From: Dan Williams <dan.j.williams@intel.com>
To: Nicholas Piggin <npiggin@gmail.com>
Cc: "Luck, Tony" <tony.luck@intel.com>,
Matthew Wilcox <mawilcox@microsoft.com>,
Michael Ellerman <mpe@ellerman.id.au>,
linux-nvdimm <linux-nvdimm@lists.01.org>,
linuxppc-dev <linuxppc-dev@lists.ozlabs.org>,
Christoph Hellwig <hch@lst.de>
Subject: Re: [RESEND 2/3] powerpc/memcpy: Add memcpy_mcsafe for pmem
Date: Wed, 4 Apr 2018 20:00:52 -0700 [thread overview]
Message-ID: <CAPcyv4hqKsOy9GU=NcMGj38pXnuEMRhXfox6jVwQ37+mcjnvhA@mail.gmail.com> (raw)
In-Reply-To: <20180405095755.58b3891f@roar.ozlabs.ibm.com>
[ adding Matthew, Christoph, and Tony ]
On Wed, Apr 4, 2018 at 4:57 PM, Nicholas Piggin <npiggin@gmail.com> wrote:
> On Thu, 5 Apr 2018 09:19:42 +1000
> Balbir Singh <bsingharora@gmail.com> wrote:
>
>> The pmem infrastructure uses memcpy_mcsafe in the pmem
>> layer so as to convert machine check excpetions into
>> a return value on failure in case a machine check
>> exception is encoutered during the memcpy.
>>
>> This patch largely borrows from the copyuser_power7
>> logic and does not add the VMX optimizations, largely
>> to keep the patch simple. If needed those optimizations
>> can be folded in.
>
> So memcpy_mcsafe doesn't return number of bytes copied?
> Huh, well that makes it simple.
Well, not in current kernels, but we need to add that support or
remove the direct call to copy_to_iter() in fs/dax.c. I'm looking
right now to add "bytes remaining" support to the x86 memcpy_mcsafe(),
but for copy_to_user we also need to handle bytes remaining for write
faults. That fix is hopefully something that can land in an early
4.17-rc, but it won't be ready for -rc1.
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next prev parent reply other threads:[~2018-04-05 3:00 UTC|newest]
Thread overview: 18+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-04-04 23:19 [RESEND 0/3] Add support for memcpy_mcsafe Balbir Singh
2018-04-04 23:19 ` [RESEND 1/3] powerpc/mce: Bug fixes for MCE handling in kernel space Balbir Singh
2018-04-04 23:49 ` Nicholas Piggin
2018-04-05 1:11 ` Balbir Singh
2018-04-04 23:19 ` [RESEND 2/3] powerpc/memcpy: Add memcpy_mcsafe for pmem Balbir Singh
2018-04-04 23:57 ` Nicholas Piggin
2018-04-05 3:00 ` Dan Williams [this message]
2018-04-05 5:04 ` Nicholas Piggin
2018-04-05 5:53 ` Balbir Singh
2018-04-05 6:45 ` Nicholas Piggin
2018-04-05 15:00 ` Dan Williams
2018-05-01 20:57 ` Dan Williams
2018-05-02 12:36 ` Balbir Singh
2018-04-05 20:40 ` Jeff Moyer
2018-04-06 1:26 ` Nicholas Piggin
2018-04-06 9:25 ` Balbir Singh
2018-04-06 15:46 ` Luck, Tony
2018-04-04 23:19 ` [RESEND 3/3] powerpc/mce: Handle memcpy_mcsafe Balbir Singh
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