From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-8.7 required=3.0 tests=BAYES_00,FROM_LOCAL_HEX, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,MENTIONS_GIT_HOSTING, SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED autolearn=unavailable autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 7C57CC4320A for ; Wed, 28 Jul 2021 14:19:26 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 5C2F961019 for ; Wed, 28 Jul 2021 14:19:26 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S236804AbhG1OT1 (ORCPT ); Wed, 28 Jul 2021 10:19:27 -0400 Received: from mail-il1-f198.google.com ([209.85.166.198]:55130 "EHLO mail-il1-f198.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S235491AbhG1OT0 (ORCPT ); Wed, 28 Jul 2021 10:19:26 -0400 Received: by mail-il1-f198.google.com with SMTP id o6-20020a056e020926b0290221b4e37e75so1550316ilt.21 for ; Wed, 28 Jul 2021 07:19:23 -0700 (PDT) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:mime-version:date:message-id:subject:from:to; bh=fs8at5oxIJu2qv6y8JFLJwnQelXth8O42Fo8cTG83tQ=; b=HlPQrwow+uirKA+8Acy+Tf6md9qfeYTUp0VylmPMCZ92Q1okGJJIGu/4Ta+XAZcbvB Nt+dTtw/mKBorXXX1fKWUaAj2LAfUkTyB1i3EMz4BqSj/riqHynK8dHDDGjLMd6txguC uytybhY3/wiTQAFHwRFi745gpciOsiZYjza8Rf1My7jsO+SxAV1exBVP2Daz9sXo++RH kFyiCeM+IKIGnJu9EgMS1ZfbnUXHdvu9OuDLa53g+NQRGJd8T1pYKHhZhjKx4K3bzeNp +Ok/L/PWMmCHzMPKASFhJRSY0syjPqjXrncLiPgDlajCh/JTTNgXH5dyCxWNVnG63r7g vGVw== X-Gm-Message-State: AOAM533edRud/H2o0+Z1oZwo7qX2lH9T0xksYVZ43baFhZTDVT/yVvyp kI3XPDhEq6HVQeRjNwelyP9/dz+ex9uKlgPzvWAHBO/StWzS X-Google-Smtp-Source: ABdhPJxugm15dJxuNz+7LufAybSBhpDUJf25KlY9mICr9CgQ3WN6psVD5E+CG6AFG9MY16XItr6LD+s4AIrLFlPkJ2S3XzfSu9pY MIME-Version: 1.0 X-Received: by 2002:a6b:e60f:: with SMTP id g15mr23353424ioh.48.1627481963666; Wed, 28 Jul 2021 07:19:23 -0700 (PDT) Date: Wed, 28 Jul 2021 07:19:23 -0700 X-Google-Appengine-App-Id: s~syzkaller X-Google-Appengine-App-Id-Alias: syzkaller Message-ID: <00000000000052a12105c82facde@google.com> Subject: [syzbot] possible deadlock in iter_file_splice_write (2) From: syzbot To: linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org, linux-unionfs@vger.kernel.org, miklos@szeredi.hu, mszeredi@redhat.com, syzkaller-bugs@googlegroups.com, viro@zeniv.linux.org.uk Content-Type: text/plain; charset="UTF-8" Precedence: bulk List-ID: X-Mailing-List: linux-unionfs@vger.kernel.org Hello, syzbot found the following issue on: HEAD commit: f0fddcec6b62 Merge tag 'for-5.14-rc2-tag' of git://git.ker.. git tree: upstream console output: https://syzkaller.appspot.com/x/log.txt?x=15a13312300000 kernel config: https://syzkaller.appspot.com/x/.config?x=5dc0e3202ae2f574 dashboard link: https://syzkaller.appspot.com/bug?extid=4bdbcaa79e8ee36fe6af compiler: Debian clang version 11.0.1-2, GNU ld (GNU Binutils for Debian) 2.35.1 syz repro: https://syzkaller.appspot.com/x/repro.syz?x=10a68b12300000 C reproducer: https://syzkaller.appspot.com/x/repro.c?x=1226e6ca300000 The issue was bisected to: commit 82a763e61e2b601309d696d4fa514c77d64ee1be Author: Miklos Szeredi Date: Mon Dec 14 14:26:14 2020 +0000 ovl: simplify file splice bisection log: