[PATCH v5 1/2] mm: Abstract THP allocation
Kefeng Wang
wangkefeng.wang at huawei.com
Tue Sep 24 04:20:03 PDT 2024
On 2024/9/24 18:16, Dev Jain wrote:
> In preparation for the second patch, abstract away the THP allocation
> logic present in the create_huge_pmd() path, which corresponds to the
> faulting case when no page is present.
>
> There should be no functional change as a result of applying this patch,
> except that, as David notes at [1], a PMD-aligned address should
> be passed to update_mmu_cache_pmd().
>
> [1]: https://lore.kernel.org/all/ddd3fcd2-48b3-4170-bcaa-2fe66e093f43@redhat.com/
>
> Acked-by: David Hildenbrand <david at redhat.com>
> Signed-off-by: Dev Jain <dev.jain at arm.com>
> ---
> mm/huge_memory.c | 98 ++++++++++++++++++++++++++++--------------------
> 1 file changed, 57 insertions(+), 41 deletions(-)
>
> diff --git a/mm/huge_memory.c b/mm/huge_memory.c
> index 4e34b7f89daf..bdbf67c18f6c 100644
> --- a/mm/huge_memory.c
> +++ b/mm/huge_memory.c
> @@ -1148,47 +1148,81 @@ unsigned long thp_get_unmapped_area(struct file *filp, unsigned long addr,
> }
> EXPORT_SYMBOL_GPL(thp_get_unmapped_area);
>
> -static vm_fault_t __do_huge_pmd_anonymous_page(struct vm_fault *vmf,
> - struct page *page, gfp_t gfp)
> +static struct folio *vma_alloc_anon_folio_pmd(struct vm_area_struct *vma,
> + unsigned long addr)
> {
> - struct vm_area_struct *vma = vmf->vma;
> - struct folio *folio = page_folio(page);
> - pgtable_t pgtable;
> - unsigned long haddr = vmf->address & HPAGE_PMD_MASK;
> - vm_fault_t ret = 0;
> + unsigned long haddr = addr & HPAGE_PMD_MASK;
> + gfp_t gfp = vma_thp_gfp_mask(vma);
> + const int order = HPAGE_PMD_ORDER;
> + struct folio *folio = vma_alloc_folio(gfp, order, vma, haddr, true);
There is a warning without NUMA,
../mm/huge_memory.c: In function ‘vma_alloc_anon_folio_pmd’:
../mm/huge_memory.c:1154:16: warning: unused variable ‘haddr’
[-Wunused-variable]
1154 | unsigned long haddr = addr & HPAGE_PMD_MASK;
| ^~~~~
diff --git a/mm/huge_memory.c b/mm/huge_memory.c
index c584e77efe10..147a6e069c71 100644
--- a/mm/huge_memory.c
+++ b/mm/huge_memory.c
@@ -1151,11 +1151,11 @@ EXPORT_SYMBOL_GPL(thp_get_unmapped_area);
static struct folio *vma_alloc_anon_folio_pmd(struct vm_area_struct *vma,
unsigned long addr)
{
- unsigned long haddr = addr & HPAGE_PMD_MASK;
gfp_t gfp = vma_thp_gfp_mask(vma);
const int order = HPAGE_PMD_ORDER;
- struct folio *folio = vma_alloc_folio(gfp, order, vma, haddr, true);
+ struct folio *folio;
+ folio = vma_alloc_folio(gfp, order, vma, addr & HPAGE_PMD_MASK,
true);
if (unlikely(!folio)) {
count_vm_event(THP_FAULT_FALLBACK);
count_mthp_stat(order, MTHP_STAT_ANON_FAULT_FALLBACK);
>
> - VM_BUG_ON_FOLIO(!folio_test_large(folio), folio);
> + if (unlikely(!folio)) {
> + count_vm_event(THP_FAULT_FALLBACK);
> + count_mthp_stat(order, MTHP_STAT_ANON_FAULT_FALLBACK);
> + goto out;
Maybe return NULL to omit the out?
Reviewed-by: Kefeng Wang <wangkefeng.wang at huawei.com>
> + }
>
> + VM_BUG_ON_FOLIO(!folio_test_large(folio), folio);
> if (mem_cgroup_charge(folio, vma->vm_mm, gfp)) {
> folio_put(folio);
> count_vm_event(THP_FAULT_FALLBACK);
> count_vm_event(THP_FAULT_FALLBACK_CHARGE);
> - count_mthp_stat(HPAGE_PMD_ORDER, MTHP_STAT_ANON_FAULT_FALLBACK);
> - count_mthp_stat(HPAGE_PMD_ORDER, MTHP_STAT_ANON_FAULT_FALLBACK_CHARGE);
> - return VM_FAULT_FALLBACK;
> + count_mthp_stat(order, MTHP_STAT_ANON_FAULT_FALLBACK);
> + count_mthp_stat(order, MTHP_STAT_ANON_FAULT_FALLBACK_CHARGE);
> + return NULL;
> }
> folio_throttle_swaprate(folio, gfp);
>
> - pgtable = pte_alloc_one(vma->vm_mm);
> - if (unlikely(!pgtable)) {
> - ret = VM_FAULT_OOM;
> - goto release;
> - }
> -
> - folio_zero_user(folio, vmf->address);
> + folio_zero_user(folio, addr);
> /*
> * The memory barrier inside __folio_mark_uptodate makes sure that
> * folio_zero_user writes become visible before the set_pmd_at()
> * write.
