Hi, I'm trying revive an old debate here[1], though with a simpler approach than was previously tried. This patch series implements a new option to sanitize freed pages, a (very) small subset of what is done in PaX/grsecurity[3], inspired by a previous submission [4]. The first patch is fairly independent, and could be taken as-is. The second is the meat and should be straight-forward to review. There are a few different uses that this can cover: - some cases of use-after-free could be detected (crashes), although this not as efficient as KAsan/kmemcheck - it can help with long-term memory consumption in an environment with multiple VMs and Kernel Same-page Merging on the host. [2] - finally, it can reduce infoleaks, although this is hard to measure. The approach is voluntarily kept as simple as possible. A single configuration option, no command line option, no sysctl nob. It can of course be changed, although I'd be wary of runtime-configuration options that could be used for races. I haven't been able to measure a meaningful performance difference when compiling a (in-cache) kernel; I'd be interested to see what difference it makes with your particular workload/hardware (I suspect mine is CPU-bound on this small laptop). [1] https://lwn.net/Articles/334747/ [2] https://staff.aist.go.jp/k.suzaki/EuroSec12-SUZAKI-revised2.pdf [3] http://en.wikibooks.org/wiki/Grsecurity/Appendix/Grsecurity_and_PaX_Configuration_Options#Sanitize_all_freed_memory [4] http://article.gmane.org/gmane.linux.kernel.mm/34398 Anisse Astier (2): mm/page_alloc.c: cleanup obsolete KM_USER* mm/page_alloc.c: add config option to sanitize freed pages mm/Kconfig | 12 ++++++++++++ mm/page_alloc.c | 15 +++++++-------- 2 files changed, 19 insertions(+), 8 deletions(-) -- 1.9.3 -- 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/ . Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>