Hugh Dickins <hughd@xxxxxxxxxx> writes: > A process spent 30 minutes exiting, just munlocking the pages of a large > anonymous area that had been alternately mprotected into page-sized vmas: > for every single page there's an anon_vma walk through all the other > little vmas to find the right one. We had the same problem recently after a mmap+touch workload: in this case it was hugepaged walking all these anon_vmas and the list was over 100k long. Had some data on this at plumbers: http://halobates.de/plumbers-fork-locks_v2.pdf > A general fix to that would be a lot more complicated (use prio_tree on > anon_vma?), but there's one very simple thing we can do to speed up the > common case: if a page to be munlocked is mapped only once, then it is > our vma that it is mapped into, and there's no need whatever to walk > through all the others. I think we need a generic fix, this problem does not only happen in munmap. -Andi -- ak@xxxxxxxxxxxxxxx -- Speaking for myself only -- 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>