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AHgh+Ro0UAbZKYUzHwM2bpjCQ1cxrkA25yBB0nsufceS0xw64k1MWffpyAo4OoOhEeaI+bAgTfT0qrQ=@vger.kernel.org X-Gm-Message-State: AOJu0YwQWlzoCQwGSa4vmZv+reTZtH0/AUQZJecqlVn7osnbPKFYQhdm xj3geZzito5zVy+SKE+2giR3wWpJopKJTk00L0j9oIhbsxSsH9ZqEMa6awZ7Nk7OG0AQS9hdCQI /sQ8ftU+ksl623No5XR0MkOY0FYgLPxGMr/1WjzUh3c0qLuc7Pr4qqgDfdgU= Precedence: bulk X-Mailing-List: netdev@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-Received: by 2002:a05:6808:1b21:b0:495:adee:29e9 with SMTP id 5614622812f47-4ab6a3e85b9mr2031099b6e.41.1784985573428; Sat, 25 Jul 2026 06:19:33 -0700 (PDT) Date: Sat, 25 Jul 2026 06:19:33 -0700 X-Google-Appengine-App-Id: s~syzkaller X-Google-Appengine-App-Id-Alias: syzkaller Message-ID: <6a64b7e5.70955b6c.323240.001d.GAE@google.com> Subject: [syzbot] [net?] [fs?] possible deadlock in rht_lock From: syzbot To: brauner@kernel.org, jack@suse.cz, linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org, netdev@vger.kernel.org, syzkaller-bugs@googlegroups.com, viro@zeniv.linux.org.uk Content-Type: text/plain; charset="UTF-8" Hello, syzbot found the following issue on: HEAD commit: 94515f3a7d42 Merge tag 'bpf-fixes' of git://git.kernel.org.. git tree: bpf console output: https://syzkaller.appspot.com/x/log.txt?x=119bf789580000 kernel config: https://syzkaller.appspot.com/x/.config?x=5c4196ba0e33631d dashboard link: https://syzkaller.appspot.com/bug?extid=ef8d17bae14efb960935 compiler: Debian clang version 22.1.8 (++20260613092233+e80beda6e255-1~exp1~20260613092250.77), Debian LLD 22.1.8 syz repro: https://syzkaller.appspot.com/x/repro.syz?x=148d72b9580000 C reproducer: https://syzkaller.appspot.com/x/repro.c?x=105a1746580000 Downloadable assets: disk image: https://storage.googleapis.com/syzbot-assets/f43aa5dbbaea/disk-94515f3a.raw.xz vmlinux: https://storage.googleapis.com/syzbot-assets/d34e80893dbb/vmlinux-94515f3a.xz kernel image: https://storage.googleapis.com/syzbot-assets/62b4a6d766f6/bzImage-94515f3a.xz IMPORTANT: if you fix the issue, please add the following tag to the commit: Reported-by: syzbot+ef8d17bae14efb960935@syzkaller.appspotmail.com ============================================ WARNING: possible recursive locking detected syzkaller #0 Not tainted -------------------------------------------- syz-executor/5768 is trying to acquire lock: ffff88807d7f7038 (rhashtable_bucket){-.-.}-{0:0}, at: rht_lock+0x8b/0x180 include/linux/rhashtable.h:331 but task is already holding lock: ffff88802cc48038 (rhashtable_bucket){-.-.}-{0:0}, at: rht_lock+0x8b/0x180 include/linux/rhashtable.h:331 other info that might help us debug this: Possible unsafe locking scenario: CPU0 ---- lock(rhashtable_bucket); lock(rhashtable_bucket); *** DEADLOCK *** May be due to missing lock nesting notation 5 locks held by syz-executor/5768: #0: ffffffff8eb59c60 (rcu_read_lock){....}-{1:3}, at: rcu_lock_acquire include/linux/rcupdate.h:300 [inline] #0: ffffffff8eb59c60 (rcu_read_lock){....}-{1:3}, at: rcu_read_lock include/linux/rcupdate.h:840 [inline] #0: ffffffff8eb59c60 (rcu_read_lock){....}-{1:3}, at: __rhashtable_insert_fast include/linux/rhashtable.h:774 [inline] #0: ffffffff8eb59c60 (rcu_read_lock){....}-{1:3}, at: rhashtable_insert_fast include/linux/rhashtable.h:887 [inline] #0: ffffffff8eb59c60 (rcu_read_lock){....}-{1:3}, at: pidfs_add_pid+0x169/0xc50 fs/pidfs.c:178 #1: ffff88802cc48038 (rhashtable_bucket){-.-.}-{0:0}, at: rht_lock+0x8b/0x180 include/linux/rhashtable.h:331 #2: ffffffff8eb59c60 (rcu_read_lock){....}-{1:3}, at: rcu_lock_acquire include/linux/rcupdate.h:300 [inline] #2: ffffffff8eb59c60 (rcu_read_lock){....}-{1:3}, at: rcu_read_lock include/linux/rcupdate.h:840 [inline] #2: ffffffff8eb59c60 (rcu_read_lock){....