Commit f4a578d3 authored Mar 12, 2025 by SeongJae Park Committed by Andrew Morton Mar 17, 2025

mm/madvise: split out populate behavior check logic

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

Link: https://lkml.kernel.org/r/20250312164750.59215-3-sj@kernel.org


Signed-off-by: SeongJae Park <sj@kernel.org>
Reviewed-by: Lorenzo Stoakes <lorenzo.stoakes@oracle.com>
Reviewed-by: Shakeel Butt <shakeel.butt@linux.dev>
Cc: David Hildenbrand <david@redhat.com>
Cc: Liam R. Howlett <howlett@gmail.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

parent 9ecd2f83

mm/madvise.c

+13 −7

Original line number	Diff line number	Diff line
		@@ -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;
		}