bug gdb/27526] Attaching to threaded process on glibc 2.33: libthread_db fails to initialize with "generic error"

[simark at simark dot ca]

https://sourceware.org/bugzilla/show_bug.cgi?id=27526

Simon Marchi <simark at simark dot ca> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|NEW                         |RESOLVED
         Resolution|---                         |FIXED

--- Comment #11 from Simon Marchi <simark at simark dot ca> ---
(In reply to Joel Brobecker from comment #10)
> Hello,
> 
> Now that https://sourceware.org/pipermail/gdb-patches/2021-June/179786.html
> has been pushed to master, do we have anything left to do for this PR, or
> can we close?
> 
> Thank you!

Yes, let's close it.  If any related problem pops up, it will be a new PR.

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