On Sun, 2014-04-06 at 15:17 -0400, Sasha Levin wrote: > On 03/11/2014 08:40 AM, tip-bot for Mike Galbraith wrote: > > Commit-ID: 156654f491dd8d52687a5fbe1637f472a52ce75b > > Gitweb: > > http://git.kernel.org/tip/156654f491dd8d52687a5fbe1637f472a52ce75b > > Author: Mike Galbraith <bitbuc...@online.de> > > AuthorDate: Fri, 28 Feb 2014 07:23:11 +0100 > > Committer: Ingo Molnar <mi...@kernel.org> > > CommitDate: Tue, 11 Mar 2014 12:05:43 +0100 > > > > sched/numa: Move task_numa_free() to __put_task_struct() > > > > Bad idea on -rt: > > > > [ 908.026136] [<ffffffff8150ad6a>] rt_spin_lock_slowlock+0xaa/0x2c0 > > [ 908.026145] [<ffffffff8108f701>] task_numa_free+0x31/0x130 > > [ 908.026151] [<ffffffff8108121e>] finish_task_switch+0xce/0x100 > > [ 908.026156] [<ffffffff81509c0a>] thread_return+0x48/0x4ae > > [ 908.026160] [<ffffffff8150a095>] schedule+0x25/0xa0 > > [ 908.026163] [<ffffffff8150ad95>] rt_spin_lock_slowlock+0xd5/0x2c0 > > [ 908.026170] [<ffffffff810658cf>] get_signal_to_deliver+0xaf/0x680 > > [ 908.026175] [<ffffffff8100242d>] do_signal+0x3d/0x5b0 > > [ 908.026179] [<ffffffff81002a30>] do_notify_resume+0x90/0xe0 > > [ 908.026186] [<ffffffff81513176>] int_signal+0x12/0x17 > > [ 908.026193] [<00007ff2a388b1d0>] 0x7ff2a388b1cf > > > > and since upstream does not mind where we do this, be a bit nicer ... > > > > Signed-off-by: Mike Galbraith <bitbuc...@online.de> > > Signed-off-by: Peter Zijlstra <pet...@infradead.org> > > Cc: Mel Gorman <mgor...@suse.com> > > Cc: Linus Torvalds <torva...@linux-foundation.org> > > Cc: Andrew Morton <a...@linux-foundation.org> > > Cc: Thomas Gleixner <t...@linutronix.de> > > Link: http://lkml.kernel.org/r/1393568591.6018.27.ca...@marge.simpson.net > > Signed-off-by: Ingo Molnar <mi...@kernel.org> > > As it seems, upstream does mind: > > [ 2590.260734] ====================================================== > [ 2590.261695] [ INFO: HARDIRQ-safe -> HARDIRQ-unsafe lock order detected ] > [ 2590.262748] 3.14.0-next-20140403-sasha-00022-g10224c0 #377 Tainted: G > W > [ 2590.263846] ------------------------------------------------------ > [ 2590.264730] trinity-c244/1210 [HC0[0]:SC0[0]:HE0:SE1] is trying to acquire: > [ 2590.265783] (&(&grp->lock)->rlock){+.+...}, at: task_numa_free > (kernel/sched/fair.c:1714) > [ 2590.267179] > [ 2590.267179] and this task is already holding: > [ 2590.267996] (&(&new_timer->it_lock)->rlock){-.....}, at: exit_itimers > (kernel/posix-timers.c:971 kernel/posix-timers.c:998) > [ 2590.269381] which would create a new lock dependency: > [ 2590.270067] (&(&new_timer->it_lock)->rlock){-.....} -> > (&(&grp->lock)->rlock){+.+...}
I'm not getting it. I moved task_numa_free() from one interrupts enabled spot to another. But, with numa=fake=4 and lockdep enabled, not only does lockdep gripe, my little box locks up on splat. Saying spin_lock/unlock_irq() did the expected, just moved lockdep gripe to task_numa_fault(). > [ 2590.270067] Possible interrupt unsafe locking scenario: > [ 2590.270067] > [ 2590.270067] CPU0 CPU1 > [ 2590.270067] ---- ---- > [ 2590.270067] lock(&(&grp->lock)->rlock); > [ 2590.270067] local_irq_disable(); > [ 2590.270067] > lock(&(&new_timer->it_lock)->rlock); > [ 2590.270067] lock(&(&grp->lock)->rlock); > [ 2590.270067] <Interrupt> > [ 2590.270067] lock(&(&new_timer->it_lock)->rlock); > [ 2590.270067] > [ 2590.270067] *** DEADLOCK *** Ok, so how did I manage that HARDIRQ-safe -> HARDIRQ-unsafe? -Mike -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
