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WARNING: lock held when returning to user space in loop_set_block_size

Status: fixed on 2025/11/05 06:26
Bug presence: origin:lts-only
[Documentation on labels]
Reported-by: syzbot+53ce52a8070d96c8f320@syzkaller.appspotmail.com
Fix commit: 42a6aeb4b238 Revert "loop: Avoid updating block size under exclusive owner"
First crash: 86d, last: 59d
Fix bisection: fixed by (bisect log) :
commit 42a6aeb4b23890a4d2323b51841690be7ea49f8d
Author: Eric Hagberg <ehagberg@janestreet.com>
Date: Mon Sep 22 17:17:04 2025 +0000

  Revert "loop: Avoid updating block size under exclusive owner"

  
▶ ▼ Bug presence (2)
Date Name Commit Repro Result
2025/09/02 linux-6.6.y (ToT) cc1a1c5b404a C [report] WARNING: lock held when returning to user space in loop_set_block_size
2025/09/02 upstream (ToT) e6b9dce0aeeb C Didn't crash

Sample crash report:
Dev loop6: unable to read RDB block 0
 loop6: unable to read partition table
loop_reread_partitions: partition scan of loop6 (3Ÿ¾x³˜CÖ) failed (rc=-5)
================================================
WARNING: lock held when returning to user space!
syzkaller #0 Not tainted
------------------------------------------------
syz.0.17/5947 is leaving the kernel with locks still held!
1 lock held by syz.0.17/5947:
 #0: ffff888021387b60 (&lo->lo_mutex){+.+.}-{3:3}, at: loop_set_block_size+0x7c/0x480 drivers/block/loop.c:1490

