diff options
Diffstat (limited to 'mm/hugetlb.c')
| -rw-r--r-- | mm/hugetlb.c | 174 |
1 files changed, 152 insertions, 22 deletions
diff --git a/mm/hugetlb.c b/mm/hugetlb.c index 51ae41d0fbc0..4e5815ed7a8e 100644 --- a/mm/hugetlb.c +++ b/mm/hugetlb.c @@ -240,11 +240,14 @@ struct file_region { /* * Add the huge page range represented by [f, t) to the reserve - * map. Existing regions will be expanded to accommodate the - * specified range. We know only existing regions need to be - * expanded, because region_add is only called after region_chg - * with the same range. If a new file_region structure must - * be allocated, it is done in region_chg. + * map. In the normal case, existing regions will be expanded + * to accommodate the specified range. Sufficient regions should + * exist for expansion due to the previous call to region_chg + * with the same range. However, it is possible that region_del + * could have been called after region_chg and modifed the map + * in such a way that no region exists to be expanded. In this + * case, pull a region descriptor from the cache associated with + * the map and use that for the new range. * * Return the number of new huge pages added to the map. This * number is greater than or equal to zero. @@ -261,6 +264,28 @@ static long region_add(struct resv_map *resv, long f, long t) if (f <= rg->to) break; + /* + * If no region exists which can be expanded to include the + * specified range, the list must have been modified by an + * interleving call to region_del(). Pull a region descriptor + * from the cache and use it for this range. + */ + if (&rg->link == head || t < rg->from) { + VM_BUG_ON(resv->region_cache_count <= 0); + + resv->region_cache_count--; + nrg = list_first_entry(&resv->region_cache, struct file_region, + link); + list_del(&nrg->link); + + nrg->from = f; + nrg->to = t; + list_add(&nrg->link, rg->link.prev); + + add += t - f; + goto out_locked; + } + /* Round our left edge to the current segment if it encloses us. */ if (f > rg->from) f = rg->from; @@ -294,6 +319,8 @@ static long region_add(struct resv_map *resv, long f, long t) add += t - nrg->to; /* Added to end of region */ nrg->to = t; +out_locked: + resv->adds_in_progress--; spin_unlock(&resv->lock); VM_BUG_ON(add < 0); return add; @@ -312,11 +339,14 @@ static long region_add(struct resv_map *resv, long f, long t) * so that the subsequent region_add call will have all the * regions it needs and will not fail. * - * Returns the number of huge pages that need to be added - * to the existing reservation map for the range [f, t). - * This number is greater or equal to zero. -ENOMEM is - * returned if a new file_region structure is needed and can - * not be allocated. + * Upon entry, region_chg will also examine the cache of region descriptors + * associated with the map. If there are not enough descriptors cached, one + * will be allocated for the in progress add operation. + * + * Returns the number of huge pages that need to be added to the existing + * reservation map for the range [f, t). This number is greater or equal to + * zero. -ENOMEM is returned if a new file_region structure or cache entry + * is needed and can not be allocated. */ static long region_chg(struct resv_map *resv, long f, long t) { @@ -326,6 +356,31 @@ static long region_chg(struct resv_map *resv, long f, long t) retry: spin_lock(&resv->lock); +retry_locked: + resv->adds_in_progress++; + + /* + * Check for sufficient descriptors in the cache to accommodate + * the number of in progress add operations. + */ + if (resv->adds_in_progress > resv->region_cache_count) { + struct