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

[Yu Zhao <yuzhao@google.com>]

On Thu, Dec 5, 2024 at 8:25 AM syzbot
<syzbot+e5a74963d40b07387bdf@syzkaller.appspotmail.com> wrote:
>
> Hello,
>
> syzbot found the following issue on:
>
> HEAD commit:    c88416ba074a Add linux-next specific files for 20241101
> git tree:       linux-next
> console output: https://syzkaller.appspot.com/x/log.txt?x=12634587980000
> kernel config:  https://syzkaller.appspot.com/x/.config?x=704b6be2ac2f205f
> dashboard link: https://syzkaller.appspot.com/bug?extid=e5a74963d40b07387bdf
> compiler:       Debian clang version 15.0.6, GNU ld (GNU Binutils for Debian) 2.40
>
> Unfortunately, I don't have any reproducer for this issue yet.
>
> Downloadable assets:
> disk image: https://storage.googleapis.com/syzbot-assets/760a8c88d0c3/disk-c88416ba.raw.xz
> vmlinux: https://storage.googleapis.com/syzbot-assets/46e4b0a851a2/vmlinux-c88416ba.xz
> kernel image: https://storage.googleapis.com/syzbot-assets/428e2c784b75/bzImage-c88416ba.xz
>
> IMPORTANT: if you fix the issue, please add the following tag to the commit:
> Reported-by: syzbot+e5a74963d40b07387bdf@syzkaller.appspotmail.com
>
> ------------[ cut here ]------------
> WARNING: CPU: 0 PID: 85 at mm/vmscan.c:3140 folio_update_gen+0x23d/0x250 mm/vmscan.c:3140
> Modules linked in:
> CPU: 0 UID: 0 PID: 85 Comm: kswapd0 Not tainted 6.12.0-rc5-next-20241101-syzkaller #0
> Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 09/13/2024
> RIP: 0010:folio_update_gen+0x23d/0x250 mm/vmscan.c:3140
> Code: 00 48 3b 4c 24 60 75 2a 48 c1 e8 29 83 e0 07 ff c8 48 8d 65 d8 5b 41 5c 41 5d 41 5e 41 5f 5d c3 cc cc cc cc e8 74 c0 bf ff 90 <0f> 0b 90 e9 91 fe ff ff e8 46 9f ee 09 66 0f 1f 44 00 00 90 90 90
> RSP: 0018:ffffc900020deb40 EFLAGS: 00010293
> RAX: ffffffff81d5fd8c RBX: 0000000000000000 RCX: ffff88801cbb8000
> RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000000
> RBP: ffffc900020dec00 R08: ffffffff81d5fc19 R09: 1ffff1100d562d00
> R10: dffffc0000000000 R11: ffffed100d562d01 R12: 0000000000000003
> R13: 1ffff9200041bd70 R14: ffffc900020deb80 R15: ffffea0001308000
> FS:  0000000000000000(0000) GS:ffff8880b8600000(0000) knlGS:0000000000000000
> CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
> CR2: 00007f7fecc34866 CR3: 00000000223a2000 CR4: 00000000003526f0
> DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
> DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
> Call Trace:
>  <TASK>
>  walk_pmd_range_locked+0x92b/0xf90 mm/vmscan.c:3514
>  walk_pmd_range mm/vmscan.c:3594 [inline]
>  walk_pud_range+0x1f16/0x2310 mm/vmscan.c:3621
>  walk_p4d_range mm/pagewalk.c:259 [inline]
>  walk_pgd_range+0x4a9/0x17e0 mm/pagewalk.c:305
>  __walk_page_range+0x15f/0x700 mm/pagewalk.c:412
>  walk_page_range_mm+0x58f/0x7c0 mm/pagewalk.c:505
>  walk_mm mm/vmscan.c:3665 [inline]
>  try_to_inc_max_seq+0xdd9/0x13b0 mm/vmscan.c:3902
>  get_nr_to_scan mm/vmscan.c:4740 [inline]
>  try_to_shrink_lruvec+0xb30/0xc70 mm/vmscan.c:4783
>  shrink_one+0x3b9/0x850 mm/vmscan.c:4832
>  shrink_many mm/vmscan.c:4895 [inline]
>  lru_gen_shrink_node mm/vmscan.c:4973 [inline]
>  shrink_node+0x37cd/0x3e60 mm/vmscan.c:5954
>  kswapd_shrink_node mm/vmscan.c:6783 [inline]
>  balance_pgdat mm/vmscan.c:6975 [inline]
>  kswapd+0x1ca9/0x3700 mm/vmscan.c:7244
>  kthread+0x2f0/0x390 kernel/kthread.c:389
>  ret_from_fork+0x4b/0x80 arch/x86/kernel/process.c:147
>  ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:244
>  </TASK>

This is caused by "mm/mglru: rework workingset protection" in
mm-unstable. Will post v2 today to fix this.