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Date: Fri, 23 Feb 2024 16:46:57 +0100
From: Greg KH <gregkh@linuxfoundation.org>
To: Mike Rapoport <rppt@kernel.org>
Cc: stable@vger.kernel.org, Lokesh Gidra <lokeshgidra@google.com>,
	Andrea Arcangeli <aarcange@redhat.com>,
	Axel Rasmussen <axelrasmussen@google.com>,
	Brian Geffon <bgeffon@google.com>,
	David Hildenbrand <david@redhat.com>, Jann Horn <jannh@google.com>,
	Kalesh Singh <kaleshsingh@google.com>,
	Matthew Wilcox <willy@infradead.org>,
	Nicolas Geoffray <ngeoffray@google.com>,
	Peter Xu <peterx@redhat.com>,
	Suren Baghdasaryan <surenb@google.com>,
	Andrew Morton <akpm@linux-foundation.org>
Subject: Re: ["PATCH 5.4.y"] userfaultfd: fix mmap_changing checking in
 mfill_atomic_hugetlb
Message-ID: <2024022345-deserve-upright-22a6@gregkh>
References: <2024021850-vaseline-mongrel-489e@gregkh>
 <20240219152802.394860-1-rppt@kernel.org>
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In-Reply-To: <20240219152802.394860-1-rppt@kernel.org>

On Mon, Feb 19, 2024 at 05:28:02PM +0200, Mike Rapoport wrote:
> From: Lokesh Gidra <lokeshgidra@google.com>
> 
> In mfill_atomic_hugetlb(), mmap_changing isn't being checked
> again if we drop mmap_lock and reacquire it. When the lock is not held,
> mmap_changing could have been incremented. This is also inconsistent
> with the behavior in mfill_atomic().
> 
> Link: https://lkml.kernel.org/r/20240117223729.1444522-1-lokeshgidra@google.com
> Fixes: df2cc96e77011 ("userfaultfd: prevent non-cooperative events vs mcopy_atomic races")
> Signed-off-by: Lokesh Gidra <lokeshgidra@google.com>
> Cc: Andrea Arcangeli <aarcange@redhat.com>
> Cc: Mike Rapoport <rppt@kernel.org>
> Cc: Axel Rasmussen <axelrasmussen@google.com>
> Cc: Brian Geffon <bgeffon@google.com>
> Cc: David Hildenbrand <david@redhat.com>
> Cc: Jann Horn <jannh@google.com>
> Cc: Kalesh Singh <kaleshsingh@google.com>
> Cc: Matthew Wilcox (Oracle) <willy@infradead.org>
> Cc: Nicolas Geoffray <ngeoffray@google.com>
> Cc: Peter Xu <peterx@redhat.com>
> Cc: Suren Baghdasaryan <surenb@google.com>
> Cc: <stable@vger.kernel.org>
> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
> (cherry picked from commit 67695f18d55924b2013534ef3bdc363bc9e14605)
> Signed-off-by: Mike Rapoport (IBM) <rppt@kernel.org>

All now queued up, thanks.

greg k-h