file_region *trg; + + VM_BUG_ON(resv->adds_in_progress - resv->region_cache_count > 1); + /* Must drop lock to allocate a new descriptor. */ + resv->adds_in_progress--; + spin_unlock(&resv->lock); + + trg = kmalloc(sizeof(*trg), GFP_KERNEL); + if (!trg) + return -ENOMEM; + + spin_lock(&resv->lock); + list_add(&trg->link, &resv->region_cache); + resv->region_cache_count++; + goto retry_locked; + } + /* Locate the region we are before or in. */ list_for_each_entry(rg, head, link) if (f <= rg->to) @@ -336,6 +391,7 @@ retry: * size such that we can guarantee to record the reservation. */ if (&rg->link == head || t < rg->from) { if (!nrg) { + resv->adds_in_progress--; spin_unlock(&resv->lock); nrg = kmalloc(sizeof(*nrg), GFP_KERNEL); if (!nrg) @@ -385,6 +441,25 @@ out_nrg: } /* + * Abort the in progress add operation. The adds_in_progress field + * of the resv_map keeps track of the operations in progress between + * calls to region_chg and region_add. Operations are sometimes + * aborted after the call to region_chg. In such cases, region_abort + * is called to decrement the adds_in_progress counter. + * + * NOTE: The range arguments [f, t) are not needed or used in this + * routine. They are kept to make reading the calling code easier as + * arguments will match the associated region_chg call. + */ +static void region_abort(struct resv_map *resv, long f, long t) +{ + spin_lock(&resv->lock); + VM_BUG_ON(!resv->region_cache_count); + resv->adds_in_progress--; + spin_unlock(&resv->lock); +} + +/* * Truncate the reserve map at index 'end'. Modify/truncate any * region which contains end. Delete any regions past end. * Return the number of huge pages removed from the map. @@ -544,22 +619,44 @@ static void set_vma_private_data(struct vm_area_struct *vma, struct resv_map *resv_map_alloc(void) { struct resv_map *resv_map = kmalloc(sizeof(*resv_map), GFP_KERNEL); - if (!resv_map) + struct file_region *rg = kmalloc(sizeof(*rg), GFP_KERNEL); + + if (!resv_map || !rg) { + kfree(resv_map); + kfree(rg); return NULL; + } kref_init(&resv_map->refs); spin_lock_init(&resv_map->lock); INIT_LIST_HEAD(&resv_map->regions); + resv_map->adds_in_progress = 0; + + INIT_LIST_HEAD(&resv_map->region_cache); + list_add(&rg->link, &resv_map->region_cache); + resv_map->region_cache_count = 1; + return resv_map; } void resv_map_release(struct kref *ref) { struct resv_map *resv_map = container_of(ref, struct resv_map, refs); + struct list_head *head = &resv_map->region_cache; + struct file_region *rg, *trg; /* Clear out any active regions before we release the map. */ region_truncate(resv_map, 0); + + /* ... and any entries left in the cache */ + list_for_each_entry_safe(rg, trg, head, link) { + list_del(&rg->link); + kfree(rg); + } + + VM_BUG_ON(resv_map->adds_in_progress); + kfree(resv_map); } @@ -1473,16 +1570,18 @@ static void return_unused_surplus_pages(struct hstate *h, } } + /* - * vma_needs_reservation and vma_commit_reservation are used by the huge - * page allocation routines to manage reservations. + * vma_needs_reservation, vma_commit_reservation and vma_abort_reservation + * are used by the huge page allocation routines to manage reservations. * * vma_needs_reservation is called to determine if the huge page at addr * within the vma has an associated reservation. If a reservation is * needed, the value 1 is returned. The caller is then responsible for * managing the global reservation and subpool usage counts. After * the huge page has been allocated, vma_commit_reservation is called - * to add the page to the reservation map. + * to add the page to the reservation