[syzbot] [iomap?] WARNING in ifs_free

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: f417b7ffcbef Add linux-next specific files for 20260109
git tree: linux-next
console output: https://syzkaller.appspot.com/x/log.txt?x=17e6943a580000
kernel config: https://syzkaller.appspot.com/x/.config?x=63a1fc1b4011ac76
dashboard link: https://syzkaller.appspot.com/bug?extid=d3a62bea0e61f9d121da
compiler: Debian clang version 20.1.8 (++20250708063551+0c9f909b7976-1~exp1~20250708183702.136), Debian LLD 20.1.8

Unfortunately, I don't have any reproducer for this issue yet.

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/1f048080a918/disk-f417b7ff.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/dfd5ea190c96/vmlinux-f417b7ff.xz
kernel image: https://storage.googleapis.com/syzbot-assets/db24c176e0df/bzImage-f417b7ff.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+d3a62b...@syzkaller.appspotmail.com

------------[ cut here ]------------
WARNING: fs/iomap/buffered-io.c:255 at ifs_free+0x358/0x420 fs/iomap/buffered-io.c:254, CPU#1: syz-executor/9813
Modules linked in:
CPU: 1 UID: 0 PID: 9813 Comm: syz-executor Not tainted syzkaller #0 PREEMPT(full)
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/25/2025
RIP: 0010:ifs_free+0x358/0x420 fs/iomap/buffered-io.c:254
Code: 41 5f 5d e9 aa ec c0 ff e8 05 d2 65 ff 90 0f 0b 90 e9 d0 fe ff ff e8 f7 d1 65 ff 90 0f 0b 90 e9 0a ff ff ff e8 e9 d1 65 ff 90 <0f> 0b 90 eb c3 44 89 e1 80 e1 07 80 c1 03 38 c1 0f 8c 06 fe ff ff
RSP: 0018:ffffc90005287670 EFLAGS: 00010293
RAX: ffffffff825ae8d7 RBX: 0000000000000008 RCX: ffff88802f4c9e40
RDX: 0000000000000000 RSI: 0000000000000008 RDI: 0000000000000000
RBP: 00000000825b5701 R08: ffffea0002bb5887 R09: 1ffffd4000576b10
R10: dffffc0000000000 R11: fffff94000576b11 R12: ffff8880202d0144
R13: ffff8880202d0100 R14: ffffea0002bb5880 R15: 1ffffd4000576b11
FS: 00005555773e5500(0000) GS:ffff888125d07000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f27239ff000 CR3: 0000000033afe000 CR4: 00000000003526f0
Call Trace:
<TASK>
folio_invalidate mm/truncate.c:140 [inline]
truncate_cleanup_folio+0x2d8/0x430 mm/truncate.c:160
truncate_inode_pages_range+0x233/0xd90 mm/truncate.c:404
ntfs_evict_inode+0x19/0x40 fs/ntfs3/inode.c:1799
evict+0x5f4/0xae0 fs/inode.c:837
dispose_list fs/inode.c:879 [inline]
evict_inodes+0x753/0x7e0 fs/inode.c:933
generic_shutdown_super+0x9a/0x2c0 fs/super.c:628
kill_block_super+0x44/0x90 fs/super.c:1722
ntfs3_kill_sb+0x44/0x1c0 fs/ntfs3/super.c:1860
deactivate_locked_super+0xbc/0x130 fs/super.c:474
cleanup_mnt+0x425/0x4c0 fs/namespace.c:1312
task_work_run+0x1d4/0x260 kernel/task_work.c:233
resume_user_mode_work include/linux/resume_user_mode.h:50 [inline]
__exit_to_user_mode_loop kernel/entry/common.c:44 [inline]
exit_to_user_mode_loop+0xef/0x4e0 kernel/entry/common.c:75
__exit_to_user_mode_prepare include/linux/irq-entry-common.h:226 [inline]
syscall_exit_to_user_mode_prepare include/linux/irq-entry-common.h:256 [inline]
syscall_exit_to_user_mode_work include/linux/entry-common.h:159 [inline]
syscall_exit_to_user_mode include/linux/entry-common.h:194 [inline]
do_syscall_64+0x2c1/0xf80 arch/x86/entry/syscall_64.c:100
entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7fba68d90a77
Code: a8 ff ff ff f7 d8 64 89 01 48 83 c8 ff c3 0f 1f 44 00 00 31 f6 e9 09 00 00 00 66 0f 1f 84 00 00 00 00 00 b8 a6 00 00 00 0f 05 <48> 3d 00 f0 ff ff 77 01 c3 48 c7 c2 a8 ff ff ff f7 d8 64 89 02 b8
RSP: 002b:00007ffc83b0f988 EFLAGS: 00000246 ORIG_RAX: 00000000000000a6
RAX: 0000000000000000 RBX: 00007fba68e13d7d RCX: 00007fba68d90a77
RDX: 0000000000000000 RSI: 0000000000000009 RDI: 00007ffc83b0fa40
RBP: 00007ffc83b0fa40 R08: 0000000000000000 R09: 0000000000000000
R10: 00000000ffffffff R11: 0000000000000246 R12: 00007ffc83b10ad0
R13: 00007fba68e13d7d R14: 0000000000069557 R15: 00007ffc83b10b10
</TASK>


