From 9ac09bb9feaccc2f45e5606dc48a3f748d478dc4 Mon Sep 17 00:00:00 2001 From: Ryan Roberts Date: Fri, 3 Oct 2025 16:53:04 +0100 Subject: mm: consistently use current->mm in mm_get_unmapped_area() mm_get_unmapped_area() is a wrapper around arch_get_unmapped_area() / arch_get_unmapped_area_topdown(), both of which search current->mm for some free space. Neither take an mm_struct - they implicitly operate on current->mm. But the wrapper takes an mm_struct and uses it to decide whether to search bottom up or top down. All callers pass in current->mm for this, so everything is working consistently. But it feels like an accident waiting to happen; eventually someone will call that function with a different mm, expecting to find free space in it, but what gets returned is free space in the current mm. So let's simplify by removing the parameter and have the wrapper use current->mm to decide which end to start at. Now everything is consistent and self-documenting. Link: https://lkml.kernel.org/r/20251003155306.2147572-1-ryan.roberts@arm.com Signed-off-by: Ryan Roberts Acked-by: David Hildenbrand Reviewed-by: Oscar Salvador Reviewed-by: Dev Jain Reviewed-by: Anshuman Khandual Reviewed-by: Lorenzo Stoakes Reviewed-by: Baolin Wang Cc: Liam Howlett Cc: Michal Hocko Cc: Mike Rapoport Cc: Suren Baghdasaryan Cc: Vlastimil Babka Signed-off-by: Andrew Morton --- drivers/char/mem.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) (limited to 'drivers/char/mem.c') diff --git a/drivers/char/mem.c b/drivers/char/mem.c index 34b815901b20..db1ca53a6d01 100644 --- a/drivers/char/mem.c +++ b/drivers/char/mem.c @@ -542,7 +542,7 @@ static unsigned long get_unmapped_area_zero(struct file *file, #ifdef CONFIG_TRANSPARENT_HUGEPAGE return thp_get_unmapped_area(file, addr, len, pgoff, flags); #else - return mm_get_unmapped_area(current->mm, file, addr, len, pgoff, flags); + return mm_get_unmapped_area(file, addr, len, pgoff, flags); #endif } #endif /* CONFIG_MMU */ -- cgit v1.2.3