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Date: Thu, 28 Jan 2016 12:51:36 +0200
From: "Kirill A. Shutemov" <kirill@shutemov.name>
To: Dmitry Vyukov <dvyukov@google.com>
Cc: Vlastimil Babka <vbabka@suse.cz>, Doug Gilbert <dgilbert@interlog.com>,
        Andrew Morton <akpm@linux-foundation.org>,
        David Rientjes <rientjes@google.com>,
        Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>,
        "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>,
        Shiraz Hashim <shashim@codeaurora.org>,
        "linux-mm@kvack.org" <linux-mm@kvack.org>,
        LKML <linux-kernel@vger.kernel.org>, Hugh Dickins <hughd@google.com>,
        Sasha Levin <sasha.levin@oracle.com>,
        syzkaller <syzkaller@googlegroups.com>,
        Kostya Serebryany <kcc@google.com>,
        Alexander Potapenko <glider@google.com>,
        linux-scsi <linux-scsi@vger.kernel.org>
Subject: Re: mm: another VM_BUG_ON_PAGE(PageTail(page))
Message-ID: <20160128105136.GD2396@node.shutemov.name>
References: <CACT4Y+Z9UDZNLsoEz-DO3fX_+0gTwPUA=uE++J=w1sAG_4CGJg@mail.gmail.com>
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On Thu, Jan 28, 2016 at 11:27:11AM +0100, Dmitry Vyukov wrote:
> Hello,
> 
> The following program triggers VM_BUG_ON_PAGE(PageTail(page)):
> 
> // autogenerated by syzkaller (http://github.com/google/syzkaller)
> #include <fcntl.h>
> #include <numaif.h>
> #include <sys/mman.h>
> #include <unistd.h>
> 
> int main()
> {
>   int fd;
> 
>   mmap((void*)0x20000000, 4096, PROT_READ|PROT_WRITE,
> MAP_PRIVATE|MAP_FIXED|MAP_ANONYMOUS, -1, 0);
>   fd = open("/dev/sg1", O_RDONLY|O_SYNC|0x100000);
>   mmap((void*)0x20001000, 0x4000, PROT_READ|PROT_WRITE,
> MAP_PRIVATE|MAP_FIXED, fd, 0);
>   mbind((void*)0x20000000, 0x4000, 0x8002, (void*)0x20002ff8, 3660,
> MPOL_MF_STRICT|MPOL_MF_MOVE);
>   return 0;
> }

I don't have sg1 in my VM. I changed it to sg0 and it doesn't trigger an
issue: mbind() returns -EINVAL as it supposed to. Hm..

-- 
 Kirill A. Shutemov