* prevent spurious OOMs when the hugepage pool is fully utilized.
*/
static int num_fault_mutexes;
-static struct mutex *htlb_fault_mutex_table ____cacheline_aligned_in_smp;
+struct mutex *hugetlb_fault_mutex_table ____cacheline_aligned_in_smp;
/* Forward declaration */
static int hugetlb_acct_memory(struct hstate *h, long delta);
/*
* 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.
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;
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;
* 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)
{
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)
* 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)
}
/*
- * 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.
+ * 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);
+}
+
+/*
+ * Delete the specified range [f, t) from the reserve map. If the
+ * t parameter is LONG_MAX, this indicates that ALL regions after f
+ * should be deleted. Locate the regions which intersect [f, t)
+ * and either trim, delete or split the existing regions.
+ *
+ * Returns the number of huge pages deleted from the reserve map.
+ * In the normal case, the return value is zero or more. In the
+ * case where a region must be split, a new region descriptor must
+ * be allocated. If the allocation fails, -ENOMEM will be returned.
+ * NOTE: If the parameter t == LONG_MAX, then we will never split
+ * a region and possibly return -ENOMEM. Callers specifying
+ * t == LONG_MAX do not need to check for -ENOMEM error.
*/
-static long region_truncate(struct resv_map *resv, long end)
+static long region_del(struct resv_map *resv, long f, long t)
{
struct list_head *head = &resv->regions;
struct file_region *rg, *trg;
- long chg = 0;
+ struct file_region *nrg = NULL;
+ long del = 0;
+retry:
spin_lock(&resv->lock);
- /* Locate the region we are either in or before. */
- list_for_each_entry(rg, head, link)
- if (end <= rg->to)
+ list_for_each_entry_safe(rg, trg, head, link) {
+ if (rg->to <= f)
+ continue;
+ if (rg->from >= t)
break;
- if (&rg->link == head)
- goto out;
- /* If we are in the middle of a region then adjust it. */
- if (end > rg->from) {
- chg = rg->to - end;
- rg->to = end;
- rg = list_entry(rg->link.next, typeof(*rg), link);
- }
+ if (f > rg->from && t < rg->to) { /* Must split region */
+ /*
+ * Check for an entry in the cache before dropping
+ * lock and attempting allocation.
+ */
+ if (!nrg &&
+ resv->region_cache_count > resv->adds_in_progress) {
+ nrg = list_first_entry(&resv->region_cache,
+ struct file_region,
+ link);
+ list_del(&nrg->link);
+ resv->region_cache_count--;
+ }
- /* Drop any remaining regions. */
- list_for_each_entry_safe(rg, trg, rg->link.prev, link) {
- if (&rg->link == head)
+ if (!nrg) {
+ spin_unlock(&resv->lock);
+ nrg = kmalloc(sizeof(*nrg), GFP_KERNEL);
+ if (!nrg)
+ return -ENOMEM;
+ goto retry;
+ }
+
+ del += t - f;
+
+ /* New entry for end of split region */
+ nrg->from = t;
+ nrg->to = rg->to;
+ INIT_LIST_HEAD(&nrg->link);
+
+ /* Original entry is trimmed */
+ rg->to = f;
+
+ list_add(&nrg->link, &rg->link);
+ nrg = NULL;
break;
- chg += rg->to - rg->from;
- list_del(&rg->link);
- kfree(rg);
+ }
+
+ if (f <= rg->from && t >= rg->to) { /* Remove entire region */
+ del += rg->to - rg->from;
+ list_del(&rg->link);
+ kfree(rg);
+ continue;
+ }
+
+ if (f <= rg->from) { /* Trim beginning of region */
+ del += t - rg->from;
+ rg->from = t;
+ } else { /* Trim end of region */
+ del += rg->to - f;
+ rg->to = f;
+ }
}
-out:
spin_unlock(&resv->lock);
- return chg;
+ kfree(nrg);
+ return del;
+}
+
+/*
+ * A rare out of memory error was encountered which prevented removal of
+ * the reserve map region for a page. The huge page itself was free'ed
+ * and removed from the page cache. This routine will adjust the subpool
+ * usage count, and the global reserve count if needed. By incrementing
+ * these counts, the reserve map entry which could not be deleted will
+ * appear as a "reserved" entry instead of simply dangling with incorrect
+ * counts.
+ */
+void hugetlb_fix_reserve_counts(struct inode *inode, bool restore_reserve)
+{
+ struct hugepage_subpool *spool = subpool_inode(inode);
+ long rsv_adjust;
+
+ rsv_adjust = hugepage_subpool_get_pages(spool, 1);
+ if (restore_reserve && rsv_adjust) {
+ struct hstate *h = hstate_inode(inode);
+
+ hugetlb_acct_memory(h, 1);
+ }
}
/*
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);
+ region_del(resv_map, 0, LONG_MAX);
+
+ /* ... 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);
}
}
/* Shared mappings always use reserves */
- if (vma->vm_flags & VM_MAYSHARE)
- return true;
+ if (vma->vm_flags & VM_MAYSHARE) {
+ /*
+ * We know VM_NORESERVE is not set. Therefore, there SHOULD
+ * be a region map for all pages. The only situation where
+ * there is no region map is if a hole was punched via
+ * fallocate. In this case, there really are no reverves to
+ * use. This situation is indicated if chg != 0.
