| Message ID | 20200120140749.69549-2-aneesh.kumar@linux.ibm.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | Validating namespace size and start address attributes. | expand |
On Mon, Jan 20, 2020 at 6:08 AM Aneesh Kumar K.V <aneesh.kumar@linux.ibm.com> wrote: > > The page size used to map the namespace is arch dependent. For example > architectures like ppc64 use 16MB page size for direct-mapping. If the namespace > size is not aligned to the mapping page size, users can observe kernel crash > during namespace init and destroy. > > This is due to kernel doing partial map/unmap of the resource range > > BUG: Unable to handle kernel data access at 0xc001000406000000 > Faulting instruction address: 0xc000000000090790 > NIP [c000000000090790] arch_add_memory+0xc0/0x130 > LR [c000000000090744] arch_add_memory+0x74/0x130 > Call Trace: > arch_add_memory+0x74/0x130 (unreliable) > memremap_pages+0x74c/0xa30 > devm_memremap_pages+0x3c/0xa0 > pmem_attach_disk+0x188/0x770 > nvdimm_bus_probe+0xd8/0x470 > really_probe+0x148/0x570 > driver_probe_device+0x19c/0x1d0 > device_driver_attach+0xcc/0x100 > bind_store+0x134/0x1c0 > drv_attr_store+0x44/0x60 > sysfs_kf_write+0x74/0xc0 > kernfs_fop_write+0x1b4/0x290 > __vfs_write+0x3c/0x70 > vfs_write+0xd0/0x260 > ksys_write+0xdc/0x130 > system_call+0x5c/0x68 > > Kernel should also ensure that namespace size is also mulitple of subsection size. > > Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@linux.ibm.com> > --- > arch/arm64/mm/flush.c | 6 ++++++ > arch/powerpc/lib/pmem.c | 9 +++++++++ > arch/x86/mm/pageattr.c | 7 +++++++ > include/linux/libnvdimm.h | 1 + > 4 files changed, 23 insertions(+) > > diff --git a/arch/arm64/mm/flush.c b/arch/arm64/mm/flush.c > index ac485163a4a7..95cb5538bc6e 100644 > --- a/arch/arm64/mm/flush.c > +++ b/arch/arm64/mm/flush.c > @@ -91,4 +91,10 @@ void arch_invalidate_pmem(void *addr, size_t size) > __inval_dcache_area(addr, size); > } > EXPORT_SYMBOL_GPL(arch_invalidate_pmem); > + > +unsigned long arch_namespace_map_size(void) > +{ > + return PAGE_SIZE; > +} > +EXPORT_SYMBOL_GPL(arch_namespace_map_size); > #endif > diff --git a/arch/powerpc/lib/pmem.c b/arch/powerpc/lib/pmem.c > index 0666a8d29596..63dca24e4a18 100644 > --- a/arch/powerpc/lib/pmem.c > +++ b/arch/powerpc/lib/pmem.c > @@ -26,6 +26,15 @@ void arch_invalidate_pmem(void *addr, size_t size) > } > EXPORT_SYMBOL_GPL(arch_invalidate_pmem); > > +unsigned long arch_namespace_map_size(void) > +{ > + if (radix_enabled()) > + return PAGE_SIZE; > + return (1UL << mmu_psize_defs[mmu_linear_psize].shift); > + > +} > +EXPORT_SYMBOL_GPL(arch_namespace_map_size); > + > /* > * CONFIG_ARCH_HAS_UACCESS_FLUSHCACHE symbols > */ > diff --git a/arch/x86/mm/pageattr.c b/arch/x86/mm/pageattr.c > index 1b99ad05b117..d78b5082f376 100644 > --- a/arch/x86/mm/pageattr.c > +++ b/arch/x86/mm/pageattr.c > @@ -310,6 +310,13 @@ void arch_invalidate_pmem(void *addr, size_t size) > } > EXPORT_SYMBOL_GPL(arch_invalidate_pmem); > > +unsigned long arch_namespace_map_size(void) > +{ > + return PAGE_SIZE; > +} > +EXPORT_SYMBOL_GPL(arch_namespace_map_size); > + > + > static