Re: [syzbot] [ocfs2?] possible deadlock in ocfs2_fiemap

[syzbot <syzbot+ca440b457d21568f8021@syzkaller.appspotmail.com>]

syzbot has found a reproducer for the following issue on:

HEAD commit:    3efc57369a0c Merge tag 'for-linus' of git://git.kernel.org..
git tree:       upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=11480127980000
kernel config:  https://syzkaller.appspot.com/x/.config?x=a4fcb065287cdb84
dashboard link: https://syzkaller.appspot.com/bug?extid=ca440b457d21568f8021
compiler:       Debian clang version 15.0.6, GNU ld (GNU Binutils for Debian) 2.40
syz repro:      https://syzkaller.appspot.com/x/repro.syz?x=109ccd9f980000
C reproducer:   https://syzkaller.appspot.com/x/repro.c?x=1476de80580000

Downloadable assets:
disk image (non-bootable): https://storage.googleapis.com/syzbot-assets/7feb34a89c2a/non_bootable_disk-3efc5736.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/d0988c372a39/vmlinux-3efc5736.xz
kernel image: https://storage.googleapis.com/syzbot-assets/8547f30d7e9d/bzImage-3efc5736.xz
mounted in repro: https://storage.googleapis.com/syzbot-assets/ac59be7d6f54/mount_0.gz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+ca440b457d21568f8021@syzkaller.appspotmail.com

ocfs2: Mounting device (7,0) on (node local, slot 0) with ordered data mode.
======================================================
WARNING: possible circular locking dependency detected
6.11.0-syzkaller-11993-g3efc57369a0c #0 Not tainted
------------------------------------------------------
syz-executor356/5112 is trying to acquire lock:
ffff8880119d4418 (&mm->mmap_lock){++++}-{3:3}, at: __might_fault+0xaa/0x120 mm/memory.c:6700

but task is already holding lock:
ffff888041bdbf60 (&oi->ip_alloc_sem){++++}-{3:3}, at: ocfs2_fiemap+0x377/0xf80 fs/ocfs2/extent_map.c:755

which lock already depends on the new lock.


the existing dependency chain (in reverse order) is:

-> #2 (&oi->ip_alloc_sem){++++}-{3:3}:
       lock_acquire+0x1ed/0x550 kernel/locking/lockdep.c:5822
       down_write+0x99/0x220 kernel/locking/rwsem.c:1579
       ocfs2_page_mkwrite+0x346/0xed0 fs/ocfs2/mmap.c:142
       do_page_mkwrite+0x198/0x480 mm/memory.c:3162
       do_shared_fault mm/memory.c:5358 [inline]
       do_fault mm/memory.c:5420 [inline]
       do_pte_missing mm/memory.c:3965 [inline]
       handle_pte_fault+0x11fa/0x6800 mm/memory.c:5751
       __handle_mm_fault mm/memory.c:5894 [inline]
       handle_mm_fault+0x1106/0x1bb0 mm/memory.c:6062
       do_user_addr_fault arch/x86/mm/fault.c:1389 [inline]
       handle_page_fault arch/x86/mm/fault.c:1481 [inline]
       exc_page_fault+0x2b9/0x8c0 arch/x86/mm/fault.c:1539
       asm_exc_page_fault+0x26/0x30 arch/x86/include/asm/idtentry.h:623

-> #1 (sb_pagefaults){.+.+}-{0:0}:
       lock_acquire+0x1ed/0x550 kernel/locking/lockdep.c:5822
       percpu_down_read include/linux/percpu-rwsem.h:51 [inline]
       __sb_start_write include/linux/fs.h:1716 [inline]
       sb_start_pagefault include/linux/fs.h:1881 [inline]
       ocfs2_page_mkwrite+0x222/0xed0 fs/ocfs2/mmap.c:122
       do_page_mkwrite+0x198/0x480 mm/memory.c:3162
       do_shared_fault mm/memory.c:5358 [inline]
       do_fault mm/memory.c:5420 [inline]
       do_pte_missing mm/memory.c:3965 [inline]
       handle_pte_fault+0x11fa/0x6800 mm/memory.c:5751
       __handle_mm_fault mm/memory.c:5894 [inline]
       handle_mm_fault+0x1106/0x1bb0 mm/memory.c:6062
       do_user_addr_fault arch/x86/mm/fault.c:1389 [inline]
       handle_page_fault arch/x86/mm/fault.c:1481 [inline]
       exc_page_fault+0x2b9/0x8c0 arch/x86/mm/fault.c:1539
       asm_exc_page_fault+0x26/0x30 arch/x86/include/asm/idtentry.h:623

