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Revert "mm: align larger anonymous mappings on THP boundaries"

This reverts commit f35b5d7d676e59e401690b678cd3cfec5e785c23.

It has been reported to cause huge performance regressions on some loads
(will-it-scale.per_process_ops, but also building the kernel with
clang).

The commit did speed up gcc builds by a small amount, so it's not an
unambiguous regression, but until the big regressions are understood,
let's revert it.

Reported-by: kernel test robot <yujie.liu@intel.com>
Link: https://lore.kernel.org/r/202210181535.7144dd15-yujie.liu@intel.com
Reported-by: Nathan Chancellor <nathan@kernel.org>
Link: https://lore.kernel.org/lkml/Y1DNQaoPWxE%2BrGce@dev-arch.thelio-3990X/
Cc: Huang, Ying <ying.huang@intel.com>
Cc: Rik van Riel <riel@surriel.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Yang Shi <shy828301@gmail.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

Linus Torvalds 0ba09b17 23393c64

-3
-3
mm/mmap.c
··· 1779 1779 */ 1780 1780 pgoff = 0; 1781 1781 get_area = shmem_get_unmapped_area; 1782 - } else if (IS_ENABLED(CONFIG_TRANSPARENT_HUGEPAGE)) { 1783 - /* Ensures that larger anonymous mappings are THP aligned. */ 1784 - get_area = thp_get_unmapped_area; 1785 1782 } 1786 1783 1787 1784 addr = get_area(file, addr, len, pgoff, flags);