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From: Andrew Morton <akpm@linux-foundation.org>
To: syzbot <syzbot+57876cfc2dca0c6b2e6a@syzkaller.appspotmail.com>
Cc: linux-kernel@vger.kernel.org, linux-mm@kvack.org,
	mike.kravetz@oracle.com, syzkaller-bugs@googlegroups.com
Subject: Re: [syzbot] BUG: unable to handle kernel paging request in alloc_huge_page
Date: Sat, 14 Aug 2021 15:06:52 -0700	[thread overview]
Message-ID: <20210814150652.c61e3c09a58222260fa2d02d@linux-foundation.org> (raw)
In-Reply-To: <000000000000fbad4305c982f836@google.com>

On Sat, 14 Aug 2021 04:07:23 -0700 syzbot <syzbot+57876cfc2dca0c6b2e6a@syzkaller.appspotmail.com> wrote:

> Hello,
> 
> syzbot found the following issue on:

Thanks.

> HEAD commit:    92d00774360d Add linux-next specific files for 20210810
> git tree:       linux-next
> console output: https://syzkaller.appspot.com/x/log.txt?x=12e2b4d9300000
> kernel config:  https://syzkaller.appspot.com/x/.config?x=a6933fa6f9a86ca9
> dashboard link: https://syzkaller.appspot.com/bug?extid=57876cfc2dca0c6b2e6a
> compiler:       gcc (Debian 10.2.1-6) 10.2.1 20210110, GNU ld (GNU Binutils for Debian) 2.35.1
> syz repro:      https://syzkaller.appspot.com/x/repro.syz?x=16f81581300000
> C reproducer:   https://syzkaller.appspot.com/x/repro.c?x=11419dfa300000
> 
> IMPORTANT: if you fix the issue, please add the following tag to the commit:
> Reported-by: syzbot+57876cfc2dca0c6b2e6a@syzkaller.appspotmail.com
> 
> BUG: unable to handle page fault for address: fffffffffffffffc
> #PF: supervisor write access in kernel mode
> #PF: error_code(0x0002) - not-present page
> PGD b68f067 P4D b68f067 PUD b691067 PMD 0 
> Oops: 0002 [#1] PREEMPT SMP KASAN
> CPU: 0 PID: 6601 Comm: syz-executor361 Not tainted 5.14.0-rc5-next-20210810-syzkaller #0
> Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
> RIP: 0010:__list_add include/linux/list.h:71 [inline]
> RIP: 0010:list_add include/linux/list.h:86 [inline]
> RIP: 0010:alloc_huge_page+0xdcb/0x11b0 mm/hugetlb.c:2821

That appears to be

		list_add(&page->lru, &h->hugepage_activelist);

I'm suspecting Mike's surplus page changes?

> C reproducer:   https://syzkaller.appspot.com/x/repro.c?x=11419dfa300000

Nice to have that,


  reply	other threads:[~2021-08-14 22:06 UTC|newest]

Thread overview: 6+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-08-14 11:07 syzbot
2021-08-14 22:06 ` Andrew Morton [this message]
2021-08-14 23:24   ` Matthew Wilcox
2021-08-15 18:17     ` Mike Kravetz
2021-08-16  7:47       ` Dmitry Vyukov
2021-08-16 17:00         ` Mike Kravetz

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