* [PATCH v1 2/2] block: loop: restore state on loop_configure() error
2026-08-31 15:20 [PATCH v1 0/2] block: brd/loop error-path cleanup Iván Ezequiel Rodriguez
2026-08-31 15:20 ` [PATCH v1 1/2] block: brd: destroy xa on allocation failure Iván Ezequiel Rodriguez
@ 2026-08-31 15:20 ` Iván Ezequiel Rodriguez
2026-09-01 6:59 ` [syzbot ci] Re: block: brd/loop error-path cleanup syzbot ci
2 siblings, 0 replies; 4+ messages in thread
From: Iván Ezequiel Rodriguez @ 2026-08-31 15:20 UTC (permalink / raw)
To: Jens Axboe; +Cc: linux-block, linux-kernel, Iván Ezequiel Rodriguez
On failure after loop_assign_backing_file(), restore the backing
file GFP mask, clear lo_backing_file/lo_device, and re-enable uevents
before unlocking and dropping the file reference.
Signed-off-by: Iván Ezequiel Rodriguez <ivanrwcm25@gmail.com>
---
drivers/block/loop.c | 7 +++++++
1 file changed, 7 insertions(+)
diff --git a/drivers/block/loop.c b/drivers/block/loop.c
index 6f12976035b0..838554bd980e 100644
--- a/drivers/block/loop.c
+++ b/drivers/block/loop.c
@@ -1123,6 +1123,13 @@ static int loop_configure(struct loop_device *lo, blk_mode_t mode,
return 0;
out_unlock:
+ if (lo->lo_backing_file) {
+ mapping_set_gfp_mask(lo->lo_backing_file->f_mapping,
+ lo->old_gfp_mask);
+ lo->lo_backing_file = NULL;
+ lo->lo_device = NULL;
+ }
+ dev_set_uevent_suppress(disk_to_dev(lo->lo_disk), 0);
loop_global_unlock(lo, is_loop);
out_bdev:
if (!(mode & BLK_OPEN_EXCL))
--
2.43.0
^ permalink raw reply related [flat|nested] 4+ messages in thread* [syzbot ci] Re: block: brd/loop error-path cleanup
2026-08-31 15:20 [PATCH v1 0/2] block: brd/loop error-path cleanup Iván Ezequiel Rodriguez
2026-08-31 15:20 ` [PATCH v1 1/2] block: brd: destroy xa on allocation failure Iván Ezequiel Rodriguez
2026-08-31 15:20 ` [PATCH v1 2/2] block: loop: restore state on loop_configure() error Iván Ezequiel Rodriguez
@ 2026-09-01 6:59 ` syzbot ci
2 siblings, 0 replies; 4+ messages in thread
From: syzbot ci @ 2026-09-01 6:59 UTC (permalink / raw)
To: axboe, ivanrwcm25, linux-block, linux-kernel; +Cc: syzbot, syzkaller-bugs
syzbot ci has tested the following series
[v1] block: brd/loop error-path cleanup
https://lore.kernel.org/all/20260831152044.166353-1-ivanrwcm25@gmail.com
* [PATCH v1 1/2] block: brd: destroy xa on allocation failure
* [PATCH v1 2/2] block: loop: restore state on loop_configure() error
and found the following issues:
* general protection fault in lo_release
* general protection fault in lo_rw_aio
Full report is available here:
https://ci.syzbot.org/series/9ab490fc-567e-414a-9754-890ca131012d
***
general protection fault in lo_release
tree: axboe
URL: https://kernel.googlesource.com/pub/scm/linux/kernel/git/axboe/linux.git
base: 44e96e364b04163ddddc8a24289cef4982b7e36e
arch: amd64
compiler: Debian clang version 22.1.8 (++20260613092233+e80beda6e255-1~exp1~20260613092250.77), Debian LLD 22.1.8
config: https://ci.syzbot.org/builds/f5d23472-69ec-45bc-b33a-b59f7c0e7493/config
syz repro: https://ci.syzbot.org/findings/a48673c0-89de-4ffc-b71c-3aa9e5313ec8/syz_repro
Oops: general protection fault, probably for non-canonical address 0xdffffc000000000a: 0000 [#1] SMP KASAN PTI
KASAN: null-ptr-deref in range [0x0000000000000050-0x0000000000000057]
CPU: 0 UID: 0 PID: 5946 Comm: syz.0.87 Not tainted syzkaller #0 PREEMPT(full)
Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.2-debian-1.16.2-1 04/01/2014
RIP: 0010:__loop_clr_fd drivers/block/loop.c:1177 [inline]
RIP: 0010:lo_release+0x47c/0x7e0 drivers/block/loop.c:1780
Code: 89 e7 e8 77 60 fc fb bf e0 01 00 00 49 03 3c 24 be 02 00 00 00 e8 84 c6 9c 05 48 8b 44 24 30 4c 8d 70 50 4c 89 f0 48 c1 e8 03 <42> 80 3c 28 00 74 08 4c 89 f7 e8 45 60 fc fb 41 bc e8 00 00 00 4d
