2009/3/31 Jan Kara <jack@xxxxxxx>: > On Thu 26-03-09 01:38:32, Alexander Beregalov wrote: >> 2009/3/25 Jan Kara <jack@xxxxxxx>: >> > On Wed 25-03-09 20:07:46, Alexander Beregalov wrote: >> >> 2009/3/25 Jan Kara <jack@xxxxxxx>: >> >> > On Wed 25-03-09 18:29:10, Alexander Beregalov wrote: >> >> >> 2009/3/25 Jan Kara <jack@xxxxxxx>: >> >> >> > On Wed 25-03-09 18:18:43, Alexander Beregalov wrote: >> >> >> >> 2009/3/25 Jan Kara <jack@xxxxxxx>: >> >> >> >> >> > So, I think I need to try it on 2.6.29-rc7 again. >> >> >> >> >> I've looked into this. Obviously, what's happenning is that we delete >> >> >> >> >> an inode and jbd2_journal_release_jbd_inode() finds inode is just under >> >> >> >> >> writeout in transaction commit and thus it waits. But it gets never woken >> >> >> >> >> up and because it has a handle from the transaction, every one eventually >> >> >> >> >> blocks on waiting for a transaction to finish. >> >> >> >> >> But I don't really see how that can happen. The code is really >> >> >> >> >> straightforward and everything happens under j_list_lock... Strange. >> >> >> >> > BTW: Is the system SMP? >> >> >> >> No, it is UP system. >> >> >> > Even stranger. And do you have CONFIG_PREEMPT set? >> >> >> > >> >> >> >> The bug exists even in 2.6.29, I posted it with a new topic. >> >> >> > OK, I've sort-of expected this. >> >> >> >> >> >> CONFIG_PREEMPT_RCU=y >> >> >> CONFIG_PREEMPT_RCU_TRACE=y >> >> >> # CONFIG_PREEMPT_NONE is not set >> >> >> # CONFIG_PREEMPT_VOLUNTARY is not set >> >> >> CONFIG_PREEMPT=y >> >> >> CONFIG_DEBUG_PREEMPT=y >> >> >> # CONFIG_PREEMPT_TRACER is not set >> >> >> >> >> >> config is attached. >> >> > Thanks for the data. I still don't see how the wakeup can get lost. The >> >> > process even cannot be preempted when we are in the section protected by >> >> > j_list_lock... Can you send me a disassembly of functions >> >> > jbd2_journal_release_jbd_inode() and journal_submit_data_buffers() so that >> >> > I can see whether the compiler has not reordered something unexpectedly? >> > Thanks for the disassembly... >> > >> >> By default gcc inlines journal_submit_data_buffers() >> >> Here is -fno-inline version. Default version is in attach. > <snip> > > I'm helpless here. I don't see how we can miss a wakeup (plus you seem to > be the only one reporting the bug). Could you please compile and test the kernel > with the attached patch? It will print to kernel log when we go to sleep > waiting for inode commit and when we send wakeups etc. When you hit the > deadlock, please send me your kernel log. It should help with debugging why do > we miss the wakeup. Thanks. Which patch? -- To unsubscribe from this list: send the line "unsubscribe linux-ext4" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