https://syzkaller.appspot.com/x/bisect.txt?x=1324e8fc300000 final oops: https://syzkaller.appspot.com/x/report.txt?x=10a4e8fc300000 console output: https://syzkaller.appspot.com/x/log.txt?x=1724e8fc300000 IMPORTANT: if you fix the issue, please add the following tag to the commit: Reported-by: syzbot+4bdbcaa79e8ee36fe6af@syzkaller.appspotmail.com Fixes: 82a763e61e2b ("ovl: simplify file splice") ====================================================== WARNING: possible circular locking dependency detected 5.14.0-rc2-syzkaller #0 Not tainted ------------------------------------------------------ syz-executor919/8626 is trying to acquire lock: ffff8880141ed068 (&pipe->mutex/1){+.+.}-{3:3}, at: iter_file_splice_write+0x257/0xf30 fs/splice.c:635 but task is already holding lock: ffff888029aac460 (sb_writers#5){.+.+}-{0:0}, at: __do_splice fs/splice.c:1144 [inline] ffff888029aac460 (sb_writers#5){.+.+}-{0:0}, at: __do_sys_splice fs/splice.c:1350 [inline] ffff888029aac460 (sb_writers#5){.+.+}-{0:0}, at: __se_sys_splice+0x32c/0x430 fs/splice.c:1332 which lock already depends on the new lock. the existing dependency chain (in reverse order) is: -> #2 (sb_writers#5){.+.+}-{0:0}: lock_acquire+0x182/0x4a0 kernel/locking/lockdep.c:5625 percpu_down_read include/linux/percpu-rwsem.h:51 [inline] __sb_start_write include/linux/fs.h:1763 [inline] sb_start_write include/linux/fs.h:1833 [inline] file_start_write+0xc7/0x230 include/linux/fs.h:3040 ovl_write_iter+0x81d/0xdb0 fs/overlayfs/file.c:357 do_iter_readv_writev+0x566/0x770 include/linux/fs.h:2108 do_iter_write+0x16c/0x5f0 fs/read_write.c:866 iter_file_splice_write+0x7c1/0xf30 fs/splice.c:689 do_splice_from fs/splice.c:767 [inline] do_splice+0xe8e/0x17e0 fs/splice.c:1079 __do_splice fs/splice.c:1144 [inline] __do_sys_splice fs/splice.c:1350 [inline] __se_sys_splice+0x32c/0x430 fs/splice.c:1332 do_syscall_x64 arch/x86/entry/common.c:50 [inline] do_syscall_64+0x3d/0xb0 arch/x86/entry/common.c:80 entry_SYSCALL_64_after_hwframe+0x44/0xae -> #1 (&ovl_i_mutex_key[depth]){+.+.}-{3:3}: lock_acquire+0x182/0x4a0 kernel/locking/lockdep.c:5625 down_write+0x97/0x170 kernel/locking/rwsem.c:1406 inode_lock include/linux/fs.h:774 [inline] ovl_write_iter+0x132/0xdb0 fs/overlayfs/file.c:341 do_iter_readv_writev+0x566/0x770 include/linux/fs.h:2108 do_iter_write+0x16c/0x5f0 fs/read_write.c:866 iter_file_splice_write+0x7c1/0xf30 fs/splice.c:689 do_splice_from fs/splice.c:767 [inline] do_splice+0xe8e/0x17e0 fs/splice.c:1079 __do_splice fs/splice.c:1144 [inline] __do_sys_splice fs/splice.c:1350 [inline] __se_sys_splice+0x32c/0x430 fs/splice.c:1332 do_syscall_x64 arch/x86/entry/common.c:50 [inline] do_syscall_64+0x3d/0xb0 arch/x86/entry/common.c:80 entry_SYSCALL_64_after_hwframe+0x44/0xae -> #0 (&pipe->mutex/1){+.+.