void __cpa_flush_all(void *arg) > { > unsigned long cache = (unsigned long)arg; > diff --git a/include/linux/libnvdimm.h b/include/linux/libnvdimm.h > index 9df091bd30ba..a3476dbd2656 100644 > --- a/include/linux/libnvdimm.h > +++ b/include/linux/libnvdimm.h > @@ -284,4 +284,5 @@ static inline void arch_invalidate_pmem(void *addr, size_t size) > } > #endif > > +unsigned long arch_namespace_map_size(void); This property is more generic than the nvdimm namespace mapping size, it's more the fundamental remap granularity that the architecture supports. So I would expect this to be defined in core header files. Something like: diff --git a/include/linux/io.h b/include/linux/io.h index a59834bc0a11..58b3b2091dbb 100644 --- a/include/linux/io.h +++ b/include/linux/io.h @@ -155,6 +155,13 @@ enum { void *memremap(resource_size_t offset, size_t size, unsigned long flags); void memunmap(void *addr); +#ifndef memremap_min_align +static inline unsigned int memremap_min_align(void) +{ + return PAGE_SIZE; +} +#endif + /* * On x86 PAT systems we have memory tracking that keeps track of * the allowed mappings on memory ranges. This tracking works for ...and then have a definition is asm/io.h like this: unsigned int memremap_min_align(void); #define memremap_min_align memremap_min_align That way only architectures that want to opt out of the default need to define something in their local header.
On 1/24/20 11:27 AM, Dan Williams wrote: > On Mon, Jan 20, 2020 at 6:08 AM Aneesh Kumar K.V > .... >> >> +unsigned long arch_namespace_map_size(void) >> +{ >> + return PAGE_SIZE; >> +} >> +EXPORT_SYMBOL_GPL(arch_namespace_map_size); >> + >> + >> static void __cpa_flush_all(void *arg) >> { >> unsigned long cache = (unsigned long)arg; >> diff --git a/include/linux/libnvdimm.h b/include/linux/libnvdimm.h >> index 9df091bd30ba..a3476dbd2656 100644 >> --- a/include/linux/libnvdimm.h >> +++ b/include/linux/libnvdimm.h >> @@ -284,4 +284,5 @@ static inline void arch_invalidate_pmem(void *addr, size_t size) >> } >> #endif >> >> +unsigned long arch_namespace_map_size(void); > > This property is more generic than the nvdimm namespace mapping size, > it's more the fundamental remap granularity that the architecture > supports. So I would expect this to be defined in core header files. > Something like: > > diff --git a/include/linux/io.h b/include/linux/io.h > index a59834bc0a11..58b3b2091dbb 100644 > --- a/include/linux/io.h > +++ b/include/linux/io.h > @@ -155,6 +155,13 @@ enum { > void *memremap(resource_size_t offset, size_t size, unsigned long flags); > void memunmap(void *addr); > > +#ifndef memremap_min_align > +static inline unsigned int memremap_min_align(void) > +{ > + return PAGE_SIZE; > +} > +#endif > + Should that be memremap_pages_min_align()? > /* > * On x86 PAT systems we have memory tracking that keeps track of > * the allowed mappings on memory ranges. This tracking works for > > ...and then have a definition is asm/io.h like this: > > unsigned int memremap_min_align(void); > #define memremap_min_align memremap_min_align > > That way only architectures that want to opt out of the default need > to define something in their local header. > -aneesh
