On Mon, 2015-02-16 at 13:24 +0200, Boaz Harrosh wrote:
> With old Kernels there was a bug in x86 where any unknown
> memory chip type would come up BUSY when calling
> request_mem_region_exclusive().
>
> So for pmem to work with old Kernels and real NvDIMM chips
> we have a new Kconfig option CONFIG_BLK_DEV_PMEM_IGNORE_REQUEST_MEM_RET.
>
> People have been running with hacked up pmem that will ignore
> the return code from request_mem_region_exclusive. So here it is
> official
>
> Signed-off-by: Boaz Harrosh <b...@plexistor.com>
I'm confused - I thought that this behavior was fixed by patch 1/3?
With that patch this memory reservation should not fail, correct?
If so, why do we need this patch?
> ---
> drivers/block/Kconfig | 12 ++++++++++++
> drivers/block/pmem.c | 11 +++++++----
> 2 files changed, 19 insertions(+), 4 deletions(-)
>
> diff --git a/drivers/block/Kconfig b/drivers/block/Kconfig
> index 3b3200f..10879b8 100644
> --- a/drivers/block/Kconfig
> +++ b/drivers/block/Kconfig
> @@ -430,6 +430,18 @@ config BLK_DEV_PMEM_USE_PAGES
> to other devices in the system, then you must say "Yes" here.
> If unsure leave as Yes.
>
> +config BLK_DEV_PMEM_IGNORE_REQUEST_MEM_RET
> + bool "Ignore the return code from request_mem_region_exclusive"
> + depends on BLK_DEV_PMEM
> + help
> + In Old Kernels type-12 Memory type which is used by NvDIMM
> + chips Comes out busy when calling request_mem_region_exclusive,
> + because of a bug.
> + If this option is set to "yes". The pmem will ignore the
> + failure, and continue as usual. If you have an old Kernel and
> + a real NvDIMM chip you must say yes here.
> + (Ignored if BLK_DEV_PMEM_USE_PAGES=y)
> +
> config CDROM_PKTCDVD
> tristate "Packet writing on CD/DVD media"
> depends on !UML
> diff --git a/drivers/block/pmem.c b/drivers/block/pmem.c
> index 9eb7ffe..f84d033 100644
> --- a/drivers/block/pmem.c
> +++ b/drivers/block/pmem.c
> @@ -197,10 +197,12 @@ int pmem_mapmem(struct pmem_device *pmem)
>
> res_mem = request_mem_region_exclusive(pmem->phys_addr, pmem->size,
> "pmem");
> - if (!res_mem) {
> + if (unlikely(!res_mem)) {
> pr_warn("pmem: request_mem_region_exclusive phys=0x%llx
> size=0x%zx failed\n",
> - pmem->phys_addr, pmem->size);
> - return -EINVAL;
> + pmem->phys_addr, pmem->size);
> +#ifndef CONFIG_BLK_DEV_PMEM_IGNORE_REQUEST_MEM_RET
> + return -EBUSY;
> +#endif
> }
>
> pmem->virt_addr = ioremap_cache(pmem->phys_addr, pmem->size);
> @@ -211,7 +213,8 @@ int pmem_mapmem(struct pmem_device *pmem)
> return 0;
>
> out_release:
> - release_mem_region(pmem->phys_addr, pmem->size);
> + if (res_mem)
> + release_mem_region(pmem->phys_addr, pmem->size);
> return err;
> }
>
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