On 16.09.24 11:43, 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@xxxxxxxxxx/
Signed-off-by: Dev Jain <dev.jain@xxxxxxx>
---
mm/huge_memory.c | 108 +++++++++++++++++++++++++++++------------------
1 file changed, 66 insertions(+), 42 deletions(-)
diff --git a/mm/huge_memory.c b/mm/huge_memory.c
index 2a73efea02d7..cdc632b8dc9c 100644
--- a/mm/huge_memory.c
+++ b/mm/huge_memory.c
@@ -1146,47 +1146,88 @@ 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);
- 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;
+ }
+ 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 __pmd_thp_fault_success_stats(struct vm_area_struct *vma)
+{
+ 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);
+}
just inline that into map_anon_folio_pmd(), please. map_anon_folio_pmd
is perfectly readable ;)
+
+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);
+ __pmd_thp_fault_success_stats(vma);
+}
+
+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;
+ pgtable_t pgtable = NULL;
+ struct folio *folio;
+ vm_fault_t ret = 0;
+
+ folio = vma_alloc_anon_folio_pmd(vma, vmf->address);
+ if (unlikely(!folio)) {
+ ret = VM_FAULT_FALLBACK;
+ goto release;
Why not simply "return VM_FAULT_FALLBACK;" ? There is nothing to
release. Then you can avoid the
"if (folio)" below and even stop initializing pgtable to NULL.
With these things take care of
Acked-by: David Hildenbrand <david@xxxxxxxxxx>
--
Cheers,
David / dhildenb