On Thu, Jan 23, 2020 at 11:34 PM Aneesh Kumar K.V <aneesh.kumar@linux.ibm.com> wrote: > > On 1/24/20 11:27 AM, Dan Williams wrote: > > On Mon, Jan 20, 2020 at 6:08 AM Aneesh Kumar K.V > > > > .... > > >> > >> +unsigned long arch_namespace_map_size(void) > >> +{ > >> + return PAGE_SIZE; > >> +} > >> +EXPORT_SYMBOL_GPL(arch_namespace_map_size); > >> + > >> + > >> static void __cpa_flush_all(void *arg) > >> { > >> unsigned long cache = (unsigned long)arg; > >> diff --git a/include/linux/libnvdimm.h b/include/linux/libnvdimm.h > >> index 9df091bd30ba..a3476dbd2656 100644 > >> --- a/include/linux/libnvdimm.h > >> +++ b/include/linux/libnvdimm.h > >> @@ -284,4 +284,5 @@ static inline void arch_invalidate_pmem(void *addr, size_t size) > >> } > >> #endif > >> > >> +unsigned long arch_namespace_map_size(void); > > > > This property is more generic than the nvdimm namespace mapping size, > > it's more the fundamental remap granularity that the architecture > > supports. So I would expect this to be defined in core header files. > > Something like: > > > > diff --git a/include/linux/io.h b/include/linux/io.h > > index a59834bc0a11..58b3b2091dbb 100644 > > --- a/include/linux/io.h > > +++ b/include/linux/io.h > > @@ -155,6 +155,13 @@ enum { > > void *memremap(resource_size_t offset, size_t size, unsigned long flags); > > void memunmap(void *addr); > > > > +#ifndef memremap_min_align > > +static inline unsigned int memremap_min_align(void) > > +{ > > + return PAGE_SIZE; > > +} > > +#endif > > + > > > Should that be memremap_pages_min_align()? No, and on second look it needs to be a common value that results in properly aligned / sized namespaces across architectures. What would it take for Power to make it's minimum mapping granularity SUBSECTION_SIZE? The minute that the minimum alignment changes across architectures we lose compatibility. The namespaces need to be sized such that the mode can be changed freely.
On 1/24/20 10:15 PM, Dan Williams wrote: > On Thu, Jan 23, 2020 at 11:34 PM Aneesh Kumar K.V > <aneesh.kumar@linux.ibm.com> wrote: >> >> On 1/24/20 11:27 AM, Dan Williams wrote: >>> On Mon, Jan 20, 2020 at 6:08 AM Aneesh Kumar K.V >>> >> >> .... >> >>>> >>>> +unsigned long arch_namespace_map_size(void) >>>> +{ >>>> + return PAGE_SIZE; >>>> +} >>>> +EXPORT_SYMBOL_GPL(arch_namespace_map_size); >>>> + >>>> + >>>> static void __cpa_flush_all(void *arg) >>>> { >>>> unsigned long cache = (unsigned long)arg; >>>> diff --git a/include/linux/libnvdimm.h b/include/linux/libnvdimm.h >>>> index 9df091bd30ba..a3476dbd2656 100644 >>>> --- a/include/linux/libnvdimm.h >>>> +++ b/include/linux/libnvdimm.h >>>> @@ -284,4 +284,5 @@ static inline void arch_invalidate_pmem(void *addr, size_t size) >>>> } >>>> #endif >>>> >>>> +unsigned long arch_namespace_map_size(void); >>> >>> This property is more generic than the nvdimm namespace mapping size, >>> it's more the fundamental remap granularity that the architecture >>> supports. So I would expect this to be defined in core header files. >>> Something like: >>> >>> diff --git