On Wed 13-07-11 03:57:40, Hugh Dickins wrote: > On Tue, 12 Jul 2011, Hugh Dickins wrote: > > On Tue, 12 Jul 2011, Hugh Dickins wrote: > > > On Mon, 11 Jul 2011, Wu Fengguang wrote: > > > > > > > > It's relatively easy to confirm, by reusing the below trace event to > > > > show the inode (together with its state) being requeued. > > > > > > > > If this is the root cause, it may equally be fixed by > > > > > > > > - requeue_io(inode, wb); > > > > + redirty_tail(inode, wb); > > > > > > > > which would be useful in case the bug is so deadly that it's no longer > > > > possible to do tracing. > > > > > > I checked again this morning that I could reproduce it on two machines, > > > one went in a few minutes, the other within the hour. Then I made that > > > patch changing the requeue_io to redirty_tail, and left home with them > > > running the test with the new kernel: we'll see at the end of the day > > > how they fared. > > > > I think that fixes it. The x86_64 is still running with that, but the > > ppc64 gave up fairly early, hitting freeze in __slab_free() instead. > > > > I've now, I believe, reconstituted what ChristophL intended from the > > mm_types.h struct page patch he posted (which applied neither to mmotm, > > nor to Pekka's for-next, so far as I could tell: maybe cl did some > > intermediate tidying of some of the random indentation). So now > > testing that with redirty_tail on ppc64: will report in 9 hours. > > Same result as before. The x86_64 is still going fine, but the ppc64 > again seized up in __slab_free() after two and a half hours of load. > > I think we should assume that your -requeue_io +redirty_tail is a good > fix for the writeback freeze (if you can reassure us, that it does not > risk postponing some writes indefinitely), and I move over to the other > thread to pursue the struct page __slab_free() freeze. Well, I_FREEING or I_WILL_FREE inodes are written back by iput_final() and it is reclaim code that is responsible for eventually removing them. So writeback code can safely ignore them. I_NEW inodes should move out of this state when they are fully set up and in the writeback round following that, we will consider them for writeback. So I think the change really makes sense. Honza -- Jan Kara <jack@xxxxxxx> SUSE Labs, CR -- To unsubscribe from this list: send the line "unsubscribe linux-fsdevel" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
