aptitude crashes on ARM64 on the kernel 5.8-rc

[Mikulas Patocka]

Hi

Aptitude crashes on the kernel 5.8-rc.

I bisected it and this is the result:

git bisect start
# good: [3d77e6a8804abcc0504c904bd6e5cdf3a5cf8162] Linux 5.7
git bisect good 3d77e6a8804abcc0504c904bd6e5cdf3a5cf8162
# bad: [48778464bb7d346b47157d21ffde2af6b2d39110] Linux 5.8-rc2
git bisect bad 48778464bb7d346b47157d21ffde2af6b2d39110
# bad: [a98f670e41a99f53acb1fb33cee9c6abbb2e6f23] Merge tag 'media/v5.8-1' of git://git.kernel.org/pub/scm/linux/kernel/git/mchehab/linux-media
git bisect bad a98f670e41a99f53acb1fb33cee9c6abbb2e6f23
# bad: [5be993432821750f382809df5e20bf4c129b24f7] mm/hugetlb: define a generic fallback for arch_clear_hugepage_flags()
git bisect bad 5be993432821750f382809df5e20bf4c129b24f7
# bad: [cfa3b8068b09f25037146bfd5eed041b78878bee] Merge tag 'for-linus-hmm' of git://git.kernel.org/pub/scm/linux/kernel/git/rdma/rdma
git bisect bad cfa3b8068b09f25037146bfd5eed041b78878bee
# good: [17e0a7cb6a254c6d086562e7adf8b7ac24d267f3] Merge tag 'x86-cleanups-2020-06-01' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
git bisect good 17e0a7cb6a254c6d086562e7adf8b7ac24d267f3
# bad: [17839856fd588f4ab6b789f482ed3ffd7c403e1f] gup: document and work around "COW can break either way" issue
git bisect bad 17839856fd588f4ab6b789f482ed3ffd7c403e1f
# bad: [c2b0fc847f3122e5a4176c3772626a7a8facced0] Merge tag 'for-linus' of git://git.armlinux.org.uk/~rmk/linux-arm
git bisect bad c2b0fc847f3122e5a4176c3772626a7a8facced0
# good: [342403bcb4dfe41324a0f6f4cb5a8d324f31c725] Merge branches 'for-next/acpi', 'for-next/bpf', 'for-next/cpufeature', 'for-next/docs', 'for-next/kconfig', 'for-next/misc', 'for-next/perf', 'for-next/ptr-auth', 'for-next/sdei', 'for-next/smccc' and 'for-next/vdso' into for-next/core
git bisect good 342403bcb4dfe41324a0f6f4cb5a8d324f31c725
# bad: [082af5ec5080b028f7d0846a6c27cbb87f288205] Merge branch 'for-next/scs' into for-next/core
git bisect bad 082af5ec5080b028f7d0846a6c27cbb87f288205
# good: [67d4a1cd09765db92581dbce8438305ea0e06004] arm64: mm: Mark executable text as guarded pages
git bisect good 67d4a1cd09765db92581dbce8438305ea0e06004
# good: [88485be531f4aee841ddc53b56e2f6e6a338854d] scs: Move scs_overflow_check() out of architecture code
git bisect good 88485be531f4aee841ddc53b56e2f6e6a338854d
# good: [9a964285572b5a3ea268bd744bb6837aecf09640] arm64: vdso: Don't prefix sigreturn trampoline with a BTI C instruction
git bisect good 9a964285572b5a3ea268bd744bb6837aecf09640
# bad: [c350717ec7de67daad26d996efe7f3d97d95aa9c] Merge branch 'for-next/kvm/errata' into for-next/core
git bisect bad c350717ec7de67daad26d996efe7f3d97d95aa9c
# good: [fe677be989146b8a8c0f26fe626c6567c4cd3837] KVM: arm64: Move __load_guest_stage2 to kvm_mmu.h
git bisect good fe677be989146b8a8c0f26fe626c6567c4cd3837
# bad: [d27865279f12035c730818aa1a0280fada866a37] Merge branch 'for-next/bti' into for-next/core
git bisect bad d27865279f12035c730818aa1a0280fada866a37
# good: [a4eb355a3fdad85d16e4b098e8d56bb28b812ce0] arm64: vdso: Fix CFI directives in sigreturn trampoline
git bisect good a4eb355a3fdad85d16e4b098e8d56bb28b812ce0
# first bad commit: [d27865279f12035c730818aa1a0280fada866a37] Merge branch 'for-next/bti' into for-next/core

The stacktrace
(gdb) bt
#0  0x0000007fa6987a78 in ?? () from /lib/aarch64-linux-gnu/libgcc_s.so.1
#1  0x0000007fa6988b44 in ?? () from /lib/aarch64-linux-gnu/libgcc_s.so.1
#2  0x0000007fa6988ef0 in _Unwind_ForcedUnwind () from /lib/aarch64-linux-gnu/libgcc_s.so.1
#3  0x0000007fa6b8a9f4 in __GI___pthread_unwind (buf=<optimized out>) at unwind.c:121
#4  0x0000007fa6b7f098 in __do_cancel () at ./pthreadP.h:309
#5  sigcancel_handler (sig=32, si=0x7fa5f55400, ctx=<optimized out>) at nptl-init.c:192
#6  sigcancel_handler (sig=<optimized out>, si=0x7fa5f55400, ctx=<optimized out>) at nptl-init.c:157
#7  <signal handler called>
#8  0x0000007fa68d7bf0 in __GI___select (nfds=<optimized out>, readfds=0x7fa5f567d8, writefds=0x0, exceptfds=0x0, timeout=0x7fa5f56748)
    at ../sysdeps/unix/sysv/linux/select.c:53
#9  0x0000007fa6f72ba4 in cwidget::toplevel::input_thread::operator()() () from /usr/lib/aarch64-linux-gnu/libcwidget.so.4
#10 0x0000007fa6f72cf0 in void* cwidget::threads::thread::bootstrap<cwidget::threads::bootstrap_proxy<cwidget::toplevel::input_thread> >(void*) ()
   from /usr/lib/aarch64-linux-gnu/libcwidget.so.4
#11 0x0000007fa6b80998 in start_thread (arg=0x7ff639ea4f) at pthread_create.c:479
#12 0x0000007fa68de76c in thread_start () at ../sysdeps/unix/sysv/linux/aarch64/clone.S:78

Mikulas