On Mon, May 15, 2017 at 9:34 PM, Dmitry Vyukov <dvyukov@xxxxxxxxxx> wrote: > On Mon, May 15, 2017 at 6:16 PM, <js1304@xxxxxxxxx> wrote: >> From: Joonsoo Kim <iamjoonsoo.kim@xxxxxxx> >> >> Hello, all. >> >> This is an attempt to recude memory consumption of KASAN. Please see >> following description to get the more information. >> >> 1. What is per-page shadow memory > > Hi Joonsoo, > > First I need to say that this is great work. I wanted KASAN to consume > 1/8-th of _kernel_ memory rather than total physical memory for a long > time. > > However, this implementation does not work inline instrumentation. And > the inline instrumentation is the main mode for KASAN. Outline > instrumentation is merely a rudiment to support gcc 4.9, and it needs > to be removed as soon as we stop caring about gcc 4.9 (do we at all? > is it the current compiler in any distro? Ubuntu 12 has 4.8, Ubuntu 14 > already has 5.4. And if you build gcc yourself or get a fresher > compiler from somewhere else, you hopefully get something better than > 4.9). > > Here is an example boot+scp log with inline instrumentation: > https://gist.githubusercontent.com/dvyukov/dfdc8b6972ddd260b201a85d5d5cdb5d/raw/2a032cd5be371c7ad6cad8f14c0a0610e6fa772e/gistfile1.txt > > Joonsoo, can you think of a way to take advantages of your approach, > but make it work with inline instrumentation? > > Will it work if we map a single zero page for whole shadow initially, > and then lazily map real shadow pages only for kernel memory, and then > remap it again to zero pages when the whole KASAN_SHADOW_SCALE_SHIFT > range of pages becomes unused (similarly to what you do in > kasan_unmap_shadow())? Just in case, I've uploaded a squashed version of this to codereview site, if somebody will find it useful: https://codereview.appspot.com/325780043 (side-by-side diffs is what you want) -- 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>