a/include/linux/io.h b/include/linux/io.h >>> index a59834bc0a11..58b3b2091dbb 100644 >>> --- a/include/linux/io.h >>> +++ b/include/linux/io.h >>> @@ -155,6 +155,13 @@ enum { >>> void *memremap(resource_size_t offset, size_t size, unsigned long flags); >>> void memunmap(void *addr); >>> >>> +#ifndef memremap_min_align >>> +static inline unsigned int memremap_min_align(void) >>> +{ >>> + return PAGE_SIZE; >>> +} >>> +#endif >>> + >> >> >> Should that be memremap_pages_min_align()? > > No, and on second look it needs to be a common value that results in > properly aligned / sized namespaces across architectures. > > What would it take for Power to make it's minimum mapping granularity > SUBSECTION_SIZE? The minute that the minimum alignment changes across > architectures we lose compatibility. > > The namespaces need to be sized such that the mode can be changed freely. > Linux on ppc64 with hash translation use just one page size for direct mapping and that is 16MB. -aneesh
On 1/24/20 10:15 PM, Dan Williams wrote: > On Thu, Jan 23, 2020 at 11:34 PM Aneesh Kumar K.V > <aneesh.kumar@linux.ibm.com> wrote: >> >> On 1/24/20 11:27 AM, Dan Williams wrote: >>> On Mon, Jan 20, 2020 at 6:08 AM Aneesh Kumar K.V >>> >> >> .... >> >>>> >>>> +unsigned long arch_namespace_map_size(void) >>>> +{ >>>> + return PAGE_SIZE; >>>> +} >>>> +EXPORT_SYMBOL_GPL(arch_namespace_map_size); >>>> + >>>> + >>>> static void __cpa_flush_all(void *arg) >>>> { >>>> unsigned long cache = (unsigned long)arg; >>>> diff --git a/include/linux/libnvdimm.h b/include/linux/libnvdimm.h >>>> index 9df091bd30ba..a3476dbd2656 100644 >>>> --- a/include/linux/libnvdimm.h >>>> +++ b/include/linux/libnvdimm.h >>>> @@ -284,4 +284,5 @@ static inline void arch_invalidate_pmem(void *addr, size_t size) >>>> } >>>> #endif >>>> >>>> +unsigned long arch_namespace_map_size(void); >>> >>> This property is more generic than the nvdimm namespace mapping size, >>> it's more the fundamental remap granularity that the architecture >>> supports. So I would expect this to be defined in core header files. >>> Something like: >>> >>> diff --git a/include/linux/io.h b/include/linux/io.h >>> index a59834bc0a11..58b3b2091dbb 100644 >>> --- a/include/linux/io.h >>> +++ b/include/linux/io.h >>> @@ -155,6 +155,13 @@ enum { >>> void *memremap(resource_size_t offset, size_t size, unsigned long flags); >>> void memunmap(void *addr); >>> >>> +#ifndef memremap_min_align >>> +static inline unsigned int memremap_min_align(void) >>> +{ >>> + return PAGE_SIZE; >>> +} >>> +#endif >>> + >> >> >> Should that be memremap_pages_min_align()? > > No, and on second look it needs to be a common value that results in > properly aligned / sized namespaces across architectures. > > What would it take for Power to make it's minimum mapping granularity > SUBSECTION_SIZE? The minute that the minimum alignment changes across > architectures we lose compatibility. > > The namespaces need to be sized such that the mode can be changed freely. > We should do a discussion for LSF/MM for architecture compatibility challenges with NVDIMM. I did post a request to attend on that. But never got a response on that submission. -aneesh
