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

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Message-ID: <6935a484.a70a0220.38f243.0061.GAE@google.com>
Date: Sun, 07 Dec 2025 08:00:04 -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 0xdffffc0000000a4f: 0000 [#1] SMP KASAN NOPTI
KASAN: probably user-memory-access in range [0x0000000000005278-0x000000000000527f]
CPU: 2 UID: 0 PID: 6563 Comm: syz.0.66 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:lru_gen_test_recent+0x1a4/0x2f0 mm/workingset.c:281
Code: 48 c1 ea 03 80 3c 02 00 0f 85 17 01 00 00 48 8d bb c0 00 00 00 49 89 1c 24 48 b8 00 00 00 00 00 fc ff df 48 89 fa 48 c1 ea 03 <80> 3c 02 00 0f 85 21 01 00 00 48 8b 9b c0 00 00 00 48 89 ea 48 b8
RSP: 0018:ffffc900027ef828 EFLAGS: 00010202
RAX: dffffc0000000000 RBX: 00000000000051b8 RCX: ffffc900027ef72c
RDX: 0000000000000a4f RSI: ffffffff820964dd RDI: 0000000000005278
RBP: ffffc900027ef8c0 R08: 0000000000000001 R09: 0000000000000000
R10: 0000000000000001 R11: ffff88802c77aff0 R12: ffffc900027ef8e0
R13: 0000000000000000 R14: ffffc900027ef8b0 R15: 0000000000000000
FS:  00007ff4529496c0(0000) GS:ffff8880d6b09000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000000409000000 CR3: 0000000055b8f000 CR4: 0000000000352ef0
Call Trace:
 <TASK>
 lru_gen_refault mm/workingset.c:300 [inline]
 workingset_refault+0x251/0xca0 mm/workingset.c:550
 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: 0033:0x7ff451b8f7c9
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:00007ff452949038 EFLAGS: 00000246 ORIG_RAX: 0000000000000010
RAX: ffffffffffffffda RBX: 00007ff451de5fa0 RCX: 00007ff451b8f7c9
RDX: 0000200000000180 RSI: 00000000c0686611 RDI: 0000000000000003
RBP: 00007ff451c13f91 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007ff451de6038 R14: 00007ff451de5fa0 R15: 00007ffda7f04458
 </TASK>
Modules linked in:
---[ end trace 0000000000000000 ]---
RIP: 0010:lru_gen_test_recent+0x1a4/0x2f0 mm/workingset.c:281
Code: 48 c1 ea 03 80 3c 02 00 0f 85 17 01 00 00 48 8d bb c0 00 00 00 49 89 1c 24 48 b8 00 00 00 00 00 fc ff df 48 89 fa 48 c1 ea 03 <80> 3c 02 00 0f 85 21 01 00 00 48 8b 9b c0 00 00 00 48 89 ea 48 b8
RSP: 0018:ffffc900027ef828 EFLAGS: 00010202
RAX: dffffc0000000000 RBX: 00000000000051b8 RCX: ffffc900027ef72c
RDX: 0000000000000a4f RSI: ffffffff820964dd RDI: 0000000000005278
RBP: ffffc900027ef8c0 R08: 0000000000000001 R09: 0000000000000000
R10: 0000000000000001 R11: ffff88802c77aff0 R12: ffffc900027ef8e0
R13: 0000000000000000 R14: ffffc900027ef8b0 R15: 0000000000000000
FS:  00007ff4529496c0(0000) GS:ffff8880d6a09000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007ff451b73460 CR3: 0000000055b8f000 CR4: 0000000000352ef0
----------------
Code disassembly (best guess):
   0:	48 c1 ea 03          	shr    $0x3,%rdx
   4:	80 3c 02 00          	cmpb   $0x0,(%rdx,%rax,1)
   8:	0f 85 17 01 00 00    	jne    0x125
   e:	48 8d bb c0 00 00 00 	lea    0xc0(%rbx),%rdi
  15:	49 89 1c 24          	mov    %rbx,(%r12)
  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:	80 3c 02 00          	cmpb   $0x0,(%rdx,%rax,1) <-- trapping instruction
  2e:	0f 85 21 01 00 00    	jne    0x155
  34:	48 8b 9b c0 00 00 00 	mov    0xc0(%rbx),%rbx
  3b:	48 89 ea             	mov    %rbp,%rdx
  3e:	48                   	rex.W
  3f:	b8                   	.byte 0xb8


Tested on:

commit:         9e906a9d Merge tag 'perf-tools-for-v6.19-2025-12-06' o..
git tree:       upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=1363ceb4580000
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=168666c2580000