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Groups > linux.kernel > #1621593 > unrolled thread

Re: [PATCH] libnvdimm: fix btt vs clear poison locking

Started byJeff Moyer <jmoyer@redhat.com>
First post2017-04-11 22:10 +0200
Last post2017-04-11 22:20 +0200
Articles 2 — 2 participants

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  Re: [PATCH] libnvdimm: fix btt vs clear poison locking Jeff Moyer <jmoyer@redhat.com> - 2017-04-11 22:10 +0200
    Re: [PATCH] libnvdimm: fix btt vs clear poison locking Dan Williams <dan.j.williams@intel.com> - 2017-04-11 22:20 +0200

#1621593 — Re: [PATCH] libnvdimm: fix btt vs clear poison locking

FromJeff Moyer <jmoyer@redhat.com>
Date2017-04-11 22:10 +0200
SubjectRe: [PATCH] libnvdimm: fix btt vs clear poison locking
Message-ID<tvagV-3eF-7@gated-at.bofh.it>
Dan Williams <dan.j.williams@intel.com> writes:

> As a minimal fix, disable error clearing when the BTT is enabled. For
> the final fix a larger rework of the poison list locking is needed.

> @@ -243,7 +243,15 @@ static int nsio_rw_bytes(struct nd_namespace_common *ndns,
>  	}
>  
>  	if (unlikely(is_bad_pmem(&nsio->bb, sector, sz_align))) {
> -		if (IS_ALIGNED(offset, 512) && IS_ALIGNED(size, 512)) {
> +		/*
> +		 * FIXME: nsio_rw_bytes() may be called from atomic
> +		 * context in the BTT case and nvdimm_clear_poison()
> +		 * takes a sleeping lock. Until the locking can be
> +		 * reworked this capability depends on !BTT or BROKEN.
> +		 */
> +		if ((!IS_ENABLED(CONFIG_BTT) || IS_ENABLED(CONFIG_BROKEN))
> +				&& IS_ALIGNED(offset, 512)
> +				&& IS_ALIGNED(size, 512)) {

I don't like that you've disabled clear error just because the btt
driver was enabled.  Can't you do something like this, instead?

	disable_clear_poison = (ndns->claim && is_nd_btt(ndns->claim));

	if (!disable_clear_poison && IS_ALIGNED(offset, 512)...

-Jeff

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#1621596

FromDan Williams <dan.j.williams@intel.com>
Date2017-04-11 22:20 +0200
Message-ID<tvaqC-3i9-7@gated-at.bofh.it>
In reply to#1621593
On Tue, Apr 11, 2017 at 1:08 PM, Jeff Moyer <jmoyer@redhat.com> wrote:
> Dan Williams <dan.j.williams@intel.com> writes:
>
>> As a minimal fix, disable error clearing when the BTT is enabled. For
>> the final fix a larger rework of the poison list locking is needed.
>
>> @@ -243,7 +243,15 @@ static int nsio_rw_bytes(struct nd_namespace_common *ndns,
>>       }
>>
>>       if (unlikely(is_bad_pmem(&nsio->bb, sector, sz_align))) {
>> -             if (IS_ALIGNED(offset, 512) && IS_ALIGNED(size, 512)) {
>> +             /*
>> +              * FIXME: nsio_rw_bytes() may be called from atomic
>> +              * context in the BTT case and nvdimm_clear_poison()
>> +              * takes a sleeping lock. Until the locking can be
>> +              * reworked this capability depends on !BTT or BROKEN.
>> +              */
>> +             if ((!IS_ENABLED(CONFIG_BTT) || IS_ENABLED(CONFIG_BROKEN))
>> +                             && IS_ALIGNED(offset, 512)
>> +                             && IS_ALIGNED(size, 512)) {
>
> I don't like that you've disabled clear error just because the btt
> driver was enabled.  Can't you do something like this, instead?

Ooh, yes we can and that's much better.

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