[syzbot] [dm?] KASAN: null-ptr-deref Read in dm_kcopyd_client_destroy

[syzbot <syzbot+a2626a25eb2595e3ec3c@syzkaller.appspotmail.com>]

Hello,

syzbot found the following issue on:

HEAD commit:    4169c9c90532 powerpc/irq: Fix build with CONFIG_PROC_FS=n
git tree:       git://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
console output: https://syzkaller.appspot.com/x/log.txt?x=126fa38e580000
kernel config:  https://syzkaller.appspot.com/x/.config?x=e397d1e24d3cb03
dashboard link: https://syzkaller.appspot.com/bug?extid=a2626a25eb2595e3ec3c
compiler:       Debian clang version 22.1.8 (1~deb13u4), Debian LLD 22.1.8
C reproducer:   https://syzkaller.appspot.com/x/repro.c?x=166fa38e580000

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+a2626a25eb2595e3ec3c@syzkaller.appspotmail.com

workqueue: Failed to create a rescuer kthread for wq "kcopyd": -EINTR
==================================================================
BUG: KASAN: null-ptr-deref in instrument_atomic_read include/linux/instrumented.h:82 [inline]
BUG: KASAN: null-ptr-deref in atomic_read include/linux/atomic/atomic-instrumented.h:32 [inline]
BUG: KASAN: null-ptr-deref in dm_kcopyd_client_destroy+0xae/0x480 drivers/md/dm-kcopyd.c:980
Read of size 4 at addr 0000000000000174 by task syz.2.19/6560

CPU: 0 UID: 0 PID: 6560 Comm: syz.2.19 Not tainted syzkaller #0 PREEMPT(full) 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/15/2026
Call Trace:
 <TASK>
 dump_stack_lvl+0xe8/0x150 lib/dump_stack.c:120
 kasan_report+0x117/0x150 mm/kasan/report.c:595
 check_region_inline mm/kasan/generic.c:-1 [inline]
 kasan_check_range+0x264/0x2c0 mm/kasan/generic.c:200
 instrument_atomic_read include/linux/instrumented.h:82 [inline]
 atomic_read include/linux/atomic/atomic-instrumented.h:32 [inline]
 dm_kcopyd_client_destroy+0xae/0x480 drivers/md/dm-kcopyd.c:980
 __destroy+0x172/0x2f0 drivers/md/dm-cache-target.c:1973
 cache_create drivers/md/dm-cache-target.c:2604 [inline]
 cache_ctr+0x1674/0x2bf0 drivers/md/dm-cache-target.c:2649
 dm_table_add_target+0x58d/0xc70 drivers/md/dm-table.c:749
 populate_table drivers/md/dm-ioctl.c:1602 [inline]
 table_load+0x325/0x8a0 drivers/md/dm-ioctl.c:1645
 ctl_ioctl drivers/md/dm-ioctl.c:2221 [inline]
 dm_ctl_ioctl+0x9ec/0xe10 drivers/md/dm-ioctl.c:2243
 vfs_ioctl fs/ioctl.c:51 [inline]
 __do_sys_ioctl fs/ioctl.c:597 [inline]
 __se_sys_ioctl+0xfc/0x170 fs/ioctl.c:583
 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: 0033:0x7fb5b039f559
Code: ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 44 00 00 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 c7 c1 e8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007fb5b11ce028 EFLAGS: 00000246 ORIG_RAX: 0000000000000010
RAX: ffffffffffffffda RBX: 00007fb5b0626180 RCX: 00007fb5b039f559
RDX: 0000200000000280 RSI: 00000000c138fd09 RDI: 0000000000000004
RBP: 00007fb5b0436b20 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007fb5b0626218 R14: 00007fb5b0626180 R15: 00007fff197480a8
 </TASK>
==================================================================


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