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Tue, 03 Sep 2024 15:01:58 -0700 (PDT) Received: from snowbird ([199.73.127.3]) by smtp.gmail.com with ESMTPSA id 41be03b00d2f7-7d4fbd8da44sm367524a12.33.2024.09.03.15.01.57 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 03 Sep 2024 15:01:58 -0700 (PDT) Date: Tue, 3 Sep 2024 15:01:53 -0700 From: Dennis Zhou To: Thomas Gleixner Cc: syzbot , linux-kernel@vger.kernel.org, syzkaller-bugs@googlegroups.com, x86@kernel.org, linux-mm@kvack.org Subject: Re: [syzbot] [kernel?] KCSAN: data-race in pcpu_alloc_noprof / pcpu_balance_workfn (2) Message-ID: References: <000000000000d47d440620d54f15@google.com> <87le0a797h.ffs@tglx> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <87le0a797h.ffs@tglx> X-Stat-Signature: tqsnb8hajqixip3kqurp8js6tsjeomua X-Rspam-User: X-Rspamd-Queue-Id: 9879E1C0028 X-Rspamd-Server: rspam02 X-HE-Tag: 1725400920-245501 X-HE-Meta: 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 UkNO4I2z 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 hv8beutQ Udwp7X5PJN5sOWJMDHH2bYNP0C6CZMZrru5H4pk38GGHucQ7NSBJ5RxrOHcv/HWTCHQ77wOnI5TlJAsknD+Nxw0Ig4f2tVWiqcGrbq+ol0hS2R0n98fxYRs5KwOLFaBTxFUMnVD0zIMu+JQSNbLoGBkzqmpXxZRjgOiBDkzGS+RAk6+kFpruvhM8vno2OSX5kXrByLCOfSgLHHa+jM5p4wNe9FEx8gRLBhe1rVQTN5g8OeKe2ANYU//SWl9qjwA6 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 Mon, Sep 02, 2024 at 10:26:10AM +0200, Thomas Gleixner wrote: > On Thu, Aug 29 2024 at 09:53, syzbot wrote: > > Cc-: x86 folks. Just because something happens on x86 does not mean it's > an x86 problem > > Cc+: mm folks. It's entirely clear where this belongs to: > > > read-write to 0xffffffff88bb27ac of 4 bytes by task 3354 on cpu 0: > > pcpu_update_empty_pages mm/percpu.c:602 [inline] > > No? > Yeah.. We discussed this a month ago [1], I just haven't had time. I'll send out the fix for this tonight/tmrw morning. Thanks, Dennis [1] https://lore.kernel.org/lkml/ZqCo7H2gcA1dvIr4@xsang-OptiPlex-9020/ > > Hello, > > > > syzbot found the following issue on: > > > > HEAD commit: d5d547aa7b51 Merge tag 'random-6.11-rc6-for-linus' of git:.. > > git tree: upstream > > console output: https://syzkaller.appspot.com/x/log.txt?x=164c067b980000 > > kernel config: https://syzkaller.appspot.com/x/.config?x=6fafac02e339cc84 > > dashboard link: https://syzkaller.appspot.com/bug?extid=6d392a44667baa45bb5a > > compiler: Debian clang version 15.0.6, GNU ld (GNU Binutils for Debian) 2.40 > > > > Unfortunately, I don't have any reproducer for this issue yet. > > > > Downloadable assets: > > disk image: https://storage.googleapis.com/syzbot-assets/e636aa58c364/disk-d5d547aa.raw.xz > > vmlinux: https://storage.googleapis.com/syzbot-assets/f5ecd0d96afa/vmlinux-d5d547aa.xz > > kernel image: https://storage.googleapis.com/syzbot-assets/fe7d474f148f/bzImage-d5d547aa.xz > > > > IMPORTANT: if you fix the issue, please add the following tag to the commit: > > Reported-by: syzbot+6d392a44667baa45bb5a@syzkaller.appspotmail.com > > > > ================================================================== > > BUG: KCSAN: data-race in pcpu_alloc_noprof / pcpu_balance_workfn > > > > read-write to 0xffffffff88bb27ac of 4 bytes by task 3354 on cpu 0: > > pcpu_update_empty_pages mm/percpu.c:602 [inline] > > pcpu_chunk_populated mm/percpu.c:1531 [inline] > > pcpu_balance_populated mm/percpu.c:2062 [inline] > > pcpu_balance_workfn+0x94e/0xa60 mm/percpu.c:2212 > > process_one_work kernel/workqueue.c:3231 [inline] > > process_scheduled_works+0x483/0x9a0 kernel/workqueue.c:3312 > > worker_thread+0x526/0x6e0 kernel/workqueue.c:3389 > > kthread+0x1d1/0x210 kernel/kthread.c:389 > > ret_from_fork+0x4b/0x60 arch/x86/kernel/process.c:147 > > ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:244 > > > > read to 0xffffffff88bb27ac of 4 bytes by task 6821 on cpu 1: > > pcpu_alloc_noprof+0x9a7/0x10c0 mm/percpu.c:1894 > > bpf_map_alloc_percpu+0xad/0x210 kernel/bpf/syscall.c:466 > > prealloc_init+0x19f/0x470 kernel/bpf/hashtab.c:341 > > htab_map_alloc+0x630/0x8e0 kernel/bpf/hashtab.c:576 > > map_create+0x83c/0xb90 kernel/bpf/syscall.c:1333 > > __sys_bpf+0x667/0x7a0 kernel/bpf/syscall.c:5692 > > __do_sys_bpf kernel/bpf/syscall.c:5817 [inline] > > __se_sys_bpf kernel/bpf/syscall.c:5815 [inline] > > __x64_sys_bpf+0x43/0x50 kernel/bpf/syscall.c:5815 > > x64_sys_call+0x2625/0x2d60 arch/x86/include/generated/asm/syscalls_64.h:322 > > do_syscall_x64 arch/x86/entry/common.c:52 [inline] > > do_syscall_64+0xc9/0x1c0 arch/x86/entry/common.c:83 > > entry_SYSCALL_64_after_hwframe+0x77/0x7f > > > > value changed: 0x00000001 -> 0x00000004 > > > > Reported by Kernel Concurrency Sanitizer on: > > CPU: 1 UID: 0 PID: 6821 Comm: syz.4.1651 Not tainted 6.11.0-rc5-syzkaller-00081-gd5d547aa7b51 #0 > > Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 08/06/2024 > > ================================================================== > > > > > > --- > > This report is generated by a bot. It may contain errors. > > See https://goo.gl/tpsmEJ for more information about syzbot. > > syzbot engineers can be reached at syzkaller@googlegroups.com. > > > > syzbot will keep track of this issue. See: > > https://goo.gl/tpsmEJ#status for how to communicate with syzbot. > > > > If the report is already addressed, let syzbot know by replying with: > > #syz fix: exact-commit-title > > > > If you want to overwrite report's subsystems, reply with: > > #syz set subsystems: new-subsystem > > (See the list of subsystem names on the web dashboard) > > > > If the report is a duplicate of another one, reply with: > > #syz dup: exact-subject-of-another-report > > > > If you want to undo deduplication, reply with: > > #syz undup >