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Date:   Thu, 26 Sep 2019 11:50:19 -0700
From:   Matthew Wilcox <willy@infradead.org>
To:     "Kirill A. Shutemov" <kirill@shutemov.name>
Cc:     Johannes Weiner <hannes@cmpxchg.org>,
        Andrew Morton <akpm@linux-foundation.org>,
        Josef Bacik <josef@toxicpanda.com>, linux-mm@kvack.org,
        linux-kernel@vger.kernel.org
Subject: Re: [PATCH] mm: drop mmap_sem before calling balance_dirty_pages()
 in write fault
Message-ID: <20190926185019.GA2147@bombadil.infradead.org>
References: <20190924171518.26682-1-hannes@cmpxchg.org>
 <20190924174809.GH1855@bombadil.infradead.org>
 <20190924194238.GA29030@cmpxchg.org>
 <20190924204608.GI1855@bombadil.infradead.org>
 <20190924214337.GA17405@cmpxchg.org>
 <20190926134923.wqlkymjdfxd4iymh@box>
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On Thu, Sep 26, 2019 at 04:49:23PM +0300, Kirill A. Shutemov wrote:
> It happens if the VMA got unmapped under us while we dropped mmap_sem
> and inode got freed.
> 
> Pinning the file if we drop mmap_sem fixes the issue.
> 
> Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
> Reported-by: syzbot+03ee87124ee05af991bd@syzkaller.appspotmail.com
> Cc: Hillf Danton <hdanton@sina.com>
> Cc: Matthew Wilcox <willy@infradead.org>
> Cc: Hugh Dickins <hughd@google.com>

Reviewed-by: Matthew Wilcox (Oracle) <willy@infradead.org>