linux-kernel - Re: [PATCH 4.19] Revert "initramfs: free initrd memory if opening /initrd.image fails"

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Message-ID: <20190806204752.GG17747@sasha-vm>
Date:   Tue, 6 Aug 2019 16:47:52 -0400
From:   Sasha Levin <sashal@...nel.org>
To:     Stephen Boyd <swboyd@...omium.org>
Cc:     stable@...r.kernel.org, linux-kernel@...r.kernel.org,
        Steven Price <steven.price@....com>,
        Mark Rutland <mark.rutland@....com>,
        Christoph Hellwig <hch@....de>
Subject: Re: [PATCH 4.19] Revert "initramfs: free initrd memory if opening
 /initrd.image fails"

On Tue, Aug 06, 2019 at 10:59:40AM -0700, Stephen Boyd wrote:
>This reverts commit 25511676362d8f7d4b8805730a3d29484ceab1ec in the 4.19
>stable trees. From what I can tell this commit doesn't do anything to
>improve the situation, mostly just reordering code to call free_initrd()
>from one place instead of many. In doing that, it causes free_initrd()
>to be called even in the case when there isn't an initrd present. That
>leads to virtual memory bugs that manifest on arm64 devices.
>
>The fix has been merged upstream in commit 5d59aa8f9ce9 ("initramfs:
>don't free a non-existent initrd"), but backporting that here is more
>complicated because the patch is stacked upon this patch being reverted
>along with more patches that rewrites the logic in this area.
>
>Let's just revert the patch from the stable tree instead of trying to
>backport a collection of fixes to get the final fix from upstream.

The only dependency for taking the fix, 5d59aa8f9ce9, into 4.19 is
23091e28735 ("initramfs: cleanup initrd freeing") which is not too
scary.

Is it the case that 25511676362d8 shouldn't have been backported to 4.19
for some reason? If it fixes something on 4.19, I think it's better to
take the dependency and the fix instead of reverting.

--
Thanks,
Sasha