syzbot


WARNING: lock held when returning to user space in lock_vma_under_rcu

Status: moderation: reported on 2026/03/18 12:51
Subsystems: mm
[Documentation on labels]
Reported-by: syzbot+a9cd727808f8f83b24f9@syzkaller.appspotmail.com
First crash: 6d04h, last: 6d04h
Discussions (1)
Title Replies (including bot) Last reply
[PATCH] userfaultfd: fix lock leak in mfill_get_vma() 1 (1) 2026/03/16 17:38

Sample crash report:
================================================
WARNING: lock held when returning to user space!
syzkaller #0 Tainted: G             L     
------------------------------------------------
syz.4.5868/25813 is leaving the kernel with locks still held!
2 locks held by syz.4.5868/25813:
 #0: ffff88806504b308 (vm_lock){++++}-{0:0}, at: lock_vma_under_rcu+0x1d1/0x500 mm/mmap_lock.c:310
 #1: ffff88807c9501f0 (&ctx->map_changing_lock){++++}-{4:4}, at: mfill_get_vma+0x162/0x660 mm/userfaultfd.c:226

Crashes (1):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2026/03/14 12:47 linux-next b84a0ebe421c ee8d34d6 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-rust-kasan-gce WARNING: lock held when returning to user space in lock_vma_under_rcu
* Struck through repros no longer work on HEAD.