[PATCH v2 3/3] hugetlb: Convert hugetlb_wp() to use struct vm_fault

Vishal Moola (Oracle)
2024-04-01T20:27:06Z

hugetlb_wp() can use the struct vm_fault passed in from hugetlb_fault().
This alleviates the stack by consolidating 5 variables into a single
struct.

Signed-off-by: Vishal Moola (Oracle) <vishal.moola@gmail.com>
---
mm/hugetlb.c | 61 ++++++++++++++++++++++++++--------------------------
1 file changed, 30 insertions(+), 31 deletions(-)

diff --git a/mm/hugetlb.c b/mm/hugetlb.c
index aca2f11b4138..d4f26947173e 100644
--- a/mm/hugetlb.c
+++ b/mm/hugetlb.c
@@ -5918,18 +5918,16 @@ static void unmap_ref_private(struct mm_struct *mm, struct vm_area_struct *vma,
* Keep the pte_same checks anyway to make transition from the mutex easier.
*/
static vm_fault_t hugetlb_wp(struct mm_struct *mm, struct vm_area_struct *vma,
- unsigned long address, pte_t *ptep, unsigned int flags,
- struct folio *pagecache_folio, spinlock_t *ptl,
+ struct folio *pagecache_folio,
struct vm_fault *vmf)
{
- const bool unshare = flags & FAULT_FLAG_UNSHARE;
- pte_t pte = huge_ptep_get(ptep);
+ const bool unshare = vmf->flags & FAULT_FLAG_UNSHARE;
+ pte_t pte = huge_ptep_get(vmf->pte);
struct hstate *h = hstate_vma(vma);
struct folio *old_folio;
struct folio *new_folio;
int outside_reserve = 0;
vm_fault_t ret = 0;
- unsigned long haddr = address & huge_page_mask(h);
struct mmu_notifier_range range;

/*
@@ -5952,7 +5950,7 @@ static vm_fault_t hugetlb_wp(struct mm_struct *mm, struct vm_area_struct *vma,

/* Let's take out MAP_SHARED mappings first. */
if (vma->vm_flags & VM_MAYSHARE) {
- set_huge_ptep_writable(vma, haddr, ptep);
+ set_huge_ptep_writable(vma, vmf->address, vmf->pte);
return 0;
}

@@ -5971,7 +5969,7 @@ static vm_fault_t hugetlb_wp(struct mm_struct *mm, struct vm_area_struct *vma,
SetPageAnonExclusive(&old_folio->page);
}
if (likely(!unshare))
- set_huge_ptep_writable(vma, haddr, ptep);
+ set_huge_ptep_writable(vma, vmf->address, vmf->pte);

delayacct_wpcopy_end();
return 0;
@@ -5998,8 +5996,8 @@ static vm_fault_t hugetlb_wp(struct mm_struct *mm, struct vm_area_struct *vma,
* Drop page table lock as buddy allocator may be called. It will
* be acquired again before returning to the caller, as expected.
*/
- spin_unlock(ptl);
- new_folio = alloc_hugetlb_folio(vma, haddr, outside_reserve);
+ spin_unlock(vmf->ptl);
+ new_folio = alloc_hugetlb_folio(vma, vmf->address, outside_reserve);

if (IS_ERR(new_folio)) {
/*
@@ -6024,19 +6022,21 @@ static vm_fault_t hugetlb_wp(struct mm_struct *mm, struct vm_area_struct *vma,
*
* Reacquire both after unmap operation.
*/
- idx = vma_hugecache_offset(h, vma, haddr);
+ idx = vma_hugecache_offset(h, vma, vmf->address);
hash = hugetlb_fault_mutex_hash(mapping, idx);
hugetlb_vma_unlock_read(vma);
mutex_unlock(&hugetlb_fault_mutex_table[hash]);

- unmap_ref_private(mm, vma, &old_folio->page, haddr);
+ unmap_ref_private(mm, vma, &old_folio->page,
+ vmf->address);

mutex_lock(&hugetlb_fault_mutex_table[hash]);
hugetlb_vma_lock_read(vma);
- spin_lock(ptl);
- ptep = hugetlb_walk(vma, haddr, huge_page_size(h));
- if (likely(ptep &&
- pte_same(huge_ptep_get(ptep), pte)))
+ spin_lock(vmf->ptl);
+ vmf->pte = hugetlb_walk(vma, vmf->address,
+ huge_page_size(h));
+ if (likely(vmf->pte &&
+ pte_same(huge_ptep_get(vmf->pte), pte)))
goto retry_avoidcopy;
/*
* race occurs while re-acquiring page table
@@ -6058,37 +6058,38 @@ static vm_fault_t hugetlb_wp(struct mm_struct *mm, struct vm_area_struct *vma,
if (unlikely(ret))
goto out_release_all;