> */
> __folio_mark_uptodate(folio);
> +out:
> + return folio;
> +}
> +
> +static void map_anon_folio_pmd(struct folio *folio, pmd_t *pmd,
> + struct vm_area_struct *vma, unsigned long haddr)
> +{
> + pmd_t entry;
> +
> + entry = mk_huge_pmd(&folio->page, vma->vm_page_prot);
> + entry = maybe_pmd_mkwrite(pmd_mkdirty(entry), vma);
> + folio_add_new_anon_rmap(folio, vma, haddr, RMAP_EXCLUSIVE);
> + folio_add_lru_vma(folio, vma);
> + set_pmd_at(vma->vm_mm, haddr, pmd, entry);
> + update_mmu_cache_pmd(vma, haddr, pmd);
> + add_mm_counter(vma->vm_mm, MM_ANONPAGES, HPAGE_PMD_NR);
> + count_vm_event(THP_FAULT_ALLOC);
> + count_mthp_stat(HPAGE_PMD_ORDER, MTHP_STAT_ANON_FAULT_ALLOC);
> + count_memcg_event_mm(vma->vm_mm, THP_FAULT_ALLOC);
> +}
> +
> +static vm_fault_t __do_huge_pmd_anonymous_page(struct vm_fault *vmf)
> +{
> + unsigned long haddr = vmf->address & HPAGE_PMD_MASK;
> + struct vm_area_struct *vma = vmf->vma;
> + struct folio *folio;
> + pgtable_t pgtable;
> + vm_fault_t ret = 0;
> +
> + folio = vma_alloc_anon_folio_pmd(vma, vmf->address);
> + if (unlikely(!folio))
> + return VM_FAULT_FALLBACK;
> +
> + pgtable = pte_alloc_one(vma->vm_mm);
> + if (unlikely(!pgtable)) {
> + ret = VM_FAULT_OOM;
> + goto release;
> + }
>
> vmf->ptl = pmd_lock(vma->vm_mm, vmf->pmd);
> if (unlikely(!pmd_none(*vmf->pmd))) {
> goto unlock_release;
> } else {
> - pmd_t entry;
> -
> ret = check_stable_address_space(vma->vm_mm);
> if (ret)
> goto unlock_release;
> @@ -1202,21 +1236,11 @@ static vm_fault_t __do_huge_pmd_anonymous_page(struct vm_fault *vmf,
> VM_BUG_ON(ret & VM_FAULT_FALLBACK);
> return ret;
> }
> -
> - entry = mk_huge_pmd(page, vma->vm_page_prot);
> - entry = maybe_pmd_mkwrite(pmd_mkdirty(entry), vma);
> - folio_add_new_anon_rmap(folio, vma, haddr, RMAP_EXCLUSIVE);
> - folio_add_lru_vma(folio, vma);
> pgtable_trans_huge_deposit(vma->vm_mm, vmf->pmd, pgtable);
> - set_pmd_at(vma->vm_mm, haddr, vmf->pmd, entry);
> - update_mmu_cache_pmd(vma, vmf->address, vmf->pmd);
> - add_mm_counter(vma->vm_mm, MM_ANONPAGES, HPAGE_PMD_NR);
> + map_anon_folio_pmd(folio, vmf->pmd, vma, haddr);
> mm_inc_nr_ptes(vma->vm_mm);
> deferred_split_folio(folio, false);
> spin_unlock(vmf->ptl);
> - count_vm_event(THP_FAULT_ALLOC);
> - count_mthp_stat(HPAGE_PMD_ORDER, MTHP_STAT_ANON_FAULT_ALLOC);
> - count_memcg_event_mm(vma->vm_mm, THP_FAULT_ALLOC);
> }
>
> return 0;
> @@ -1283,8 +1307,6 @@ static void set_huge_zero_folio(pgtable_t pgtable, struct mm_struct *mm,
> vm_fault_t do_huge_pmd_anonymous_page(struct vm_fault *vmf)
> {
> struct vm_area_struct *vma = vmf->vma;
> - gfp_t gfp;
> - struct folio *folio;
> unsigned long haddr = vmf->address & HPAGE_PMD_MASK;
> vm_fault_t ret;
>
> @@ -1335,14 +1357,8 @@ vm_fault_t do_huge_pmd_anonymous_page(struct vm_fault *vmf)
> }
> return ret;
> }
> - gfp = vma_thp_gfp_mask(vma);
> - folio = vma_alloc_folio(gfp, HPAGE_PMD_ORDER, vma, haddr, true);
> - if (unlikely(!folio)) {
> - count_vm_event(THP_FAULT_FALLBACK);
> - count_mthp_stat(HPAGE_PMD_ORDER, MTHP_STAT_ANON_FAULT_FALLBACK);
> - return VM_FAULT_FALLBACK;
> - }
> - return __do_huge_pmd_anonymous_page(vmf, &folio->page, gfp);
> +
> + return __do_huge_pmd_anonymous_page(vmf);
> }
>
> static void insert_pfn_pmd(struct vm_area_struct *vma, unsigned long addr,
More information about the linux-arm-kernel
mailing list