[PATCH v2 2/3] hugetlb: Convert hugetlb_no_page() to use struct vm_fault

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

hugetlb_no_page() can use the struct vm_fault passed in from
hugetlb_fault(). This alleviates the stack by consolidating 7
variables into a single struct.

Signed-off-by: Vishal Moola (Oracle) <vishal.moola@gmail.com>
---
mm/hugetlb.c | 59 ++++++++++++++++++++++++++--------------------------
1 file changed, 29 insertions(+), 30 deletions(-)

diff --git a/mm/hugetlb.c b/mm/hugetlb.c
index 360b82374a89..aca2f11b4138 100644
--- a/mm/hugetlb.c
+++ b/mm/hugetlb.c
@@ -6189,9 +6189,7 @@ static bool hugetlb_pte_stable(struct hstate *h, struct mm_struct *mm,

static vm_fault_t hugetlb_no_page(struct mm_struct *mm,
struct vm_area_struct *vma,
- struct address_space *mapping, pgoff_t idx,
- unsigned long address, pte_t *ptep,
- pte_t old_pte, unsigned int flags,
+ struct address_space *mapping,
struct vm_fault *vmf)
{
struct hstate *h = hstate_vma(vma);
@@ -6200,10 +6198,8 @@ static vm_fault_t hugetlb_no_page(struct mm_struct *mm,
unsigned long size;
struct folio *folio;
pte_t new_pte;
- spinlock_t *ptl;
- unsigned long haddr = address & huge_page_mask(h);
bool new_folio, new_pagecache_folio = false;
- u32 hash = hugetlb_fault_mutex_hash(mapping, idx);
+ u32 hash = hugetlb_fault_mutex_hash(mapping, vmf->pgoff);

/*
* Currently, we are forced to kill the process in the event the
@@ -6222,10 +6218,10 @@ static vm_fault_t hugetlb_no_page(struct mm_struct *mm,
* before we get page_table_lock.
*/
new_folio = false;
- folio = filemap_lock_hugetlb_folio(h, mapping, idx);
+ folio = filemap_lock_hugetlb_folio(h, mapping, vmf->pgoff);
if (IS_ERR(folio)) {
size = i_size_read(mapping->host) >> huge_page_shift(h);
- if (idx >= size)
+ if (vmf->pgoff >= size)
goto out;
/* Check for page in userfault range */
if (userfaultfd_missing(vma)) {
@@ -6246,7 +6242,7 @@ static vm_fault_t hugetlb_no_page(struct mm_struct *mm,
* never happen on the page after UFFDIO_COPY has
* correctly installed the page and returned.
*/
- if (!hugetlb_pte_stable(h, mm, ptep, old_pte)) {
+ if (!hugetlb_pte_stable(h, mm, vmf->pte, vmf->orig_pte)) {
ret = 0;
goto out;
}
@@ -6255,7 +6251,7 @@ static vm_fault_t hugetlb_no_page(struct mm_struct *mm,
VM_UFFD_MISSING);
}

- folio = alloc_hugetlb_folio(vma, haddr, 0);
+ folio = alloc_hugetlb_folio(vma, vmf->address, 0);
if (IS_ERR(folio)) {
/*
* Returning error will result in faulting task being
@@ -6269,18 +6265,20 @@ static vm_fault_t hugetlb_no_page(struct mm_struct *mm,
* here. Before returning error, get ptl and make
* sure there really is no pte entry.
*/
- if (hugetlb_pte_stable(h, mm, ptep, old_pte))
+ if (hugetlb_pte_stable(h, mm, vmf->pte, vmf->orig_pte))
ret = vmf_error(PTR_ERR(folio));
else
ret = 0;
goto out;
}
- clear_huge_page(&folio->page, address, pages_per_huge_page(h));
+ clear_huge_page(&folio->page, vmf->real_address,
+ pages_per_huge_page(h));
__folio_mark_uptodate(folio);
new_folio = true;

