On Tue, Mar 27, 2012 at 09:53:41PM -0700, Hugh Dickins wrote: > On Wed, 28 Mar 2012, Sasha Levin wrote: > > On Tue, Mar 27, 2012 at 1:17 AM, Andrew Morton > > <akpm@xxxxxxxxxxxxxxxxxxxx> wrote: > > > The task is waiting for IO to complete against a page, and it isn't > > > happening. > > > > > > There are quite a lot of things which could cause this, alas. VM, > > > readahead, scheduler, core wait/wakeup code, IO system, interrupt > > > system (if it happens outside KVM, I guess). > > > > > > So.... ugh. Hopefully someone will hit this in a situation where it > > > can be narrowed down or bisected. > > > > I've only managed to reproduce it once, and was unable to get anything > > useful out of it due to technical reasons. > > > > The good part is that I've managed to hit something similar (although > > I'm not 100% sure it's the same problem as the one in the original > > mail). > > I don't think this one has anything to do with the first you posted, > but it does look like a good catch against current linux-next, where > pagemap_pte_range() appears to do a spin_lock(&walk->mm->page_table_lock) > which should have been removed by "thp: optimize away unnecessary page > table locking". Some kind of mismerge perhaps: Horiguchi-san added to Cc. Thanks for reporting. This spin_lock() also exists in mainline, so we need a fix on it. I'll post later for -stable tree. Thanks, Naoya -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@xxxxxxxxx. For more info on Linux MM, see: http://www.linux-mm.org/ . Fight unfair telecom internet charges in Canada: sign http://stopthemeter.ca/ Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>