On Tue, 2009-09-08 at 12:00 +0100, Mel Gorman wrote: > On Sat, Sep 05, 2009 at 10:28:37AM -0400, Theodore Tso wrote: > > On Thu, Sep 03, 2009 at 01:49:14PM +0100, Mel Gorman wrote: > > > > > > > > This looks very similar to the kmemleak ext4 reports upon a mount. If > > > > it is the same issue, which from the trace it seems it is, then this > > > > is due to an extra kmalloc() allocation and this apparently will not > > > > get fixed on 2.6.31 due to the closeness of the merge window and the > > > > non-criticalness this issue has been deemed. > > > > No, it's a different problem. > > > > > I suspect the more pressing concern is why is this kmalloc() resulting in > > > an order-5 allocation request? What size is the buffer being requested? > > > Was that expected? What is the contents of /proc/slabinfo in case a buffer > > > that should have required order-1 or order-2 is using a higher order for > > > some reason. > > > > It's allocating 68,000 bytes for the mb_history structure, which is > > used for debugging purposes. That's why it's optional and we continue > > if it's not allocated. We should fix it to use vmalloc() > > You could call with kmalloc(FLAGS|GFP_NOWARN) with a fallback to > vmalloc() and a disable if vmalloc() fails as well. Maybe check out what > kernel/profile.c#profile_init() to allocate a large buffer and do something > similar? > > > and I'm > > inclined to turn it off by default since it's not worth the overhead, > > and most ext4 users won't find it useful or interesting. > > > > I can't comment as I don't know what sort of debugging it's useful for. > Perhaps this is a suitable use for the new proposed flex_array? From an initial glance, I can't see why the allocated memory has to be contiguous.. http://lwn.net/Articles/345273/ Cheers, Simon -- To unsubscribe from this list: send the line "unsubscribe linux-wireless" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