RSP: 0018:ffffc90003787b60 EFLAGS: 00010206
RAX: 000000000000000a RBX: ffff8881063f93c8 RCX: 0000000000000046
RDX: 0000000000000006 RSI: ffffffff8e46de57 RDI: ffffffff8c6d5780
RBP: ffffc90003787d08 R08: ffffffff9079c73f R09: 1ffffffff20f38e7
R10: dffffc0000000000 R11: fffffbfff20f38e8 R12: ffff8881063f8080
R13: dffffc0000000000 R14: 0000000000000050 R15: 1ffff920006f0f74
FS: 00007fae103d46c0(0000) GS:ffff88818d6f1000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007fae0f5eb840 CR3: 000000010c31a000 CR4: 00000000000006f0
Call Trace:
<TASK>
bdev_release+0x571/0x690 block/bdev.c:-1
blkdev_release+0x15/0x20 block/fops.c:682
__fput+0x418/0xa50 fs/file_table.c:512
fput_close_sync+0x11f/0x240 fs/file_table.c:617
__do_sys_close fs/open.c:1560 [inline]
__se_sys_close fs/open.c:1545 [inline]
__x64_sys_close+0x7e/0x110 fs/open.c:1545
do_syscall_x64 arch/x86/entry/syscall_64.c:61 [inline]
do_syscall_64+0x166/0x520 arch/x86/entry/syscall_64.c:84
entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7fae0f55e98e
Code: 08 0f 85 a5 a8 ff ff 49 89 fb 48 89 f0 48 89 d7 48 89 ce 4c 89 c2 4d 89 ca 4c 8b 44 24 08 4c 8b 4c 24 10 4c 89 5c 24 08 0f 05 <c3> 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 80 00 00 00 00 48 83 ec 08
RSP: 002b:00007fae103d3da8 EFLAGS: 00000246 ORIG_RAX: 0000000000000003
RAX: ffffffffffffffda RBX: 00007fae103d46c0 RCX: 00007fae0f55e98e
RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000004
RBP: 0000000000000010 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000003
R13: 00007fae103d3ee0 R14: 00007fae103d46a8 R15: 00007fae06600000
</TASK>
Modules linked in:
---[ end trace 0000000000000000 ]---
RIP: 0010:__loop_clr_fd drivers/block/loop.c:1177 [inline]
RIP: 0010:lo_release+0x47c/0x7e0 drivers/block/loop.c:1780
Code: 89 e7 e8 77 60 fc fb bf e0 01 00 00 49 03 3c 24 be 02 00 00 00 e8 84 c6 9c 05 48 8b 44 24 30 4c 8d 70 50 4c 89 f0 48 c1 e8 03 <42> 80 3c 28 00 74 08 4c 89 f7 e8 45 60 fc fb 41 bc e8 00 00 00 4d
RSP: 0018:ffffc90003787b60 EFLAGS: 00010206
RAX: 000000000000000a RBX: ffff8881063f93c8 RCX: 0000000000000046
RDX: 0000000000000006 RSI: ffffffff8e46de57 RDI: ffffffff8c6d5780
RBP: ffffc90003787d08 R08: ffffffff9079c73f R09: 1ffffffff20f38e7
R10: dffffc0000000000 R11: fffffbfff20f38e8 R12: ffff8881063f8080
R13: dffffc0000000000 R14: 0000000000000050 R15: 1ffff920006f0f74
FS: 00007fae103d46c0(0000) GS:ffff8882a8cf1000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007ffd52a75ff8 CR3: 000000010c31a000 CR4: 00000000000006f0
----------------
Code disassembly (best guess):
0: 89 e7 mov %esp,%edi
2: e8 77 60 fc fb call 0xfbfc607e
7: bf e0 01 00 00 mov $0x1e0,%edi
c: 49 03 3c 24 add (%r12),%rdi
10: be 02 00 00 00 mov $0x2,%esi
15: e8 84 c6 9c 05 call 0x59cc69e
1a: 48 8b 44 24 30 mov 0x30(%rsp),%rax
1f: 4c 8d 70 50 lea 0x50(%rax),%r14
23: 4c 89 f0 mov %r14,%rax
26: 48 c1 e8 03 shr $0x3,%rax
* 2a: 42 80 3c 28 00 cmpb $0x0,(%rax,%r13,1) <-- trapping instruction
2f: 74 08 je 0x39
31: 4c 89 f7 mov %r14,%rdi
34: e8 45 60 fc fb call 0xfbfc607e
39: 41 bc e8 00 00 00 mov $0xe8,%r12d
3f: 4d rex.WRB
***
general protection fault in lo_rw_aio
tree: axboe
URL: https://kernel.googlesource.com/pub/scm/linux/kernel/git/axboe/linux.git
base: 44e96e364b04163ddddc8a24289cef4982b7e36e
arch: amd64
compiler: Debian clang version 22.1.8 (++20260613092233+e80beda6e255-1~exp1~20260613092250.77), Debian LLD 22.1.8
config: https://ci.syzbot.org/builds/f5d23472-69ec-45bc-b33a-b59f7c0e7493/config
syz repro: https://ci.syzbot.org/findings/556532c0-64a7-4471-9558-ea3a7a213af7/syz_repro
Oops: general protection fault, probably for non-canonical address 0xdffffc0000000009: 0000 [#1] SMP KASAN PTI