On Fri, Jan 24, 2020 at 9:07 AM Aneesh Kumar K.V <aneesh.kumar@linux.ibm.com> wrote: > > On 1/24/20 10:15 PM, Dan Williams wrote: > > On Thu, Jan 23, 2020 at 11:34 PM Aneesh Kumar K.V > > <aneesh.kumar@linux.ibm.com> wrote: > >> > >> On 1/24/20 11:27 AM, Dan Williams wrote: > >>> On Mon, Jan 20, 2020 at 6:08 AM Aneesh Kumar K.V > >>> > >> > >> .... > >> > >>>> > >>>> +unsigned long arch_namespace_map_size(void) > >>>> +{ > >>>> + return PAGE_SIZE; > >>>> +} > >>>> +EXPORT_SYMBOL_GPL(arch_namespace_map_size); > >>>> + > >>>> + > >>>> static void __cpa_flush_all(void *arg) > >>>> { > >>>> unsigned long cache = (unsigned long)arg; > >>>> diff --git a/include/linux/libnvdimm.h b/include/linux/libnvdimm.h > >>>> index 9df091bd30ba..a3476dbd2656 100644 > >>>> --- a/include/linux/libnvdimm.h > >>>> +++ b/include/linux/libnvdimm.h > >>>> @@ -284,4 +284,5 @@ static inline void arch_invalidate_pmem(void *addr, size_t size) > >>>> } > >>>> #endif > >>>> > >>>> +unsigned long arch_namespace_map_size(void); > >>> > >>> This property is more generic than the nvdimm namespace mapping size, > >>> it's more the fundamental remap granularity that the architecture > >>> supports. So I would expect this to be defined in core header files. > >>> Something like: > >>> > >>> diff --git a/include/linux/io.h b/include/linux/io.h > >>> index a59834bc0a11..58b3b2091dbb 100644 > >>> --- a/include/linux/io.h > >>> +++ b/include/linux/io.h > >>> @@ -155,6 +155,13 @@ enum { > >>> void *memremap(resource_size_t offset, size_t size, unsigned long flags); > >>> void memunmap(void *addr); > >>> > >>> +#ifndef memremap_min_align > >>> +static inline unsigned int memremap_min_align(void) > >>> +{ > >>> + return PAGE_SIZE; > >>> +} > >>> +#endif > >>> + > >> > >> > >> Should that be memremap_pages_min_align()? > > > > No, and on second look it needs to be a common value that results in > > properly aligned / sized namespaces across architectures. > > > > What would it take for Power to make it's minimum mapping granularity > > SUBSECTION_SIZE? The minute that the minimum alignment changes across > > architectures we lose compatibility. > > > > The namespaces need to be sized such that the mode can be changed freely. > > > > Linux on ppc64 with hash translation use just one page size for direct > mapping and that is 16MB. Ok, I think this means that the dream of SUBSECTION_SIZE being the minimum compat alignment is dead, or at least a dream deferred. Let's do this, change the name of this function to: memremap_compat_align() ...and define it to be the max() of all the alignment constraints that the arch may require through either memremap(), or memremap_pages(). Then, teach ndctl to make its default alignment compatible by default, 16MiB, with an override to allow namespace creation with the current architecture's memremap_compat_align(), exported via sysfs, if it happens to be less then 16MiB. Finally, cross our fingers and hope that Power remains the only arch that violates the SUBSECTION_SIZE minimum value for memremap_compat_align().
