syzbot


WARNING: suspicious RCU usage in validate_mm

Status: fixed on 2021/11/10 00:50
Reported-by: syzbot+@syzkaller.appspotmail.com
Fix commit: 3066820034b5 rcu: Reject RCU_LOCKDEP_WARN() false positives
First crash: 601d, last: 601d

Sample crash report:
=============================
WARNING: suspicious RCU usage
5.13.0-rc5-syzkaller #0 Not tainted
-----------------------------
kernel/sched/core.c:8304 Illegal context switch in RCU-bh read-side critical section!

other info that might help us debug this:


rcu_scheduler_active = 2, debug_locks = 0
1 lock held by syz-executor.3/10482:
 #0: 
ffff8880127a3218
 (
&mm->mmap_lock
#2
){++++}-{3:3}
, at: mmap_write_lock_killable include/linux/mmap_lock.h:87 [inline]
, at: vm_mmap_pgoff+0x15c/0x290 mm/util.c:517

stack backtrace:
CPU: 1 PID: 10482 Comm: syz-executor.3 Not tainted 5.13.0-rc5-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Call Trace:
 __dump_stack lib/dump_stack.c:79 [inline]
 dump_stack+0x141/0x1d7 lib/dump_stack.c:120
 ___might_sleep+0x229/0x2c0 kernel/sched/core.c:8304
 down_read+0x73/0x440 kernel/locking/rwsem.c:1352
 anon_vma_lock_read include/linux/rmap.h:129 [inline]
 validate_mm+0xd3/0x810 mm/mmap.c:406
 mmap_region+0xeff/0x1730 mm/mmap.c:1864
 do_mmap+0xcff/0x11d0 mm/mmap.c:1587
 vm_mmap_pgoff+0x1b7/0x290 mm/util.c:519
 ksys_mmap_pgoff+0xe4/0x620 mm/mmap.c:1638
 do_syscall_64+0x3a/0xb0 arch/x86/entry/common.c:47
 entry_SYSCALL_64_after_hwframe+0x44/0xae
RIP: 0033:0x466622
Code: 00 00 00 00 00 0f 1f 00 41 f7 c1 ff 0f 00 00 75 27 55 48 89 fd 53 89 cb 48 85 ff 74 3b 41 89 da 48 89 ef b8 09 00 00 00 0f 05 <48> 3d 00 f0 ff ff 77 66 5b 5d c3 0f 1f 00 48 c7 c0 bc ff ff ff 64
RSP: 002b:00007fff6b288bd8 EFLAGS: 00000246 ORIG_RAX: 0000000000000009
RAX: ffffffffffffffda RBX: 0000000000020022 RCX: 0000000000466622
RDX: 0000000000000000 RSI: 0000000000021000 RDI: 0000000000000000
RBP: 0000000000000000 R08: 00000000ffffffff R09: 0000000000000000
R10: 0000000000020022 R11: 0000000000000246 R12: 00007fff6b288dd0
R13: 00007f6a5677f700 R14: 0000000000000000 R15: 0000000000022000

Crashes (1):
Manager Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets Title
ci-upstream-kasan-gce-selinux-root 2021/06/07 18:11 upstream 614124bea77e e59537be .config console log report info WARNING: suspicious RCU usage in validate_mm
* Struck through repros no longer work on HEAD.