On Tue 24-04-18 13:00:11, Mikulas Patocka wrote: > > > On Tue, 24 Apr 2018, Michal Hocko wrote: > > > On Tue 24-04-18 11:50:30, Mikulas Patocka wrote: > > > > > > > > > On Tue, 24 Apr 2018, Michal Hocko wrote: > > > > > > > On Mon 23-04-18 20:06:16, Mikulas Patocka wrote: > > > > [...] > > > > > @@ -404,6 +405,12 @@ void *kvmalloc_node(size_t size, gfp_t f > > > > > */ > > > > > WARN_ON_ONCE((flags & GFP_KERNEL) != GFP_KERNEL); > > > > > > > > > > +#ifdef CONFIG_DEBUG_SG > > > > > + /* Catch bugs when the caller uses DMA API on the result of > > > > > kvmalloc. */ > > > > > + if (!(prandom_u32_max(2) & 1)) > > > > > + goto do_vmalloc; > > > > > +#endif > > > > > > > > I really do not think there is anything DEBUG_SG specific here. Why you > > > > simply do not follow should_failslab path or even reuse the function? > > > > > > CONFIG_DEBUG_SG is enabled by default in RHEL and Fedora debug kernel (if > > > you don't like CONFIG_DEBUG_SG, pick any other option that is enabled > > > there). > > > > Are you telling me that you are shaping a debugging functionality basing > > on what RHEL has enabled? And you call me evil. This is just rediculous. > > > > > Fail-injection framework is if off by default and it must be explicitly > > > enabled and configured by the user - and most users won't enable it. > > > > It can be enabled easily. And if you care enough for your debugging > > kernel then just make it enabled unconditionally. > > So, should we add a new option CONFIG_KVMALLOC_FALLBACK_DEFAULT? I'm not > quite sure if 3 lines of debugging code need an extra option, but if you > don't want to reuse any existing debug option, it may be possible. Adding > it to the RHEL debug kernel would be trivial.
Wouldn't it be equally trivial to simply enable the fault injection? You would get additional failure paths testing as a bonus. -- Michal Hocko SUSE Labs