}-{1:3}, at: trace_call_bpf+0xb6/0xb80 kernel/trace/bpf_trace.c:-1 #3: ffffffff8eb59c60 (rcu_read_lock){....}-{1:3}, at: rcu_lock_acquire include/linux/rcupdate.h:300 [inline] #3: ffffffff8eb59c60 (rcu_read_lock){....}-{1:3}, at: rcu_read_lock include/linux/rcupdate.h:840 [inline] #3: ffffffff8eb59c60 (rcu_read_lock){....}-{1:3}, at: class_rcu_constructor include/linux/rcupdate.h:1183 [inline] #3: ffffffff8eb59c60 (rcu_read_lock){....}-{1:3}, at: rhtab_map_delete_elem+0x21/0x190 kernel/bpf/hashtab.c:2979 #4: ffffffff8eb59c60 (rcu_read_lock){....}-{1:3}, at: rcu_lock_acquire include/linux/rcupdate.h:300 [inline] #4: ffffffff8eb59c60 (rcu_read_lock){....}-{1:3}, at: rcu_read_lock include/linux/rcupdate.h:840 [inline] #4: ffffffff8eb59c60 (rcu_read_lock){....}-{1:3}, at: __rhashtable_remove_fast include/linux/rhashtable.h:1137 [inline] #4: ffffffff8eb59c60 (rcu_read_lock){....}-{1:3}, at: rhashtable_remove_fast include/linux/rhashtable.h:1175 [inline] #4: ffffffff8eb59c60 (rcu_read_lock){....}-{1:3}, at: rhtab_delete_elem+0x15c/0x1b30 kernel/bpf/hashtab.c:-1 stack backtrace: CPU: 1 UID: 0 PID: 5768 Comm: syz-executor Not tainted syzkaller #0 PREEMPT(full) Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 06/25/2026 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+0x24df/0x2cf0 kernel/locking/lockdep.c:5237 lock_acquire+0x106/0x350 kernel/locking/lockdep.c:5868 rht_lock+0xa3/0x180 include/linux/rhashtable.h:331 __rhashtable_remove_fast_one include/linux/rhashtable.h:1065 [inline] __rhashtable_remove_fast include/linux/rhashtable.h:1146 [inline] rhashtable_remove_fast include/linux/rhashtable.h:1175 [inline] rhtab_delete_elem+0x404/0x1b30 kernel/bpf/hashtab.c:2954 rhtab_map_delete_elem+0xe2/0x190 kernel/bpf/hashtab.c:2985 bpf_prog_a4f1e23443ac9f8e+0x4e/0x56 bpf_dispatcher_nop_func include/linux/bpf.h:1454 [inline] __bpf_prog_run include/linux/filter.h:724 [inline] bpf_prog_run include/linux/filter.h:731 [inline] bpf_prog_run_array include/linux/bpf.h:2597 [inline] trace_call_bpf+0x3f0/0xb80 kernel/trace/bpf_trace.c:147 perf_trace_run_bpf_submit+0x78/0x170 kernel/events/core.c:11398 do_perf_trace_lock include/trace/events/lock.h:49 [inline] perf_trace_lock+0x32d/0x410 include/trace/events/lock.h:49 __do_trace_lock_release include/trace/events/lock.h:68 [inline] trace_lock_release include/trace/events/lock.h:68 [inline] lock_release+0x38e/0x3c0 kernel/locking/lockdep.c:5879 rht_assign_unlock include/linux/rhashtable.h:431 [inline] __rhashtable_insert_fast include/linux/rhashtable.h:850 [inline] rhashtable_insert_fast include/linux/rhashtable.h:887 [inline] pidfs_add_pid+0x650/0xc50 fs/pidfs.c:178 alloc_pid+0xe7a/0x1310 kernel/pid.c:338 copy_process+0x20ea/0x4390 kernel/fork.c:2305 kernel_clone+0x2d7/0x940 kernel/fork.c:2748 __do_sys_clone kernel/fork.c:2889 [inline] __se_sys_clone kernel/fork.c:2873 [inline] __x64_sys_clone+0x1b6/0x230 kernel/fork.c:2873 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline] do_syscall_64+0x174/0x580 arch/x86/entry/syscall_64.c:94 entry_SYSCALL_64_after_hwframe+0x77/0x7f RIP: 0033:0x7f703d7c6912 Code: 89 e7 e8 71 8b f7 ff 45 31 c0 31 d2 31 f6 64 48 8b 04 25 10 00 00 00 bf 11 00 20 01 4c 8d 90 d0 02 00 00 b8 38 00 00 00 0f 05 <48> 3d 00 f0 ff ff 77 66 89 c5 85 c0 75 3b 64 48 8b 04 25 10 00 00 RSP: 002b:00007ffe5db74e40 EFLAGS: 00000246 ORIG_RAX: 0000000000000038 RAX: ffffffffffffffda RBX: 00007ffe5db74e40 RCX: 00007f703d7c6912 RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000001200011 RBP: 00007ffe5db74fcc R08: 0000000000000000 R09: 0000000000000000 R10: 000055556f65e7d0 R11: 0000000000000246 R12: 0000000000000001 R13: 00000000000927c0 R14: 0000000000025e7d R15: 00007ffe5db75020 --- This report is generated by a bot. 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