* Fengguang Wu <wfg@xxxxxxxxxxxxxxxx> wrote: > On Mon, Jan 14, 2008 at 12:41:26PM +0100, Peter Zijlstra wrote: > > > > On Mon, 2008-01-14 at 12:30 +0100, Joerg Platte wrote: > > > Am Montag, 14. Januar 2008 schrieb Fengguang Wu: > > > > > > > Joerg, this patch fixed the bug for me :-) > > > > > > Fengguang, congratulations, I can confirm that your patch fixed the bug! With > > > previous kernels the bug showed up after each reboot. Now, when booting the > > > patched kernel everything is fine and there is no longer any suspicious > > > iowait! > > > > > > Do you have an idea why this problem appeared in 2.6.24? Did somebody change > > > the ext2 code or is it related to the changes in the scheduler? > > > > It was Fengguang who changed the inode writeback code, and I guess the > > new and improved code was less able do deal with these funny corner > > cases. But he has been very good in tracking them down and solving them, > > kudos to him for that work! > > Thank you. > > In particular the bug is triggered by the patch named: > "writeback: introduce writeback_control.more_io to indicate more io" > That patch means to speed up writeback, but unfortunately its > aggressiveness has disclosed bugs in reiserfs, jfs and now ext2. > > Linus, given the number of bugs it triggered, I'd recommend revert > this patch(git commit 2e6883bdf49abd0e7f0d9b6297fc3be7ebb2250b). Let's > push it back to -mm tree for more testings? i dont think a revert at this stage is a good idea and i'm not sure pushing it back into -mm would really expose more of these bugs. And these are real bugs in filesystems - bugs which we want to see fixed anyway. You are also tracking down those bugs very fast. [ perhaps, if it's possible technically (and if it is clean enough), you might want to offer a runtime debug tunable that can be used to switch off the new aspects of your code. That would speed up testing, in case anyone suspects the new writeback code. ] Ingo - 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
