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Date: Thu, 5 Mar 2020 17:16:22 +0800 From: Walter Wu <walter-zh.wu@...iatek.com> To: Peter Zijlstra <peterz@...radead.org> CC: Randy Dunlap <rdunlap@...radead.org>, <akpm@...ux-foundation.org>, <broonie@...nel.org>, <linux-fsdevel@...r.kernel.org>, <linux-kernel@...r.kernel.org>, <linux-mm@...ck.org>, <linux-next@...r.kernel.org>, <mhocko@...e.cz>, <mm-commits@...r.kernel.org>, <sfr@...b.auug.org.au>, Josh Poimboeuf <jpoimboe@...hat.com>, <dvyukov@...gle.com>, Stephen Rothwell <sfr@...b.auug.org.au> Subject: Re: mmotm 2020-03-03-22-28 uploaded (warning: objtool:) 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; > > }
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