On Wed, 2012-10-24 at 17:08 -0700, David Rientjes wrote: > Ok, this looks the same but it's actually a different issue: > mpol_misplaced(), which now only exists in linux-next and not in 3.7-rc2, > calls get_vma_policy() which may take the shared policy mutex. This > happens while holding page_table_lock from do_huge_pmd_numa_page() but > also from do_numa_page() while holding a spinlock on the ptl, which is > coming from the sched/numa branch. > > Is there anyway that we can avoid changing the shared policy mutex back > into a spinlock (it was converted in b22d127a39dd ["mempolicy: fix a race > in shared_policy_replace()"])? > > Adding Peter, Rik, and Mel to the cc.
Urgh, crud I totally missed that. So the problem is that we need to compute if the current page is placed 'right' while holding pte_lock in order to avoid multiple pte_lock acquisitions on the 'fast' path. I'll look into this in a bit, but one thing that comes to mind is having both a spnilock and a mutex and require holding both for modification while either one is sufficient for read. That would allow sp_lookup() to use the spinlock, while insert and replace can hold both. Not sure it will work for this, need to stare at this code a little more. -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
