Re: [PATCH v2 16/33] mm/vma: minor cleanup of expand_[upwards, downwards]()
From: "Vlastimil Babka (SUSE)" <vbabka@kernel.org>
Date: 2026-07-15 14:54:22
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damon, dri-devel, kvm, linux-arm-msm, linux-fsdevel, linux-iommu, linux-mm, linux-perf-users, linux-tegra, lkml, nvdimm
On 7/10/26 22:16, Lorenzo Stoakes wrote:
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 <pfalcato@suse.de> Reviewed-by: Gregory Price <gourry@gourry.net> Signed-off-by: Lorenzo Stoakes <ljs@kernel.org>
Reviewed-by: Vlastimil Babka (SUSE) <vbabka@kernel.org>
quoted hunk ↗ jump to hunk
--- 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))