Re: FAILED: patch "[PATCH] arm64: Update PTE_RDONLY in set_pte_at() for PROT_NONE" failed to apply to 4.4-stable tree

["gregkh@linuxfoundation.org" <gregkh@linuxfoundation.org>]

On Mon, Apr 11, 2016 at 03:48:40PM +0100, Catalin Marinas wrote:
> Hi Greg,
> 
> On Sun, Apr 10, 2016 at 01:53:35AM +0100, gregkh@linuxfoundation.org wrote:
> > The patch below does not apply to the 4.4-stable tree.
> > If someone wants it applied there, or to any other stable or longterm
> > tree, then please email the backport, including the original git commit
> > id to <stable@vger.kernel.org>.
> > 
> > thanks,
> > 
> > greg k-h
> > 
> > ------------------ original commit in Linus's tree ------------------
> > 
> > From fdc69e7df3cb24f18a93192641786e5b7ecd1dfe Mon Sep 17 00:00:00 2001
> > From: Catalin Marinas <catalin.marinas@arm.com>
> > Date: Wed, 9 Mar 2016 16:31:29 +0000
> > Subject: [PATCH] arm64: Update PTE_RDONLY in set_pte_at() for PROT_NONE
> >  permission
> > 
> > The set_pte_at() function must update the hardware PTE_RDONLY bit
> > depending on the state of the PTE_WRITE and PTE_DIRTY bits of the given
> > entry value. However, it currently only performs this for pte_valid()
> > entries, ignoring PTE_PROT_NONE. The side-effect is that PROT_NONE
> > mappings would not have the PTE_RDONLY bit set. Without
> > CONFIG_ARM64_HW_AFDBM, this is not an issue since such PROT_NONE pages
> > are not accessible anyway.
> > 
> > With commit 2f4b829c625e ("arm64: Add support for hardware updates of
> > the access and dirty pte bits"), the ptep_set_wrprotect() function was
> > re-written to cope with automatic hardware updates of the dirty state.
> > As an optimisation, only PTE_RDONLY is checked to assess the "dirty"
> > status. Since set_pte_at() does not set this bit for PROT_NONE mappings,
> > such pages may be considered "dirty" as a result of
> > ptep_set_wrprotect().
> > 
> > This patch updates the pte_valid() check to pte_present() in
> > set_pte_at(). It also adds PTE_PROT_NONE to the swap entry bits comment.
> > 
> > Fixes: 2f4b829c625e ("arm64: Add support for hardware updates of the access and dirty pte bits")
> > Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
> > Reported-by: Ganapatrao Kulkarni <gkulkarni@caviumnetworks.com>
> > Tested-by: Ganapatrao Kulkarni <gkulkarni@cavium.com>
> > Cc: <stable@vger.kernel.org>
> 
> This patch requires another commit that was merged in 4.5. The actual
> "Cc: stable" line above should have been:
> 
> Cc: <stable@vger.kernel.org> # 4.4.x: ac15bd63bbb2: arm64: Honour !PTE_WRITE in set_pte_at() for kernel mappings
> 
> Shall I re-send commit fdc69e7df3cb ("arm64: Update PTE_RDONLY in
> set_pte_at() for PROT_NONE permission") with the amended "Cc: stable"
> line or you're OK to cherry-pick the dependency?

I can cherry-pick, thanks.

greg k-h