-> #0 (&mm->mmap_lock){++++}-{3:3}:
       check_prev_add kernel/locking/lockdep.c:3158 [inline]
       check_prevs_add kernel/locking/lockdep.c:3277 [inline]
       validate_chain+0x18ef/0x5920 kernel/locking/lockdep.c:3901
       __lock_acquire+0x1384/0x2050 kernel/locking/lockdep.c:5199
       lock_acquire+0x1ed/0x550 kernel/locking/lockdep.c:5822
       __might_fault+0xc6/0x120 mm/memory.c:6700
       _inline_copy_to_user include/linux/uaccess.h:183 [inline]
       _copy_to_user+0x2a/0xb0 lib/usercopy.c:26
       copy_to_user include/linux/uaccess.h:216 [inline]
       fiemap_fill_next_extent+0x235/0x410 fs/ioctl.c:145
       ocfs2_fiemap+0x9f1/0xf80 fs/ocfs2/extent_map.c:796
       ioctl_fiemap fs/ioctl.c:220 [inline]
       do_vfs_ioctl+0x1bf8/0x2e40 fs/ioctl.c:841
       __do_sys_ioctl fs/ioctl.c:905 [inline]
       __se_sys_ioctl+0x81/0x170 fs/ioctl.c:893
       do_syscall_x64 arch/x86/entry/common.c:52 [inline]
       do_syscall_64+0xf3/0x230 arch/x86/entry/common.c:83
       entry_SYSCALL_64_after_hwframe+0x77/0x7f

other info that might help us debug this:

Chain exists of:
  &mm->mmap_lock --> sb_pagefaults --> &oi->ip_alloc_sem

 Possible unsafe locking scenario:

       CPU0                    CPU1
       ----                    ----
  rlock(&oi->ip_alloc_sem);
                               lock(sb_pagefaults);
                               lock(&oi->ip_alloc_sem);
  rlock(&mm->mmap_lock);

 *** DEADLOCK ***

1 lock held by syz-executor356/5112:
 #0: ffff888041bdbf60 (&oi->ip_alloc_sem){++++}-{3:3}, at: ocfs2_fiemap+0x377/0xf80 fs/ocfs2/extent_map.c:755

stack backtrace:
CPU: 0 UID: 0 PID: 5112 Comm: syz-executor356 Not tainted 6.11.0-syzkaller-11993-g3efc57369a0c #0
Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.3-debian-1.16.3-2~bpo12+1 04/01/2014
Call Trace:
 <TASK>
 __dump_stack lib/dump_stack.c:94 [inline]
 dump_stack_lvl+0x241/0x360 lib/dump_stack.c:120
 print_circular_bug+0x13a/0x1b0 kernel/locking/lockdep.c:2074
 check_noncircular+0x36a/0x4a0 kernel/locking/lockdep.c:2203
 check_prev_add kernel/locking/lockdep.c:3158 [inline]
 check_prevs_add kernel/locking/lockdep.c:3277 [inline]
 validate_chain+0x18ef/0x5920 kernel/locking/lockdep.c:3901
 __lock_acquire+0x1384/0x2050 kernel/locking/lockdep.c:5199
 lock_acquire+0x1ed/0x550 kernel/locking/lockdep.c:5822
 __might_fault+0xc6/0x120 mm/memory.c:6700
 _inline_copy_to_user include/linux/uaccess.h:183 [inline]
 _copy_to_user+0x2a/0xb0 lib/usercopy.c:26
 copy_to_user include/linux/uaccess.h:216 [inline]
 fiemap_fill_next_extent+0x235/0x410 fs/ioctl.c:145
 ocfs2_fiemap+0x9f1/0xf80 fs/ocfs2/extent_map.c:796
 ioctl_fiemap fs/ioctl.c:220 [inline]
 do_vfs_ioctl+0x1bf8/0x2e40 fs/ioctl.c:841
 __do_sys_ioctl fs/ioctl.c:905 [inline]
 __se_sys_ioctl+0x81/0x170 fs/ioctl.c:893
 do_syscall_x64 arch/x86/entry/common.c:52 [inline]
 do_syscall_64+0xf3/0x230 arch/x86/entry/common.c:83
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f0c21255d99
Code: 28 00 00 00 75 05 48 83 c4 28 c3 e8 f1 17 00 00 90 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 b8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007ffc7eb343e8 EFLAGS: 00000246 ORIG_RAX: 0000000000000010
RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 00007f0c21255d99
RDX: 00000000200001c0 RSI: 00000000c020660b RDI: 0000000000000005
RBP: 00007f0c212ce5f0 R08: 0000000000000000 R09: 00005555783d34c0
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f0c212ce5f0 R14: 431bde82d7b634db R15: 00007f0c2129f03b
 </TASK>


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