/* Num pages scanned per node */
u32 node_load[MAX_NUMNODES];
- /* Last target selected in hpage_collapse_find_target_node() */
- int last_target_node;
+ /* nodemask for allocation fallback */
+ nodemask_t alloc_nmask;
};
/**
struct collapse_control khugepaged_collapse_control = {
.is_khugepaged = true,
- .last_target_node = NUMA_NO_NODE,
};
static bool hpage_collapse_scan_abort(int nid, struct collapse_control *cc)
target_node = nid;
}
- /* do some balance if several nodes have the same hit record */
- if (target_node <= cc->last_target_node)
- for (nid = cc->last_target_node + 1; nid < MAX_NUMNODES;
- nid++)
- if (max_value == cc->node_load[nid]) {
- target_node = nid;
- break;
- }
+ for_each_online_node(nid) {
+ if (max_value == cc->node_load[nid])
+ node_set(nid, cc->alloc_nmask);
+ }
- cc->last_target_node = target_node;
return target_node;
}
#else
}
#endif
-static bool hpage_collapse_alloc_page(struct page **hpage, gfp_t gfp, int node)
+static bool hpage_collapse_alloc_page(struct page **hpage, gfp_t gfp, int node,
+ nodemask_t *nmask)
{
- *hpage = __alloc_pages_node(node, gfp, HPAGE_PMD_ORDER);
+ *hpage = __alloc_pages(gfp, HPAGE_PMD_ORDER, node, nmask);
if (unlikely(!*hpage)) {
count_vm_event(THP_COLLAPSE_ALLOC_FAILED);
return false;
static int alloc_charge_hpage(struct page **hpage, struct mm_struct *mm,
struct collapse_control *cc)
{
- /* Only allocate from the target node */
gfp_t gfp = (cc->is_khugepaged ? alloc_hugepage_khugepaged_gfpmask() :
- GFP_TRANSHUGE) | __GFP_THISNODE;
+ GFP_TRANSHUGE);
int node = hpage_collapse_find_target_node(cc);
- if (!hpage_collapse_alloc_page(hpage, gfp, node))
+ if (!hpage_collapse_alloc_page(hpage, gfp, node, &cc->alloc_nmask))
return SCAN_ALLOC_HUGE_PAGE_FAIL;
if (unlikely(mem_cgroup_charge(page_folio(*hpage), mm, gfp)))
return SCAN_CGROUP_CHARGE_FAIL;
_pmd = pmdp_collapse_flush(vma, address, pmd);
spin_unlock(pmd_ptl);
mmu_notifier_invalidate_range_end(&range);
+ tlb_remove_table_sync_one();
spin_lock(pte_ptl);
result = __collapse_huge_page_isolate(vma, address, pte, cc,
goto out;
memset(cc->node_load, 0, sizeof(cc->node_load));
+ nodes_clear(cc->alloc_nmask);
pte = pte_offset_map_lock(mm, pmd, address, &ptl);
for (_address = address, _pte = pte; _pte < pte + HPAGE_PMD_NR;
_pte++, _address += PAGE_SIZE) {
return SCAN_SUCCEED;
}
+/*
+ * A note about locking:
+ * Trying to take the page table spinlocks would be useless here because those
+ * are only used to synchronize:
+ *
+ * - modifying terminal entries (ones that point to a data page, not to another
+ * page table)
+ * - installing *new* non-terminal entries
+ *
+ * Instead, we need roughly the same kind of protection as free_pgtables() or
+ * mm_take_all_locks() (but only for a single VMA):
+ * The mmap lock together with this VMA's rmap locks covers all paths towards
+ * the page table entries we're messing with here, except for hardware page
+ * table walks and lockless_pages_from_mm().
+ */
static void collapse_and_free_pmd(struct mm_struct *mm, struct vm_area_struct *vma,
unsigned long addr, pmd_t *pmdp)
{
- spinlock_t *ptl;
pmd_t pmd;
+ struct mmu_notifier_range range;
mmap_assert_write_locked(mm);
- ptl = pmd_lock(vma->vm_mm, pmdp);
+ if (vma->vm_file)
+ lockdep_assert_held_write(&vma->vm_file->f_mapping->i_mmap_rwsem);
+ /*
+ * All anon_vmas attached to the VMA have the same root and are
+ * therefore locked by the same lock.