KASAN: null-ptr-deref in range [0x0000000000000048-0x000000000000004f]
CPU: 0 UID: 0 PID: 83 Comm: kworker/u9:3 Not tainted syzkaller #0 PREEMPT(full)
Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.2-debian-1.16.2-1 04/01/2014
Workqueue: loop0 loop_rootcg_workfn
RIP: 0010:lo_rw_aio+0xc36/0xf20 include/linux/percpu-rwsem.h:-1
Code: fb 48 8d 35 00 00 00 00 bf 60 04 00 00 48 03 3b e8 9f 51 68 fb bb 30 00 00 00 4c 8b 74 24 58 49 83 c6 48 4c 89 f0 48 c1 e8 03 <42> 80 3c 20 00 74 08 4c 89 f7 e8 8b 6c fc fb 49 03 1e 48 89 d8 48
RSP: 0018:ffffc9000277f620 EFLAGS: 00010206
RAX: 0000000000000009 RBX: 0000000000000028 RCX: ffff888102725a00
RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000000
RBP: ffffc9000277f790 R08: ffff88810aa529a7 R09: 1ffff1102154a534
R10: dffffc0000000000 R11: ffffed102154a535 R12: dffffc0000000000
R13: 0000000000000000 R14: 0000000000000048 R15: ffff88810aa529b0
FS: 0000000000000000(0000) GS:ffff88818d6f1000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000558fd5b46210 CR3: 00000001bb152000 CR4: 00000000000006f0
Call Trace:
<TASK>
do_req_filebacked drivers/block/loop.c:432 [inline]
loop_handle_cmd drivers/block/loop.c:1954 [inline]
loop_process_work+0x960/0x11c0 drivers/block/loop.c:1989
process_one_work kernel/workqueue.c:3387 [inline]
process_scheduled_works+0xc3d/0x1630 kernel/workqueue.c:3470
worker_thread+0xa47/0xfb0 kernel/workqueue.c:3551
kthread+0x38b/0x480 kernel/kthread.c:436
ret_from_fork+0x514/0xb70 arch/x86/kernel/process.c:158
ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245
</TASK>
Modules linked in:
---[ end trace 0000000000000000 ]---
RIP: 0010:lo_rw_aio+0xc36/0xf20 include/linux/percpu-rwsem.h:-1
Code: fb 48 8d 35 00 00 00 00 bf 60 04 00 00 48 03 3b e8 9f 51 68 fb bb 30 00 00 00 4c 8b 74 24 58 49 83 c6 48 4c 89 f0 48 c1 e8 03 <42> 80 3c 20 00 74 08 4c 89 f7 e8 8b 6c fc fb 49 03 1e 48 89 d8 48
RSP: 0018:ffffc9000277f620 EFLAGS: 00010206
RAX: 0000000000000009 RBX: 0000000000000028 RCX: ffff888102725a00
RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000000
RBP: ffffc9000277f790 R08: ffff88810aa529a7 R09: 1ffff1102154a534
R10: dffffc0000000000 R11: ffffed102154a535 R12: dffffc0000000000
R13: 0000000000000000 R14: 0000000000000048 R15: ffff88810aa529b0
FS: 0000000000000000(0000) GS:ffff88818d6f1000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000558fd5b46210 CR3: 0000000169ee2000 CR4: 00000000000006f0
----------------
Code disassembly (best guess):
0: fb sti
1: 48 8d 35 00 00 00 00 lea 0x0(%rip),%rsi # 0x8
8: bf 60 04 00 00 mov $0x460,%edi
d: 48 03 3b add (%rbx),%rdi
10: e8 9f 51 68 fb call 0xfb6851b4
15: bb 30 00 00 00 mov $0x30,%ebx
1a: 4c 8b 74 24 58 mov 0x58(%rsp),%r14
1f: 49 83 c6 48 add $0x48,%r14
23: 4c 89 f0 mov %r14,%rax
26: 48 c1 e8 03 shr $0x3,%rax
* 2a: 42 80 3c 20 00 cmpb $0x0,(%rax,%r12,1) <-- trapping instruction
2f: 74 08 je 0x39
31: 4c 89 f7 mov %r14,%rdi
34: e8 8b 6c fc fb call 0xfbfc6cc4
39: 49 03 1e add (%r14),%rbx
3c: 48 89 d8 mov %rbx,%rax
3f: 48 rex.W
***
If these findings have caused you to resend the series or submit a
separate fix, please add the following tag to your commit message:
Tested-by: syzbot@syzkaller.appspotmail.com
---
This report is generated by a bot. It may contain errors.
syzbot ci engineers can be reached at syzkaller@googlegroups.com.
To test a fix for this bug, please reply with `#syz test`
(on a separate line) and attach the patch to the email.
Notes:
- The patch will be applied on top of the tested series (as an
incremental fix).
- To test a new version of the whole series, please send it directly
to syzbot@lists.linux.dev.
- Arguments like custom git repos and branches are not supported.
^ permalink raw reply [flat|nested] 4+ messages in thread