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uma: Avoid unmapping direct-mapped slabs

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startup_alloc() uses pmap_map() to map slabs used for bootstrapping the
VM.  pmap_map() may ignore the hint address and simply return a range
from the direct map.  In this case we must not unmap the range in
startup_free().

UMA uses bootstart and bootmem to track the range of KVA into which
slabs are mapped if the direct map is not used.  Unmap a startup slab
only if it was mapped into that range.

Reported by:	alc
Reviewed by:	alc, kib
Sponsored by:	The FreeBSD Foundation
Differential Revision:	https://reviews.freebsd.org/D27885
This commit is contained in:
Mark Johnston 2021-01-03 11:31:00 -05:00
parent 6a5c55666b
commit 663de81f85
1 changed files with 7 additions and 1 deletions
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8
sys/vm/uma_core.c
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@ -1691,7 +1691,13 @@ startup_free(void *mem, vm_size_t bytes)
va = (vm_offset_t)mem;
m = PHYS_TO_VM_PAGE(pmap_kextract(va));
pmap_remove(kernel_pmap, va, va + bytes);
/*
* startup_alloc() returns direct-mapped slabs on some platforms. Avoid
* unmapping ranges of the direct map.
*/
if (va >= bootstart && va + bytes <= bootmem)
pmap_remove(kernel_pmap, va, va + bytes);
for (; bytes != 0; bytes -= PAGE_SIZE, m++) {
#if defined(__aarch64__) || defined(__amd64__) || defined(__mips__) || \
defined(__riscv) || defined(__powerpc64__)