linux-kernel - Re: [syzbot] [mm?] general protection fault in lru_gen_test

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Message-ID: <69357caa.a70a0220.38f243.0053.GAE@google.com>
Date: Sun, 07 Dec 2025 05:10:02 -0800
From: syzbot <syzbot+e008db2ac01e282550ee@...kaller.appspotmail.com>
To: kartikey406@...il.com, linux-kernel@...r.kernel.org, 
	syzkaller-bugs@...glegroups.com
Subject: Re: [syzbot] [mm?] general protection fault in lru_gen_test_recent (2)

Hello,

syzbot has tested the proposed patch but the reproducer is still triggering an issue:
general protection fault in lru_gen_test_recent

Oops: general protection fault, probably for non-canonical address 0xdffffc00000009c0: 0000 [#1] SMP KASAN NOPTI
KASAN: probably user-memory-access in range [0x0000000000004e00-0x0000000000004e07]
CPU: 0 UID: 0 PID: 6513 Comm: syz.0.29 Not tainted syzkaller #0 PREEMPT(full) 
Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.3-debian-1.16.3-2~bpo12+1 04/01/2014
RIP: 0010:mem_cgroup_lruvec include/linux/memcontrol.h:720 [inline]
RIP: 0010:lru_gen_test_recent+0xfc/0x370 mm/workingset.c:277
Code: 2a 80 b5 ff 48 85 db 0f 84 a9 01 00 00 e8 1c 80 b5 ff 49 8d bd 00 4e 00 00 48 b8 00 00 00 00 00 fc ff df 48 89 fa 48 c1 ea 03 <0f> b6 04 02 84 c0 74 08 3c 03 0f 8e d3 01 00 00 4d 63 b5 00 4e 00
RSP: 0018:ffffc900035f7828 EFLAGS: 00010206
RAX: dffffc0000000000 RBX: ffff88801d688000 RCX: ffffc900035f772c
RDX: 00000000000009c0 RSI: ffffffff82096454 RDI: 0000000000004e00
RBP: ffffc900035f78c0 R08: 0000000000000001 R09: 0000000000000000
R10: 0000000000000001 R11: ffff88802b10aff0 R12: ffffc900035f78e0
R13: 0000000000000000 R14: ffffc900035f78b0 R15: 0000000000000000
FS:  00007f7ae80646c0(0000) GS:ffff8880d6909000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000000409000000 CR3: 000000002e141000 CR4: 0000000000352ef0
Call Trace:
 <TASK>
 lru_gen_refault mm/workingset.c:298 [inline]
 workingset_refault+0x251/0xca0 mm/workingset.c:548
 filemap_add_folio+0x23d/0x610 mm/filemap.c:981
 do_read_cache_folio+0x23c/0x5c0 mm/filemap.c:4063
 freader_get_folio+0x33a/0x930 lib/buildid.c:58
 freader_fetch+0xbd/0x740 lib/buildid.c:101
 __build_id_parse.isra.0+0xdd/0x6c0 lib/buildid.c:289
 do_procmap_query+0xb0e/0x1080 fs/proc/task_mmu.c:733
 procfs_procmap_ioctl+0x9d/0xe0 fs/proc/task_mmu.c:813
 vfs_ioctl fs/ioctl.c:51 [inline]
 __do_sys_ioctl fs/ioctl.c:597 [inline]
 __se_sys_ioctl fs/ioctl.c:583 [inline]
 __x64_sys_ioctl+0x18e/0x210 fs/ioctl.c:583
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0xcd/0xf80 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f7ae718f7c9
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:00007f7ae8064038 EFLAGS: 00000246 ORIG_RAX: 0000000000000010
RAX: ffffffffffffffda RBX: 00007f7ae73e5fa0 RCX: 00007f7ae718f7c9
RDX: 0000200000000180 RSI: 00000000c0686611 RDI: 0000000000000003
RBP: 00007f7ae7213f91 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f7ae73e6038 R14: 00007f7ae73e5fa0 R15: 00007ffdab92bc98
 </TASK>
Modules linked in:
---[ end trace 0000000000000000 ]---
RIP: 0010:mem_cgroup_lruvec include/linux/memcontrol.h:720 [inline]
RIP: 0010:lru_gen_test_recent+0xfc/0x370 mm/workingset.c:277
Code: 2a 80 b5 ff 48 85 db 0f 84 a9 01 00 00 e8 1c 80 b5 ff 49 8d bd 00 4e 00 00 48 b8 00 00 00 00 00 fc ff df 48 89 fa 48 c1 ea 03 <0f> b6 04 02 84 c0 74 08 3c 03 0f 8e d3 01 00 00 4d 63 b5 00 4e 00
RSP: 0018:ffffc900035f7828 EFLAGS: 00010206
RAX: dffffc0000000000 RBX: ffff88801d688000 RCX: ffffc900035f772c
RDX: 00000000000009c0 RSI: ffffffff82096454 RDI: 0000000000004e00
RBP: ffffc900035f78c0 R08: 0000000000000001 R09: 0000000000000000
R10: 0000000000000001 R11: ffff88802b10aff0 R12: ffffc900035f78e0
R13: 0000000000000000 R14: ffffc900035f78b0 R15: 0000000000000000
FS:  00007f7ae80646c0(0000) GS:ffff8880d6909000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000000409000000 CR3: 000000002e141000 CR4: 0000000000352ef0
----------------
Code disassembly (best guess):
   0:	2a 80 b5 ff 48 85    	sub    -0x7ab7004b(%rax),%al
   6:	db 0f                	fisttpl (%rdi)
   8:	84 a9 01 00 00 e8    	test   %ch,-0x17ffffff(%rcx)
   e:	1c 80                	sbb    $0x80,%al
  10:	b5 ff                	mov    $0xff,%ch
  12:	49 8d bd 00 4e 00 00 	lea    0x4e00(%r13),%rdi
  19:	48 b8 00 00 00 00 00 	movabs $0xdffffc0000000000,%rax
  20:	fc ff df
  23:	48 89 fa             	mov    %rdi,%rdx
  26:	48 c1 ea 03          	shr    $0x3,%rdx
* 2a:	0f b6 04 02          	movzbl (%rdx,%rax,1),%eax <-- trapping instruction
  2e:	84 c0                	test   %al,%al
  30:	74 08                	je     0x3a
  32:	3c 03                	cmp    $0x3,%al
  34:	0f 8e d3 01 00 00    	jle    0x20d
  3a:	4d                   	rex.WRB
  3b:	63                   	.byte 0x63
  3c:	b5 00                	mov    $0x0,%ch
  3e:	4e                   	rex.WRX


Tested on:

commit:         37bb2e72 Merge tag 'staging-6.19-rc1' of git://git.ker..
git tree:       upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=13f6ceb4580000
kernel config:  https://syzkaller.appspot.com/x/.config?x=dbcb767d1e1208ac
dashboard link: https://syzkaller.appspot.com/bug?extid=e008db2ac01e282550ee
compiler:       gcc (Debian 12.2.0-14+deb12u1) 12.2.0, GNU ld (GNU Binutils for Debian) 2.40
patch:          https://syzkaller.appspot.com/x/patch.diff?x=1336a992580000