RFC: jemalloc: qdbus sigsegv in malloc_init
Gustau Pérez i Querol
gperez at entel.upc.edu
Mon Apr 30 14:12:57 UTC 2012
Hi,
the kde team is seeing some strange problems with the new version
(4.8.1) of devel/dbus-qt4 with current. It does work with stable. I also
suspect that the problem described below is affecting the experimental
cinnamon port (an alternative to gnome3, possible replacement of gnome2).
The problem happens with both i386 and amd64 with empty
/etc/malloc.conf and simple /etc/make.conf. Everything compiled with
base gcc (no clang). The kernel was compiled with no debug support, but
it can enable if needed. There are reports from avilla at freebsd.org of
the same behavior with clang compiled world and kernel and with
MALLOC_PRODUCTION=yes.
When qdbus starts, it segfauts. The backtrace of the problem with
r234769 can be found here: http://pastebin.com/ryBXtqGF. When starting
the qdbus daemon by hand in a X+twm session, we see it calls calloc many
times and after a fixed number of times segfaults. We see it segfaults
at rb_gen (a quite large macro defined at
$SRC_BASE/contrib/jemalloc/include/jemalloc/internal/rb.h).
If the daemon is started by hand, I'm able to skip all the calls qdbus
makes to calloc till the one causing the segfault. At that point, at
rb_gen, we don't exactly know what is going on or how to debug the
macro. Ktrace are available, but we were unable to find anything new
from them.
With old versions of current before the jemalloc imports (as of March
30th) the daemon segfaulted at malloc.c:2426. With revisions during
April 20 to 24th (can be more precise, it was during the jemalloc
imports) the daemon segfaulted at malloc_init. Bts are available if
needed, and if necessary I can go back to those revision and recompile
world+kernel to see its behavior.
Any help from freebsd-current@ (perhaps Jason Evans can help us) will
be appreciated. Any additional info, like source revisions, can be
provided. I would like to stress that the experimental devel/dbus-qt4
works fine with recent stable.
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