Am 28.12.23 um 03:57 schrieb Qi Zheng:
On 2023/12/28 04:51, syzbot wrote:
Hello,
syzbot found the following issue on:
HEAD commit: 5254c0cbc92d Merge tag 'block-6.7-2023-12-22' of
git://git..
git tree: upstream
console+strace: https://syzkaller.appspot.com/x/log.txt?x=10cc6995e80000
kernel config:
https://syzkaller.appspot.com/x/.config?x=314e9ad033a7d3a7
dashboard link:
https://syzkaller.appspot.com/bug?extid=59dcc2e7283a6f5f5ba1
compiler: gcc (Debian 12.2.0-14) 12.2.0, GNU ld (GNU Binutils
for Debian) 2.40
syz repro: https://syzkaller.appspot.com/x/repro.syz?x=13e35809e80000
C reproducer: https://syzkaller.appspot.com/x/repro.c?x=155d5fd6e80000
Downloadable assets:
disk image:
https://storage.googleapis.com/syzbot-assets/ebe09a5995ee/disk-5254c0cb.raw.xz
vmlinux:
https://storage.googleapis.com/syzbot-assets/02178d7f5f98/vmlinux-5254c0cb.xz
kernel image:
https://storage.googleapis.com/syzbot-assets/12307f47d87c/bzImage-5254c0cb.xz
The issue was bisected to:
commit ea4452de2ae987342fadbdd2c044034e6480daad
Author: Qi Zheng <zhengqi.arch@xxxxxxxxxxxxx>
Date: Fri Nov 18 10:00:11 2022 +0000
mm: fix unexpected changes to {failslab|fail_page_alloc}.attr
bisection log:
https://syzkaller.appspot.com/x/bisect.txt?x=13027f76e80000
final oops: https://syzkaller.appspot.com/x/report.txt?x=10827f76e80000
console output: https://syzkaller.appspot.com/x/log.txt?x=17027f76e80000
IMPORTANT: if you fix the issue, please add the following tag to the
commit:
Reported-by: syzbot+59dcc2e7283a6f5f5ba1@xxxxxxxxxxxxxxxxxxxxxxxxx
Fixes: ea4452de2ae9 ("mm: fix unexpected changes to
{failslab|fail_page_alloc}.attr")
R10: 0000000000000000 R11: 0000000000000246 R12: 00007efe98069194
R13: 00007efe97fd2210 R14: 0000000000000002 R15: 6972642f7665642f
</TASK>
------------[ cut here ]------------
WARNING: CPU: 0 PID: 5107 at drivers/gpu/drm/drm_prime.c:227
drm_prime_destroy_file_private+0x43/0x60 drivers/gpu/drm/drm_prime.c:227
The warning is caused by !RB_EMPTY_ROOT(&prime_fpriv->dmabufs):
drm_prime_destroy_file_private
--> WARN_ON(!RB_EMPTY_ROOT(&prime_fpriv->dmabufs));
It seems irrelevant to the logic of fault injection. So I don't see
why the commit ea4452de2ae9 can cause this warning. :(
Making an educated guess I strongly think syzbot incorrectly bisected this.
What basically happens is that a DRM test case crashes because a file
private data structure is destroyed before all DMA-bufs referring to it
are destroyed.
Looks like a random race condition in a test case to me. Question is
really what test is syzbot running and who is maintaining this test case?
Regards,
Christian.
Modules linked in:
CPU: 0 PID: 5107 Comm: syz-executor227 Not tainted
6.7.0-rc6-syzkaller-00248-g5254c0cbc92d #0
Hardware name: Google Google Compute Engine/Google Compute Engine,
BIOS Google 11/17/2023
RIP: 0010:drm_prime_destroy_file_private+0x43/0x60
drivers/gpu/drm/drm_prime.c:227
Code: 00 00 fc ff df 48 89 fa 48 c1 ea 03 80 3c 02 00 75 21 48 8b 83
90 00 00 00 48 85 c0 75 06 5b e9 13 f1 93 fc e8 0e f1 93 fc 90 <0f>
0b 90 5b e9 04 f1 93 fc e8 3f 9b ea fc eb d8 66 66 2e 0f 1f 84
RSP: 0018:ffffc90003bdf9e0 EFLAGS: 00010293
RAX: 0000000000000000 RBX: ffff888019f28378 RCX: ffffc90003bdf9b0
RDX: ffff888018ff9dc0 RSI: ffffffff84f380c2 RDI: ffff888019f28408
RBP: ffff888019f28000 R08: 0000000000000001 R09: 0000000000000001
R10: ffffffff8f193a57 R11: 0000000000000000 R12: ffff88814829a000
R13: ffff888019f282a8 R14: ffff88814829a068 R15: ffff88814829a0a0
FS: 0000000000000000(0000) GS:ffff8880b9800000(0000)
knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007efe98050410 CR3: 000000006d1ff000 CR4: 0000000000350ef0
Call Trace:
<TASK>
drm_file_free.part.0+0x738/0xb90 drivers/gpu/drm/drm_file.c:290
drm_file_free drivers/gpu/drm/drm_file.c:247 [inline]
drm_close_helper.isra.0+0x180/0x1f0 drivers/gpu/drm/drm_file.c:307
drm_release+0x22a/0x4f0 drivers/gpu/drm/drm_file.c:494
__fput+0x270/0xb70 fs/file_table.c:394
task_work_run+0x14d/0x240 kernel/task_work.c:180
exit_task_work include/linux/task_work.h:38 [inline]
do_exit+0xa8a/0x2ad0 kernel/exit.c:869
do_group_exit+0xd4/0x2a0 kernel/exit.c:1018
get_signal+0x23b5/0x2790 kernel/signal.c:2904
arch_do_signal_or_restart+0x90/0x7f0 arch/x86/kernel/signal.c:309
exit_to_user_mode_loop kernel/entry/common.c:168 [inline]
exit_to_user_mode_prepare+0x121/0x240 kernel/entry/common.c:204
__syscall_exit_to_user_mode_work kernel/entry/common.c:285 [inline]
syscall_exit_to_user_mode+0x1e/0x60 kernel/entry/common.c:296
do_syscall_64+0x4d/0x110 arch/x86/entry/common.c:89
entry_SYSCALL_64_after_hwframe+0x63/0x6b
RIP: 0033:0x7efe98014769
Code: Unable to access opcode bytes at 0x7efe9801473f.
RSP: 002b:00007efe97fd2208 EFLAGS: 00000246 ORIG_RAX: 00000000000000ca
RAX: fffffffffffffe00 RBX: 00007efe9809c408 RCX: 00007efe98014769
RDX: 0000000000000000 RSI: 0000000000000080 RDI: 00007efe9809c408
RBP: 00007efe9809c400 R08: 0000000000003131 R09: 0000000000003131
R10: 0000000000000000 R11: 0000000000000246 R12: 00007efe98069194
R13: 00007efe97fd2210 R14: 0000000000000002 R15: 6972642f7665642f
</TASK>
---
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