Dan Williams <dan.j.williams@intel.com> writes: > On Fri, Jan 24, 2020 at 9:07 AM Aneesh Kumar K.V > <aneesh.kumar@linux.ibm.com> wrote: >> >> On 1/24/20 10:15 PM, Dan Williams wrote: >> > On Thu, Jan 23, 2020 at 11:34 PM Aneesh Kumar K.V >> > <aneesh.kumar@linux.ibm.com> wrote: >> >> >> >> On 1/24/20 11:27 AM, Dan Williams wrote: >> >>> On Mon, Jan 20, 2020 at 6:08 AM Aneesh Kumar K.V >> >>> >> >> >> >> .... >> >> >> >>>> >> >>>> +unsigned long arch_namespace_map_size(void) >> >>>> +{ >> >>>> + return PAGE_SIZE; >> >>>> +} >> >>>> +EXPORT_SYMBOL_GPL(arch_namespace_map_size); >> >>>> + >> >>>> + >> >>>> static void __cpa_flush_all(void *arg) >> >>>> { >> >>>> unsigned long cache = (unsigned long)arg; >> >>>> diff --git a/include/linux/libnvdimm.h b/include/linux/libnvdimm.h >> >>>> index 9df091bd30ba..a3476dbd2656 100644 >> >>>> --- a/include/linux/libnvdimm.h >> >>>> +++ b/include/linux/libnvdimm.h >> >>>> @@ -284,4 +284,5 @@ static inline void arch_invalidate_pmem(void *addr, size_t size) >> >>>> } >> >>>> #endif >> >>>> >> >>>> +unsigned long arch_namespace_map_size(void); >> >>> >> >>> This property is more generic than the nvdimm namespace mapping size, >> >>> it's more the fundamental remap granularity that the architecture >> >>> supports. So I would expect this to be defined in core header files. >> >>> Something like: >> >>> >> >>> diff --git a/include/linux/io.h b/include/linux/io.h >> >>> index a59834bc0a11..58b3b2091dbb 100644 >> >>> --- a/include/linux/io.h >> >>> +++ b/include/linux/io.h >> >>> @@ -155,6 +155,13 @@ enum { >> >>> void *memremap(resource_size_t offset, size_t size, unsigned long flags); >> >>> void memunmap(void *addr); >> >>> >> >>> +#ifndef memremap_min_align >> >>> +static inline unsigned int memremap_min_align(void) >> >>> +{ >> >>> + return PAGE_SIZE; >> >>> +} >> >>> +#endif >> >>> + >> >> >> >> >> >> Should that be memremap_pages_min_align()? >> > >> > No, and on second look it needs to be a common value that results in >> > properly aligned / sized namespaces across architectures. >> > >> > What would it take for Power to make it's minimum mapping granularity >> > SUBSECTION_SIZE? The minute that the minimum alignment changes across >> > architectures we lose compatibility. >> > >> > The namespaces need to be sized such that the mode can be changed freely. >> > >> >> Linux on ppc64 with hash translation use just one page size for direct >> mapping and that is 16MB. > > Ok, I think this means that the dream of SUBSECTION_SIZE being the > minimum compat alignment is dead, or at least a dream deferred. > > Let's do this, change the name of this function to: > > memremap_compat_align() > > ...and define it to be the max() of all the alignment constraints that > the arch may require through either memremap(), or memremap_pages(). > Then, teach ndctl to make its default alignment compatible by default, > 16MiB, with an override to allow namespace creation with the current > architecture's memremap_compat_align(), exported via sysfs, if it > happens to be less then 16MiB. Finally, cross our fingers and hope > that Power remains the only arch that violates the SUBSECTION_SIZE > minimum value for memremap_compat_align(). We do have two issues related to alignment here. 1) With upstream kernel, we don't validate the namespace start and size value and hence we can end up creating namespace that is not aligned to SUBSECTION_SIZE. This was observed by Jeff Moyer in his test. That means we will fail to enable already created namespace if we use SUBSECTION_SIZE to validate their alignment. The solution I came up with was arch_namespace_map_size() that depends on the direct-map mapping page size. On architecture like ppc64, this value can be 16MB. 3) For