linux-kernel - Re: [syzbot] [btrfs?] general protection fault in create_empty

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Message-ID: <6960bb5e.050a0220.1c677c.03bb.GAE@google.com>
Date: Fri, 09 Jan 2026 00:25:02 -0800
From: syzbot <syzbot+b4a2af3000eaa84d95d5@...kaller.appspotmail.com>
To: kartikey406@...il.com, linux-kernel@...r.kernel.org, 
	syzkaller-bugs@...glegroups.com
Subject: Re: [syzbot] [btrfs?] general protection fault in create_empty_buffers
 (5)

Hello,

syzbot has tested the proposed patch but the reproducer is still triggering an issue:
kernel BUG in __filemap_add_folio

 kernel_clone+0xfc/0x910 kernel/fork.c:2651
 __do_sys_clone+0xce/0x120 kernel/fork.c:2792
 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
------------[ cut here ]------------
kernel BUG at mm/filemap.c:858!
Oops: invalid opcode: 0000 [#1] SMP KASAN NOPTI
CPU: 2 UID: 0 PID: 6603 Comm: syz.0.90 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:__filemap_add_folio+0xf29/0x11b0 mm/filemap.c:858
Code: 96 c6 ff 48 c7 c6 80 ed 99 8b 4c 89 ef e8 bf 72 11 00 90 0f 0b e8 77 96 c6 ff 48 c7 c6 e0 ed 99 8b 4c 89 ef e8 a8 72 11 00 90 <0f> 0b e8 60 96 c6 ff 90 0f 0b 90 e9 1c fc ff ff e8 52 96 c6 ff 48
RSP: 0018:ffffc900040af808 EFLAGS: 00010293
RAX: 0000000000000000 RBX: 0000000000000000 RCX: 0000000000000000
RDX: ffff88802b89c980 RSI: ffffffff81f85248 RDI: ffff88802b89ce04
RBP: 0000000000000c40 R08: 0000000000000001 R09: 0000000000000001
R10: ffffffff9088b8d7 R11: 0000000000000001 R12: 0000000000000002
R13: ffffea0000936400 R14: 0000000000000000 R15: 0000000000000000
FS:  00007f83919c36c0(0000) GS:ffff8880d6af5000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f83919c2f98 CR3: 000000002db08000 CR4: 0000000000352ef0
Call Trace:
 <TASK>
 filemap_add_folio+0x19a/0x610 mm/filemap.c:966
 do_read_cache_folio+0x23c/0x5c0 mm/filemap.c:4063
 do_read_cache_page mm/filemap.c:4162 [inline]
 read_cache_page_gfp+0x29/0x120 mm/filemap.c:4195
 btrfs_read_disk_super+0x192/0x500 fs/btrfs/volumes.c:1367
 btrfs_scan_one_device+0x109/0x820 fs/btrfs/volumes.c:1475
 btrfs_get_tree_super fs/btrfs/super.c:1860 [inline]
 btrfs_get_tree_subvol fs/btrfs/super.c:2089 [inline]
 btrfs_get_tree+0x5b3/0x2710 fs/btrfs/super.c:2123
 vfs_get_tree+0x8e/0x330 fs/super.c:1751
 fc_mount fs/namespace.c:1199 [inline]
 do_new_mount_fc fs/namespace.c:3636 [inline]
 do_new_mount fs/namespace.c:3712 [inline]
 path_mount+0x7bf/0x23a0 fs/namespace.c:4022
 do_mount fs/namespace.c:4035 [inline]
 __do_sys_mount fs/namespace.c:4224 [inline]
 __se_sys_mount fs/namespace.c:4201 [inline]
 __x64_sys_mount+0x293/0x310 fs/namespace.c:4201
 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: 0033:0x7f8390b8f7c9
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:00007f83919c3038 EFLAGS: 00000246 ORIG_RAX: 00000000000000a5
RAX: ffffffffffffffda RBX: 00007f8390de6090 RCX: 00007f8390b8f7c9
RDX: 00002000000000c0 RSI: 0000200000000080 RDI: 00002000000001c0
RBP: 00007f8390c13f91 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000004418 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f8390de6128 R14: 00007f8390de6090 R15: 00007ffc2a9b3b58
 </TASK>
Modules linked in:
---[ end trace 0000000000000000 ]---
RIP: 0010:__filemap_add_folio+0xf29/0x11b0 mm/filemap.c:858
Code: 96 c6 ff 48 c7 c6 80 ed 99 8b 4c 89 ef e8 bf 72 11 00 90 0f 0b e8 77 96 c6 ff 48 c7 c6 e0 ed 99 8b 4c 89 ef e8 a8 72 11 00 90 <0f> 0b e8 60 96 c6 ff 90 0f 0b 90 e9 1c fc ff ff e8 52 96 c6 ff 48
RSP: 0018:ffffc900040af808 EFLAGS: 00010293
RAX: 0000000000000000 RBX: 0000000000000000 RCX: 0000000000000000
RDX: ffff88802b89c980 RSI: ffffffff81f85248 RDI: ffff88802b89ce04
RBP: 0000000000000c40 R08: 0000000000000001 R09: 0000000000000001
R10: ffffffff9088b8d7 R11: 0000000000000001 R12: 0000000000000002
R13: ffffea0000936400 R14: 0000000000000000 R15: 0000000000000000
FS:  00007f83919c36c0(0000) GS:ffff8880d6af5000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f83919c2f98 CR3: 000000002db08000 CR4: 0000000000352ef0


Tested on:

commit:         623fb991 Merge tag 'pinctrl-v6.19-2' of git://git.kern..
git tree:       upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=15105074580000
kernel config:  https://syzkaller.appspot.com/x/.config?x=a11e0f726bfb6765
dashboard link: https://syzkaller.appspot.com/bug?extid=b4a2af3000eaa84d95d5
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=10205074580000