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* [next-20130419] ipc: sem: BROKEN
@ 2013-04-20 12:42 Sedat Dilek
  0 siblings, 0 replies; only message in thread
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 [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).


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

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.


      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

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.


[-- Attachment #2: revert-ipc-sem-next_from-dileks.tar.xz --]
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e700454434c40bbd45638f3d83312b9142eabacf5ba6be8b82792dd912d2888f  revert-ipc-sem-next_from-dileks.tar.xz

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