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a=rsa-sha256; c=relaxed/simple; d=linux-foundation.org; s=korg; t=1628978813; bh=DbknUOPIPPc6SG9JbTMauk/L0G2VZm9flyfYhsntT+c=; h=Date:From:To:Cc:Subject:In-Reply-To:References:From; b=b5v4VJKXLKGf4wlGL/ZVRl0uKrWMmEu9PdDMXPmf1xWXUiSQHszWHRNcDmfzWyPEG CEDMz3PiN3zkezBSiFChwDBMvRJWkvGtdFCOyTGWZ7f5TxGhul61EFQ/F0d7d9lqm9 DqmKBbgge6IcxKKxgYTRowuzqsJkGpWzi+vQt13U= Date: Sat, 14 Aug 2021 15:06:52 -0700 From: Andrew Morton To: syzbot 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 Message-Id: <20210814150652.c61e3c09a58222260fa2d02d@linux-foundation.org> In-Reply-To: <000000000000fbad4305c982f836@google.com> References: <000000000000fbad4305c982f836@google.com> X-Mailer: Sylpheed 3.5.1 (GTK+ 2.24.32; x86_64-pc-linux-gnu) Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit X-Rspamd-Queue-Id: A56A9100151F Authentication-Results: imf12.hostedemail.com; dkim=pass header.d=linux-foundation.org header.s=korg header.b=b5v4VJKX; dmarc=none; spf=pass (imf12.hostedemail.com: domain of akpm@linux-foundation.org designates 198.145.29.99 as permitted sender) smtp.mailfrom=akpm@linux-foundation.org X-Rspamd-Server: rspam04 X-Stat-Signature: 1yfmbihim1fq1scug8gapdgunk8wm8x1 X-HE-Tag: 1628978814-383868 X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: On Sat, 14 Aug 2021 04:07:23 -0700 syzbot 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,