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AJvYcCWwH+lT98BmjZ1cGfAEH+tFQsk6e7ZQYe7E1FnPOLcIxLDu79boBvk3b6+IIzBqyrfc7I4nECcnyc59jQF/7k1H+bs= X-Gm-Message-State: AOJu0Yx0eXHH7LT1k83UmI70NLRIRxW/jaZ4f1gvCW71V7vZDd2NI2Qo omVQpnpw9XDtYyOd9bW/AE+OXIt4DebUoqqyMWSRhP582Ns+6yLKePRLbS614EFXEYT3oLy3SNa 2CY2UdomxH6ru0u/42H58W2n4rG8= X-Google-Smtp-Source: AGHT+IHqimg10K1/L+NRQXdNA2GGrmNDOmgRLEkO8bWLdybN2k28avxqLXsoB1b3MUY5xGyvrKtcfZlp0iCGclsq5VA= X-Received: by 2002:a05:6402:5201:b0:565:a5e1:3a10 with SMTP id s1-20020a056402520100b00565a5e13a10mr183414edd.36.1708743337653; Fri, 23 Feb 2024 18:55:37 -0800 (PST) MIME-Version: 1.0 References: <202402201506.b7e4b9b6-oliver.sang@intel.com> In-Reply-To: From: Neeraj upadhyay Date: Sat, 24 Feb 2024 08:25:24 +0530 Message-ID: Subject: Re: [linux-next:master] [kasan] 187292be96: WARNING:suspicious_RCU_usage To: Marco Elver Cc: kernel test robot , "Paul E. McKenney" , RCU , Frederic Weisbecker , Neeraj Upadhyay , Joel Fernandes , Josh Triplett , Boqun Feng , oe-lkp@lists.linux.dev, lkp@intel.com, Linux Memory Management List , Andrew Morton , Andrey Konovalov , Alexander Potapenko , Dmitry Vyukov , Andrey Ryabinin , Vincenzo Frascino , Vlastimil Babka , kasan-dev@googlegroups.com Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable X-Rspamd-Queue-Id: B759410000A X-Rspam-User: X-Rspamd-Server: rspam11 X-Stat-Signature: 9k8f3bf6qy3g6jhx4wmg75ftkmwoq6en X-HE-Tag: 1708743339-634023 X-HE-Meta: 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 fiSWUpsi mivpQBXqnxwJQwB/Wrbt/AF9REJSZnWtE5c4znD1DZZUUnhunZiNNMR87fxZclRhkc7fVnU5f1aXh22udpZhuf86iD0f4wcFANs3XZxDvL24PRZKKglPDsP9Wy7xOiETMKEYUe2n9qmppYlb2oZcqKExmttECrG5S6PF4lFRMDA1Lv95Neohz/jyDkQ== 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: List-Subscribe: List-Unsubscribe: Hi, On Tue, Feb 20, 2024 at 1:33=E2=80=AFPM Marco Elver wrot= e: > > On Tue, 20 Feb 2024 at 08:35, kernel test robot w= rote: > > > > > > > > Hello, > > > > we noticed this is a revert commit, below report is for an issue we obs= erved > > on this commit but not on its parent. just FYI. > > > > 113edefd366346b3 187292be96ae2be247807fac1c3 > > ---------------- --------------------------- > > fail:runs %reproduction fail:runs > > | | | > > :6 100% 6:6 dmesg.WARNING:suspicious_= RCU_usage > > > > > > kernel test robot noticed "WARNING:suspicious_RCU_usage" on: > > > > commit: 187292be96ae2be247807fac1c3a6d89a7cc2a84 ("kasan: revert evicti= on of stack traces in generic mode") > > https://git.kernel.org/cgit/linux/kernel/git/next/linux-next.git master > > This commit didn't touch rcutorture or the rcu subsystem in any way, > so I currently don't understand how rcutorture would be affected. > While stackdepot has started to use RCU, this already happened in a > previous commit, and this particular commit actually reduced RCU usage > (no more evictions and re-allocations of stacktraces). > > The only explanation I have is that it improved performance of a > KASAN-enabled kernel (which the config here has enabled) so much that > previously undiscovered issues have now become much more likely to > occur. > > [+Cc rcu folks] > > > in testcase: rcutorture The rcutorture test type executed here is busted_srcud (torture_type: busted_srcud). The busted_srcud torture test creates bad reader critical section usages - in this case the rcu reader lock acquired was not srcu lock, which subsequently resulted in rcu_dereference_check() to cause a splat due to srcu read lock not being held. So, this is expected behavior, and not a problem in either KASAN or RCU. Thanks Neeraj > > version: > > with following parameters: > > > > runtime: 300s > > test: cpuhotplug > > torture_type: busted_srcud > > > > > > > > compiler: clang-17 > > test machine: qemu-system-x86_64 -enable-kvm -cpu SandyBridge -smp 2 -m= 16G > > > > (please refer to attached dmesg/kmsg for entire log/backtrace) > > > > > > > > If you fix the issue in a separate patch/commit (i.e. not just a new ve= rsion of > > the same patch/commit), kindly add following tags > > | Reported-by: kernel test robot > > | Closes: https://lore.kernel.org/oe-lkp/202402201506.b7e4b9b6-oliver.s= ang@intel.com > > > > > > [ 292.513535][ T653] WARNING: suspicious RCU usage > > [ 292.514923][ T653] 6.8.0-rc4-00126-g187292be96ae #1 Not tainted > > [ 292.516369][ T653] ----------------------------- > > [ 292.517743][ T653] kernel/rcu/rcutorture.c:1983 suspicious rcu_dere= ference_check() usage! > > [ 292.519310][ T653] > > [ 292.519310][ T653] other info that might help us debug this: > > [ 292.519310][ T653] > > [ 292.523130][ T653] > > [ 292.523130][ T653] rcu_scheduler_active =3D 2, debug_locks =3D 1 > > [ 292.525644][ T653] no locks held by rcu_torture_rea/653. > > [ 292.526974][ T653] > > [ 292.526974][ T653] stack backtrace: > > [ 292.529271][ T653] CPU: 0 PID: 653 Comm: rcu_torture_rea Not tainte= d 6.8.0-rc4-00126-g187292be96ae #1 > > [ 292.530780][ T653] Hardware name: QEMU Standard PC (i440FX + PIIX, = 1996), BIOS 1.16.2-debian-1.16.2-1 04/01/2014 > > [ 292.532329][ T653] Call Trace: > > [ 292.533524][ T653] > > [ 292.534696][ T653] dump_stack_lvl (lib/dump_stack.c:?) > > [ 292.535941][ T653] ? __cfi_dump_stack_lvl (lib/dump_stack.c:98) > > [ 292.537221][ T653] ? lockdep_rcu_suspicious (kernel/locking/lockdep.c= :6712) > > [ 292.538523][ T653] rcu_torture_one_read (kernel/rcu/rcutorture.c:?) r= cutorture > > [ 292.539887][ T653] ? __cfi_lockdep_hardirqs_on_prepare (kernel/lockin= g/lockdep.c:4312) > > [ 292.541226][ T653] ? rcu_torture_timer (kernel/rcu/rcutorture.c:1955)= rcutorture > > [ 292.542621][ T653] ? __cfi_rcu_torture_timer (kernel/rcu/rcutorture.c= :2055) rcutorture > > [ 292.544012][ T653] ? init_timer_key (include/linux/lockdep.h:135 incl= ude/linux/lockdep.h:142 include/linux/lockdep.h:148 kernel/time/timer.c:847= kernel/time/timer.c:867) > > [ 292.545262][ T653] rcu_torture_reader (kernel/rcu/rcutorture.c:2093) = rcutorture > > [ 292.546579][ T653] ? __cfi_rcu_torture_reader (kernel/rcu/rcutorture.= c:2076) rcutorture > > [ 292.547872][ T653] ? __cfi__raw_spin_unlock_irqrestore (kernel/lockin= g/spinlock.c:193) > > [ 292.549108][ T653] ? __cfi_rcu_torture_timer (kernel/rcu/rcutorture.c= :2055) rcutorture > > [ 292.550341][ T653] ? __kthread_parkme (kernel/kthread.c:?) > > [ 292.551425][ T653] ? __kthread_parkme (include/linux/instrumented.h:?= include/asm-generic/bitops/instrumented-non-atomic.h:141 kernel/kthread.c:= 280) > > [ 292.552489][ T653] kthread (kernel/kthread.c:390) > > [ 292.553504][ T653] ? __cfi_rcu_torture_reader (kernel/rcu/rcutorture.= c:2076) rcutorture > > [ 292.554689][ T653] ? __cfi_kthread (kernel/kthread.c:341) > > [ 292.555749][ T653] ret_from_fork (arch/x86/kernel/process.c:153) > > [ 292.556792][ T653] ? __cfi_kthread (kernel/kthread.c:341) > > [ 292.557852][ T653] ret_from_fork_asm (arch/x86/entry/entry_64.S:250) > > [ 292.558920][ T653] > > > > > > > > The kernel config and materials to reproduce are available at: > > https://download.01.org/0day-ci/archive/20240220/202402201506.b7e4b9b6-= oliver.sang@intel.com > > > > > > > > -- > > 0-DAY CI Kernel Test Service > > https://github.com/intel/lkp-tests/wiki > > >