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AJvYcCUeLXjjIDGaT0CbAJcxxgQ/CNuDItEAMep+zjQeexGeqHJpxqAecAIaI+5jvWDsk7Ywi0udi4kZlq6ippNbndkr@vger.kernel.org X-Gm-Message-State: AOJu0Yy2upoIXtSD8az2Nq2p8M65zZh5qZ4sB7F0nq2DJSN9fdGIU/3g 2ipAfjv5F4XUVfEb1owE1o44q2OuEr34rkDsWTJAzNSY5ye5ZEuBUj/pTAaBbAA72EwHhm+5+HN 2a9RAj/cWLtTvfdpHbNv3YH1Q5stVtJ8DVqG6393upc9rdvMHET0WRBMp/FU= Precedence: bulk X-Mailing-List: linux-perf-users@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-Received: by 2002:a05:6820:80f:b0:67a:1d3d:a295 with SMTP id 006d021491bc7-67b9bb70413mr2959795eaf.0.1772866401657; Fri, 06 Mar 2026 22:53:21 -0800 (PST) Date: Fri, 06 Mar 2026 22:53:21 -0800 X-Google-Appengine-App-Id: s~syzkaller X-Google-Appengine-App-Id-Alias: syzkaller Message-ID: <69abcb61.050a0220.13f275.0040.GAE@google.com> Subject: [syzbot] [perf?] possible deadlock in refcount_dec_and_mutex_lock (2) From: syzbot To: acme@kernel.org, adrian.hunter@intel.com, alexander.shishkin@linux.intel.com, irogers@google.com, james.clark@linaro.org, jolsa@kernel.org, linux-kernel@vger.kernel.org, linux-perf-users@vger.kernel.org, mark.rutland@arm.com, mingo@redhat.com, namhyung@kernel.org, peterz@infradead.org, syzkaller-bugs@googlegroups.com Content-Type: text/plain; charset="UTF-8" Hello, syzbot found the following issue on: HEAD commit: 5ee8dbf54602 Merge tag 'fsverity-for-linus' of git://git.k.. git tree: upstream console output: https://syzkaller.appspot.com/x/log.txt?x=101d5b5a580000 kernel config: https://syzkaller.appspot.com/x/.config?x=c5c49ee0942d1cdb dashboard link: https://syzkaller.appspot.com/bug?extid=196a82fd904572696b3c compiler: Debian clang version 21.1.8 (++20251221033036+2078da43e25a-1~exp1~20251221153213.50), Debian LLD 21.1.8 syz repro: https://syzkaller.appspot.com/x/repro.syz?x=11b888ba580000 C reproducer: https://syzkaller.appspot.com/x/repro.c?x=12f758d6580000 Downloadable assets: disk image (non-bootable): https://storage.googleapis.com/syzbot-assets/d900f083ada3/non_bootable_disk-5ee8dbf5.raw.xz vmlinux: https://storage.googleapis.com/syzbot-assets/3cd4daffdac9/vmlinux-5ee8dbf5.xz kernel image: https://storage.googleapis.com/syzbot-assets/7a6fec327094/bzImage-5ee8dbf5.xz IMPORTANT: if you fix the issue, please add the following tag to the commit: Reported-by: syzbot+196a82fd904572696b3c@syzkaller.appspotmail.com R10: 0000000000000013 R11: 0000000000000246 R12: 0000000000000002 R13: 00007ff784215fac R14: 00007ff784215fa0 R15: 00007ff784215fa0 ============================================ WARNING: possible recursive locking detected syzkaller #0 Not tainted -------------------------------------------- syz.0.17/5460 is trying to acquire lock: ffff88801f26c9e0 (&event->mmap_mutex){+.+.}-{4:4}, at: refcount_dec_and_mutex_lock+0x30/0xa0 lib/refcount.c:118 but task is already holding lock: ffff88801f26c9e0 (&event->mmap_mutex){+.+.}-{4:4}, at: class_mutex_constructor include/linux/mutex.h:253 [inline] ffff88801f26c9e0 (&event->mmap_mutex){+.