Re: [PATCH] powerpc/mm: Don't kmap_atomic() in pte_offset_map() on PPC32
From: Michael Ellerman <hidden>
Date: 2020-03-06 00:28:04
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On Mon, 2020-02-17 at 09:41:35 UTC, Christophe Leroy wrote:
On PPC32, pte_offset_map() does a kmap_atomic() in order to support
page tables allocated in high memory, just like ARM and x86/32.
But since at least 2008 and commit 8054a3428fbe ("powerpc: Remove dead
CONFIG_HIGHPTE"), page tables are never allocated in high memory.
When the page is in low mem, kmap_atomic() just returns the page
address but still disable preemption and pagefault. And it is
not an inlined function, so we suffer function call for no reason.
Make pte_offset_map() the same as pte_offset_kernel() and make
pte_unmap() void, in the same way as PPC64 which doesn't have HIGHMEM.
Signed-off-by: Christophe Leroy <redacted>Applied to powerpc next, thanks. https://git.kernel.org/powerpc/c/6453f9ed9d4e4b4cdf201bf34bf460c436bf50ea cheers