[[!meta copyright="Copyright © 2012, 2013, 2014 Free Software Foundation, Inc."]] [[!meta license="""[[!toggle id="license" text="GFDL 1.2+"]][[!toggleable id="license" text="Permission is granted to copy, distribute and/or modify this document under the terms of the GNU Free Documentation License, Version 1.2 or any later version published by the Free Software Foundation; with no Invariant Sections, no Front-Cover Texts, and no Back-Cover Texts. A copy of the license is included in the section entitled [[GNU Free Documentation License|/fdl]]."]]"""]] [[!tag open_issue_hurd]] libports/port-ref.c:31: ports_port_ref: Assertion `pi->refcnt || pi->weakrefcnt' failed This is seen every now and then. # [[gnumach_page_cache_policy]] With that patch in place, the assertion failure is seen more often. ## IRC, freenode, #hurd, 2012-07-14 braunr: I'm getting ext2fs.static: /usr/src/hurd-debian/./libports/port-ref.c:31: ports_port_ref: Assertion `pi->refcnt || pi->weakrefcnt' failed. oddly enough, that happens on one of the buildds only :/ i fear the patch can wake many of these issues ## IRC, freenode, #hurd, 2012-07-15 braunr: same assertion failed on a second buildd can you paste it again please ? ext2fs.static: /usr/src/hurd-debian/./libports/port-ref.c:31: ports_port_ref: Assertion `pi->refcnt || pi->weakrefcnt' failed. or better, answer the ml thread for future reference thanks braunr: I can't keep your patch on the buildds, it makes them too unreliable youpi: ok i never got this error though, that's weird youpi: was the failure during the same build ? no, it was during package installation, and not the same braunr: note that I've already seen such errors, it's not new, but it was way rarer like every month only ah ok yes it's less surprising then a tricky reference counting / locking mistake somewhere in the hurd :) ... ah ! just got it ! braunr: Got the error or found the problem? :) the former unfortunately :/ ## IRC, freenode, #hurd, 2012-07-19 hm, i think those ext2fs port refs errors may also be due to stack overflows --verbose hm ? http://lists.gnu.org/archive/html/bug-hurd/2012-07/msg00051.html i mean, why do you think they could be due to that? the error is that both strong and weak refs in a port are 0 when adding a reference weak refs are almost never used so let's forget about them when a ref count drops to 0, the port is automatically deallocated so what other than memory corruption setting this counter to 0 could possibly do that ? :) one could also guess an unbalanced ref/unref logic, somehow what do you mean ? that for a bug, an early return, etc a port gets unref'ed often than it is ref'ed highly unlikely, as they're protected by a lock pinotree: ah you mean, the object gets deallocated early because of an deref overflow ? pinotree: could be, yes pinotree: i wonder if it could happen because of the periodic sync duplicating the node table without holding references rah, libports uses a big lock in many places :( braunr: yes, i meant that we could try using libduma some day i wonder if it could work out of the box but that wouldn't help to find out whether a port gets deref'ed too often, for instance although it could be adapted to do so, i guess reproducing + a call trace or core would be best, but i'm not even sure we can get that easily lol [[automatic_backtraces_when_assertions_hit]]. # IRC, freenode, #hurd, 2013-10-09 mhmm, i may have an explanation for the weird assertions we sometimes see in ext2fs glibc uses alloca to reserve memory for one reply port per thread in abort_all_rpcs if this erases the thread-specific area, we can expect all kinds of wreckage i'm not sure how to fix this though # IRC, freenode, #hurd, 2014-01-29 ext2fs: ../../libports/port-ref.c:30: ports_port_ref: Assertion `pi->refcnt || pi->weakrefcnt' failed.