new namespaces, we can now ensure they are properly aligned. For architectures other than ppc64 that value is SUBSECTION_SIZE; ie, the resource start address and the size value should be aligned to SUBSECTION_SIZE. For ppc64 this value should be 16MB because if they are not 16MB aligned we cannot direct-map them. I guess this can be memremap_compat_align() and we expose this value via namespace attribute. By default, all architecture will now to try to align things to 16MB unless specified --nocompat as ndctl create-namespace command-line option. When used we use the architecture-specific sysfs value (SUBSECTION_SIZE) to align things correctly. -aneesh
diff --git a/arch/arm64/mm/flush.c b/arch/arm64/mm/flush.c index ac485163a4a7..95cb5538bc6e 100644 --- a/arch/arm64/mm/flush.c +++ b/arch/arm64/mm/flush.c @@ -91,4 +91,10 @@ void arch_invalidate_pmem(void *addr, size_t size) __inval_dcache_area(addr, size); } EXPORT_SYMBOL_GPL(arch_invalidate_pmem); + +unsigned long arch_namespace_map_size(void) +{ + return PAGE_SIZE; +} +EXPORT_SYMBOL_GPL(arch_namespace_map_size); #endif diff --git a/arch/powerpc/lib/pmem.c b/arch/powerpc/lib/pmem.c index 0666a8d29596..63dca24e4a18 100644 --- a/arch/powerpc/lib/pmem.c +++ b/arch/powerpc/lib/pmem.c @@ -26,6 +26,15 @@ void arch_invalidate_pmem(void *addr, size_t size) } EXPORT_SYMBOL_GPL(arch_invalidate_pmem); +unsigned long arch_namespace_map_size(void) +{ + if (radix_enabled()) + return PAGE_SIZE; + return (1UL << mmu_psize_defs[mmu_linear_psize].shift); + +} +EXPORT_SYMBOL_GPL(arch_namespace_map_size); + /* * CONFIG_ARCH_HAS_UACCESS_FLUSHCACHE symbols */ diff --git a/arch/x86/mm/pageattr.c b/arch/x86/mm/pageattr.c index 1b99ad05b117..d78b5082f376 100644 --- a/arch/x86/mm/pageattr.c +++ b/arch/x86/mm/pageattr.c @@ -310,6 +310,13 @@ void arch_invalidate_pmem(void *addr, size_t size) } EXPORT_SYMBOL_GPL(arch_invalidate_pmem); +unsigned long arch_namespace_map_size(void) +{ + return PAGE_SIZE; +} +EXPORT_SYMBOL_GPL(arch_namespace_map_size); + + static void __cpa_flush_all(void *arg) { unsigned long cache = (unsigned long)arg; diff --git a/include/linux/libnvdimm.h b/include/linux/libnvdimm.h index 9df091bd30ba..a3476dbd2656 100644 --- a/include/linux/libnvdimm.h +++ b/include/linux/libnvdimm.h @@ -284,4 +284,5 @@ static inline void arch_invalidate_pmem(void *addr, size_t size) } #endif +unsigned long arch_namespace_map_size(void); #endif /* __LIBNVDIMM_H__ */
The page size used to map the namespace is arch dependent. For example architectures like ppc64 use 16MB page size for direct-mapping. If the namespace size is not aligned to the mapping page size, users can observe kernel crash during namespace init and destroy. This is due to kernel doing partial map/unmap of the resource range BUG: Unable to handle kernel data access at 0xc001000406000000 Faulting instruction address: 0xc000000000090790 NIP [c000000000090790] arch_add_memory+0xc0/0x130 LR [c000000000090744] arch_add_memory+0x74/0x130 Call Trace: arch_add_memory+0x74/0x130 (unreliable) memremap_pages+0x74c/0xa30 devm_memremap_pages+0x3c/0xa0 pmem_attach_disk+0x188/0x770 nvdimm_bus_probe+0xd8/0x470 really_probe+0x148/0x570 driver_probe_device+0x19c/0x1d0 device_driver_attach+0xcc/0x100 bind_store+0x134/0x1c0 drv_attr_store+0x44/0x60 sysfs_kf_write+0x74/0xc0 kernfs_fop_write+0x1b4/0x290 __vfs_write+0x3c/0x70 vfs_write+0xd0/0x260 ksys_write+0xdc/0x130 system_call+0x5c/0x68 Kernel should also ensure that namespace size is also mulitple of subsection size. Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@linux.ibm.com> --- arch/arm64/mm/flush.c | 6 ++++++ arch/powerpc/lib/pmem.c | 9 +++++++++ arch/x86/mm/pageattr.c | 7 +++++++ include/linux/libnvdimm.h | 1 + 4 files changed, 23 insertions(+)