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Wed, 23 Oct 2019 06:44:15 -0700 (PDT) Received: from uranus.localdomain ([5.18.199.94]) by smtp.gmail.com with ESMTPSA id n11sm13123511lfd.88.2019.10.23.06.44.13 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 23 Oct 2019 06:44:13 -0700 (PDT) Received: by uranus.localdomain (Postfix, from userid 1000) id 4C2A34610AC; Wed, 23 Oct 2019 16:44:13 +0300 (MSK) Date: Wed, 23 Oct 2019 16:44:13 +0300 From: Cyrill Gorcunov To: Thomas Gleixner Cc: LKML , Ingo Molnar , Peter Zijlstra , linux-mm@kvack.org, Catalin Marinas Subject: Re: [BUG -tip] kmemleak and stacktrace cause page faul Message-ID: <20191023134413.GI12121@uranus.lan> References: <20191019114421.GK9698@uranus.lan> <20191022142325.GD12121@uranus.lan> <20191022145619.GE12121@uranus.lan> <20191023133204.GH12121@uranus.lan> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.12.1 (2019-06-15) X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: On Wed, Oct 23, 2019 at 03:38:40PM +0200, Thomas Gleixner wrote: > > > > > > [0,2,4,5,6,8,10,12] are guard pages so 0 is not that crappy at all > > > > Wait, Thomas, I might be wrong, but per-cpu is initialized to the pointer, > > the memory for this estack_pages has not yet been allocated, no? > > static const > struct estack_pages estack_pages[CEA_ESTACK_PAGES] ____cacheline_aligned = { > EPAGERANGE(DF), > EPAGERANGE(NMI), > EPAGERANGE(DB1), > EPAGERANGE(DB), > EPAGERANGE(MCE), > }; > > It's statically allocated. So it's available from the very beginning. Indeed, thanks! I happened to overlooked this moment. ... > And as I explained to you properly decoded the values _ARE_ correct and > make sense. Yes, just posted the diff itself to be sure. Thanks a huge for explanation, Thomas!