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[46.135.8.232]) by smtp.gmail.com with ESMTPSA id a640c23a62f3a-a67eb3444bfsm71394366b.201.2024.05.31.03.29.31 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Fri, 31 May 2024 03:29:34 -0700 (PDT) Date: Fri, 31 May 2024 12:29:21 +0200 From: Mateusz Guzik To: kernel test robot Cc: Hugh Dickins , oe-lkp@lists.linux.dev, lkp@intel.com, linux-kernel@vger.kernel.org, Andrew Morton , Jan Kara , Tim Chen , Dave Chinner , "Darrick J. Wong" , Axel Rasmussen , Carlos Maiolino , Christian Brauner , Chuck Lever , Johannes Weiner , Matthew Wilcox , linux-mm@kvack.org Subject: Re: [linus:master] [shmem,percpu_counter] beb9868628: BUG:KCSAN:data-race_in__percpu_counter_limited_add/__percpu_counter_limited_add Message-ID: References: <202405311100.d46f2cc1-lkp@intel.com> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: <202405311100.d46f2cc1-lkp@intel.com> X-Rspam-User: X-Rspamd-Server: rspam09 X-Rspamd-Queue-Id: 9917710001A X-Stat-Signature: qphbowg6ocaadabck6rzr97b1693y914 X-HE-Tag: 1717151377-854102 X-HE-Meta: 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 JOSnB8b5 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 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: On Fri, May 31, 2024 at 01:52:40PM +0800, kernel test robot wrote: > > > Hello, > > kernel test robot noticed "BUG:KCSAN:data-race_in__percpu_counter_limited_add/__percpu_counter_limited_add" on: > > commit: beb9868628445306958fd7b2da1cd369a4a381cc ("shmem,percpu_counter: add _limited_add(fbc, limit, amount)") > https://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git master > > [test failed on linus/master 2bfcfd584ff5ccc8bb7acde19b42570414bf880b] > [test failed on linux-next/master 6dc544b66971c7f9909ff038b62149105272d26a] > > in testcase: trinity > version: > with following parameters: > > runtime: 300s > group: group-01 > nr_groups: 5 > > > > compiler: gcc-12 > test machine: qemu-system-x86_64 -enable-kvm -cpu SandyBridge -smp 2 -m 16G > > (please refer to attached dmesg/kmsg for entire log/backtrace) > > > in our tests, > dmesg.BUG:KCSAN:data-race_in__percpu_counter_limited_add/__percpu_counter_limited_add > does not always happen, 88 times out of 150 runs as below. > > > 3022fd7af9604d44 beb9868628445306958fd7b2da1 > ---------------- --------------------------- > fail:runs %reproduction fail:runs > | | | > :60 147% 88:150 dmesg.BUG:KCSAN:data-race_in__percpu_counter_limited_add/__percpu_counter_limited_add > > > > If you fix the issue in a separate patch/commit (i.e. not just a new version of > the same patch/commit), kindly add following tags > | Reported-by: kernel test robot > | Closes: https://lore.kernel.org/oe-lkp/202405311100.d46f2cc1-lkp@intel.com > > > > [ 301.127451][ T4651] ================================================================== > [ 301.128485][ T4651] BUG: KCSAN: data-race in __percpu_counter_limited_add / __percpu_counter_limited_add > [ 301.129715][ T4651] > [ 301.130014][ T4651] write to 0xffff88810ffc3450 of 8 bytes by task 4674 on cpu 0: > [ 301.130981][ T4651] __percpu_counter_limited_add (lib/percpu_counter.c:325) > [ 301.131692][ T4651] shmem_inode_acct_blocks (mm/shmem.c:220) > [ 301.132319][ T4651] shmem_get_folio_gfp+0x3a9/0x750 > [ 301.133054][ T4651] shmem_write_begin (mm/shmem.c:2135 mm/shmem.c:2692) > [ 301.133690][ T4651] generic_perform_write (mm/filemap.c:3962) > [ 301.134347][ T4651] shmem_file_write_iter (mm/shmem.c:2868) > [ 301.134956][ T4651] do_iter_readv_writev (include/linux/fs.h:1956 fs/read_write.c:735) > [ 301.135628][ T4651] do_iter_write (fs/read_write.c:860) > [ 301.136178][ T4651] vfs_writev (fs/read_write.c:933) > [ 301.136716][ T4651] __x64_sys_pwritev2 (fs/read_write.c:1030 fs/read_write.c:1089 fs/read_write.c:1080 fs/read_write.c:1080) > [ 301.139719][ T4651] do_syscall_64 (arch/x86/entry/common.c:50 arch/x86/entry/common.c:80) > [ 301.140316][ T4651] entry_SYSCALL_64_after_hwframe (arch/x86/entry/entry_64.S:120) > [ 301.141129][ T4651] > [ 301.141465][ T4651] read to 0xffff88810ffc3450 of 8 bytes by task 4651 on cpu 1: > [ 301.142436][ T4651] __percpu_counter_limited_add (lib/percpu_counter.c:302 (discriminator 1)) > [ 301.143222][ T4651] shmem_inode_acct_blocks (mm/shmem.c:220) > [ 301.143931][ T4651] shmem_get_folio_gfp+0x3a9/0x750 > [ 301.144696][ T4651] shmem_write_begin (mm/shmem.c:2135 mm/shmem.c:2692) > [ 301.145370][ T4651] generic_perform_write (mm/filemap.c:3962) > [ 301.146112][ T4651] shmem_file_write_iter (mm/shmem.c:2868) > [ 301.146697][ T4651] do_iter_readv_writev (include/linux/fs.h:1956 fs/read_write.c:735) > [ 301.147330][ T4651] do_iter_write (fs/read_write.c:860) > [ 301.147918][ T4651] vfs_writev (fs/read_write.c:933) > [ 301.148480][ T4651] __x64_sys_pwritev2 (fs/read_write.c:1030 fs/read_write.c:1089 fs/read_write.c:1080 fs/read_write.c:1080) > [ 301.149047][ T4651] do_syscall_64 (arch/x86/entry/common.c:50 arch/x86/entry/common.c:80) > [ 301.149629][ T4651] entry_SYSCALL_64_after_hwframe (arch/x86/entry/entry_64.S:120) > [ 301.150358][ T4651] > [ 301.150643][ T4651] value changed: 0x0000000000059e35 -> 0x0000000000059e56 > [ 301.151483][ T4651] > [ 301.151778][ T4651] Reported by Kernel Concurrency Sanitizer on: > [ 301.152559][ T4651] CPU: 1 PID: 4651 Comm: trinity-c7 Not tainted 6.6.0-rc4-00235-gbeb986862844 #1 > [ 301.153676][ T4651] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.16.2-debian-1.16.2-1 04/01/2014 > [ 301.154962][ T4651] ================================================================== > This is the bug I described in my mail: https://lore.kernel.org/linux-mm/5eemkb4lo5eefp7ijgncgogwmadyzmvjfjmmmvfiki6cwdskfs@hi2z4drqeuz6/ write side: if (good) { count = __this_cpu_read(*fbc->counters); fbc->count += count + amount; <---- line 325 __this_cpu_sub(*fbc->counters, count); } read side: /* Skip taking the lock when safe */ if (abs(count + amount) <= batch && fbc->count + unknown <= limit) { <---- line 302 this_cpu_add(*fbc->counters, amount); local_irq_restore(flags); return true; } As described in the e-mail I don't believe the existence of the routine is warranted to begin with. > > > The kernel config and materials to reproduce are available at: > https://download.01.org/0day-ci/archive/20240531/202405311100.d46f2cc1-lkp@intel.com > > > > -- > 0-DAY CI Kernel Test Service > https://github.com/intel/lkp-tests/wiki >