On Wed, 2015-02-11 at 16:34 -0800, Paul E. McKenney wrote: > Hello! > > Did an earlier-than-usual port of v3.21 patches to post-v3.19, and > hit the following on x86_64. This happened after about 15 minutes of > rcutorture. In contrast, I have been doing successful 15-hour runs > on v3.19. I will check reproducibility and try to narrow it down. > Might this be a duplicate of the bug that Raghavendra posted a fix for? > > Anyway, this was on 3e8c04eb1174 (Merge branch 'for-3.20' of > git://git.kernel.org/pub/scm/linux/kernel/git/tj/libata). > > [ 837.287011] BUG: spinlock bad magic on CPU#0, migration/0/9 > [ 837.287013] lock: 0xffff88001ea0fe80, .magic: ffffffff, .owner: > gî<81>ÿÿÿÿ/0, .owner_cpu: -42 > [ 837.287013] CPU: 0 PID: 9 Comm: migration/0 Not tainted 3.19.0+ #1 > [ 837.287013] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS > Bochs 01/01/2011 > [ 837.287013] ffff88001ea0fe80 ffff88001ea0bc78 ffffffff818f6f4b > ffffffff810a5a51 > [ 837.287013] ffffffff81e500e0 ffff88001ea0bc98 ffffffff818f3755 > ffff88001ea0fe80 > [ 837.287013] ffffffff81ca4396 ffff88001ea0bcb8 ffffffff818f377b > ffff88001ea0fe80 > [ 837.287013] Call Trace: > [ 837.287013] [<ffffffff818f6f4b>] dump_stack+0x45/0x57 > [ 837.287013] [<ffffffff810a5a51>] ? console_unlock+0x1f1/0x4c0 > [ 837.287013] [<ffffffff818f3755>] spin_dump+0x8b/0x90 > [ 837.287013] [<ffffffff818f377b>] spin_bug+0x21/0x26 > [ 837.287013] [<ffffffff8109923c>] do_raw_spin_unlock+0x5c/0xa0 > [ 837.287013] [<ffffffff81902587>] _raw_spin_unlock_irqrestore+0x27/0x50 > [ 837.287013] [<ffffffff8108f0a1>] complete+0x41/0x50
We did have some recent changes in completions: 7c34e318 (sched/completion: Add lock-free checking of the blocking case) de30ec47 (sched/completion: Remove unnecessary ->wait.lock serialization when reading completion state) The second one being more related (although both appear to make sense). Perhaps some subtle implication in the completion_done side that disappeared with the spinlock? Thanks, Davidlohr -- 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/