+ */
+ if (chg)
+ return false;
+ else
+ return true;
+ }
/*
* Only the process that called mmap() has reserves for
}
}
+
/*
- * 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_end_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 page allocation fails,
+ * the reservation must be ended instead of committed. vma_end_reservation
+ * is called in such cases.
*
* In the normal case, vma_commit_reservation returns the same value
* as the preceding vma_needs_reservation call. The only time this
* 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_END_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;
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_END_RESV:
+ region_abort(resv, idx, idx + 1);
+ ret = 0;
+ break;
+ default:
+ BUG();
+ }
if (vma->vm_flags & VM_MAYSHARE)
return ret;
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_end_reservation(struct hstate *h,
+ struct vm_area_struct *vma, unsigned long addr)
+{
+ (void)__vma_reservation_common(h, vma, addr, VMA_END_RESV);
}
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_end_reservation(h, vma, addr);
return ERR_PTR(-ENOSPC);
+ }
ret = hugetlb_cgroup_charge_cgroup(idx, pages_per_huge_page(h), &h_cg);
if (ret)
out_subpool_put:
if (chg || avoid_reserve)
hugepage_subpool_put_pages(spool, 1);
+ vma_end_reservation(h, vma, addr);
return ERR_PTR(-ENOSPC);
}
}
kobject_put(hugepages_kobj);
- kfree(htlb_fault_mutex_table);
+ kfree(hugetlb_fault_mutex_table);
}
module_exit(hugetlb_exit);
#else
num_fault_mutexes = 1;
#endif
- htlb_fault_mutex_table =
+ hugetlb_fault_mutex_table =
kmalloc(sizeof(struct mutex) * num_fault_mutexes, GFP_KERNEL);
- BUG_ON(!htlb_fault_mutex_table);
+ BUG_ON(!hugetlb_fault_mutex_table);
for (i = 0; i < num_fault_mutexes; i++)
- mutex_init(&htlb_fault_mutex_table[i]);
+ mutex_init(&hugetlb_fault_mutex_table[i]);
return 0;
}
module_init(hugetlb_init);
* 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_end_reservation(h, vma, address);
+ }
ptl = huge_pte_lockptr(h, mm, ptep);
spin_lock(ptl);
}
#ifdef CONFIG_SMP
-static u32 fault_mutex_hash(struct hstate *h, struct mm_struct *mm,
+u32 hugetlb_fault_mutex_hash(struct hstate *h, struct mm_struct *mm,
struct vm_area_struct *vma,
struct address_space *mapping,
pgoff_t idx, unsigned long address)
* For uniprocesor systems we always use a single mutex, so just
* return 0 and avoid the hashing overhead.
*/
-static u32 fault_mutex_hash(struct hstate *h, struct mm_struct *mm,
+u32 hugetlb_fault_mutex_hash(struct hstate *h, struct mm_struct *mm,
struct vm_area_struct *vma,
struct address_space *mapping,
pgoff_t idx, unsigned long address)
* get spurious allocation failures if two CPUs race to instantiate
* the same page in the page cache.
*/
- hash = fault_mutex_hash(h, mm, vma, mapping, idx, address);
- mutex_lock(&htlb_fault_mutex_table[hash]);
+ hash = hugetlb_fault_mutex_hash(h, mm, vma, mapping, idx, address);
+ mutex_lock(&hugetlb_fault_mutex_table[hash]);
entry = huge_ptep_get(ptep);
if (huge_pte_none(entry)) {
ret = VM_FAULT_OOM;
goto out_mutex;
}
+ /* Just decrements count, does not deallocate */
+ vma_end_reservation(h, vma, address);
if (!(vma->vm_flags & VM_MAYSHARE))
pagecache_page = hugetlbfs_pagecache_page(h,
put_page(pagecache_page);
}
out_mutex:
- mutex_unlock(&htlb_fault_mutex_table[hash]);
+ mutex_unlock(&hugetlb_fault_mutex_table[hash]);
/*
* Generally it's safe to hold refcount during waiting page lock. But
* here we just wait to defer the next page fault to avoid busy loop and
}
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;
}
-void hugetlb_unreserve_pages(struct inode *inode, long offset, long freed)
+long hugetlb_unreserve_pages(struct inode *inode, long start, long end,
+ long freed)
{
struct hstate *h = hstate_inode(inode);
struct resv_map *resv_map = inode_resv_map(inode);
struct hugepage_subpool *spool = subpool_inode(inode);
long gbl_reserve;
- if (resv_map)
- chg = region_truncate(resv_map, offset);
+ if (resv_map) {
+ chg = region_del(resv_map, start, end);
+ /*
+ * region_del() can fail in the rare case where a region
+ * must be split and another region descriptor can not be
+ * allocated. If end == LONG_MAX, it will not fail.
+ */
+ if (chg < 0)
+ return chg;
+ }
+
spin_lock(&inode->i_lock);
inode->i_blocks -= (blocks_per_huge_page(h) * freed);
spin_unlock(&inode->i_lock);
*/
gbl_reserve = hugepage_subpool_put_pages(spool, (chg - freed));
hugetlb_acct_memory(h, -gbl_reserve);
+
+ return 0;
}
#ifdef CONFIG_ARCH_WANT_HUGE_PMD_SHARE
projects / linux-2.6-microblaze.git / blobdiff