On Tue, Dec 08, 2015 at 05:12:04PM +0100, Dmitry Vyukov wrote: > On Tue, Dec 8, 2015 at 4:24 AM, Alexei Starovoitov > <alexei.starovoi...@gmail.com> wrote: > > On Mon, Dec 07, 2015 at 05:09:21PM +0100, Dmitry Vyukov wrote: > >> > So it would be _awesome_ if we could somehow extend this callchain to > >> > include the site that calls call_rcu(). > >> > >> We have a patch for KASAN in works that adds so-called stack depot > >> which allows to map a stack trace onto uint32 id. Then we can plumb > > > > I was hacking something similar to categorize stack traces with u32 id. > > How are you planning to limit the number of such stack traces ? > > and what is the interface for user space to get stack trace from an id? > > > We don't limit number of stack traces. Kernel does not seem to use > data-driven recursion extensively, so there is limited number of > stacks. Though, probably we will need to strip non-interrupt part for > interrupt stacks, otherwise that can produce unbounded number of > different stacks. > There is no interface for user-space, it is used only inside of kernel > to save stacks for memory blocks (rcu callbacks, thread pool items in > the future). > The design is based on what we successfully and extensively use in > user-space sanitizers for years. Current code is here: > https://github.com/ramosian-glider/kasan/commit/fb0eefd212366401ed5ad244233ef379a27bfb46
why did you pick approach to never free accumulated stacks? That limits usability a lot, since once kasan starts using it only reboot will free the memory. ouch. what worked for user space doesn't work for kernel. -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
