[PATCH 2/9] mm/madvise: split out populate behavior check logic

SeongJae Park
2025-03-10T17:23:26Z

madvise_do_behavior() has a long open-coded 'behavior' check for
MADV_POPULATE_{READ,WRITE}. It adds multiple layers[1] and make the
code arguably take longer time to read. Like is_memory_failure(), split
out the check to a separate function. This is not technically removing
the additional layer but discourage further extending the switch-case.
Also it makes madvise_do_behavior() code shorter and therefore easier to
read.

[1] https://lore.kernel.org/bd6d0bf1-c79e-46bd-a810-9791efb9ad73@lucifer.local

Signed-off-by: SeongJae Park <sj@kernel.org>
---
mm/madvise.c | 20 +++++++++++++-------
1 file changed, 13 insertions(+), 7 deletions(-)

diff --git a/mm/madvise.c b/mm/madvise.c
index c3ab1f283b18..611db868ae38 100644
--- a/mm/madvise.c
+++ b/mm/madvise.c
@@ -1640,6 +1640,17 @@ static bool is_valid_madvise(unsigned long start, size_t len_in, int behavior)
return true;
}

+static bool is_madvise_populate(int behavior)
+{
+ switch (behavior) {
+ case MADV_POPULATE_READ:
+ case MADV_POPULATE_WRITE:
+ return true;
+ default:
+ return false;
+ }
+}
+
static int madvise_do_behavior(struct mm_struct *mm,
unsigned long start, size_t len_in, size_t len, int behavior)
{
@@ -1653,16 +1664,11 @@ static int madvise_do_behavior(struct mm_struct *mm,
end = start + len;

blk_start_plug(&plug);
- switch (behavior) {
- case MADV_POPULATE_READ:
- case MADV_POPULATE_WRITE:
+ if (is_madvise_populate(behavior))
error = madvise_populate(mm, start, end, behavior);
- break;
- default:
+ else
error = madvise_walk_vmas(mm, start, end, behavior,
madvise_vma_behavior);
- break;
- }
blk_finish_plug(&plug);
return error;
}
--
2.39.5