if (vma->vm_flags & VM_MAYSHARE) {
- int err = hugetlb_add_to_page_cache(folio, mapping, idx);
+ int err = hugetlb_add_to_page_cache(folio, mapping,
+ vmf->pgoff);
if (err) {
/*
* err can't be -EEXIST which implies someone
@@ -6289,7 +6287,8 @@ static vm_fault_t hugetlb_no_page(struct mm_struct *mm,
* to the page cache. So it's safe to call
* restore_reserve_on_error() here.
*/
- restore_reserve_on_error(h, vma, haddr, folio);
+ restore_reserve_on_error(h, vma, vmf->address,
+ folio);
folio_put(folio);
goto out;
}
@@ -6319,7 +6318,7 @@ static vm_fault_t hugetlb_no_page(struct mm_struct *mm,
folio_unlock(folio);
folio_put(folio);
/* See comment in userfaultfd_missing() block above */
- if (!hugetlb_pte_stable(h, mm, ptep, old_pte)) {
+ if (!hugetlb_pte_stable(h, mm, vmf->pte, vmf->orig_pte)) {
ret = 0;
goto out;
}
@@ -6334,23 +6333,23 @@ static vm_fault_t hugetlb_no_page(struct mm_struct *mm,
* any allocations necessary to record that reservation occur outside
* the spinlock.
*/
- if ((flags & FAULT_FLAG_WRITE) && !(vma->vm_flags & VM_SHARED)) {
- if (vma_needs_reservation(h, vma, haddr) < 0) {
+ if ((vmf->flags & FAULT_FLAG_WRITE) && !(vma->vm_flags & VM_SHARED)) {
+ if (vma_needs_reservation(h, vma, vmf->address) < 0) {
ret = VM_FAULT_OOM;
goto backout_unlocked;
}
/* Just decrements count, does not deallocate */
- vma_end_reservation(h, vma, haddr);
+ vma_end_reservation(h, vma, vmf->address);
}

- ptl = huge_pte_lock(h, mm, ptep);
+ vmf->ptl = huge_pte_lock(h, mm, vmf->pte);
ret = 0;
/* If pte changed from under us, retry */
- if (!pte_same(huge_ptep_get(ptep), old_pte))
+ if (!pte_same(huge_ptep_get(vmf->pte), vmf->orig_pte))
goto backout;

if (anon_rmap)
- hugetlb_add_new_anon_rmap(folio, vma, haddr);
+ hugetlb_add_new_anon_rmap(folio, vma, vmf->address);
else
hugetlb_add_file_rmap(folio);
new_pte = make_huge_pte(vma, &folio->page, ((vma->vm_flags & VM_WRITE)
@@ -6359,17 +6358,18 @@ static vm_fault_t hugetlb_no_page(struct mm_struct *mm,
* If this pte was previously wr-protected, keep it wr-protected even
* if populated.
*/
- if (unlikely(pte_marker_uffd_wp(old_pte)))
+ if (unlikely(pte_marker_uffd_wp(vmf->orig_pte)))
new_pte = huge_pte_mkuffd_wp(new_pte);
- set_huge_pte_at(mm, haddr, ptep, new_pte, huge_page_size(h));
+ set_huge_pte_at(mm, vmf->address, vmf->pte, new_pte, huge_page_size(h));

hugetlb_count_add(pages_per_huge_page(h), mm);
- if ((flags & FAULT_FLAG_WRITE) && !(vma->vm_flags & VM_SHARED)) {
+ if ((vmf->flags & FAULT_FLAG_WRITE) && !(vma->vm_flags & VM_SHARED)) {
/* Optimization, do the COW without a second fault */
- ret = hugetlb_wp(mm, vma, address, ptep, flags, folio, ptl, vmf);
+ ret = hugetlb_wp(mm, vma, vmf->real_address, vmf->pte,
+ vmf->flags, folio, vmf->ptl, vmf);
}

- spin_unlock(ptl);
+ spin_unlock(vmf->ptl);

/*
* Only set hugetlb_migratable in newly allocated pages. Existing pages
@@ -6386,10 +6386,10 @@ static vm_fault_t hugetlb_no_page(struct mm_struct *mm,
return ret;

backout:
- spin_unlock(ptl);
+ spin_unlock(vmf->ptl);
backout_unlocked:
if (new_folio && !new_pagecache_folio)
- restore_reserve_on_error(h, vma, haddr, folio);
+ restore_reserve_on_error(h, vma, vmf->address, folio);

folio_unlock(folio);
folio_put(folio);
@@ -6485,8 +6485,7 @@ vm_fault_t hugetlb_fault(struct mm_struct *mm, struct vm_area_struct *vma,
* hugetlb_no_page will drop vma lock and hugetlb fault
* mutex internally, which make us return immediately.
*/
- return hugetlb_no_page(mm, vma, mapping, vmf.pgoff, address,
- vmf.pte, vmf.orig_pte, flags, &vmf);
+ return hugetlb_no_page(mm, vma, mapping, &vmf);
}

ret = 0;
--
2.43.0