linux-kernel - Re: [PATCH] pmem: report error on clear poison failure

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Date:   Thu, 13 Oct 2016 16:08:02 +0000
From:   "Kani, Toshimitsu" <toshi.kani@....com>
To:     "dan.j.williams@...el.com" <dan.j.williams@...el.com>
CC:     "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "linux-nvdimm@...ts.01.org" <linux-nvdimm@...ts.01.org>,
        "vishal.l.verma@...el.com" <vishal.l.verma@...el.com>
Subject: Re: [PATCH] pmem: report error on clear poison failure

On Thu, 2016-10-13 at 09:01 -0700, Dan Williams wrote:
> On Thu, Oct 13, 2016 at 8:54 AM, Toshi Kani <toshi.kani@....com>
> wrote:
> > 
> > ACPI Clear Uncorrectable Error DSM function may fail or may be
> > unsupported on a platform.  pmem_clear_poison() returns without
> > clearing badblocks in such cases, which leads to a silent data
> > corruption.
> > 
> > Change pmem_do_bvec() and pmem_clear_poison() to return -EIO
> > so that filesystem can log an error message.
> 
> What's the silent data corruption scenario?  If the clear poison
> fails I'm assuming that the poison will still be notified on the next
> read.

I agree that the data is eventually read, but there is no guranteed
that when it is read soon enough, i.e. user might not access to the
data for a long time.

Thanks,
-Toshi