Crashes (100):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2025/09/18 03:10 linux-6.6.y 60a9e718726f e2beed91 .config console log report syz / log C [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan WARNING: lock held when returning to user space in loop_set_block_size
2025/09/18 02:03 linux-6.6.y 60a9e718726f e2beed91 .config console log report syz / log C [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan WARNING: lock held when returning to user space in loop_set_block_size
2025/08/30 18:35 linux-6.6.y cc1a1c5b404a 807a3b61 .config console log report syz / log C [disk image] [vmlinux] [kernel image] [mounted in repro] ci2-linux-6-6-kasan WARNING: lock held when returning to user space in loop_set_block_size
2025/09/24 23:46 linux-6.6.y af1544b5d072 0abd0691 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan WARNING: lock held when returning to user space in loop_set_block_size
2025/09/24 02:28 linux-6.6.y af1544b5d072 e667a34f .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan WARNING: lock held when returning to user space in loop_set_block_size
2025/09/23 16:03 linux-6.6.y af1544b5d072 0ac7291c .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan WARNING: lock held when returning to user space in loop_set_block_size
2025/09/23 07:44 linux-6.6.y af1544b5d072 0ac7291c .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan WARNING: lock held when returning to user space in loop_set_block_size
2025/09/23 06:20 linux-6.6.y af1544b5d072 0ac7291c .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan WARNING: lock held when returning to user space in loop_set_block_size
2025/09/22 22:49 linux-6.6.y af1544b5d072 0ac7291c .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan WARNING: lock held when returning to user space in loop_set_block_size
2025/09/22 20:59 linux-6.6.y af1544b5d072 0ac7291c .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan WARNING: lock held when returning to user space in loop_set_block_size
2025/09/21 12:27 linux-6.6.y af1544b5d072 67c37560 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan WARNING: lock held when returning to user space in loop_set_block_size
2025/09/21 03:54 linux-6.6.y af1544b5d072 67c37560 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan WARNING: lock held when returning to user space in loop_set_block_size
2025/09/20 23:00 linux-6.6.y af1544b5d072 67c37560 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan WARNING: lock held when returning to user space in loop_set_block_size
2025/09/20 21:29 linux-6.6.y af1544b5d072 67c37560 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan WARNING: lock held when returning to user space in loop_set_block_size
2025/09/20 17:38 linux-6.6.y af1544b5d072 67c37560 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan WARNING: lock held when returning to user space in loop_set_block_size
2025/09/20 17:38 linux-6.6.y af1544b5d072 67c37560 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan WARNING: lock held when returning to user space in loop_set_block_size
2025/09/18 15:06 linux-6.6.y 60a9e718726f e2beed91 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan WARNING: lock held when returning to user space in loop_set_block_size
2025/09/18 11:44 linux-6.6.y 60a9e718726f e2beed91 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan WARNING: lock held when returning to user space in loop_set_block_size
2025/09/18 04:28 linux-6.6.y 60a9e718726f e2beed91 .config console log report syz / log C [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan WARNING: lock held when returning to user space in loop_set_block_size
2025/09/18 00:12 linux-6.6.y 60a9e718726f e2beed91 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan WARNING: lock held when returning to user space in loop_set_block_size
2025/09/17 01:52 linux-6.6.y 60a9e718726f e2beed91 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan WARNING: lock held when returning to user space in loop_set_block_size
2025/09/16 02:15 linux-6.6.y 60a9e718726f e2beed91 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan WARNING: lock held when returning to user space in loop_set_block_size
2025/09/15 03:26 linux-6.6.y 60a9e718726f e2beed91 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan WARNING: lock held when returning to user space in loop_set_block_size
2025/09/15 03:25 linux-6.6.y 60a9e718726f e2beed91 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan WARNING: lock held when returning to user space in loop_set_block_size
2025/09/14 14:28 linux-6.6.y 60a9e718726f e2beed91 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan WARNING: lock held when returning to user space in loop_set_block_size
2025/09/13 19:03 linux-6.6.y 60a9e718726f e2beed91 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan WARNING: lock held when returning to user space in loop_set_block_size
2025/09/11 11:35 linux-6.6.y fe9731e10004 fdeaa69b .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan WARNING: lock held when returning to user space in loop_set_block_size
2025/09/11 09:34 linux-6.6.y fe9731e10004 fdeaa69b .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan WARNING: lock held when returning to user space in loop_set_block_size
2025/09/10 12:07 linux-6.6.y fe9731e10004 fdeaa69b .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan WARNING: lock held when returning to user space in loop_set_block_size
2025/09/10 10:00 linux-6.6.y fe9731e10004 fdeaa69b .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan WARNING: lock held when returning to user space in loop_set_block_size
2025/09/08 20:05 linux-6.6.y 355bd0b51d2f d291dd2d .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan WARNING: lock held when returning to user space in loop_set_block_size
2025/09/08 18:54 linux-6.6.y 355bd0b51d2f d291dd2d .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan WARNING: lock held when returning to user space in loop_set_block_size
2025/09/08 03:05 linux-6.6.y 355bd0b51d2f d291dd2d .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan WARNING: lock held when returning to user space in loop_set_block_size
2025/09/08 00:23 linux-6.6.y 355bd0b51d2f d291dd2d .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan WARNING: lock held when returning to user space in loop_set_block_size
2025/09/08 00:22 linux-6.6.y 355bd0b51d2f d291dd2d .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan WARNING: lock held when returning to user space in loop_set_block_size
2025/09/07 23:43 linux-6.6.y 355bd0b51d2f d291dd2d .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan WARNING: lock held when returning to user space in loop_set_block_size
2025/09/07 23:43 linux-6.6.y 355bd0b51d2f d291dd2d .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan WARNING: lock held when returning to user space in loop_set_block_size
2025/09/07 22:37 linux-6.6.y 355bd0b51d2f d291dd2d .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan WARNING: lock held when returning to user space in loop_set_block_size
2025/09/07 22:37 linux-6.6.y 355bd0b51d2f d291dd2d .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan WARNING: lock held when returning to user space in loop_set_block_size
2025/09/07 22:18 linux-6.6.y 355bd0b51d2f d291dd2d .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan WARNING: lock held when returning to user space in loop_set_block_size
2025/09/07 22:18 linux-6.6.y 355bd0b51d2f d291dd2d .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan WARNING: lock held when returning to user space in loop_set_block_size
2025/09/06 21:32 linux-6.6.y 355bd0b51d2f d291dd2d .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan WARNING: lock held when returning to user space in loop_set_block_size
2025/09/06 21:32 linux-6.6.y 355bd0b51d2f d291dd2d .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan WARNING: lock held when returning to user space in loop_set_block_size
2025/09/06 10:23 linux-6.6.y 355bd0b51d2f d291dd2d .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan WARNING: lock held when returning to user space in loop_set_block_size
2025/09/06 01:15 linux-6.6.y 355bd0b51d2f d291dd2d .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan WARNING: lock held when returning to user space in loop_set_block_size
2025/09/06 01:12 linux-6.6.y 355bd0b51d2f d291dd2d .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan WARNING: lock held when returning to user space in loop_set_block_size
2025/09/05 19:21 linux-6.6.y 355bd0b51d2f d291dd2d .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan WARNING: lock held when returning to user space in loop_set_block_size
2025/09/05 19:21 linux-6.6.y 355bd0b51d2f d291dd2d .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan WARNING: lock held when returning to user space in loop_set_block_size
2025/09/05 11:01 linux-6.6.y 355bd0b51d2f d291dd2d .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan WARNING: lock held when returning to user space in loop_set_block_size
2025/09/05 11:01 linux-6.6.y 355bd0b51d2f d291dd2d .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan WARNING: lock held when returning to user space in loop_set_block_size
2025/09/04 22:28 linux-6.6.y 355bd0b51d2f d291dd2d .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan WARNING: lock held when returning to user space in loop_set_block_size
2025/08/28 22:58 linux-6.6.y cc1a1c5b404a d401b9d7 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan WARNING: lock held when returning to user space in loop_set_block_size
* Struck through repros no longer work on HEAD.