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mm/page_alloc: reduce potential fragmentation in make_alloc_exact()

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Try to avoid using the left over split page on the next request for a page
by calling __free_pages_ok() with FPI_TO_TAIL.  This increases the
potential of defragmenting memory when it's used for a short period of
time.

Link: https://lkml.kernel.org/r/20220531185626.yvlmymbxyoe5vags@revolver
Signed-off-by: Liam R. Howlett <Liam.Howlett@oracle.com>
Suggested-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
This commit is contained in:
Liam R. Howlett 2022-05-31 09:20:51 -04:00 committed by Andrew Morton
parent 08ac85521c
commit df48a5f7a3
1 changed files with 11 additions and 7 deletions
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18
mm/page_alloc.c
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@ -5784,14 +5784,18 @@ static void *make_alloc_exact(unsigned long addr, unsigned int order,
size_t size)
{
if (addr) {
unsigned long alloc_end = addr + (PAGE_SIZE << order);
unsigned long used = addr + PAGE_ALIGN(size);
unsigned long nr = DIV_ROUND_UP(size, PAGE_SIZE);
struct page *page = virt_to_page((void *)addr);
struct page *last = page + nr;
split_page(virt_to_page((void *)addr), order);
while (used < alloc_end) {
free_page(used);
used += PAGE_SIZE;
}
split_page_owner(page, 1 << order);
split_page_memcg(page, 1 << order);
while (page < --last)
set_page_refcounted(last);
last = page + (1UL << order);
for (page += nr; page < last; page++)
__free_pages_ok(page, 0, FPI_TO_TAIL);
}
return (void *)addr;
}