Hi, On Wed, 9 Jan 2019 00:27:03 +0200 Faidon Liambotis <parav...@debian.org> wrote: > So jemalloc 5.1.0-2 was recently uploaded to unstable. The build currently > fails due to the explicit dependency on libjemalloc1 (cf. #918741), but as > soon as this gets fixed, another issue is uncovered: > > While building this package, the jemalloc test deadlocks, and the build > hangs. This can be easily reproduced as follows: > apt install libfakechroot libjemalloc2 > LD_PRELOAD="libjemalloc.so.2 libfakechroot.so" /bin/true > <hangs> > > The test isn't spurious but an actual issue. One could do: > fakechroot <binary compiled with -ljemalloc> > ...and still hit this bug. > > The bug is effectively the same as #872669, which I had previously > resolved by disabling jemalloc's --enable-prof. This option was > re-enabled in 5.x (I forgot about that bug :/) and... I'd like to keep > it that way, so I tried to troubleshoot this further. > > It looks like there's a preloading loop between those libraries that > results in deadlocking. Effectively, during its initialization > (malloc_init) jemalloc tries to initialize libgcc's unwind code > (_Unwind_Backtrace), which in turn calls dl_iterate_phdr, which is > captured by libfakechroot, which calls dlsym()/dlerror(), which tries to > allocate memory back again, which deadlocks jemalloc. > > The backtrace is (note how #6 and #20 are the same): > #0 __lll_lock_wait () at ../sysdeps/unix/sysv/linux/x86_64/lowlevellock.S:103 > #1 0x00007fd764008704 in __GI___pthread_mutex_lock (mutex=0x7fd7647a0500 > <init_lock+64>) at ../nptl/pthread_mutex_lock.c:80 > #2 0x00007fd76475f0dc in malloc_mutex_lock_final (mutex=0x7fd7647a04c0 > <init_lock>) at include/jemalloc/internal/mutex.h:141 > #3 je_malloc_mutex_lock_slow (mutex=mutex@entry=0x7fd7647a04c0 <init_lock>) > at src/mutex.c:84 > #4 0x00007fd76470e244 in malloc_mutex_lock (mutex=0x7fd7647a04c0 > <init_lock>, tsdn=0x0) at include/jemalloc/internal/mutex.h:205 > #5 malloc_init_hard () at src/jemalloc.c:1506 > #6 0x00007fd76471524d in malloc_init () at src/jemalloc.c:217 > #7 imalloc (dopts=<synthetic pointer>, sopts=<synthetic pointer>) at > src/jemalloc.c:1986 > #8 calloc (num=num@entry=1, size=size@entry=32) at src/jemalloc.c:2138 > #9 0x00007fd763ff8a25 in _dlerror_run (operate=operate@entry=0x7fd763ff8390 > <dlsym_doit>, args=args@entry=0x7ffdd14ddfa0) at dlerror.c:141 > #10 0x00007fd763ff840f in __dlsym (handle=<optimized out>, name=<optimized > out>) at dlsym.c:70 > #11 0x00007fd7644f49b4 in ?? () from > /usr/lib/x86_64-linux-gnu/fakechroot/libfakechroot.so > #12 0x00007fd7644edffc in dl_iterate_phdr () from > /usr/lib/x86_64-linux-gnu/fakechroot/libfakechroot.so > #13 0x00007fd763ff02a1 in _Unwind_Find_FDE (pc=0x7fd763fee867 > <_Unwind_Backtrace+55>, bases=bases@entry=0x7ffdd14de368) at > ../../../src/libgcc/unwind-dw2-fde-dip.c:469 > #14 0x00007fd763fec983 in uw_frame_state_for > (context=context@entry=0x7ffdd14de2c0, fs=fs@entry=0x7ffdd14de110) at > ../../../src/libgcc/unwind-dw2.c:1257 > #15 0x00007fd763fedb60 in uw_init_context_1 (context=0x7ffdd14de2c0, > outer_cfa=0x7ffdd14de570, outer_ra=0x7fd76476a878 <je_prof_boot2+56>) > at ../../../src/libgcc/unwind-dw2.c:1586 > #16 0x00007fd763fee868 in _Unwind_Backtrace (trace=trace@entry=0x7fd76475fdb0 > <prof_unwind_init_callback>, trace_argument=trace_argument@entry=0x0) > at ../../../src/libgcc/unwind.inc:295 > #17 0x00007fd76476a878 in je_prof_boot2 (tsd=tsd@entry=0x7fd763fd7740) at > src/prof.c:2392 > #18 0x00007fd76470e308 in malloc_init_hard () at src/jemalloc.c:1538 > #19 malloc_init_hard () at src/jemalloc.c:1500 > #20 0x00007fd764710a85 in malloc_init () at src/jemalloc.c:217 > > I don't think it's a bug on either library per se. I was wondering if > you had any insight on how we could address this in fakechroot somehow > rather than in jemalloc, as that doesn't look to be easy without disabling > the profiling feature.
Maybe you can report this directly to upstream? Until it is properly fixed upstream we can just temporarily disable --enable-prof, right? Thanks! cheers, josch
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