linux-kernel - Re: [syzbot] [mm?] WARNING in try_to_migrate

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Message-ID: <68980a43.050a0220.7f033.00b6.GAE@google.com>
Date: Sat, 09 Aug 2025 19:56:03 -0700
From: syzbot <syzbot+63859a31071a369082b1@...kaller.appspotmail.com>
To: hdanton@...a.com, linux-kernel@...r.kernel.org, 
	syzkaller-bugs@...glegroups.com
Subject: Re: [syzbot] [mm?] WARNING in try_to_migrate_one (3)

Hello,

syzbot has tested the proposed patch but the reproducer is still triggering an issue:
WARNING in try_to_migrate_one

 folios_put include/linux/mm.h:1419 [inline]
 folio_batch_move_lru+0x319/0x3a0 mm/swap.c:175
 __folio_batch_add_and_move+0x5ad/0xd20 mm/swap.c:196
 map_anon_folio_pmd+0x1c9/0x5a0 mm/huge_memory.c:1208
 __do_huge_pmd_anonymous_page mm/huge_memory.c:1253 [inline]
 do_huge_pmd_anonymous_page+0x518/0xb60 mm/huge_memory.c:1371
 create_huge_pmd mm/memory.c:5917 [inline]
 __handle_mm_fault+0x1139/0x5440 mm/memory.c:6166
 handle_mm_fault+0x40a/0x8e0 mm/memory.c:6364
 do_user_addr_fault+0xa81/0x1390 arch/x86/mm/fault.c:1336
 handle_page_fault arch/x86/mm/fault.c:1476 [inline]
 exc_page_fault+0x76/0xf0 arch/x86/mm/fault.c:1532
 asm_exc_page_fault+0x26/0x30 arch/x86/include/asm/idtentry.h:623
------------[ cut here ]------------
WARNING: CPU: 0 PID: 6632 at mm/rmap.c:2453 try_to_migrate_one+0xf99/0x3540 mm/rmap.c:2452
Modules linked in:
CPU: 0 UID: 0 PID: 6632 Comm: syz.0.17 Not tainted 6.16.0-syzkaller-12256-g561c80369df0-dirty #0 PREEMPT(full) 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/12/2025
RIP: 0010:try_to_migrate_one+0xf99/0x3540 mm/rmap.c:2452
Code: 00 e8 cb 3f ae ff 49 be 00 00 00 00 00 fc ff df e9 f2 f7 ff ff e8 b7 3f ae ff 4c 89 ff 48 c7 c6 00 79 96 8b e8 08 90 16 ff 90 <0f> 0b 90 e9 52 ff ff ff e8 9a 3f ae ff 49 ff cf e9 bb f8 ff ff e8
RSP: 0018:ffffc900034f7360 EFLAGS: 00010246
RAX: ac960e1a3b7e2b00 RBX: 0400000000000000 RCX: ac960e1a3b7e2b00
RDX: 0000000000000003 RSI: ffffffff8dba5fb3 RDI: ffff888029dd9e00
RBP: ffffc900034f75b0 R08: 0000000000000003 R09: 0000000000000004
R10: dffffc0000000000 R11: fffffbfff1bfa1ec R12: ffffea0001c1c198
R13: 0000000070706867 R14: dffffc0000000000 R15: ffffea0001c1c180
FS:  00007fbdca6816c0(0000) GS:ffff888125c1c000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00002000000012c0 CR3: 000000002d9e6000 CR4: 00000000003526f0
Call Trace:
 <TASK>
 rmap_walk_anon+0x550/0x730 mm/rmap.c:2843
 rmap_walk mm/rmap.c:2948 [inline]
 try_to_migrate+0x3bc/0x670 mm/rmap.c:2622
 migrate_folio_unmap mm/migrate.c:1302 [inline]
 migrate_pages_batch+0x116f/0x3620 mm/migrate.c:1851
 migrate_pages_sync mm/migrate.c:1974 [inline]
 migrate_pages+0x1bcc/0x2930 mm/migrate.c:2083
 do_mbind mm/mempolicy.c:1539 [inline]
 kernel_mbind mm/mempolicy.c:1682 [inline]
 __do_sys_mbind mm/mempolicy.c:1756 [inline]
 __se_sys_mbind+0xa3e/0xc30 mm/mempolicy.c:1752
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0xfa/0x3b0 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7fbdc978ebe9
Code: ff ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 40 00 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 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:00007fbdca681038 EFLAGS: 00000246 ORIG_RAX: 00000000000000ed
RAX: ffffffffffffffda RBX: 00007fbdc99b5fa0 RCX: 00007fbdc978ebe9
RDX: 0000000000000001 RSI: 0000000000600000 RDI: 0000200000000000
RBP: 00007fbdc9811e19 R08: 0000000000000000 R09: 0000000000000002
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007fbdc99b6038 R14: 00007fbdc99b5fa0 R15: 00007ffd9d17a4b8
 </TASK>


Tested on:

commit:         561c8036 Merge tag 'tty-6.16-rc1-2' of git://git.kerne..
git tree:       upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=1109fea2580000
kernel config:  https://syzkaller.appspot.com/x/.config?x=2ae1da3a7f4a6ba4
dashboard link: https://syzkaller.appspot.com/bug?extid=63859a31071a369082b1
compiler:       Debian clang version 20.1.7 (++20250616065708+6146a88f6049-1~exp1~20250616065826.132), Debian LLD 20.1.7
patch:          https://syzkaller.appspot.com/x/patch.diff?x=15403434580000