ARM, xtensa: highmem: avoid clobbering non-page aligned memory reservations

free_highpages() iterates over the free memblock regions in high
memory, and marks each page as available for the memory management
system.

Until commit cddb5ddf2b76 ("arm, xtensa: simplify initialization of
high memory pages") it rounded beginning of each region upwards and end of
each region downwards.

However, after that commit free_highmem() rounds the beginning and end of
each region downwards, and we may end up freeing a page that is
memblock_reserve()d, resulting in memory corruption.

Restore the original rounding of the region boundaries to avoid freeing
reserved pages.

Fixes: cddb5ddf2b76 ("arm, xtensa: simplify initialization of high memory pages")
Link: https://lore.kernel.org/r/[email protected]/
Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Ard Biesheuvel <[email protected]>
Co-developed-by:  Mike Rapoport <[email protected]>
Signed-off-by: Mike Rapoport <[email protected]>
Acked-by: Max Filippov <[email protected]>

0 files changed, 0 insertions, 0 deletions