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Date:   Fri, 7 Jul 2023 17:55:26 +0200
From:   Greg KH <gregkh@linuxfoundation.org>
To:     "Liam R. Howlett" <Liam.Howlett@oracle.com>
Cc:     linux-kernel@vger.kernel.org,
        Andrew Morton <akpm@linux-foundation.org>,
        John Hsu <John.Hsu@mediatek.com>, stable@vger.kernel.org,
        linux-mm@kvack.org
Subject: Re: [PATCH stable v6.1] mm/mmap: Fix extra maple tree write
Message-ID: <2023070748-confiding-abnormal-b7e3@gregkh>
References: <20230706185135.2235532-1-Liam.Howlett@oracle.com>
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On Thu, Jul 06, 2023 at 02:51:35PM -0400, Liam R. Howlett wrote:
> commit 0503ea8f5ba73eb3ab13a81c1eefbaf51405385a upstream.
> 
> This was inadvertently fixed during the removal of __vma_adjust().
> 
> When __vma_adjust() is adjusting next with a negative value (pushing
> vma->vm_end lower), there would be two writes to the maple tree.  The
> first write is unnecessary and uses all allocated nodes in the maple
> state.  The second write is necessary but will need to allocate nodes
> since the first write has used the allocated nodes.  This may be a
> problem as it may not be safe to allocate at this time, such as a low
> memory situation.  Fix the issue by avoiding the first write and only
> write the adjusted "next" VMA.

Are you sure this is the same git id?  The one you reference above is
_VERY_ different from your 2 line change below.

And the changelog text is not the same.

confused,

greg k-h