From: Muchun Song <muchun.song@linux.dev>
To: syzbot <syzbot+3b9148f91b7869120e81@syzkaller.appspotmail.com>,
Oscar Salvador <osalvador@suse.de>,
David Hildenbrand <david@redhat.com>,
Matthew Wilcox <willy@infradead.org>
Cc: Andrew Morton <akpm@linux-foundation.org>,
LKML <linux-kernel@vger.kernel.org>,
Linux-MM <linux-mm@kvack.org>,
syzkaller-bugs@googlegroups.com
Subject: Re: [syzbot] [mm?] kernel BUG in const_folio_flags
Date: Thu, 21 Mar 2024 17:49:49 +0800 [thread overview]
Message-ID: <812E97E8-668F-414D-9480-1D284834A034@linux.dev> (raw)
In-Reply-To: <0000000000006cfe98061423cde7@google.com>
> On Mar 21, 2024, at 12:04, syzbot <syzbot+3b9148f91b7869120e81@syzkaller.appspotmail.com> wrote:
>
> Hello,
>
> syzbot found the following issue on:
>
> HEAD commit: 78c3925c048c Merge tag 'soc-late-6.9' of git://git.kernel...
> git tree: upstream
> console output: https://syzkaller.appspot.com/x/log.txt?x=1267d879180000
> kernel config: https://syzkaller.appspot.com/x/.config?x=f3c2635ded15fbc9
> dashboard link: https://syzkaller.appspot.com/bug?extid=3b9148f91b7869120e81
> compiler: gcc (Debian 12.2.0-14) 12.2.0, GNU ld (GNU Binutils for Debian) 2.40
> userspace arch: i386
>
> Unfortunately, I don't have any reproducer for this issue yet.
>
> Downloadable assets:
> disk image (non-bootable): https://storage.googleapis.com/syzbot-assets/7bc7510fe41f/non_bootable_disk-78c3925c.raw.xz
> vmlinux: https://storage.googleapis.com/syzbot-assets/cf2bceeccde3/vmlinux-78c3925c.xz
> kernel image: https://storage.googleapis.com/syzbot-assets/fc938dfaea6d/bzImage-78c3925c.xz
>
> IMPORTANT: if you fix the issue, please add the following tag to the commit:
> Reported-by: syzbot+3b9148f91b7869120e81@syzkaller.appspotmail.com
>
> veth_newlink+0x627/0xa10 drivers/net/veth.c:1895
> rtnl_newlink_create net/core/rtnetlink.c:3494 [inline]
> __rtnl_newlink+0x119c/0x1960 net/core/rtnetlink.c:3714
> rtnl_newlink+0x67/0xa0 net/core/rtnetlink.c:3727
> rtnetlink_rcv_msg+0x3c7/0xe60 net/core/rtnetlink.c:6595
> ------------[ cut here ]------------
> kernel BUG at include/linux/page-flags.h:315!
There are some more page dumping information from console:
[ 61.367144][ T42] page: refcount:0 mapcount:0 mapping:0000000000000000 index:0xffff888028132880 pfn:0x28130
[ 61.371430][ T42] flags: 0xfff80000000000(node=0|zone=1|lastcpupid=0xfff)
[ 61.374455][ T42] page_type: 0xffffffff()
[ 61.376096][ T42] raw: 00fff80000000000 ffff888015ecd540 dead000000000100 0000000000000000
[ 61.379994][ T42] raw: ffff888028132880 0000000000190000 00000000ffffffff 0000000000000000
Alright, the page is freed (with a refcount of 0).
> invalid opcode: 0000 [#1] PREEMPT SMP KASAN NOPTI
> CPU: 1 PID: 42 Comm: kcompactd0 Not tainted 6.8.0-syzkaller-11725-g78c3925c048c #0
> Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.2-debian-1.16.2-1 04/01/2014
> RIP: 0010:const_folio_flags+0x1bd/0x1f0 include/linux/page-flags.h:315
The RIP is in const_folio_flags() (called from folio_test_hugetlb()):
VM_BUG_ON_PGFLAGS(n > 0 && !test_bit(PG_head, &page->flags), page);
It is reasonable to WARN because the page is freed (PG_head is not set
in this case).
The comments from folio_test_hugetlb() says "Caller should have a
reference on the folio", so the caller of PageHuge() should grab
a refcount before calling folio_test_hugetlb() since commit
9c5ccf2db04b. But it does not mean that the @page must be a HugeTLB page
even if PageHuge(@page) returns true when the user does not hold
a extra refcount on the @page. Seems the WARN could be acceptable, so
should we remove this WARN? I am not sure. Cc more experts.
Thanks.