+ */
+ if (vma->anon_vma)
+ lockdep_assert_held_write(&vma->anon_vma->root->rwsem);
+
+ mmu_notifier_range_init(&range, MMU_NOTIFY_CLEAR, 0, NULL, mm, addr,
+ addr + HPAGE_PMD_SIZE);
+ mmu_notifier_invalidate_range_start(&range);
pmd = pmdp_collapse_flush(vma, addr, pmdp);
- spin_unlock(ptl);
+ tlb_remove_table_sync_one();
+ mmu_notifier_invalidate_range_end(&range);
mm_dec_nr_ptes(mm);
page_table_check_pte_clear_range(mm, addr, pmd);
pte_free(mm, pmd_pgtable(pmd));
goto drop_hpage;
}
+ /*
+ * We need to lock the mapping so that from here on, only GUP-fast and
+ * hardware page walks can access the parts of the page tables that
+ * we're operating on.
+ * See collapse_and_free_pmd().
+ */
+ i_mmap_lock_write(vma->vm_file->f_mapping);
+
+ /*
+ * This spinlock should be unnecessary: Nobody else should be accessing
+ * the page tables under spinlock protection here, only
+ * lockless_pages_from_mm() and the hardware page walker can access page
+ * tables while all the high-level locks are held in write mode.
+ */
start_pte = pte_offset_map_lock(mm, pmd, haddr, &ptl);
result = SCAN_FAIL;
}
/* step 4: remove pte entries */
+ /* we make no change to anon, but protect concurrent anon page lookup */
+ if (vma->anon_vma)
+ anon_vma_lock_write(vma->anon_vma);
+
collapse_and_free_pmd(mm, vma, haddr, pmd);
+ if (vma->anon_vma)
+ anon_vma_unlock_write(vma->anon_vma);
+ i_mmap_unlock_write(vma->vm_file->f_mapping);
+
maybe_install_pmd:
/* step 5: install pmd entry */
result = install_pmd
abort:
pte_unmap_unlock(start_pte, ptl);
+ i_mmap_unlock_write(vma->vm_file->f_mapping);
goto drop_hpage;
}
* An alternative would be drop the check, but check that page
* table is clear before calling pmdp_collapse_flush() under
* ptl. It has higher chance to recover THP for the VMA, but
- * has higher cost too.
+ * has higher cost too. It would also probably require locking
+ * the anon_vma.
*/
if (vma->anon_vma) {
result = SCAN_PAGE_ANON;
present = 0;
swap = 0;
memset(cc->node_load, 0, sizeof(cc->node_load));
+ nodes_clear(cc->alloc_nmask);
rcu_read_lock();
xas_for_each(&xas, page, start + HPAGE_PMD_NR - 1) {
if (xas_retry(&xas, page))
}
}
- trace_mm_khugepaged_scan_file(mm, page, file->f_path.dentry->d_iname,
- present, swap, result);
+ trace_mm_khugepaged_scan_file(mm, page, file, present, swap, result);
return result;
}
#else
if (!cc)
return -ENOMEM;
cc->is_khugepaged = false;
- cc->last_target_node = NUMA_NO_NODE;
mmgrab(mm);
lru_add_drain_all();
goto out_nolock;
}
- hend = vma->vm_end & HPAGE_PMD_MASK;
+ hend = min(hend, vma->vm_end & HPAGE_PMD_MASK);
}
mmap_assert_locked(mm);
memset(cc->node_load, 0, sizeof(cc->node_load));
+ nodes_clear(cc->alloc_nmask);
if (IS_ENABLED(CONFIG_SHMEM) && vma->vm_file) {
struct file *file = get_file(vma->vm_file);
pgoff_t pgoff = linear_page_index(vma, addr);
projects / platform / kernel / linux-starfive.git / blobdiff