Re: [syzbot ci] Re: ext4: deferred iput framework for EA inodes

[Jan Kara]

On Thu 02-07-26 15:57:01, syzbot ci wrote:
> syzbot ci has tested the following series
> 
> [v13] ext4: deferred iput framework for EA inodes
> https://lore.kernel.org/all/20260702152225.4071746-1-yun.zhou@xxxxxxxxxxxxx
> * [PATCH v13 1/4] fs: add iput_if_not_last() helper
> * [PATCH v13 2/4] ext4: introduce ext4_put_ea_inode() for safe deferred iput
> * [PATCH v13 3/4] ext4: convert all EA inode iput() calls to ext4_put_ea_inode()
> * [PATCH v13 4/4] ext4: remove ea_inode_array mechanism in favor of ext4_put_ea_inode()
> 
> and found the following issue:
> WARNING in ext4_journal_check_start

Good catch. We need to flush the pending work with iputs also in
ext4_sync_fs() which should also take care of this race with remount
read-only (and the same issue with filesystem freezing etc.).

								Honza

> 
> Full report is available here:
> https://ci.syzbot.org/series/ce304d7b-7f32-44b5-bf6f-e579abb42a5c
> 
> ***
> 
> WARNING in ext4_journal_check_start
> 
> tree:      torvalds
> URL:       https://kernel.googlesource.com/pub/scm/linux/kernel/git/torvalds/linux
> base:      4a50a141f05a8d1737661b19ee22ff8455b94409
> arch:      amd64
> compiler:  Debian clang version 22.1.6 (++20260514074242+fc4aad7b5db3-1~exp1~20260514074407.73), Debian LLD 22.1.6
> config:    https://ci.syzbot.org/builds/e5413370-cf09-4540-b9d3-7d280f314ae0/config
> syz repro: https://ci.syzbot.org/findings/e7cd69b7-8bb9-4554-bd84-b5ebcd7a8089/syz_repro
> 
> ------------[ cut here ]------------
> sb_rdonly(sb)
> WARNING: fs/ext4/ext4_jbd2.c:75 at ext4_journal_check_start+0x24f/0x2b0 fs/ext4/ext4_jbd2.c:75, CPU#0: kworker/0:5/5860
> Modules linked in:
> CPU: 0 UID: 0 PID: 5860 Comm: kworker/0:5 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: events ext4_ea_inode_work
> RIP: 0010:ext4_journal_check_start+0x24f/0x2b0 fs/ext4/ext4_jbd2.c:75
> Code: 5b 41 5c 41 5d 41 5e 41 5f 5d c3 cc cc cc cc cc e8 06 75 42 ff 41 bf fb ff ff ff eb e0 e8 f9 74 42 ff eb d3 e8 f2 74 42 ff 90 <0f> 0b 90 eb c8 e8 e7 74 42 ff 90 0f 0b 90 43 80 7c 25 00 00 0f 85
> RSP: 0018:ffffc900036bf888 EFLAGS: 00010293
> RAX: ffffffff8283ecce RBX: ffff888170078000 RCX: ffff888107390000
> RDX: 0000000000000000 RSI: 0000000000000001 RDI: 0000000000000000
> RBP: 00000000000000ef R08: ffff8881bb53440f R09: 1ffff110376a6881
> R10: dffffc0000000000 R11: ffffed10376a6882 R12: dffffc0000000000
> R13: 1ffff1102e00f0cd R14: ffff888170078668 R15: 0000000000000001
> FS:  0000000000000000(0000) GS:ffff88818dc20000(0000) knlGS:0000000000000000
> CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
> CR2: 000055557b325a28 CR3: 0000000114bfe000 CR4: 00000000000006f0
> Call Trace:
>  <TASK>
>  __ext4_journal_start_sb+0x147/0x5d0 fs/ext4/ext4_jbd2.c:107
>  __ext4_journal_start fs/ext4/ext4_jbd2.h:242 [inline]
>  ext4_evict_inode+0x7cb/0xf70 fs/ext4/inode.c:238
>  evict+0x624/0xb50 fs/inode.c:825
>  ext4_ea_inode_work+0x5c/0x90 fs/ext4/xattr.c:2974
>  process_one_work kernel/workqueue.c:3322 [inline]
>  process_scheduled_works+0xa8e/0x14e0 kernel/workqueue.c:3405
>  worker_thread+0xa47/0xfb0 kernel/workqueue.c:3486
>  kthread+0x388/0x470 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>
> 
> 
> ***
> 
> 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@xxxxxxxxxxxxxxxxxxxxxxxxx
> 
> ---
> This report is generated by a bot. It may contain errors.
> syzbot ci engineers can be reached at syzkaller@xxxxxxxxxxxxxxxx.
> 
> To test a patch for this bug, please reply with `#syz test`
> (should be on a separate line).
> 
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-- 
Jan Kara <jack@xxxxxxxx>
SUSE Labs, CR