> Code: 41 83 e4 01 44 89 e6 e8 b1 e6 a9 ff 45 84 e4 0f 85 c4 fe ff ff e8 23 ec a9 ff 48 c7 c6 e0 07 1b 8b 48 89 ef e8 34 2e ed ff 90 <0f> 0b e8 8c 6b 06 00 e9 66 fe ff ff 48 89 ef e8 7f 6b 06 00 eb b6
> RSP: 0018:ffffc9000068f7f0 EFLAGS: 00010293
> RAX: 0000000000000000 RBX: 0000000000000001 RCX: ffffc9000068f698
> RDX: ffff88801744c880 RSI: ffffffff81e4265c RDI: ffffffff8b6f0060
> RBP: ffffea0000a04c00 R08: 0000000000000000 R09: fffffbfff1f3deca
> R10: ffffffff8f9ef657 R11: 0000000000000000 R12: 0000000000000000
> R13: ffffea0000a04dc0 R14: 0000000000028137 R15: ffffc9000068fbe8
> FS: 0000000000000000(0000) GS:ffff88802c300000(0000) knlGS:0000000000000000
> CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
> CR2: 00007ffe623b9138 CR3: 000000001c22c000 CR4: 0000000000350ef0
> DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
> DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
> Call Trace:
> <TASK>
> folio_test_hugetlb include/linux/page-flags.h:875 [inline]
> PageHuge+0x219/0x2b0 mm/hugetlb.c:2174
> isolate_migratepages_block+0x4a0/0x5110 mm/compaction.c:1004
> isolate_migratepages mm/compaction.c:2182 [inline]
> compact_zone+0x1a5c/0x4280 mm/compaction.c:2629
> kcompactd_do_work+0x340/0x720 mm/compaction.c:3100
> kcompactd+0x8d7/0xde0 mm/compaction.c:3199
> kthread+0x2c1/0x3a0 kernel/kthread.c:388
> ret_from_fork+0x45/0x80 arch/x86/kernel/process.c:147
> ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:243
> </TASK>
> Modules linked in:
> ---[ end trace 0000000000000000 ]---
> RIP: 0010:const_folio_flags+0x1bd/0x1f0 include/linux/page-flags.h:315
> Code: 41 83 e4 01 44 89 e6 e8 b1 e6 a9 ff 45 84 e4 0f 85 c4 fe ff ff e8 23 ec a9 ff 48 c7 c6 e0 07 1b 8b 48 89 ef e8 34 2e ed ff 90 <0f> 0b e8 8c 6b 06 00 e9 66 fe ff ff 48 89 ef e8 7f 6b 06 00 eb b6
> RSP: 0018:ffffc9000068f7f0 EFLAGS: 00010293
> RAX: 0000000000000000 RBX: 0000000000000001 RCX: ffffc9000068f698
> RDX: ffff88801744c880 RSI: ffffffff81e4265c RDI: ffffffff8b6f0060
> RBP: ffffea0000a04c00 R08: 0000000000000000 R09: fffffbfff1f3deca
> R10: ffffffff8f9ef657 R11: 0000000000000000 R12: 0000000000000000
> R13: ffffea0000a04dc0 R14: 0000000000028137 R15: ffffc9000068fbe8
> FS: 0000000000000000(0000) GS:ffff88802c300000(0000) knlGS:0000000000000000
> CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
> CR2: 00007ffe623b9138 CR3: 000000001c22c000 CR4: 0000000000350ef0
> DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
> DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
>
>
> ---
> This report is generated by a bot. It may contain errors.
> See https://goo.gl/tpsmEJ for more information about syzbot.
> syzbot engineers can be reached at syzkaller@googlegroups.com.
>
> syzbot will keep track of this issue. See:
> https://goo.gl/tpsmEJ#status for how to communicate with syzbot.
>
> If the report is already addressed, let syzbot know by replying with:
> #syz fix: exact-commit-title
>
> If you want to overwrite report's subsystems, reply with:
> #syz set subsystems: new-subsystem
> (See the list of subsystem names on the web dashboard)
>
> If the report is a duplicate of another one, reply with:
> #syz dup: exact-subject-of-another-report
>
> If you want to undo deduplication, reply with:
> #syz undup
next prev parent reply other threads:[~2024-03-21 9:50 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2024-03-21 4:04 [syzbot] [mm?] kernel BUG in const_folio_flags syzbot
2024-03-21 9:49 ` Muchun Song [this message]
2024-03-21 9:58 ` David Hildenbrand
2024-03-21 10:20 ` Oscar Salvador
2024-03-22 3:24 ` Muchun Song
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=812E97E8-668F-414D-9480-1D284834A034@linux.dev \
--to=muchun.song@linux.dev \
--cc=akpm@linux-foundation.org \
--cc=david@redhat.com \
--cc=linux-kernel@vger.kernel.org \
--cc=linux-mm@kvack.org \
--cc=osalvador@suse.de \
--cc=syzbot+3b9148f91b7869120e81@syzkaller.appspotmail.com \
--cc=syzkaller-bugs@googlegroups.com \
--cc=willy@infradead.org \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is an external index of several public inboxes,
see mirroring instructions on how to clone and mirror
all data and code used by this external index.