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[syzbot]

syzbot has found a reproducer for the following issue on:

HEAD commit: 2b7a25df823d Merge tag 'mm-nonmm-stable-2026-02-18-19-56' ..
git tree: upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=10c21722580000
kernel config: https://syzkaller.appspot.com/x/.config?x=65722f41f7edc17e
dashboard link: https://syzkaller.appspot.com/bug?extid=d3a62bea0e61f9d121da
compiler: Debian clang version 21.1.8 (++20251221033036+2078da43e25a-1~exp1~20251221153213.50), Debian LLD 21.1.8
syz repro: https://syzkaller.appspot.com/x/repro.syz?x=1501dc02580000
C reproducer: https://syzkaller.appspot.com/x/repro.c?x=1357f652580000

Downloadable assets:
disk image (non-bootable): https://storage.googleapis.com/syzbot-assets/d900f083ada3/non_bootable_disk-2b7a25df.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/f3a54d09b17c/vmlinux-2b7a25df.xz
kernel image: https://storage.googleapis.com/syzbot-assets/fb704901bce5/bzImage-2b7a25df.xz
mounted in repro: https://storage.googleapis.com/syzbot-assets/b778b9903de5/mount_0.gz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+d3a62b...@syzkaller.appspotmail.com

------------[ cut here ]------------

ifs_is_fully_uptodate(folio, ifs) != folio_test_uptodate(folio)
WARNING: fs/iomap/buffered-io.c:256 at ifs_free+0x358/0x420 fs/iomap/buffered-io.c:255, CPU#0: syz-executor/5453
Modules linked in:
CPU: 0 UID: 0 PID: 5453 Comm: syz-executor Not tainted syzkaller #0 PREEMPT(full)
Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.3-debian-1.16.3-2 04/01/2014
RIP: 0010:ifs_free+0x358/0x420 fs/iomap/buffered-io.c:255
Code: 41 5f 5d e9 7a fb bd ff e8 45 5a 5e ff 90 0f 0b 90 e9 d0 fe ff ff e8 37 5a 5e ff 90 0f 0b 90 e9 0a ff ff ff e8 29 5a 5e ff 90 <0f> 0b 90 eb c3 44 89 e1 80 e1 07 80 c1 03 38 c1 0f 8c 06 fe ff ff
RSP: 0018:ffffc9000dfcf688 EFLAGS: 00010293
RAX: ffffffff82674207 RBX: 0000000000000008 RCX: ffff88801f834900

RDX: 0000000000000000 RSI: 0000000000000008 RDI: 0000000000000000

RBP: 000000008267bc01 R08: ffffea00010fb747 R09: 1ffffd400021f6e8
R10: dffffc0000000000 R11: fffff9400021f6e9 R12: ffff888051c7da44
R13: ffff888051c7da00 R14: ffffea00010fb740 R15: 1ffffd400021f6e9
FS: 0000555586def500(0000) GS:ffff88808ca5b000(0000) knlGS:0000000000000000

CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033

CR2: 0000555586e0aa28 CR3: 00000000591fe000 CR4: 0000000000352ef0

Call Trace:
<TASK>
folio_invalidate mm/truncate.c:140 [inline]

truncate_cleanup_folio+0xcb/0x190 mm/truncate.c:160
truncate_inode_pages_range+0x2ce/0xe30 mm/truncate.c:404
ntfs_evict_inode+0x19/0x40 fs/ntfs3/inode.c:1861
evict+0x61e/0xb10 fs/inode.c:846
dispose_list fs/inode.c:888 [inline]
evict_inodes+0x75a/0x7f0 fs/inode.c:942
generic_shutdown_super+0xaa/0x2d0 fs/super.c:632
kill_block_super+0x44/0x90 fs/super.c:1725
ntfs3_kill_sb+0x44/0x1c0 fs/ntfs3/super.c:1889
deactivate_locked_super+0xbc/0x130 fs/super.c:476
cleanup_mnt+0x437/0x4d0 fs/namespace.c:1312
task_work_run+0x1d9/0x270 kernel/task_work.c:233
resume_user_mode_work include/linux/resume_user_mode.h:50 [inline]
__exit_to_user_mode_loop kernel/entry/common.c:67 [inline]
exit_to_user_mode_loop+0xed/0x480 kernel/entry/common.c:98

__exit_to_user_mode_prepare include/linux/irq-entry-common.h:226 [inline]
syscall_exit_to_user_mode_prepare include/linux/irq-entry-common.h:256 [inline]

syscall_exit_to_user_mode include/linux/entry-common.h:325 [inline]
do_syscall_64+0x32d/0xf80 arch/x86/entry/syscall_64.c:100
entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7fb0f859d897
Code: a2 c7 05 5c ee 24 00 00 00 00 00 eb 96 e8 e1 12 00 00 90 31 f6 e9 09 00 00 00 66 0f 1f 84 00 00 00 00 00 b8 a6 00 00 00 0f 05 <48> 3d 00 f0 ff ff 77 01 c3 48 c7 c2 e8 ff ff ff f7 d8 64 89 02 b8
RSP: 002b:00007ffd23732b28 EFLAGS: 00000246 ORIG_RAX: 00000000000000a6
RAX: 0000000000000000 RBX: 00007fb0f8631ef0 RCX: 00007fb0f859d897
RDX: 0000000000000000 RSI: 0000000000000009 RDI: 00007ffd23732be0
RBP: 00007ffd23732be0 R08: 00007ffd23733be0 R09: 00000000ffffffff
R10: 0000000000000000 R11: 0000000000000246 R12: 00007ffd23733c70
R13: 00007fb0f8631ef0 R14: 000000000001b126 R15: 00007ffd23733cb0
</TASK>


---
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[Joanne Koong]

I ran the repro locally to see if it's the same issue fixed by [1] but
this is a different unrelated issue.

The folio is uptodate but the ifs uptodate bitmap is not reflected as
fully uptodate. I think this is because ntfs3 handles writes for
compressed files through its own interface that doesn't go through
iomap where it calls folio_mark_uptodate() but the ifs bitmap doesn't
get updated. fuse-blk servers that operate in writethrough mode run
into something like this as well [2].

This doesn't lead to any data corruption issues. Should we get rid of
the WARN_ON_ONCE(ifs_is_fully_uptodate(folio, ifs) !=
folio_test_uptodate(folio))? The alternative is to make a modified
version of the functionality in "iomap_set_range_uptodate()" a public
api callable by subsystems.

Thanks,
Joanne

[1] https://lore.kernel.org/linux-fsdevel/20260219003911.344...@gmail.com/
[2] https://lore.kernel.org/linux-fsdevel/20251223223018....@kernel.org/