From: Brendan Higgins <brendanhiggins@google.com>
To: David Gow <davidgow@google.com>
Cc: Shuah Khan <skhan@linuxfoundation.org>,
Vlastimil Babka <vbabka@suse.cz>,
KUnit Development <kunit-dev@googlegroups.com>,
"open list:KERNEL SELFTEST FRAMEWORK"
<linux-kselftest@vger.kernel.org>,
linux-um <linux-um@lists.infradead.org>,
Linux Kernel Mailing List <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH] kunit: tool: Disable PAGE_POISONING under --alltests
Date: Fri, 26 Feb 2021 12:57:32 -0800 [thread overview]
Message-ID: <CAFd5g47=Tzsj+yw6Poj47Y68__eYnrWhOxfSmvCLwsgBvfn8vQ@mail.gmail.com> (raw)
In-Reply-To: <20210209071034.3268897-1-davidgow@google.com>
On Mon, Feb 8, 2021 at 11:10 PM David Gow <davidgow@google.com> wrote:
>
> kunit_tool maintains a list of config options which are broken under
> UML, which we exclude from an otherwise 'make ARCH=um allyesconfig'
> build used to run all tests with the --alltests option.
>
> Something in UML allyesconfig is causing segfaults when page poisining
> is enabled (and is poisoning with a non-zero value). Previously, this
> didn't occur, as allyesconfig enabled the CONFIG_PAGE_POISONING_ZERO
> option, which worked around the problem by zeroing memory. This option
> has since been removed, and memory is now poisoned with 0xAA, which
> triggers segfaults in many different codepaths, preventing UML from
> booting.
>
> Note that we have to disable both CONFIG_PAGE_POISONING and
> CONFIG_DEBUG_PAGEALLOC, as the latter will 'select' the former on
> architectures (such as UML) which don't implement __kernel_map_pages().
>
> Ideally, we'd fix this properly by tracking down the real root cause,
> but since this is breaking KUnit's --alltests feature, it's worth
> disabling there in the meantime so the kernel can boot to the point
> where tests can actually run.
>
> Fixes: f289041ed4 ("mm, page_poison: remove CONFIG_PAGE_POISONING_ZERO")
> Signed-off-by: David Gow <davidgow@google.com>
Reviewed-by: Brendan Higgins <brendanhiggins@google.com>
prev parent reply other threads:[~2021-02-26 20:58 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-02-09 7:10 [PATCH] kunit: tool: Disable PAGE_POISONING under --alltests David Gow
2021-02-09 12:30 ` Vlastimil Babka
2021-02-26 20:57 ` Brendan Higgins [this message]
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