linux-kernel - Re: [syzbot] [fs?] [mm?] kernel BUG in __filemap_add

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Message-ID: <68ea4a0a.050a0220.1186a4.0012.GAE@google.com>
Date: Sat, 11 Oct 2025 05:14:02 -0700
From: syzbot <syzbot+4d3cc33ef7a77041efa6@...kaller.appspotmail.com>
To: dileepsankhla.ds@...il.com, linux-kernel@...r.kernel.org, 
	syzkaller-bugs@...glegroups.com
Subject: Re: [syzbot] [fs?] [mm?] kernel BUG in __filemap_add_folio

Hello,

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

------------[ cut here ]------------
kernel BUG at ./include/linux/pagemap.h:1398!
Oops: invalid opcode: 0000 [#1] SMP KASAN NOPTI
CPU: 0 UID: 0 PID: 15521 Comm: syz-executor273 Not tainted syzkaller #0 PREEMPT(full) 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/02/2025
RIP: 0010:__readahead_folio include/linux/pagemap.h:1398 [inline]
RIP: 0010:readahead_folio include/linux/pagemap.h:1424 [inline]
RIP: 0010:mpage_readahead+0x399/0x590 fs/mpage.c:367
Code: 24 84 c0 74 08 3c 03 0f 8e 61 01 00 00 44 8b 7b 20 89 ef 44 89 fe e8 f6 a2 72 ff 41 39 ef 0f 83 9f fd ff ff e8 68 a8 72 ff 90 <0f> 0b e8 60 a8 72 ff 4c 89 ea 48 b8 00 00 00 00 00 fc ff df 48 c1
RSP: 0018:ffffc9000e897640 EFLAGS: 00010293
RAX: 0000000000000000 RBX: ffffc9000e897af8 RCX: ffffffff8248e65a
RDX: ffff888078074880 RSI: ffffffff8248e668 RDI: 0000000000000004
RBP: 0000000000000004 R08: 0000000000000004 R09: 0000000000000004
R10: 0000000000000001 R11: 0000000000000000 R12: dffffc0000000000
R13: ffffc9000e897b1c R14: fffff52001d12f63 R15: 0000000000000001
FS:  0000555574632380(0000) GS:ffff8881246b5000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007fbdedf84130 CR3: 00000000697eb000 CR4: 00000000003526f0
Call Trace:
 <TASK>
 read_pages+0x1c4/0xc70 mm/readahead.c:160
 page_cache_ra_unbounded+0x5d2/0x7d0 mm/readahead.c:264
 do_page_cache_ra mm/readahead.c:327 [inline]
 page_cache_ra_order+0xa28/0xd60 mm/readahead.c:532
 do_sync_mmap_readahead mm/filemap.c:3304 [inline]
 filemap_fault+0x152e/0x2930 mm/filemap.c:3445
 __do_fault+0x10d/0x490 mm/memory.c:5152
 do_shared_fault mm/memory.c:5637 [inline]
 do_fault mm/memory.c:5711 [inline]
 do_pte_missing+0x1a6/0x3ba0 mm/memory.c:4234
 handle_pte_fault mm/memory.c:6052 [inline]
 __handle_mm_fault+0x152a/0x2a50 mm/memory.c:6195
 handle_mm_fault+0x589/0xd10 mm/memory.c:6364
 do_user_addr_fault+0x60c/0x1370 arch/x86/mm/fault.c:1336
 handle_page_fault arch/x86/mm/fault.c:1476 [inline]
 exc_page_fault+0x5c/0xb0 arch/x86/mm/fault.c:1532
 asm_exc_page_fault+0x26/0x30 arch/x86/include/asm/idtentry.h:623
RIP: 0033:0x7fbdeded986d
Code: 03 00 b9 03 10 12 00 45 31 c0 48 ba 80 00 00 00 00 20 00 00 48 b8 2f 64 65 76 2f 6e 75 6c 48 c7 c6 9c ff ff ff bf 01 01 00 00 <48> 89 02 48 b8 88 00 00 00 00 20 00 00 c7 00 6c 62 30 00 31 c0 e8
RSP: 002b:00007ffc828830a0 EFLAGS: 00010246
RAX: 6c756e2f7665642f RBX: 0000000000000000 RCX: 0000000000121003
RDX: 0000200000000080 RSI: ffffffffffffff9c RDI: 0000000000000101
RBP: 00000000000f4240 R08: 0000000000000000 R09: 0000000000002000
R10: 0000000000000013 R11: 0000000000000206 R12: 0000000000078a5d
R13: 00007ffc828830bc R14: 00007ffc828830d0 R15: 00007ffc828830c0
 </TASK>
Modules linked in:
---[ end trace 0000000000000000 ]---
RIP: 0010:__readahead_folio include/linux/pagemap.h:1398 [inline]
RIP: 0010:readahead_folio include/linux/pagemap.h:1424 [inline]
RIP: 0010:mpage_readahead+0x399/0x590 fs/mpage.c:367
Code: 24 84 c0 74 08 3c 03 0f 8e 61 01 00 00 44 8b 7b 20 89 ef 44 89 fe e8 f6 a2 72 ff 41 39 ef 0f 83 9f fd ff ff e8 68 a8 72 ff 90 <0f> 0b e8 60 a8 72 ff 4c 89 ea 48 b8 00 00 00 00 00 fc ff df 48 c1
RSP: 0018:ffffc9000e897640 EFLAGS: 00010293
RAX: 0000000000000000 RBX: ffffc9000e897af8 RCX: ffffffff8248e65a
RDX: ffff888078074880 RSI: ffffffff8248e668 RDI: 0000000000000004
RBP: 0000000000000004 R08: 0000000000000004 R09: 0000000000000004
R10: 0000000000000001 R11: 0000000000000000 R12: dffffc0000000000
R13: ffffc9000e897b1c R14: fffff52001d12f63 R15: 0000000000000001
FS:  0000555574632380(0000) GS:ffff8881246b5000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007fbdedf84130 CR3: 00000000697eb000 CR4: 00000000003526f0


Tested on:

commit:         9dd1835e Merge tag 'dma-mapping-6.17-2025-09-09' of gi..
git tree:       git://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
console output: https://syzkaller.appspot.com/x/log.txt?x=17224dcd980000
kernel config:  https://syzkaller.appspot.com/x/.config?x=c53bac41b8ca5327
dashboard link: https://syzkaller.appspot.com/bug?extid=4d3cc33ef7a77041efa6
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=124659e2580000