[PATCH] fs: warn on dirty inode in writeback paired with I_WILL_FREE

[PATCH] fs: warn on dirty inode in writeback paired with I_WILL_FREE

[Mateusz Guzik]

This is in preparation for removing the flag down the road.

Signed-off-by: Mateusz Guzik <mjguzik@gmail.com>
---
 fs/fs-writeback.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/fs/fs-writeback.c b/fs/fs-writeback.c
index 6800886c4d10..633537003b88 100644
--- a/fs/fs-writeback.c
+++ b/fs/fs-writeback.c
@@ -1866,6 +1866,8 @@ static int writeback_single_inode(struct inode *inode,
 	 * as it can be finally deleted at this moment.
 	 */
 	if (!(inode_state_read(inode) & I_FREEING)) {
+		if (inode_state_read(inode) & I_WILL_FREE)
+			WARN_ON_ONCE(inode_state_read(inode) & I_DIRTY_ALL);
 		/*
 		 * If the inode is now fully clean, then it can be safely
 		 * removed from its writeback list (if any). Otherwise the
-- 
2.48.1

[syzbot ci] Re: fs: warn on dirty inode in writeback paired with I_WILL_FREE

[syzbot ci]

syzbot ci has tested the following series

[v1] fs: warn on dirty inode in writeback paired with I_WILL_FREE
https://lore.kernel.org/all/20251210134303.1310039-1-mjguzik@gmail.com
* [PATCH] fs: warn on dirty inode in writeback paired with I_WILL_FREE

and found the following issues:
* SYZFAIL: failed to recv rpc
* WARNING in writeback_single_inode

Full report is available here:
https://ci.syzbot.org/series/c3a011ac-952a-4fbf-867d-b7f98dcaaf3a

***

SYZFAIL: failed to recv rpc

tree:      torvalds
URL:       https://kernel.googlesource.com/pub/scm/linux/kernel/git/torvalds/linux
base:      67a454e6b1c604555c04501c77b7fedc5d98a779
arch:      amd64
compiler:  Debian clang version 20.1.8 (++20250708063551+0c9f909b7976-1~exp1~20250708183702.136), Debian LLD 20.1.8
config:    https://ci.syzbot.org/builds/5b151469-2ba7-47b6-bf4b-00ea2f6df1d8/config
C repro:   https://ci.syzbot.org/findings/9adaaed3-7016-4f9d-9b65-1a4aa9a7a127/c_repro
syz repro: https://ci.syzbot.org/findings/9adaaed3-7016-4f9d-9b65-1a4aa9a7a127/syz_repro

SYZFAIL: failed to recv rpc


***

WARNING in writeback_single_inode

tree:      torvalds
URL:       https://kernel.googlesource.com/pub/scm/linux/kernel/git/torvalds/linux
base:      67a454e6b1c604555c04501c77b7fedc5d98a779
arch:      amd64
compiler:  Debian clang version 20.1.8 (++20250708063551+0c9f909b7976-1~exp1~20250708183702.136), Debian LLD 20.1.8
config:    https://ci.syzbot.org/builds/5b151469-2ba7-47b6-bf4b-00ea2f6df1d8/config
C repro:   https://ci.syzbot.org/findings/6a7382a1-4230-4aa8-8594-a23b2365ee14/c_repro
syz repro: https://ci.syzbot.org/findings/6a7382a1-4230-4aa8-8594-a23b2365ee14/syz_repro

EXT4-fs error (device loop0): ext4_clear_blocks:876: inode #13: comm syz.0.17: attempt to clear invalid blocks 2 len 1
EXT4-fs (loop0): Remounting filesystem read-only
------------[ cut here ]------------
WARNING: fs/fs-writeback.c:1870 at writeback_single_inode+0xa39/0xe40 fs/fs-writeback.c:1870, CPU#1: syz.0.17/5986
Modules linked in:
CPU: 1 UID: 0 PID: 5986 Comm: syz.0.17 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:writeback_single_inode+0xa39/0xe40 fs/fs-writeback.c:1870
Code: 0f 0b 90 e9 25 f7 ff ff e8 64 8d 79 ff 90 0f 0b 90 e9 9c fb ff ff e8 56 8d 79 ff 90 0f 0b 90 e9 c1 fc ff ff e8 48 8d 79 ff 90 <0f> 0b 90 e9 54 fc ff ff e8 3a 8d 79 ff 90 0f 0b 90 e9 47 fd ff ff
RSP: 0018:ffffc900037c7558 EFLAGS: 00010293
RAX: ffffffff824823a8 RBX: dffffc0000000000 RCX: ffff8881113657c0
RDX: 0000000000000000 RSI: 0000000000000040 RDI: 0000000000000000
RBP: ffff888108eb4068 R08: 0000000000000003 R09: 0000000000000004
R10: dffffc0000000000 R11: fffff520006f8e9c R12: ffff8881b1810d08
R13: 0000000000000040 R14: ffff8881b1810c38 R15: 1ffff110363021a1
FS:  00005555567e1500(0000) GS:ffff8882a9e44000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f67c0f73ea0 CR3: 000000017655e000 CR4: 00000000000006f0
Call Trace:
 <TASK>
 write_inode_now+0x160/0x1d0 fs/fs-writeback.c:2926
 iput_final fs/inode.c:1941 [inline]
 iput+0xa77/0x1030 fs/inode.c:2003
 ext4_orphan_cleanup+0xc20/0x1460 fs/ext4/orphan.c:472
 __ext4_fill_super fs/ext4/super.c:5658 [inline]
 ext4_fill_super+0x58a1/0x6160 fs/ext4/super.c:5777
 get_tree_bdev_flags+0x40e/0x4d0 fs/super.c:1691
 vfs_get_tree+0x92/0x2a0 fs/super.c:1751
 fc_mount fs/namespace.c:1199 [inline]
 do_new_mount_fc fs/namespace.c:3636 [inline]
 do_new_mount+0x302/0xa10 fs/namespace.c:3712
 do_mount fs/namespace.c:4035 [inline]
 __do_sys_mount fs/namespace.c:4224 [inline]
 __se_sys_mount+0x313/0x410 fs/namespace.c:4201
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0xfa/0xf80 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f67c0f90f6a
Code: d8 64 89 02 48 c7 c0 ff ff ff ff eb a6 e8 de 1a 00 00 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 40 00 49 89 ca b8 a5 00 00 00 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 c7 c1 a8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007ffc812989c8 EFLAGS: 00000246 ORIG_RAX: 00000000000000a5
RAX: ffffffffffffffda RBX: 00007ffc81298a50 RCX: 00007f67c0f90f6a
RDX: 0000200000000440 RSI: 0000200000000040 RDI: 00007ffc81298a10
RBP: 0000200000000440 R08: 00007ffc81298a50 R09: 0000000000000001
R10: 0000000000000001 R11: 0000000000000246 R12: 0000200000000040
R13: 00007ffc81298a10 R14: 0000000000000450 R15: 000000000000002c
 </TASK>


***

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.