Re: [PATCH] MIPS: math-emu: Write-protect delay slot emulation pages

From: Paul Burton <paul.burton@mips.com>
To: Sasha Levin <sashal@kernel.org>
Cc: "linux-mips@vger.kernel.org" <linux-mips@vger.kernel.org>,
	"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
	"stable@vger.kernel.org" <stable@vger.kernel.org>
Subject: Re: [PATCH] MIPS: math-emu: Write-protect delay slot emulation pages
Date: Fri, 21 Dec 2018 21:16:37 +0000	[thread overview]
Message-ID: <20181221211603.r7226vjkubi3lfzg@pburton-laptop> (raw)
In-Reply-To: <20181220192616.42976218FE@mail.kernel.org>

Hi Sasha,

On Thu, Dec 20, 2018 at 07:26:15PM +0000, Sasha Levin wrote:
> Hi,
> 
> [This is an automated email]
> 
> This commit has been processed because it contains a "Fixes:" tag,
> fixing commit: 432c6bacbd0c MIPS: Use per-mm page to execute branch delay slot instructions.
> 
> The bot has tested the following trees: v4.19.10, v4.14.89, v4.9.146, 

Neat! I like the idea of this automation :)

> v4.19.10: Build OK!
> v4.14.89: Build OK!
> v4.9.146: Failed to apply! Possible dependencies:
>     05ce77249d50 ("userfaultfd: non-cooperative: add madvise() event for MADV_DONTNEED request")
>     163e11bc4f6e ("userfaultfd: hugetlbfs: UFFD_FEATURE_MISSING_HUGETLBFS")
>     67dece7d4c58 ("x86/vdso: Set vDSO pointer only after success")
>     72f87654c696 ("userfaultfd: non-cooperative: add mremap() event")
>     893e26e61d04 ("userfaultfd: non-cooperative: Add fork() event")
>     897ab3e0c49e ("userfaultfd: non-cooperative: add event for memory unmaps")
>     9cd75c3cd4c3 ("userfaultfd: non-cooperative: add ability to report non-PF events from uffd descriptor")
>     d811914d8757 ("userfaultfd: non-cooperative: rename *EVENT_MADVDONTNEED to *EVENT_REMOVE")

This list includes the correct soft dependency - commit 897ab3e0c49e
("userfaultfd: non-cooperative: add event for memory unmaps") which
added an extra argument to mmap_region().

> How should we proceed with this patch?

The backport to v4.9 should simply drop the last argument (NULL) in the
call to mmap_region().

Is there some way I can indicate this sort of thing in future patches so
that the automation can spot that I already know it won't apply cleanly
to a particular range of kernel versions? Or even better, that I could
indicate what needs to be changed when backporting to those kernel
versions?

Thanks,
    Paul