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Mon, 04 Apr 2022 01:10:09 -0700 (PDT) Date: Mon, 4 Apr 2022 10:10:03 +0200 From: Marco Elver To: Hyeonggon Yoo <42.hyeyoo@gmail.com> Cc: kernel test robot , Oliver Glitta , lkp@lists.01.org, lkp@intel.com, LKML , Vlastimil Babka , Imran Khan , Andrey Konovalov , Zhen Lei , Zqiang , linux-mm@kvack.org Subject: Re: [mm/slub] 555b8c8cb3: WARNING:at_lib/stackdepot.c:#stack_depot_fetch Message-ID: References: <20220323090520.GG16885@xsang-OptiPlex-9020> <20220324095218.GA2108184@odroid> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/2.1.4 (2021-12-11) X-Rspamd-Server: rspam06 X-Rspamd-Queue-Id: 8859C140034 X-Rspam-User: Authentication-Results: imf23.hostedemail.com; dkim=pass header.d=google.com header.s=20210112 header.b=RnsSCFrn; dmarc=pass (policy=reject) header.from=google.com; spf=pass (imf23.hostedemail.com: domain of elver@google.com designates 209.85.221.42 as permitted sender) smtp.mailfrom=elver@google.com X-Stat-Signature: kxc8hrp8wr36oubtrrsyq98jusxeetee X-HE-Tag: 1649059810-258781 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 Mon, Apr 04, 2022 at 12:05PM +0900, Hyeonggon Yoo wrote: > On Sat, Apr 02, 2022 at 12:50:14AM +0900, Hyeonggon Yoo wrote: > > On Thu, Mar 24, 2022 at 09:52:18AM +0000, Hyeonggon Yoo wrote: > > > On Wed, Mar 23, 2022 at 05:05:20PM +0800, kernel test robot wrote: > > > > > > > > > > > > Greeting, > > > > > > > > FYI, we noticed the following commit (built with gcc-9): > > > > > > > > commit: 555b8c8cb3f335ec8fd9d1ffd25e1395790d102d ("mm/slub: use stackdepot to save stack trace in objects") > > > > https://git.kernel.org/cgit/linux/kernel/git/vbabka/linux.git slub-stackdepot-v3r1 > > > > > > > > in testcase: rcutorture > > > > version: > > > > with following parameters: > > > > > > > > runtime: 300s > > > > test: cpuhotplug > > > > torture_type: tasks > > > > > > > > > > [+Cc Vlastimil, linux-mm, and people related to stackdepot] > > > > > > I'm going to spend time on it. > > > I have no clue why this happened yet. > > > > > > > I modified alloc/free debug processing to check if handle is valid, but > > it couldn't detect something wrong. Everything was fine when allocating/freeing objects. > > > > Handles must be modified outside SLUB code. > > (Or maybe SLUB code related to cpu hotplugging did cause this.) > > > > I reproduced this problem on x86_64 with KASAN enabled, but KASAN > > detects nothing. > > > > I suspect this would be memory corruption bug, race condition, or > > wrong calculation of object metadata offset. But still have no clue. > > > > I'm going to check if KCSAN detects something. > > > > KCSAN also didn't help. (Maybe CONFIG_KCSAN_STRICT=y is going to yield something? I still doubt it thought, this bug is related to corrupted stackdepot handle somewhere...) > I noticed that it is not reproduced when KASAN=y and KFENCE=n (reproduced 0 of 181). > and it was reproduced 56 of 196 when KASAN=n and KFENCE=y > > maybe this issue is related to kfence? What about KASAN=n and KFENCE=n? Thanks, -- Marco