http://bugzilla.kernel.org/show_bug.cgi?id=12579 ------- Comment #14 from aneesh.kumar@xxxxxxxxxxxxxxxxxx 2009-02-14 01:42 ------- On Sat, Feb 14, 2009 at 02:10:04PM +0530, Aneesh Kumar K.V wrote: > On Fri, Feb 13, 2009 at 08:50:18PM -0500, Theodore Tso wrote: > > > Patch from Aneesh, un-whitespace-mangled. > > > > > > Ted, can you push this out? Works great. :) We might want to ask > > > the other reporter of something similar (next-20090206: deadlock on > > > ext4) to test it too. I'll ping him. > > > > Do we completely understand the root cause, in terms of which commit > > broken the mm/page-writeback.c code we were depending on? And if so, > > what of the code in mm/page-writeback.c? Does anyone else use it? > > Can anyone sanely use it? > > AFAIU we need the changes even for older kernels. The > reasoning is, with delayed allocation we cannot allow to retry with lower > page index in write_cache_pages. We do retry even in older version of > kernel. What made it so easy to reproduce it on later kernels is that > we were doing a retry even if nr_to_write was zero. This got fixed on > mainline by 3a4c6800f31ea8395628af5e7e490270ee5d0585. So with that > change we are logically back to 2.6.28 state, But still the possibility > of deadlock remain. > I found commit 31a12666d8f0c22235297e1c1575f82061480029 to be the root cause. The commit is correct in what it does. Ext4 was dependent on the wrong behaviour. The relevant change is @@ -897,7 +903,6 @@ retry: min(end - index, (pgoff_t)PAGEVEC_SIZE-1) + 1))) { unsigned i; - scanned = 1; for (i = 0; i < nr_pages; i++) { I think that caused us the retry. That would imply we may not need the patch I did for 2.6.28. But given that Ext4 was dependent on the wrong behaviour of write_cache_pages i would suggest we still push the patch to 2.6.28 -aneesh -- Configure bugmail: http://bugzilla.kernel.org/userprefs.cgi?tab=email ------- You are receiving this mail because: ------- You are the assignee for the bug, or are watching the assignee. -- 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
