Adjust the stack expansion functions expand_upwards() and expand_downwards() such that they are expressed in terms of named constant values, and make use of vma_start_pgoff().
This clearly documents that we are referencing the page offset of the start of the VMA. Additionally this cleans up the overflow check in expand_upwards(). No functional change intended. Reviewed-by: Pedro Falcato <[email protected]> Reviewed-by: Gregory Price <[email protected]> Signed-off-by: Lorenzo Stoakes <[email protected]> --- mm/vma.c | 17 +++++++---------- 1 file changed, 7 insertions(+), 10 deletions(-) diff --git a/mm/vma.c b/mm/vma.c index 7265a054cfa3..5d5e60ea8a25 100644 --- a/mm/vma.c +++ b/mm/vma.c @@ -3216,13 +3216,12 @@ int expand_upwards(struct vm_area_struct *vma, unsigned long address) /* Somebody else might have raced and expanded it already */ if (address > vma->vm_end) { - unsigned long size, grow; - - size = address - vma->vm_start; - grow = (address - vma->vm_end) >> PAGE_SHIFT; + const unsigned long size = address - vma->vm_start; + const unsigned long grow = (address - vma->vm_end) >> PAGE_SHIFT; + const pgoff_t pgoff = vma_start_pgoff(vma); error = -ENOMEM; - if (vma->vm_pgoff + (size >> PAGE_SHIFT) >= vma->vm_pgoff) { + if (pgoff + (size >> PAGE_SHIFT) >= pgoff) { error = acct_stack_growth(vma, size, grow); if (!error) { if (vma_test(vma, VMA_LOCKED_BIT)) @@ -3295,13 +3294,11 @@ int expand_downwards(struct vm_area_struct *vma, unsigned long address) /* Somebody else might have raced and expanded it already */ if (address < vma->vm_start) { - unsigned long size, grow; - - size = vma->vm_end - address; - grow = (vma->vm_start - address) >> PAGE_SHIFT; + const unsigned long size = vma->vm_end - address; + const unsigned long grow = (vma->vm_start - address) >> PAGE_SHIFT; error = -ENOMEM; - if (grow <= vma->vm_pgoff) { + if (grow <= vma_start_pgoff(vma)) { error = acct_stack_growth(vma, size, grow); if (!error) { if (vma_test(vma, VMA_LOCKED_BIT)) -- 2.55.0
