From: "Verma, Vishal L" <vishal.l.verma@intel.com>
To: "Williams, Dan J" <dan.j.williams@intel.com>,
"linux-nvdimm@lists.01.org" <linux-nvdimm@lists.01.org>
Subject: Re: [ndctl PATCH] test, device-dax: Fix intermittent poison handling failures
Date: Mon, 15 Oct 2018 22:59:14 +0000 [thread overview]
Message-ID: <4ceb4de847d5ede7d2a1c38e0cf6260109578b66.camel@intel.com> (raw)
In-Reply-To: <153940497244.1425803.2319137619591631976.stgit@dwillia2-desk3.amr.corp.intel.com>
On Fri, 2018-10-12 at 21:29 -0700, Dan Williams wrote:
> The device-dax unit test sometimes fails with the following kernel
> message signature:
>
> Memory failure: Unable to find user space address 204300 in lt-device-dax
> Memory failure: 0x204300: forcibly killing lt-device-dax:1334 because of failure to unmap
>
> This happens when there is a 3rd party vma in the rmap that has an entry
> at the same index as the currently failing page. While the test has
> munmap()'d the previous mapping we still trip over the fact that the
> kernel memory-failure code does not differentiate munmap vs mremap and
> upgrades the failure to process fatal.
>
> The add_to_kill() routine in the kernel has a comment that says:
>
> /*
> * In theory we don't have to kill when the page was
> * munmaped. But it could be also a mremap. Since that's
> * likely very rare kill anyways just out of paranoia, but use
> * a SIGKILL because the error is not contained anymore.
> */
>
> ...when it is determining what to do when it can't find the given pfn
> mapped into the process at the given index.
>
> Avoid this case by munmap()'ing *and* closing the file to trigger old /
> stale vma's to be reaped. With that the only vma that can be looked up
> is the one the error was injected, the lookup succeeds, and the test
> passes.
>
> Signed-off-by: Dan Williams <dan.j.williams@intel.com>
> ---
> test/device-dax.c | 49 ++++++++++++++++++++++++++++++++++---------------
> 1 file changed, 34 insertions(+), 15 deletions(-)
Looks good, applied.
>
>
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prev parent reply other threads:[~2018-10-15 22:59 UTC|newest]
Thread overview: 2+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-10-13 4:29 [ndctl PATCH] test, device-dax: Fix intermittent poison handling failures Dan Williams
2018-10-15 22:59 ` Verma, Vishal L [this message]
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