From: syzbot ci <syzbot+ci021c8fe727674a70@syzkaller.appspotmail.com>
To: adilger.kernel@dilger.ca, jack@suse.cz,
libaokun@linux.alibaba.com, linux-ext4@vger.kernel.org,
linux-kernel@vger.kernel.org, rafad900@gmail.com, tytso@mit.edu
Cc: syzbot@lists.linux.dev, syzkaller-bugs@googlegroups.com
Subject: [syzbot ci] Re: ext4: convert pa_count from atomic_t to refcount_t
Date: Mon, 20 Jul 2026 00:25:25 -0700 [thread overview]
Message-ID: <6a5dcd65.5028b7d0.1f0bb.02e3.GAE@google.com> (raw)
In-Reply-To: <20260720034441.3900050-1-rafad900@gmail.com>
syzbot ci has tested the following series
[v1] ext4: convert pa_count from atomic_t to refcount_t
https://lore.kernel.org/all/20260720034441.3900050-1-rafad900@gmail.com
* [PATCH] ext4: convert pa_count from atomic_t to refcount_t
and found the following issue:
WARNING: refcount bug in ext4_mb_use_preallocated
Full report is available here:
https://ci.syzbot.org/series/34fda797-e979-409c-bc2d-7af3e163df14
***
WARNING: refcount bug in ext4_mb_use_preallocated
tree: torvalds
URL: https://kernel.googlesource.com/pub/scm/linux/kernel/git/torvalds/linux
base: 1590cf0329716306e948a8fc29f1d3ee87d3989f
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/05fa6c1d-a594-4691-ace3-ded3fc2ca4dc/config
------------[ cut here ]------------
refcount_t: addition on 0; use-after-free.
WARNING: lib/refcount.c:25 at refcount_warn_saturate+0x9f/0x110, CPU#0: kworker/u9:2/51
Modules linked in:
CPU: 0 UID: 0 PID: 51 Comm: kworker/u9:2 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: writeback wb_workfn (flush-8:0)
RIP: 0010:refcount_warn_saturate+0x9f/0x110
Code: eb 66 85 db 74 3e 83 fb 01 75 4c e8 8b 73 0c fd 48 8d 3d 34 58 84 0b 67 48 0f b9 3a eb 4a e8 78 73 0c fd 48 8d 3d 31 58 84 0b <67> 48 0f b9 3a eb 37 e8 65 73 0c fd 48 8d 3d 2e 58 84 0b 67 48 0f
RSP: 0018:ffffc90000bb6590 EFLAGS: 00010293
RAX: ffffffff84b9ee08 RBX: 0000000000000002 RCX: ffff8881072a8000
RDX: 0000000000000000 RSI: ffffffff8f126800 RDI: ffffffff903e4640
RBP: ffff888112257dd0 R08: ffff8881072a8000 R09: 0000000000000005
R10: 0000000000000004 R11: 0000000000000000 R12: dffffc0000000000
R13: ffff888112257d98 R14: ffff888112257e10 R15: 0000000000000008
FS: 0000000000000000(0000) GS:ffff88818dc15000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007fc831b2c080 CR3: 0000000112724000 CR4: 00000000000006f0
Call Trace:
<TASK>
ext4_mb_use_preallocated+0xaa0/0x14e0
ext4_mb_new_blocks+0x5a0/0x4560
ext4_ext_map_blocks+0x1534/0x5850
ext4_map_create_blocks+0x116/0x530
ext4_map_blocks+0x7e4/0x1240
ext4_do_writepages+0x23d3/0x47a0
ext4_writepages+0x241/0x3b0
do_writepages+0x338/0x560
__writeback_single_inode+0x12e/0xf90
writeback_sb_inodes+0x9de/0x1b00
__writeback_inodes_wb+0x114/0x240
wb_writeback+0x42f/0xad0
wb_workfn+0x980/0x10f0
process_scheduled_works+0xa8e/0x14e0
worker_thread+0xa47/0xfb0
kthread+0x388/0x470
ret_from_fork+0x514/0xb70
ret_from_fork_asm+0x1a/0x30
</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.
To test a patch for this bug, please reply with `#syz test`
(should be on a separate line).
The patch should be attached to the email.
Note: arguments like custom git repos and branches are not supported.
prev parent reply other threads:[~2026-07-20 7:25 UTC|newest]
Thread overview: 2+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-07-20 3:44 [PATCH] ext4: convert pa_count from atomic_t to refcount_t rafad900
2026-07-20 7:25 ` syzbot ci [this message]
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