diff options
| -rw-r--r-- | include/linux/pagewalk.h | 34 | ||||
| -rw-r--r-- | mm/hmm.c | 58 | ||||
| -rw-r--r-- | mm/pagewalk.c | 50 |
3 files changed, 95 insertions, 47 deletions
diff --git a/include/linux/pagewalk.h b/include/linux/pagewalk.h index 6ec82e92c87f..aa6a0b63964e 100644 --- a/include/linux/pagewalk.h +++ b/include/linux/pagewalk.h @@ -8,15 +8,15 @@ struct mm_walk; /** * mm_walk_ops - callbacks for walk_page_range - * @pud_entry: if set, called for each non-empty PUD (2nd-level) entry - * this handler should only handle pud_trans_huge() puds. - * the pmd_entry or pte_entry callbacks will be used for - * regular PUDs. - * @pmd_entry: if set, called for each non-empty PMD (3rd-level) entry + * @pgd_entry: if set, called for each non-empty PGD (top-level) entry + * @p4d_entry: if set, called for each non-empty P4D entry + * @pud_entry: if set, called for each non-empty PUD entry + * @pmd_entry: if set, called for each non-empty PMD entry * this handler is required to be able to handle * pmd_trans_huge() pmds. They may simply choose to * split_huge_page() instead of handling it explicitly. - * @pte_entry: if set, called for each non-empty PTE (4th-level) entry + * @pte_entry: if set, called for each non-empty PTE (lowest-level) + * entry * @pte_hole: if set, called for each hole at all levels * @hugetlb_entry: if set, called for each hugetlb entry * @test_walk: caller specific callback function to determine whether @@ -27,8 +27,15 @@ struct mm_walk; * @pre_vma: if set, called before starting walk on a non-null vma. * @post_vma: if set, called after a walk on a non-null vma, provided * that @pre_vma and the vma walk succeeded. + * + * p?d_entry callbacks are called even if those levels are folded on a + * particular architecture/configuration. */ struct mm_walk_ops { + int (*pgd_entry)(pgd_t *pgd, unsigned long addr, + unsigned long next, struct mm_walk *walk); + int (*p4d_entry)(p4d_t *p4d, unsigned long addr, + unsigned long next, struct mm_walk *walk); int (*pud_entry)(pud_t *pud, unsigned long addr, unsigned long next, struct mm_walk *walk); int (*pmd_entry)(pmd_t *pmd, unsigned long addr, @@ -47,11 +54,25 @@ struct mm_walk_ops { void (*post_vma)(struct mm_walk *walk); }; +/* + * Action for pud_entry / pmd_entry callbacks. + * ACTION_SUBTREE is the default + */ +enum page_walk_action { + /* Descend to next level, splitting huge pages if needed and possible */ + ACTION_SUBTREE = 0, + /* Continue to next entry at this level (ignoring any subtree) */ + ACTION_CONTINUE = 1, + /* Call again for this entry */ + ACTION_AGAIN = 2 +}; + /** * mm_walk - walk_page_range data * @ops: operation to call during the walk * @mm: mm_struct representing the target process of page table walk * @vma: vma currently walked (NULL if walking outside vmas) + * @action: next action to perform (see enum page_walk_action) * @private: private data for callbacks' usage * * (see the comment on walk_page_range() for more details) @@ -60,6 +81,7 @@ struct mm_walk { const struct mm_walk_ops *ops; struct mm_struct *mm; struct vm_area_struct *vma; + enum page_walk_action action; void *private; }; @@ -474,23 +474,32 @@ static int hmm_vma_walk_pud(pud_t *pudp, unsigned long start, unsigned long end, { struct hmm_vma_walk *hmm_vma_walk = walk->private; struct hmm_range *range = hmm_vma_walk->range; - unsigned long addr = start, next; - pmd_t *pmdp; + unsigned long addr = start; pud_t pud; - int ret; + int ret = 0; + spinlock_t *ptl = pud_trans_huge_lock(pudp, walk->vma); + + if (!ptl) + return 0; + + /* Normally we don't want to split the huge page */ + walk->action = ACTION_CONTINUE; -again: pud = READ_ONCE(*pudp); - if (pud_none(pud)) - return hmm_vma_walk_hole(start, end, walk); + if (pud_none(pud)) { + ret = hmm_vma_walk_hole(start, end, walk); + goto out_unlock; + } if (pud_huge(pud) && pud_devmap(pud)) { unsigned long i, npages, pfn; uint64_t *pfns, cpu_flags; bool fault, write_fault; - if (!pud_present(pud)) - return hmm_vma_walk_hole(start, end, walk); + if (!pud_present(pud)) { + ret = hmm_vma_walk_hole(start, end, walk); + goto out_unlock; + } i = (addr - range->start) >> PAGE_SHIFT; npages = (end - addr) >> PAGE_SHIFT; @@ -499,16 +508,20 @@ again: cpu_flags = pud_to_hmm_pfn_flags(range, pud); hmm_range_need_fault(hmm_vma_walk, pfns, npages, cpu_flags, &fault, &write_fault); - if (fault || write_fault) - return hmm_vma_walk_hole_(addr, end, fault, - write_fault, walk); + if (fault || write_fault) { + ret = hmm_vma_walk_hole_(addr, end, fault, + write_fault, walk); + goto out_unlock; + } pfn = pud_pfn(pud) + ((addr & ~PUD_MASK) >> PAGE_SHIFT); for (i = 0; i < npages; ++i, ++pfn) { hmm_vma_walk->pgmap = get_dev_pagemap(pfn, hmm_vma_walk->pgmap); - if (unlikely(!hmm_vma_walk->pgmap)) - return -EBUSY; + if (unlikely(!hmm_vma_walk->pgmap)) { + ret = -EBUSY; + goto out_unlock; + } pfns[i] = hmm_device_entry_from_pfn(range, pfn) | cpu_flags; } @@ -517,22 +530,15 @@ again: hmm_vma_walk->pgmap = NULL; } hmm_vma_walk->last = end; - return 0; + goto out_unlock; } - split_huge_pud(walk->vma, pudp, addr); - if (pud_none(*pudp)) - goto again; + /* Ask for the PUD to be split */ + walk->action = ACTION_SUBTREE; - pmdp = pmd_offset(pudp, addr); - do { - next = pmd_addr_end(addr, end); - ret = hmm_vma_walk_pmd(pmdp, addr, next, walk); - if (ret) - return ret; - } while (pmdp++, addr = next, addr != end); - - return 0; +out_unlock: + spin_unlock(ptl); + return ret; } #else #define hmm_vma_walk_pud NULL diff --git a/mm/pagewalk.c b/mm/pagewalk.c index ea0b9e606ad1..690af44609e2 100644 --- a/mm/pagewalk.c +++ b/mm/pagewalk.c @@ -46,6 +46,9 @@ again: break; continue; } + + walk->action = ACTION_SUBTREE; + /* * This implies that each ->pmd_entry() handler * needs to know about pmd_trans_huge() pmds @@ -55,16 +58,21 @@ again: if (err) break; + if (walk->action == ACTION_AGAIN) + goto again; + /* * Check this here so we only break down trans_huge * pages when we _need_ to */ - if (!ops->pte_entry) + if (walk->action == ACTION_CONTINUE || + !(ops->pte_entry)) continue; split_huge_pmd(walk->vma, pmd, addr); if (pmd_trans_unstable(pmd)) goto again; + err = walk_pte_range(pmd, addr, next, walk); if (err) break; @@ -93,24 +101,25 @@ static int walk_pud_range(p4d_t *p4d, unsigned long addr, unsigned long end, continue; } - if (ops->pud_entry) { - spinlock_t *ptl = pud_trans_huge_lock(pud, walk->vma); + walk->action = ACTION_SUBTREE; - if (ptl) { - err = ops->pud_entry(pud, addr, next, walk); - spin_unlock(ptl); - if (err) - break; - continue; - } - } + if (ops->pud_entry) + err = ops->pud_entry(pud, addr, next, walk); + if (err) + break; + + if (walk->action == ACTION_AGAIN) + goto again; + + if (walk->action == ACTION_CONTINUE || + !(ops->pmd_entry || ops->pte_entry)) + continue; split_huge_pud(walk->vma, pud, addr); if (pud_none(*pud)) goto again; - if (ops->pmd_entry || ops->pte_entry) - err = walk_pmd_range(pud, addr, next, walk); + err = walk_pmd_range(pud, addr, next, walk); if (err) break; } while (pud++, addr = next, addr != end); @@ -136,7 +145,12 @@ static int walk_p4d_range(pgd_t *pgd, unsigned long addr, unsigned long end, break; continue; } - if (ops->pmd_entry || ops->pte_entry) + if (ops->p4d_entry) { + err = ops->p4d_entry(p4d, addr, next, walk); + if (err) + break; + } + if (ops->pud_entry || ops->pmd_entry || ops->pte_entry) err = walk_pud_range(p4d, addr, next, walk); if (err) break; @@ -163,7 +177,13 @@ static int walk_pgd_range(unsigned long addr, unsigned long end, break; continue; } - if (ops->pmd_entry || ops->pte_entry) + if (ops->pgd_entry) { + err = ops->pgd_entry(pgd, addr, next, walk); + if (err) + break; + } + if (ops->p4d_entry || ops->pud_entry || ops->pmd_entry || + ops->pte_entry) err = walk_p4d_range(pgd, addr, next, walk); if (err) break; |