Re: [syzbot] [mm?] WARNING in swap_put_entries_direct

[Andrew Morton]

On Mon, 07 Sep 2026 18:22:24 -0700 syzbot <syzbot+23b25ba3c6bf971f9c57@xxxxxxxxxxxxxxxxxxxxxxxxx> wrote:

> Hello,
> 
> syzbot found the following issue on:
> 
> HEAD commit:    8ab1afb2eb24 Merge tag 'for-7.3/dm-fixes' of git://git.ker..
> git tree:       upstream
> console output: https://syzkaller.appspot.com/x/log.txt?x=1034a125580000
> kernel config:  https://syzkaller.appspot.com/x/.config?x=85bc5cc2fc7394d9
> dashboard link: https://syzkaller.appspot.com/bug?extid=23b25ba3c6bf971f9c57
> compiler:       gcc (Debian 14.2.0-19) 14.2.0, GNU ld (GNU Binutils for Debian) 2.44
> userspace arch: i386
> 
> Unfortunately, I don't have any reproducer for this issue yet.
> 
> Downloadable assets:
> disk image (non-bootable): https://storage.googleapis.com/syzbot-assets/d900f083ada3/non_bootable_disk-8ab1afb2.raw.xz
> vmlinux: https://storage.googleapis.com/syzbot-assets/4767b33b6704/vmlinux-8ab1afb2.xz
> kernel image: https://storage.googleapis.com/syzbot-assets/aa0bdf390bbc/bzImage-8ab1afb2.xz
> 
> IMPORTANT: if you fix the issue, please add the following tag to the commit:
> Reported-by: syzbot+23b25ba3c6bf971f9c57@xxxxxxxxxxxxxxxxxxxxxxxxx
> 
> get_swap_device: Bad swap file entry 7c00000000000002

hm, thanks.

https://syzkaller.appspot.com/x/log.txt?x=1034a125580000 reveals a huge
storm of I/O errors:

[ 1175.396574][ T1132] ata2: SATA link down (SStatus 0 SControl 300)
[ 1175.417415][ T1123] ata1: SATA link up 1.5 Gbps (SStatus 113 SControl 300)
[ 1175.421618][ T1123] ata1.00: configured for UDMA/100
[ 1175.447991][ T1137] ata3: SATA link up 1.5 Gbps (SStatus 113 SControl 300)
[ 1175.456823][ T1137] ata3.00: configured for UDMA/100
[ 1175.614247][ T5836] usb usb50-port1: unable to enumerate USB device
[ 1175.647906][ T5108] Aborting journal on device sda1-8.
[ 1175.651011][T12337] buffer_io_error: 18 callbacks suppressed
[ 1175.651033][T12337] Buffer I/O error on dev sda1, logical block 131072, lost sync page write
[ 1175.657294][T20237] EXT4-fs error (device sda1): ext4_journal_check_start:94: comm syz.5.3709: Detected aborted journal
[ 1175.665579][ T5108] JBD2: I/O error when updating journal superblock for sda1-8.
[ 1175.673842][T20239] EXT4-fs error (device sda1): ext4_journal_check_start:94: comm syz.6.3710: Detected aborted journal
[ 1175.721163][ T5923] Buffer I/O error on dev sda1, logical block 0, lost sync page write
[ 1175.723567][T20239] EXT4-fs (sda1): previous I/O error to superblock detected
[ 1175.730930][ T5923] Buffer I/O error on dev sda1, logical block 0, lost sync page write
[ 1175.731190][T20239] EXT4-fs (sda1): I/O error while writing superblock
[ 1175.731223][T20239] EXT4-fs (sda1): Remounting filesystem read-only
[ 1175.791874][T11112] Read-error on swap-device (8:0:516182)
[ 1175.863539][T10850] Read-error on swap-device (8:0:364134)
[ 1175.888507][T20241] EXT4-fs (sda1): shut down requested (2)
[ 1175.908145][ T5726] Read-error on swap-device (8:0:332990)
[ 1175.908919][ T5923] Read-error on swap-device (8:0:333014)
[ 1175.909235][ T5923] Read-error on swap-device (8:0:313854)
[ 1175.939843][T11112] Read-error on swap-device (8:0:356918)
[ 1175.967225][ T5148] Read-error on swap-device (8:0:364766)
[ 1175.979645][ T5724] Read-error on sw


So I suspect something's wrong with shmem/swap error handling.  ie, the
code which doesn't get tested :(

> ------------[ cut here ]------------
> !si
> WARNING: mm/swapfile.c:2130 at swap_put_entries_direct+0x17d/0x1b0 mm/swapfile.c:2130, CPU#1: udevd/13167