* [next-20130419] ipc: sem: BROKEN
@ 2013-04-20 12:42 Sedat Dilek
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From: Sedat Dilek @ 2013-04-20 12:42 UTC (permalink / raw)
To: Linus Torvalds, Davidlohr Bueso, Rik van Riel
Cc: LKML, Andrew Morton, Emmanuel Benisty, linux-mm,
Stephen Rothwell, linux-next, Paul McKenney, Paul McKenney
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as discussed in  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  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" .
Paul helped with some aid regarding towards RCU debug kconfig
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 "ipc,sem: open code and rename sem_lock"
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
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.
- Sedat -
P.S.: All relevant material collected in the attached tarball.
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