On 07/10/14 01:59, Vegard Nossum wrote: > On 9 July 2014 23:44, Andi Kleen <andi@xxxxxxxxxxxxxx> wrote: >> Dave Hansen <dave.hansen@xxxxxxxxx> writes: >>> >>> You're also claiming that "KASAN is better than all of >> >> better as in finding more bugs, but surely not better as in >> "do so with less overhead" >> >>> CONFIG_DEBUG_PAGEALLOC". So should we just disallow (or hide) >>> DEBUG_PAGEALLOC on kernels where KASAN is available? >> >> I don't think DEBUG_PAGEALLOC/SLUB debug and kasan really conflict. >> >> DEBUG_PAGEALLOC/SLUB is "much lower overhead but less bugs found". >> KASAN is "slow but thorough" There are niches for both. >> >> But I could see KASAN eventually deprecating kmemcheck, which >> is just incredible slow. > > FWIW, I definitely agree with this -- if KASAN can do everything that > kmemcheck can, it is no doubt the right way forward. > AFAIK kmemcheck could catch reads of uninitialized memory. KASAN can't do it now, but It should be possible to implementation. There is such tool for userspace - https://code.google.com/p/memory-sanitizer/wiki/MemorySanitizer However detection of reads of uninitialized memory will require a different shadow encoding. Therefore I think it would be better to make it as a separate feature, incompatible with kasan. > > Vegard > -- 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>