map. If the reservation must be + * aborted instead of committed, vma_abort_reservation is called. * * In the normal case, vma_commit_reservation returns the same value * as the preceding vma_needs_reservation call. The only time this @@ -1490,9 +1589,14 @@ static void return_unused_surplus_pages(struct hstate *h, * is the responsibility of the caller to notice the difference and * take appropriate action. */ +enum vma_resv_mode { + VMA_NEEDS_RESV, + VMA_COMMIT_RESV, + VMA_ABORT_RESV, +}; static long __vma_reservation_common(struct hstate *h, struct vm_area_struct *vma, unsigned long addr, - bool commit) + enum vma_resv_mode mode) { struct resv_map *resv; pgoff_t idx; @@ -1503,10 +1607,20 @@ static long __vma_reservation_common(struct hstate *h, return 1; idx = vma_hugecache_offset(h, vma, addr); - if (commit) - ret = region_add(resv, idx, idx + 1); - else + switch (mode) { + case VMA_NEEDS_RESV: ret = region_chg(resv, idx, idx + 1); + break; + case VMA_COMMIT_RESV: + ret = region_add(resv, idx, idx + 1); + break; + case VMA_ABORT_RESV: + region_abort(resv, idx, idx + 1); + ret = 0; + break; + default: + BUG(); + } if (vma->vm_flags & VM_MAYSHARE) return ret; @@ -1517,13 +1631,19 @@ static long __vma_reservation_common(struct hstate *h, static long vma_needs_reservation(struct hstate *h, struct vm_area_struct *vma, unsigned long addr) { - return __vma_reservation_common(h, vma, addr, false); + return __vma_reservation_common(h, vma, addr, VMA_NEEDS_RESV); } static long vma_commit_reservation(struct hstate *h, struct vm_area_struct *vma, unsigned long addr) { - return __vma_reservation_common(h, vma, addr, true); + return __vma_reservation_common(h, vma, addr, VMA_COMMIT_RESV); +} + +static void vma_abort_reservation(struct hstate *h, + struct vm_area_struct *vma, unsigned long addr) +{ + (void)__vma_reservation_common(h, vma, addr, VMA_ABORT_RESV); } static struct page *alloc_huge_page(struct vm_area_struct *vma, @@ -1549,8 +1669,10 @@ static struct page *alloc_huge_page(struct vm_area_struct *vma, if (chg < 0) return ERR_PTR(-ENOMEM); if (chg || avoid_reserve) - if (hugepage_subpool_get_pages(spool, 1) < 0) + if (hugepage_subpool_get_pages(spool, 1) < 0) { + vma_abort_reservation(h, vma, addr); return ERR_PTR(-ENOSPC); + } ret = hugetlb_cgroup_charge_cgroup(idx, pages_per_huge_page(h), &h_cg); if (ret) @@ -1596,6 +1718,7 @@ out_uncharge_cgroup: out_subpool_put: if (chg || avoid_reserve) hugepage_subpool_put_pages(spool, 1); + vma_abort_reservation(h, vma, addr); return ERR_PTR(-ENOSPC); } @@ -3236,11 +3359,14 @@ retry: * any allocations necessary to record that reservation occur outside * the spinlock. */ - if ((flags & FAULT_FLAG_WRITE) && !(vma->vm_flags & VM_SHARED)) + if ((flags & FAULT_FLAG_WRITE) && !(vma->vm_flags & VM_SHARED)) { if (vma_needs_reservation(h, vma, address) < 0) { ret = VM_FAULT_OOM; goto backout_unlocked; } + /* Just decrements count, does not deallocate */ + vma_abort_reservation(h, vma, address); + } ptl = huge_pte_lockptr(h, mm, ptep); spin_lock(ptl); @@ -3387,6 +3513,8 @@ int hugetlb_fault(struct mm_struct *mm, struct vm_area_struct *vma, ret = VM_FAULT_OOM; goto out_mutex; } + /* Just decrements count, does not deallocate */ + vma_abort_reservation(h, vma, address); if (!(vma->vm_flags & VM_MAYSHARE)) pagecache_page = hugetlbfs_pagecache_page(h, @@ -3726,6 +3854,8 @@ int hugetlb_reserve_pages(struct inode *inode, } return 0; out_err: + if (!vma || vma->vm_flags & VM_MAYSHARE) + region_abort(resv_map, from, to); if (vma && is_vma_resv_set(vma, HPAGE_RESV_OWNER)) kref_put(&resv_map->refs, resv_map_release); return ret; |