On Thu, 22 Apr 2010 14:40:46 -0500 (CDT) Christoph Lameter <cl@xxxxxxxxx> wrote: > On Thu, 22 Apr 2010, Mel Gorman wrote: > > > vma_adjust() is updating anon VMA information without any locks taken. > > In constract, file-backed mappings use the i_mmap_lock. This lack of > > locking can result in races with page migration. During rmap_walk(), > > vma_address() can return -EFAULT for an address that will soon be valid. > > This leaves a dangling migration PTE behind which can later cause a > > BUG_ON to trigger when the page is faulted in. > > Isnt this also a race with reclaim / swap? > Yes, it's also race in reclaim/swap ... page_referenced() try_to_unmap(). rmap_walk() <==== we hit this case. But above 2 are not considered to be critical. I'm not sure how this race affect KSM. Thanks, -Kame -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@xxxxxxxxxx For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>