+.}-{4:4}, at: perf_mmap+0x1bb/0x4b0 kernel/events/core.c:7453 other info that might help us debug this: Possible unsafe locking scenario: CPU0 ---- lock(&event->mmap_mutex); lock(&event->mmap_mutex); *** DEADLOCK *** May be due to missing lock nesting notation 2 locks held by syz.0.17/5460: #0: ffff888011a94080 (&mm->mmap_lock){++++}-{4:4}, at: mmap_write_lock_killable include/linux/mmap_lock.h:554 [inline] #0: ffff888011a94080 (&mm->mmap_lock){++++}-{4:4}, at: vm_mmap_pgoff+0x234/0x4f0 mm/util.c:579 #1: ffff88801f26c9e0 (&event->mmap_mutex){+.+.}-{4:4}, at: class_mutex_constructor include/linux/mutex.h:253 [inline] #1: ffff88801f26c9e0 (&event->mmap_mutex){+.+.}-{4:4}, at: perf_mmap+0x1bb/0x4b0 kernel/events/core.c:7453 stack backtrace: CPU: 0 UID: 0 PID: 5460 Comm: syz.0.17 Not tainted syzkaller #0 PREEMPT(full) Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.3-debian-1.16.3-2 04/01/2014 Call Trace: dump_stack_lvl+0xe8/0x150 lib/dump_stack.c:120 print_deadlock_bug+0x279/0x290 kernel/locking/lockdep.c:3041 check_deadlock kernel/locking/lockdep.c:3093 [inline] validate_chain kernel/locking/lockdep.c:3895 [inline] __lock_acquire+0x253f/0x2cf0 kernel/locking/lockdep.c:5237 lock_acquire+0xf0/0x2e0 kernel/locking/lockdep.c:5868 __mutex_lock_common kernel/locking/mutex.c:614 [inline] __mutex_lock+0x19f/0x1300 kernel/locking/mutex.c:776 refcount_dec_and_mutex_lock+0x30/0xa0 lib/refcount.c:118 perf_mmap_close+0x953/0xf90 kernel/events/core.c:7064 perf_mmap+0x418/0x4b0 kernel/events/core.c:7488 vfs_mmap include/linux/fs.h:2070 [inline] mmap_file mm/internal.h:167 [inline] __mmap_new_file_vma mm/vma.c:2468 [inline] __mmap_new_vma mm/vma.c:2532 [inline] __mmap_region mm/vma.c:2759 [inline] mmap_region+0x18fe/0x2240 mm/vma.c:2837 do_mmap+0xc39/0x10c0 mm/mmap.c:559 vm_mmap_pgoff+0x2c9/0x4f0 mm/util.c:581 ksys_mmap_pgoff+0x51e/0x760 mm/mmap.c:605 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline] do_syscall_64+0x14d/0xf80 arch/x86/entry/syscall_64.c:94 entry_SYSCALL_64_after_hwframe+0x77/0x7f RIP: 0033:0x7ff783f9c799 Code: ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 44 00 00 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 e8 ff ff ff f7 d8 64 89 01 48 RSP: 002b:00007ffeef4c8518 EFLAGS: 00000246 ORIG_RAX: 0000000000000009 RAX: ffffffffffffffda RBX: 00007ff784215fa0 RCX: 00007ff783f9c799 RDX: 0000000001000008 RSI: 0000000000002000 RDI: 0000200000ffe000 RBP: 00007ffeef4c8580 R08: 0000000000000003 R09: 0000000000000000 R10: 0000000000000013 R11: 0000000000000246 R12: 0000000000000002 R13: 00007ff784215fac R14: 00007ff784215fa0 R15: 00007ff784215fa0 --- 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 syzbot to run the reproducer, reply with: #syz test: git://repo/address.git branch-or-commit-hash If you attach or paste a git patch, syzbot will apply it before testing. 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