linux-kernel - Re: [syzbot] kernel BUG in __filemap_get

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Date:   Thu, 21 Apr 2022 17:25:18 -0700
From:   syzbot <syzbot+cf4cf13056f85dec2c40@...kaller.appspotmail.com>
To:     hdanton@...a.com, linux-kernel@...r.kernel.org,
        syzkaller-bugs@...glegroups.com
Subject: Re: [syzbot] kernel BUG in __filemap_get_folio

Hello,

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

 shrink_dcache_parent+0x1fe/0x3c0 fs/dcache.c:1628
 do_one_tree fs/dcache.c:1682 [inline]
 shrink_dcache_for_umount+0x71/0x330 fs/dcache.c:1699
 generic_shutdown_super+0x68/0x400 fs/super.c:444
 kill_anon_super fs/super.c:1056 [inline]
 kill_litter_super+0x6e/0xa0 fs/super.c:1065
------------[ cut here ]------------
kernel BUG at mm/filemap.c:1974!
invalid opcode: 0000 [#1] PREEMPT SMP KASAN
CPU: 0 PID: 4274 Comm: syz-executor.1 Not tainted 5.18.0-rc3-syzkaller-00007-g559089e0a93d-dirty #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
RIP: 0010:__filemap_get_folio+0xc2b/0x1290 mm/filemap.c:1974
Code: 0b f6 d8 ff 31 ff 89 ee e8 e2 f9 d8 ff 40 84 ed 0f 85 54 f8 ff ff e8 f4 f5 d8 ff 48 c7 c6 80 d9 d5 89 48 89 df e8 35 91 0e 00 <0f> 0b 44 8b 6c 24 10 31 db 45 31 f6 e9 05 f6 ff ff 44 8b 6c 24 10
RSP: 0018:ffffc90003ab78b0 EFLAGS: 00010293
RAX: 0000000000000000 RBX: ffffea00018c8500 RCX: 0000000000000000
RDX: ffff8880738f8280 RSI: ffffffff819f582b RDI: 0000000000000003
RBP: 0000000000000000 R08: 000000000000001c R09: 00000000ffffffff
R10: ffffffff891d5eec R11: 00000000ffffffff R12: 00000000000001c0
R13: 0000000000000182 R14: 0000000000000000 R15: dffffc0000000000
FS:  00007f1719c18700(0000) GS:ffff8880b9c00000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f3b2bd6c058 CR3: 00000000775ab000 CR4: 00000000003506f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
 <TASK>
 pagecache_get_page+0x2e/0x290 mm/folio-compat.c:126
 shmem_getpage_gfp+0x471/0x2370 mm/shmem.c:1812
 shmem_getpage mm/shmem.c:149 [inline]
 shmem_write_begin+0xff/0x1e0 mm/shmem.c:2446
 generic_perform_write+0x249/0x560 mm/filemap.c:3790
 __generic_file_write_iter+0x2aa/0x4d0 mm/filemap.c:3918
 generic_file_write_iter+0xd7/0x220 mm/filemap.c:3950
 call_write_iter include/linux/fs.h:2050 [inline]
 new_sync_write+0x38a/0x560 fs/read_write.c:504
 vfs_write+0x7c0/0xac0 fs/read_write.c:591
 ksys_write+0x127/0x250 fs/read_write.c:644
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x35/0xb0 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x44/0xae
RIP: 0033:0x7f1718a890e9
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 b8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007f1719c18168 EFLAGS: 00000246 ORIG_RAX: 0000000000000001
RAX: ffffffffffffffda RBX: 00007f1718b9bf60 RCX: 00007f1718a890e9
RDX: 000000000208e24b RSI: 0000000020000080 RDI: 0000000000000004
RBP: 00007f1718ae308d R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007ffd921fc6af R14: 00007f1719c18300 R15: 0000000000022000
 </TASK>
Modules linked in:
---[ end trace 0000000000000000 ]---
RIP: 0010:__filemap_get_folio+0xc2b/0x1290 mm/filemap.c:1974
Code: 0b f6 d8 ff 31 ff 89 ee e8 e2 f9 d8 ff 40 84 ed 0f 85 54 f8 ff ff e8 f4 f5 d8 ff 48 c7 c6 80 d9 d5 89 48 89 df e8 35 91 0e 00 <0f> 0b 44 8b 6c 24 10 31 db 45 31 f6 e9 05 f6 ff ff 44 8b 6c 24 10
RSP: 0018:ffffc90003ab78b0 EFLAGS: 00010293
RAX: 0000000000000000 RBX: ffffea00018c8500 RCX: 0000000000000000
RDX: ffff8880738f8280 RSI: ffffffff819f582b RDI: 0000000000000003
RBP: 0000000000000000 R08: 000000000000001c R09: 00000000ffffffff
R10: ffffffff891d5eec R11: 00000000ffffffff R12: 00000000000001c0
R13: 0000000000000182 R14: 0000000000000000 R15: dffffc0000000000
FS:  00007f1719c18700(0000) GS:ffff8880b9d00000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007fb799b6c058 CR3: 00000000775ab000 CR4: 00000000003506e0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400


Tested on:

commit:         559089e0 vmalloc: replace VM_NO_HUGE_VMAP with VM_ALLO..
git tree:       https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/
console output: https://syzkaller.appspot.com/x/log.txt?x=17daede8f00000
kernel config:  https://syzkaller.appspot.com/x/.config?x=dd7c9a79dfcfa205
dashboard link: https://syzkaller.appspot.com/bug?extid=cf4cf13056f85dec2c40
compiler:       gcc (Debian 10.2.1-6) 10.2.1 20210110, GNU ld (GNU Binutils for Debian) 2.35.2
patch:          https://syzkaller.appspot.com/x/patch.diff?x=15e90f84f00000