From: Greg KH <gregkh@linuxfoundation.org>
To: Yang Shi <shy828301@gmail.com>
Cc: hughd@google.com, sunhao.th@gmail.com, willy@infradead.org,
kirill.shutemov@linux.intel.com, songliubraving@fb.com,
andrea.righi@canonical.com, akpm@linux-foundation.org,
stable@vger.kernel.org, linux-mm@kvack.org,
linux-kernel@vger.kernel.org
Subject: Re: [stable 5.10 PATCH] mm: khugepaged: skip huge page collapse for special files
Date: Thu, 4 Nov 2021 09:19:01 +0100 [thread overview]
Message-ID: <YYOXdQbeNGHb0ewM@kroah.com> (raw)
In-Reply-To: <20211103202258.3564-1-shy828301@gmail.com>
On Wed, Nov 03, 2021 at 01:22:58PM -0700, Yang Shi wrote:
> commit a4aeaa06d45e90f9b279f0b09de84bd00006e733 upstream.
>
> The read-only THP for filesystems will collapse THP for files opened
> readonly and mapped with VM_EXEC. The intended usecase is to avoid TLB
> misses for large text segments. But it doesn't restrict the file types
> so a THP could be collapsed for a non-regular file, for example, block
> device, if it is opened readonly and mapped with EXEC permission. This
> may cause bugs, like [1] and [2].
>
> This is definitely not the intended usecase, so just collapse THP for
> regular files in order to close the attack surface.
>
> [shy828301@gmail.com: fix vm_file check [3]]
Now queued up, thanks.
greg k-h
prev parent reply other threads:[~2021-11-04 8:19 UTC|newest]
Thread overview: 2+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-11-03 20:22 [stable 5.10 PATCH] mm: khugepaged: skip huge page collapse for special files Yang Shi
2021-11-04 8:19 ` Greg KH [this message]
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