syzbot

=============================
WARNING: suspicious RCU usage
6.2.0-syzkaller-12485-gf3a2439f20d9 #0 Not tainted
-----------------------------
lib/maple_tree.c:856 suspicious rcu_dereference_check() usage!

other info that might help us debug this:


rcu_scheduler_active = 2, debug_locks = 1
5 locks held by syz-executor379/5138:
 #0: ffff88802c37c460 (sb_writers#8){.+.+}-{0:0}, at: ksys_write+0x12b/0x250 fs/read_write.c:637
 #1: ffff8880202f6888 (&of->mutex){+.+.}-{3:3}, at: kernfs_fop_write_iter+0x285/0x600 fs/kernfs/file.c:325
 #2: ffff8880178b4490 (kn->active#47){.+.+}-{0:0}, at: kernfs_fop_write_iter+0x2a9/0x600 fs/kernfs/file.c:326
 #3: ffffffff8c90bce8 (ksm_thread_mutex){+.+.}-{3:3}, at: run_store+0xd5/0xa30 mm/ksm.c:2953
 #4: ffff888076a84258 (&mm->mmap_lock){++++}-{3:3}, at: mmap_read_lock include/linux/mmap_lock.h:117 [inline]
 #4: ffff888076a84258 (&mm->mmap_lock){++++}-{3:3}, at: unmerge_and_remove_all_rmap_items mm/ksm.c:990 [inline]
 #4: ffff888076a84258 (&mm->mmap_lock){++++}-{3:3}, at: run_store+0x2a9/0xa30 mm/ksm.c:2959

stack backtrace:
CPU: 0 PID: 5138 Comm: syz-executor379 Not tainted 6.2.0-syzkaller-12485-gf3a2439f20d9 #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 02/16/2023
Call Trace:
 <TASK>
 __dump_stack lib/dump_stack.c:88 [inline]
 dump_stack_lvl+0x136/0x150 lib/dump_stack.c:106
 lockdep_rcu_suspicious+0x208/0x3a0 kernel/locking/lockdep.c:6599
 mas_root lib/maple_tree.c:856 [inline]
 mas_start lib/maple_tree.c:1357 [inline]
 mas_state_walk lib/maple_tree.c:3838 [inline]
 mas_walk+0x473/0x6e0 lib/maple_tree.c:5052
 mas_find+0x150/0x200 lib/maple_tree.c:6030
 vma_next include/linux/mm.h:745 [inline]
 unmerge_and_remove_all_rmap_items mm/ksm.c:991 [inline]
 run_store+0x2e7/0xa30 mm/ksm.c:2959
 kobj_attr_store+0x54/0x80 lib/kobject.c:832
 sysfs_kf_write+0x114/0x170 fs/sysfs/file.c:136
 kernfs_fop_write_iter+0x3f1/0x600 fs/kernfs/file.c:334
 call_write_iter include/linux/fs.h:1851 [inline]
 new_sync_write fs/read_write.c:491 [inline]
 vfs_write+0x9ed/0xe10 fs/read_write.c:584
 ksys_write+0x12b/0x250 fs/read_write.c:637
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x39/0xb0 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x63/0xcd
RIP: 0033:0x7f9fbf756e49
Code: 28 00 00 00 75 05 48 83 c4 28 c3 e8 b1 14 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 c0 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007fff4fa8ea58 EFLAGS: 00000246 ORIG_RAX: 0000000000000001
RAX: ffffffffffffffda RBX: 00000000000f4240 RCX: 00007f9fbf756e49
RDX: 0000000000000002 RSI: 0000000020000000 RDI: 0000000000000003
RBP: 0000000000000000 R08: 0000000000000001 R09: 0000000000000001
R10: 0000000000000001 R11: 0000000000000246 R12: 000000000000e6c1
R13: 00007fff4fa8ea6c R14: 00007fff4fa8ea80 R15: 00007fff4fa8ea70
 </TASK>