From fe3e9cf0d7a28d333523189d1405770d980b07d6 Mon Sep 17 00:00:00 2001 From: Lorenzo Stoakes Date: Fri, 31 Jan 2025 12:31:51 +0000 Subject: mm: eliminate adj_start parameter from commit_merge() Introduce internal vmg->__adjust_middle_start and vmg->__adjust_next_start merge flags, enabling us to indicate to commit_merge() that we are performing a merge which either spans only part of vmg->middle, or part of vmg->next respectively. In the former instance, we change the start of vmg->middle to match the attributes of vmg->prev, without spanning all of vmg->middle. This implies that vmg->prev->vm_end and vmg->middle->vm_start are both increased to form the new merged VMA (vmg->prev) and the new subsequent VMA (vmg->middle). In the latter case, we change the end of vmg->middle to match the attributes of vmg->next, without spanning all of vmg->next. This implies that vmg->middle->vm_end and vmg->next->vm_start are both decreased to form the new merged VMA (vmg->next) and the new prior VMA (vmg->middle). Since we now have a stable set of prev, middle, next VMAs threaded through vmg and with these flags set know what is happening, we can perform the calculation in commit_merge() instead. This allows us to drop the confusing adj_start parameter and instead pass semantic information to commit_merge(). In the latter case the -(middle->vm_end - start) calculation becomes -(middle->vm-end - vmg->end), however this is correct as vmg->end is set to the start parameter. This is because in this case (rather confusingly), we manipulate vmg->middle, but ultimately return vmg->next, whose range will be correctly specified. At this point vmg->start, end is the new range for the prior VMA rather than the merged one. This patch has no change in functional behaviour. Link: https://lkml.kernel.org/r/bcec0cd980b373a5eb02236cb033034ce1effe42.1738326519.git.lorenzo.stoakes@oracle.com Signed-off-by: Lorenzo Stoakes Reviewed-by: Vlastimil Babka Cc: Jann Horn Cc: Liam Howlett Signed-off-by: Andrew Morton --- tools/testing/vma/vma.c | 2 ++ 1 file changed, 2 insertions(+) (limited to 'tools/testing') diff --git a/tools/testing/vma/vma.c b/tools/testing/vma/vma.c index 7728498b2f7e..c7ffa71841ca 100644 --- a/tools/testing/vma/vma.c +++ b/tools/testing/vma/vma.c @@ -159,6 +159,8 @@ static void vmg_set_range(struct vma_merge_struct *vmg, unsigned long start, vmg->just_expand = false; vmg->__remove_middle = false; vmg->__remove_next = false; + vmg->__adjust_middle_start = false; + vmg->__adjust_next_start = false; } /* -- cgit v1.2.3