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Peter Anvin" , Andy Lutomirski , Peter Zijlstra , Thomas Gleixner Cc: linux-kernel@vger.kernel.org, Brendan Jackman Content-Type: text/plain; charset="utf-8" The phys_*_init()s return the "last physical address mapped". The exact definition of this is pretty fiddly, but only in these conditions: 1. There is a mismatch between the alignment of the requested range and the page sizes allowed by page_size_mask 2. The range ends in a region that is not mapped according to e820. 3. The range ends in a region that was already mapped (note this case is particularly fiddly because the return value depends on what level the existing mapping is at. This is probably a bug, see [0] for discussion). Luckily, init_memory_mapping() avoids all these conditions. In that case, the return value is just paddr_end. And that value is already present, no need to depend on the confusing return value. [0]: https://lore.kernel.org/all/84b2e7a3-7115-45fe-89ff-db8ee46729f2@intel.com/ Signed-off-by: Brendan Jackman --- arch/x86/mm/init.c | 9 +++++---- 1 file changed, 5 insertions(+), 4 deletions(-) diff --git a/arch/x86/mm/init.c b/arch/x86/mm/init.c index ae3e9e0820153..1a6a6fc700bb5 100644 --- a/arch/x86/mm/init.c +++ b/arch/x86/mm/init.c @@ -544,10 +544,11 @@ void __ref init_memory_mapping(unsigned long start, memset(mr, 0, sizeof(mr)); nr_range = split_mem_range(mr, 0, start, end); - for (i = 0; i < nr_range; i++) - paddr_last = kernel_physical_mapping_init(mr[i].start, mr[i].end, - mr[i].page_size_mask, - prot); + for (i = 0; i < nr_range; i++) { + kernel_physical_mapping_init(mr[i].start, mr[i].end, + mr[i].page_size_mask, prot); + paddr_last = mr[i].end; + } add_pfn_range_mapped(start >> PAGE_SHIFT, paddr_last >> PAGE_SHIFT); } -- 2.51.2