}-{3:3}: check_prev_add kernel/locking/lockdep.c:3051 [inline] check_prevs_add+0x4f9/0x5b30 kernel/locking/lockdep.c:3174 validate_chain kernel/locking/lockdep.c:3789 [inline] __lock_acquire+0x4476/0x6100 kernel/locking/lockdep.c:5015 lock_acquire+0x182/0x4a0 kernel/locking/lockdep.c:5625 __mutex_lock_common+0x1ad/0x3770 kernel/locking/mutex.c:959 __mutex_lock kernel/locking/mutex.c:1104 [inline] mutex_lock_nested+0x1a/0x20 kernel/locking/mutex.c:1119 iter_file_splice_write+0x257/0xf30 fs/splice.c:635 do_splice_from fs/splice.c:767 [inline] do_splice+0xe8e/0x17e0 fs/splice.c:1079 __do_splice fs/splice.c:1144 [inline] __do_sys_splice fs/splice.c:1350 [inline] __se_sys_splice+0x32c/0x430 fs/splice.c:1332 do_syscall_x64 arch/x86/entry/common.c:50 [inline] do_syscall_64+0x3d/0xb0 arch/x86/entry/common.c:80 entry_SYSCALL_64_after_hwframe+0x44/0xae other info that might help us debug this: Chain exists of: &pipe->mutex/1 --> &ovl_i_mutex_key[depth] --> sb_writers#5 Possible unsafe locking scenario: CPU0 CPU1 ---- ---- lock(sb_writers#5); lock(&ovl_i_mutex_key[depth]); lock(sb_writers#5); lock(&pipe->mutex/1); *** DEADLOCK *** 1 lock held by syz-executor919/8626: #0: ffff888029aac460 (sb_writers#5){.+.+}-{0:0}, at: __do_splice fs/splice.c:1144 [inline] #0: ffff888029aac460 (sb_writers#5){.+.+}-{0:0}, at: __do_sys_splice fs/splice.c:1350 [inline] #0: ffff888029aac460 (sb_writers#5){.+.+}-{0:0}, at: __se_sys_splice+0x32c/0x430 fs/splice.c:1332 stack backtrace: CPU: 0 PID: 8626 Comm: syz-executor919 Not tainted 5.14.0-rc2-syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 Call Trace: __dump_stack lib/dump_stack.c:88 [inline] dump_stack_lvl+0x1ae/0x29f lib/dump_stack.c:105 print_circular_bug+0xb17/0xdc0 kernel/locking/lockdep.c:2009 check_noncircular+0x2cc/0x390 kernel/locking/lockdep.c:2131 check_prev_add kernel/locking/lockdep.c:3051 [inline] check_prevs_add+0x4f9/0x5b30 kernel/locking/lockdep.c:3174 validate_chain kernel/locking/lockdep.c:3789 [inline] __lock_acquire+0x4476/0x6100 kernel/locking/lockdep.c:5015 lock_acquire+0x182/0x4a0 kernel/locking/lockdep.c:5625 __mutex_lock_common+0x1ad/0x3770 kernel/locking/mutex.c:959 __mutex_lock kernel/locking/mutex.c:1104 [inline] mutex_lock_nested+0x1a/0x20 kernel/locking/mutex.c:1119 iter_file_splice_write+0x257/0xf30 fs/splice.c:635 do_splice_from fs/splice.c:767 [inline] do_splice+0xe8e/0x17e0 fs/splice.c:1079 __do_splice fs/splice.c:1144 [inline] __do_sys_splice fs/splice.c:1350 [inline] __se_sys_splice+0x32c/0x430 fs/splice.c:1332 do_syscall_x64 arch/x86/entry/common.c:50 [inline] do_syscall_64+0x3d/0xb0 arch/x86/entry/common.c:80 entry_SYSCALL_64_after_hwframe+0x44/0xae RIP: 0033:0x4461b9 Code: 28 00 00 00 75 05 48 83 c4 28 c3 e8 41 15 00 00 90 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 c7 c1 b8 ff ff ff f7 d8 64 89 01 48 RSP: 002b:00007f7b06be32e8 EFLAGS: 00000246 ORIG_RAX: 0000000000000113 RAX: ffffffffffffffda RBX: 00000000004cb4f0 RCX: 00000000004461b9 RDX: 0000000000000005 RSI: 0000000000000000 RDI: 0000000000000003 RBP: 000000000049b06c R08: 000000000004ffdc R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 3d72696472657070 R13: 0079616c7265766f R14: 69662f7375622f2e R15: 00000000004cb4f8 --- 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. For information about bisection process see: https://goo.gl/tpsmEJ#bisection syzbot can test patches for this issue, for details see: https://goo.gl/tpsmEJ#testing-patches