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mm/hugetlb: add region_del() to delete a specific range of entries

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fallocate hole punch will want to remove a specific range of pages.  The
existing region_truncate() routine deletes all region/reserve map
entries after a specified offset.  region_del() will provide this same
functionality if the end of region is specified as LONG_MAX.  Hence,
region_del() can replace region_truncate().

Unlike region_truncate(), region_del() can return an error in the rare
case where it can not allocate memory for a region descriptor.  This
ONLY happens in the case where an existing region must be split.
Current callers passing LONG_MAX as end of range will never experience
this error and do not need to deal with error handling.  Future callers
of region_del() (such as fallocate hole punch) will need to handle this
error.

Signed-off-by: Mike Kravetz <mike.kravetz@oracle.com>
Reviewed-by: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>
Acked-by: Hillf Danton <hillf.zj@alibaba-inc.com>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: David Rientjes <rientjes@google.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: Davidlohr Bueso <dave@stgolabs.net>
Cc: Aneesh Kumar <aneesh.kumar@linux.vnet.ibm.com>
Cc: Christoph Hellwig <hch@infradead.org>
Cc: Michal Hocko <mhocko@suse.cz>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Mike Kravetz 2015-09-08 15:01:31 -07:00 committed by Linus Torvalds
parent 5e9113731a
commit feba16e25a
1 changed files with 87 additions and 39 deletions
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126
mm/hugetlb.c
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@ -460,43 +460,90 @@ static void region_abort(struct resv_map *resv, long f, long t)
}
/*
* 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.
* 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--;
}
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;
}
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;
}
}
/* Drop any remaining regions. */
list_for_each_entry_safe(rg, trg, rg->link.prev, link) {
if (&rg->link == head)
break;
chg += rg->to - rg->from;
list_del(&rg->link);
kfree(rg);
}
out:
spin_unlock(&resv->lock);
return chg;
kfree(nrg);
return del;
}
/*
@ -647,7 +694,7 @@ void resv_map_release(struct kref *ref)
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) {
@ -1572,7 +1619,7 @@ static void return_unused_surplus_pages(struct hstate *h,
/*
* vma_needs_reservation, vma_commit_reservation and vma_abort_reservation
* 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
@ -1580,8 +1627,9 @@ static void return_unused_surplus_pages(struct hstate *h,
* 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. If the reservation must be
* aborted instead of committed, vma_abort_reservation is called.
* 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
@ -1592,7 +1640,7 @@ static void return_unused_surplus_pages(struct hstate *h,
enum vma_resv_mode {
VMA_NEEDS_RESV,
VMA_COMMIT_RESV,
VMA_ABORT_RESV,
VMA_END_RESV,
};
static long __vma_reservation_common(struct hstate *h,
struct vm_area_struct *vma, unsigned long addr,
@ -1614,7 +1662,7 @@ static long __vma_reservation_common(struct hstate *h,
case VMA_COMMIT_RESV:
ret = region_add(resv, idx, idx + 1);
break;
case VMA_ABORT_RESV:
case VMA_END_RESV:
region_abort(resv, idx, idx + 1);
ret = 0;
break;
@ -1640,10 +1688,10 @@ static long vma_commit_reservation(struct hstate *h,
return __vma_reservation_common(h, vma, addr, VMA_COMMIT_RESV);
}
static void vma_abort_reservation(struct hstate *h,
static void vma_end_reservation(struct hstate *h,
struct vm_area_struct *vma, unsigned long addr)
{
(void)__vma_reservation_common(h, vma, addr, VMA_ABORT_RESV);
(void)__vma_reservation_common(h, vma, addr, VMA_END_RESV);
}
static struct page *alloc_huge_page(struct vm_area_struct *vma,
@ -1670,7 +1718,7 @@ static struct page *alloc_huge_page(struct vm_area_struct *vma,
return ERR_PTR(-ENOMEM);
if (chg || avoid_reserve)
if (hugepage_subpool_get_pages(spool, 1) < 0) {
vma_abort_reservation(h, vma, addr);
vma_end_reservation(h, vma, addr);
return ERR_PTR(-ENOSPC);
}
@ -1718,7 +1766,7 @@ static struct page *alloc_huge_page(struct vm_area_struct *vma,
out_subpool_put:
if (chg || avoid_reserve)
hugepage_subpool_put_pages(spool, 1);
vma_abort_reservation(h, vma, addr);
vma_end_reservation(h, vma, addr);
return ERR_PTR(-ENOSPC);
}
@ -3365,7 +3413,7 @@ static int hugetlb_no_page(struct mm_struct *mm, struct vm_area_struct *vma,
goto backout_unlocked;
}
/* Just decrements count, does not deallocate */
vma_abort_reservation(h, vma, address);
vma_end_reservation(h, vma, address);
}
ptl = huge_pte_lockptr(h, mm, ptep);
@ -3514,7 +3562,7 @@ int hugetlb_fault(struct mm_struct *mm, struct vm_area_struct *vma,
goto out_mutex;
}
/* Just decrements count, does not deallocate */
vma_abort_reservation(h, vma, address);
vma_end_reservation(h, vma, address);
if (!(vma->vm_flags & VM_MAYSHARE))
pagecache_page = hugetlbfs_pagecache_page(h,
@ -3870,7 +3918,7 @@ void hugetlb_unreserve_pages(struct inode *inode, long offset, long freed)
long gbl_reserve;
if (resv_map)
chg = region_truncate(resv_map, offset);
chg = region_del(resv_map, offset, LONG_MAX);
spin_lock(&inode->i_lock);
inode->i_blocks -= (blocks_per_huge_page(h) * freed);
spin_unlock(&inode->i_lock);