Hi Dan, On Thu, 05 Nov 2020 14:20:45 -0800 Dan Williams <[email protected]> wrote: > > The core-mm has a default __weak implementation of phys_to_target_node() > to mirror the weak definition of memory_add_physaddr_to_nid(). That > symbol is exported for modules. However, while the export in > mm/memory_hotplug.c exported the symbol in the configuration cases of: > > CONFIG_NUMA_KEEP_MEMINFO=y > CONFIG_MEMORY_HOTPLUG=y > > ...and: > > CONFIG_NUMA_KEEP_MEMINFO=n > CONFIG_MEMORY_HOTPLUG=y > > ...it failed to export the symbol in the case of: > > CONFIG_NUMA_KEEP_MEMINFO=y > CONFIG_MEMORY_HOTPLUG=n > > Not only is that broken, but Christoph points out that the kernel should > not be exporting any __weak symbol, which means that > memory_add_physaddr_to_nid() example that phys_to_target_node() copied > is broken too. > > Rework the definition of phys_to_target_node() and > memory_add_physaddr_to_nid() to not require weak symbols. Move to the > common arch override design-pattern of an asm header defining a symbol > to replace the default implementation. > > The only common header that all memory_add_physaddr_to_nid() producing > architectures implement is asm/sparsemem.h. In fact, powerpc already > defines its memory_add_physaddr_to_nid() helper in sparsemem.h. > Double-down on that observation and define phys_to_target_node() where > necessary in asm/sparsemem.h. An alternate consideration that was > discarded was to put this override in asm/numa.h, but that entangles > with the definition of MAX_NUMNODES relative to the inclusion of > linux/nodemask.h, and requires powerpc to grow a new header. > > The dependency on NUMA_KEEP_MEMINFO for DEV_DAX_HMEM_DEVICES is invalid > now that the symbol is properly exported / stubbed in all combinations > of CONFIG_NUMA_KEEP_MEMINFO and CONFIG_MEMORY_HOTPLUG. > > Reported-by: Randy Dunlap <[email protected]> > Tested-by: Randy Dunlap <[email protected]> > Reported-by: Thomas Gleixner <[email protected]> > Tested-by: Thomas Gleixner <[email protected]> > Reviewed-by: Thomas Gleixner <[email protected]> > Reported-by: kernel test robot <[email protected]> > Reported-by: Christoph Hellwig <[email protected]> > Reviewed-by: Christoph Hellwig <[email protected]> > Reported-by: Stephen Rothwell <[email protected]> > Fixes: a035b6bf863e ("mm/memory_hotplug: introduce default > phys_to_target_node() implementation") > Cc: Joao Martins <[email protected]> > Cc: Andrew Morton <[email protected]> > Cc: [email protected] > Cc: Tony Luck <[email protected]> > Cc: Fenghua Yu <[email protected]> > Cc: Michael Ellerman <[email protected]> > Cc: Benjamin Herrenschmidt <[email protected]> > Cc: Paul Mackerras <[email protected]> > Cc: Vishal Verma <[email protected]> > Signed-off-by: Dan Williams <[email protected]> > --- > Changes since v3 [1]: > - (Stephen) PowerPC header include dependencies make it difficult to > include asm/sparsemem.h in linux/numa.h due to missing definition of > pgprot. Move the declaration of create_section_mapping() to > asm/mmzone.h. This has received a build success notification from the > kbuild-robot over 159 configs.
I replaced the previous version in linux-next with this today. Thanks. -- Cheers, Stephen Rothwell
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