From: Hugh Dickins <hughd@xxxxxxxxxx> Date: Wed, 25 Aug 2010 23:12:54 -0700 (PDT) > After several hours, kbuild tests hang with anon_vma_prepare() spinning on > a newly allocated anon_vma's lock - on a box with CONFIG_TREE_PREEMPT_RCU=y > (which makes this very much more likely, but it could happen without). > > The ever-subtle page_lock_anon_vma() now needs a further twist: since > anon_vma_prepare() and anon_vma_fork() are liable to change the ->root > of a reused anon_vma structure at any moment, page_lock_anon_vma() > needs to check page_mapped() again before succeeding, otherwise > page_unlock_anon_vma() might address a different root->lock. > > Signed-off-by: Hugh Dickins <hughd@xxxxxxxxxx> Interesting, is the condition which allows this to trigger specific to this merge window or was it always possible? -- 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>