- if (copy_user_large_folio(new_folio, old_folio, address, vma)) {
+ if (copy_user_large_folio(new_folio, old_folio, vmf->real_address, vma)) {
ret = VM_FAULT_HWPOISON_LARGE;
goto out_release_all;
}
__folio_mark_uptodate(new_folio);

- mmu_notifier_range_init(&range, MMU_NOTIFY_CLEAR, 0, mm, haddr,
- haddr + huge_page_size(h));
+ mmu_notifier_range_init(&range, MMU_NOTIFY_CLEAR, 0, mm, vmf->address,
+ vmf->address + huge_page_size(h));
mmu_notifier_invalidate_range_start(&range);

/*
* Retake the page table lock to check for racing updates
* before the page tables are altered
*/
- spin_lock(ptl);
- ptep = hugetlb_walk(vma, haddr, huge_page_size(h));
- if (likely(ptep && pte_same(huge_ptep_get(ptep), pte))) {
+ spin_lock(vmf->ptl);
+ vmf->pte = hugetlb_walk(vma, vmf->address, huge_page_size(h));
+ if (likely(vmf->pte && pte_same(huge_ptep_get(vmf->pte), pte))) {
pte_t newpte = make_huge_pte(vma, &new_folio->page, !unshare);

/* Break COW or unshare */
- huge_ptep_clear_flush(vma, haddr, ptep);
+ huge_ptep_clear_flush(vma, vmf->address, vmf->pte);
hugetlb_remove_rmap(old_folio);
- hugetlb_add_new_anon_rmap(new_folio, vma, haddr);
+ hugetlb_add_new_anon_rmap(new_folio, vma, vmf->address);
if (huge_pte_uffd_wp(pte))
newpte = huge_pte_mkuffd_wp(newpte);
- set_huge_pte_at(mm, haddr, ptep, newpte, huge_page_size(h));
+ set_huge_pte_at(mm, vmf->address, vmf->pte, newpte,
+ huge_page_size(h));
folio_set_hugetlb_migratable(new_folio);
/* Make the old page be freed below */
new_folio = old_folio;
}
- spin_unlock(ptl);
+ spin_unlock(vmf->ptl);
mmu_notifier_invalidate_range_end(&range);
out_release_all:
/*
@@ -6096,12 +6097,12 @@ static vm_fault_t hugetlb_wp(struct mm_struct *mm, struct vm_area_struct *vma,
* unshare)
*/
if (new_folio != old_folio)
- restore_reserve_on_error(h, vma, haddr, new_folio);
+ restore_reserve_on_error(h, vma, vmf->address, new_folio);
folio_put(new_folio);
out_release_old:
folio_put(old_folio);

- spin_lock(ptl); /* Caller expects lock to be held */
+ spin_lock(vmf->ptl); /* Caller expects lock to be held */

delayacct_wpcopy_end();
return ret;
@@ -6365,8 +6366,7 @@ static vm_fault_t hugetlb_no_page(struct mm_struct *mm,
hugetlb_count_add(pages_per_huge_page(h), mm);
if ((vmf->flags & FAULT_FLAG_WRITE) && !(vma->vm_flags & VM_SHARED)) {
/* Optimization, do the COW without a second fault */
- ret = hugetlb_wp(mm, vma, vmf->real_address, vmf->pte,
- vmf->flags, folio, vmf->ptl, vmf);
+ ret = hugetlb_wp(mm, vma, folio, vmf);
}

spin_unlock(vmf->ptl);
@@ -6579,8 +6579,7 @@ vm_fault_t hugetlb_fault(struct mm_struct *mm, struct vm_area_struct *vma,

if (flags & (FAULT_FLAG_WRITE|FAULT_FLAG_UNSHARE)) {
if (!huge_pte_write(vmf.orig_pte)) {
- ret = hugetlb_wp(mm, vma, address, vmf.pte, flags,
- pagecache_folio, vmf.ptl, &vmf);
+ ret = hugetlb_wp(mm, vma, pagecache_folio, &vmf);
goto out_put_page;
} else if (likely(flags & FAULT_FLAG_WRITE)) {
vmf.orig_pte = huge_pte_mkdirty(vmf.orig_pte);
--
2.43.0