Re: [PATCH v1 01/11] arm/pgtable: define PFN_PTE_SHIFT on arm and arm64
From: Matthew Wilcox <willy@infradead.org>
Date: 2024-01-23 15:01:41
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linux-mm, linux-riscv, linux-s390, linuxppc-dev, lkml, sparclinux
On Tue, Jan 23, 2024 at 10:34:21AM +0000, Ryan Roberts wrote:
quoted
+#define PFN_PTE_SHIFT PAGE_SHIFTI think this is buggy. And so is the arm64 implementation of set_ptes(). It works fine for 48-bit output address, but for 52-bit OAs, the high bits are not kept contigously, so if you happen to be setting a mapping for which the physical memory block straddles bit 48, this won't work.
I'd like to see the folio allocation that can straddle bit 48 ... agreed, it's not workable _in general_, but specifically for a memory allocation from a power-of-two allocator, you'd have to do a 49-bit allocation (half a petabyte) to care. _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel