=============================
WARNING: suspicious RCU usage
syzkaller #0 Not tainted
-----------------------------
lib/maple_tree.c:720 suspicious rcu_dereference_check() usage!

other info that might help us debug this:


rcu_scheduler_active = 2, debug_locks = 1
locks held by syz.3.362/7036: 1, last CPU#1:
 #0: ffff88803422e0a0 (&ctx->uring_lock){+.+.}-{4:4}, at: tctx_task_work_run+0x1cd/0xbf0 io_uring/tw.c:92

stack backtrace:
CPU: 1 UID: 0 PID: 7036 Comm: syz.3.362 Not tainted syzkaller #0 PREEMPT(full) 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 08/26/2026
Call Trace:
 <TASK>
 __dump_stack lib/dump_stack.c:94 [inline]
 dump_stack_lvl+0x100/0x190 lib/dump_stack.c:120
 lockdep_rcu_suspicious.cold+0x4f/0xb2 kernel/locking/lockdep.c:6972
 mas_root lib/maple_tree.c:720 [inline]
 mas_start+0x621/0x7c0 lib/maple_tree.c:1250
 mas_state_walk lib/maple_tree.c:3006 [inline]
 mas_walk+0x82/0x310 lib/maple_tree.c:4458
 ublk_try_buf_match+0x469/0x7e0 drivers/block/ublk_drv.c:5639
 ublk_init_iod+0x4a4/0x5b0 drivers/block/ublk_drv.c:521
 ublk_setup_iod+0x145/0x2f0 drivers/block/ublk_drv.c:1536
 ublk_dispatch_req+0x4e/0xb00 drivers/block/ublk_drv.c:1776
 ublk_cmd_tw_cb+0xbe/0x110 drivers/block/ublk_drv.c:2067
 tctx_task_work_run+0xabe/0xbf0 io_uring/tw.c:96
 tctx_task_work+0x7a/0xa0 io_uring/tw.c:133
 task_work_run+0x150/0x240 kernel/task_work.c:233
 io_run_task_work+0x19f/0x630 io_uring/tw.h:84
 io_cqring_wait+0xe8d/0x2980 io_uring/wait.c:278
 __do_sys_io_uring_enter+0x1136/0x1b10 io_uring/io_uring.c:2676
 do_syscall_x64 arch/x86/entry/syscall_64.c:61 [inline]
 do_syscall_64+0x123/0x790 arch/x86/entry/syscall_64.c:84
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f356199e159
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:00007f35627f6f78 EFLAGS: 00000246 ORIG_RAX: 00000000000001aa
RAX: ffffffffffffffda RBX: 0000200000000800 RCX: 00007f356199e159
RDX: 0000000000000001 RSI: 0000000000000000 RDI: 0000000000000006
RBP: 0000000000000000 R08: 00007f35627f6fd0 R09: 0000000000000018
R10: 0000000000000009 R11: 0000000000000246 R12: 0000200000000e00
R13: 0000000000000000 R14: 00007f3561c25fa0 R15: 00007fff32985f98
 </TASK>