linux-kernel - Re: [syzbot] [mm?] WARNING: lock held when returning to user space in lock_next

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Message-ID: <20250711003220.3259-1-hdanton@sina.com>
Date: Fri, 11 Jul 2025 08:32:18 +0800
From: Hillf Danton <hdanton@...a.com>
To: syzbot <syzbot+80011ad33eec39e6ce42@...kaller.appspotmail.com>
Cc: linux-kernel@...r.kernel.org,
	syzkaller-bugs@...glegroups.com
Subject: Re: [syzbot] [mm?] WARNING: lock held when returning to user space in lock_next_vma

> Date: Tue, 08 Jul 2025 10:52:27 -0700	[thread overview]
> Hello,
> 
> syzbot found the following issue on:
> 
> HEAD commit:    26ffb3d6f02c Add linux-next specific files for 20250704
> git tree:       linux-next
> console output: https://syzkaller.appspot.com/x/log.txt?x=1719df70580000
> kernel config:  https://syzkaller.appspot.com/x/.config?x=1e4f88512ae53408
> dashboard link: https://syzkaller.appspot.com/bug?extid=80011ad33eec39e6ce42
> syz repro:      https://syzkaller.appspot.com/x/repro.syz?x=1124abd4580000
> C reproducer:   https://syzkaller.appspot.com/x/repro.c?x=1099df70580000

#syz test

--- x/fs/proc/task_mmu.c
+++ y/fs/proc/task_mmu.c
@@ -187,6 +187,7 @@ static struct vm_area_struct *get_next_v
 }
 
 #else /* CONFIG_PER_VMA_LOCK */
+static void unlock_vma(struct proc_maps_private *priv) {}
 
 static inline bool lock_vma_range(struct seq_file *m,
 				  struct proc_maps_private *priv)
@@ -582,6 +583,7 @@ skip_vma:
 	if (flags & PROCMAP_QUERY_COVERING_OR_NEXT_VMA)
 		goto next_vma;
 
+	unlock_vma(priv);
 no_vma:
 	return ERR_PTR(-ENOENT);
 }
--