From: Dan Williams <dan.j.williams@intel.com>
To: Vishal Verma <vishal.l.verma@intel.com>
Cc: "linux-nvdimm@lists.01.org" <linux-nvdimm@lists.01.org>,
Linux ACPI <linux-acpi@vger.kernel.org>,
Jeff Moyer <jmoyer@redhat.com>,
"Rafael J. Wysocki" <rafael.j.wysocki@intel.com>,
Toshi Kani <toshi.kani@hpe.com>,
"Moore, Robert" <robert.moore@intel.com>
Subject: Re: [PATCH 5/6] acpi: change memory allocations to GFP_NOIO
Date: Fri, 14 Jul 2017 22:26:42 -0700 [thread overview]
Message-ID: <CAPcyv4jkJHKh0kXA3jGSU=QdmoZCVQuM7YaMBzoSPqn4hVXk4g@mail.gmail.com> (raw)
In-Reply-To: <20170714221148.11232-6-vishal.l.verma@intel.com>
[ adding Bob ]
On Fri, Jul 14, 2017 at 3:11 PM, Vishal Verma <vishal.l.verma@intel.com> wrote:
> With the ACPI NFIT 'DSM' methods, acpi can be called from IO paths.
> Specifically, the DSM to clear media errors is called during writes, so
> that we can provide a writes-fix-errors model.
>
> However it is easy to imagine a scenario like:
> - write through the nvdimm driver
> - acpi allocation
> - writeback, causes more IO through the nvdimm driver
> - deadlock
>
> Making the acpi allocations GPF_NOIO would ensure that it doesn't
> trigger writeback, and avoids the above deadlock.
Another option would be to custom code an acpi_ars_clear_error()
routine that manages to issue the proper DSM without needing to
perform any memory allocations, but this will have implications for
the common ACPICA code.
next prev parent reply other threads:[~2017-07-15 5:26 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-07-14 22:11 [PATCH 0/6] BTT error clearing rework Vishal Verma
2017-07-14 22:11 ` [PATCH 1/6] btt: fix a missed NVDIMM_IO_ATOMIC case in the write path Vishal Verma
2017-07-14 22:11 ` [PATCH 2/6] btt: refactor map entry operations with macros Vishal Verma
2017-07-14 22:11 ` [PATCH 4/6] btt: cache sector_size in arena_info Vishal Verma
2017-07-14 22:11 ` [PATCH 5/6] acpi: change memory allocations to GFP_NOIO Vishal Verma
2017-07-15 5:26 ` Dan Williams [this message]
2017-07-15 12:45 ` Rafael J. Wysocki
[not found] ` <20170714221148.11232-1-vishal.l.verma-ral2JQCrhuEAvxtiuMwx3w@public.gmane.org>
2017-07-14 22:11 ` [PATCH 3/6] btt: ensure that flags were also unchanged during a map_read Vishal Verma
2017-07-14 22:11 ` [PATCH 6/6] libnvdimm, btt: rework error clearing Vishal Verma
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