Hi, as discussed in [1] it turned out to be a ipc-sem issue. [ TEST-CASE / USE-CASE (reproducible) ] Build a Linux-Next (next-20130419) kernel with 4 parallel-make-jobs (see scripts-dir in unpacked tarball). [ TRYOUTS ] I tried to switch to "stable" kernel-config options (disable intel_pstate, full-dynticks-cputime, etc.) and/or switch from slub to slab for example. Rik pointed to eventually missing ipc-sem patches and wanted to check his INBOX after the conference he his visiting. Then Davidlohr pointed to three missing ipc-sem patches [3] which did not help here (might be some patches still missing?). Linus helped to trigger down the problem with his "crazy rcu double-free debug hack" [4]. Paul helped with some aid regarding towards RCU debug kconfig (CONFIG_DEBUG_OBJECTS_RCU_HEAD=y). Emmanuel reported same problems especially with gcc-builds (see my test-case). ( What I could not test: Turn off APPARMOR and SELINUX in Ubuntu/precise x86-64. ) All these taken actions did not help. [ TEMPORARY WORKAROUND ] Revert "ipc/sem.c: alternatives to preempt_disable()" Revert "ipc, sem: prevent possible deadlock" Revert "fix for sem_lock" Revert "ipc,sem: fine grained locking for semtimedop" Revert "ipc,sem: have only one list in struct sem_queue" Revert "ipcsem-open-code-and-rename-sem_lock-fix" Revert "ipc,sem: open code and rename sem_lock" Revert "ipcsem-do-not-hold-ipc-lock-more-than-necessary-fix-checkpatch-fixes" Revert "ipc,sem: prevent releasing RCU read lock twice in semctl_main" Revert "ipc,sem: do not hold ipc lock more than necessary" NOTE: I have rebuilt 3 times successfully my latest kernel with these revert-patchset! As some developers attend a conference ATM, I leave this up to you experts. Thanks to all folks with their feedback, help and patches! Hope this pre-analyze helps a bit. Regards, - Sedat - P.S.: All relevant material collected in the attached tarball. [1] http://marc.info/?t=136631457900005&r=1&w=2 [2] http://git.kernel.org/cgit/linux/kernel/git/next/linux-next.git/log/ipc/sem.c?id=next-20130419 [3] http://marc.info/?l=linux-next&m=136640233601913&w=2 [4] http://marc.info/?l=linux-next&m=136640665503325&w=2 [5] https://lkml.org/lkml/2013/3/30/1
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