2022-09-28 23:01:07

by Doug Berger

[permalink] [raw]
Subject: [PATCH v2 4/9] mm/page_alloc.c: allow oversized movablecore

Now that the error in computation of corepages has been corrected
by commit 9fd745d450e7 ("mm: fix overflow in
find_zone_movable_pfns_for_nodes()"), oversized specifications of
movablecore will result in a zero value for required_kernelcore if
it is not also specified.

It is unintuitive for such a request to lead to no ZONE_MOVABLE
memory when the kernel parameters are clearly requesting some.

The current behavior when requesting an oversized kernelcore is to
classify all of the pages in movable_zone as kernelcore. The new
behavior when requesting an oversized movablecore (when not also
specifying kernelcore) is to similarly classify all of the pages
in movable_zone as movablecore.

Signed-off-by: Doug Berger <[email protected]>
---
mm/page_alloc.c | 10 +++++-----
1 file changed, 5 insertions(+), 5 deletions(-)

diff --git a/mm/page_alloc.c b/mm/page_alloc.c
index 3412d644c230..81f97c5ed080 100644
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -8041,13 +8041,13 @@ static void __init find_zone_movable_pfns_for_nodes(void)
corepages = totalpages - required_movablecore;

required_kernelcore = max(required_kernelcore, corepages);
+ } else if (!required_kernelcore) {
+ /* If kernelcore was not specified, there is no ZONE_MOVABLE */
+ goto out;
}

- /*
- * If kernelcore was not specified or kernelcore size is larger
- * than totalpages, there is no ZONE_MOVABLE.
- */
- if (!required_kernelcore || required_kernelcore >= totalpages)
+ /* If kernelcore size exceeds totalpages, there is no ZONE_MOVABLE */
+ if (required_kernelcore >= totalpages)
goto out;

/* usable_startpfn is the lowest possible pfn ZONE_MOVABLE can be at */
--
2.25.1