From: Andrew Morton <akpm@linux-foundation.org>
To: Lokesh Gidra <lokeshgidra@google.com>
Cc: linux-mm@kvack.org, linux-kernel@vger.kernel.org,
surenb@google.com, kernel-team@android.com, aarcange@redhat.com,
peterx@redhat.com, david@redhat.com, axelrasmussen@google.com,
bgeffon@google.com, jannh@google.com, kaleshsingh@google.com,
ngeoffray@google.com, rppt@kernel.org, hdanton@sina.com,
syzbot+49056626fe41e01f2ba7@syzkaller.appspotmail.com
Subject: Re: [PATCH] userfaultfd: fix deadlock warning when locking src and dst VMAs
Date: Thu, 21 Mar 2024 17:47:42 -0700 [thread overview]
Message-ID: <20240321174742.6c5622f4406673629e266db7@linux-foundation.org> (raw)
In-Reply-To: <20240321235818.125118-1-lokeshgidra@google.com>
On Thu, 21 Mar 2024 16:58:18 -0700 Lokesh Gidra <lokeshgidra@google.com> wrote:
> Use down_read_nested() to avoid the warning.
>
> --- a/mm/userfaultfd.c
> +++ b/mm/userfaultfd.c
> @@ -1444,7 +1444,8 @@ static int uffd_move_lock(struct mm_struct *mm,
> */
> down_read(&(*dst_vmap)->vm_lock->lock);
> if (*dst_vmap != *src_vmap)
> - down_read(&(*src_vmap)->vm_lock->lock);
> + down_read_nested(&(*src_vmap)->vm_lock->lock,
> + SINGLE_DEPTH_NESTING);
> }
> mmap_read_unlock(mm);
> return err;
Thanks, I added
Fixes: 867a43a34ff8a ("userfaultfd: use per-vma locks in userfaultfd operations")
prev parent reply other threads:[~2024-03-22 0:47 UTC|newest]
Thread overview: 2+ messages / expand[flat|nested] mbox.gz Atom feed top
2024-03-21 23:58 Lokesh Gidra
2024-03-22 0:47 ` Andrew Morton [this message]
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