On Thu, 2020-03-05 at 09:18 +0100, Peter Zijlstra wrote: > On Thu, Mar 05, 2020 at 09:17:17AM +0100, Peter Zijlstra wrote: > > On Wed, Mar 04, 2020 at 09:34:49AM -0800, Randy Dunlap wrote: > > > > mm/kasan/common.o: warning: objtool: kasan_report()+0x13: call to report_enabled() with UACCESS enabled > > > > I used next/master instead, and found the below broken commit > > responsible for this. > > > @@ -634,12 +637,20 @@ void kasan_free_shadow(const struct vm_struct *vm) > > #endif > > > > extern void __kasan_report(unsigned long addr, size_t size, bool is_write, unsigned long ip); > > +extern bool report_enabled(void); > > > > -void kasan_report(unsigned long addr, size_t size, bool is_write, unsigned long ip) > > +bool kasan_report(unsigned long addr, size_t size, bool is_write, unsigned long ip) > > { > > - unsigned long flags = user_access_save(); > > + unsigned long flags; > > + > > + if (likely(!report_enabled())) > > + return false; > > This adds an explicit call before the user_access_save() and that is a > straight on bug. > Hi Peter, Thanks for your help. Unfortunately, I don't reproduce it in our environment, so I have asked Stephen, if I can reproduce it, then we will send new patch. Thanks. Walter > > + > > + flags = user_access_save(); > > __kasan_report(addr, size, is_write, ip); > > user_access_restore(flags); > > + > > + return true; > > }