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Subject[PATCH -V1 8/9] hugetlbfs: Add task migration support
Date
From: "Aneesh Kumar K.V" <aneesh.kumar@linux.vnet.ibm.com>

This patch add task migration support to hugetlb cgroup. When task migrate we
don't move charge across hugetlb cgroup.

Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
---
fs/hugetlbfs/hugetlb_cgroup.c | 74 ----------------------
fs/hugetlbfs/region.c | 24 -------
include/linux/hugetlb.h | 1 -
include/linux/hugetlb_cgroup.h | 17 -----
mm/hugetlb.c | 134 +++++++++++++++-------------------------
5 files changed, 49 insertions(+), 201 deletions(-)

diff --git a/fs/hugetlbfs/hugetlb_cgroup.c b/fs/hugetlbfs/hugetlb_cgroup.c
index b8b319b..44b3d5e 100644
--- a/fs/hugetlbfs/hugetlb_cgroup.c
+++ b/fs/hugetlbfs/hugetlb_cgroup.c
@@ -114,29 +114,6 @@ int hugetlb_cgroup_reset(struct cgroup *cgroup, unsigned int event)
return 0;
}

-static int hugetlbcgroup_can_attach(struct cgroup_subsys *ss,
- struct cgroup *new_cgrp,
- struct cgroup_taskset *set)
-{
- struct hugetlb_cgroup *h_cg;
- struct task_struct *task = cgroup_taskset_first(set);
- /*
- * Make sure all the task in the set are in root cgroup
- * We only allow move from root cgroup to other cgroup.
- */
- while (task != NULL) {
- rcu_read_lock();
- h_cg = task_hugetlbcgroup(task);
- if (!hugetlb_cgroup_is_root(h_cg)) {
- rcu_read_unlock();
- return -EOPNOTSUPP;
- }
- rcu_read_unlock();
- task = cgroup_taskset_next(set);
- }
- return 0;
-}
-
/*
* called from kernel/cgroup.c with cgroup_lock() held.
*/
@@ -202,7 +179,6 @@ static int hugetlbcgroup_populate(struct cgroup_subsys *ss,

struct cgroup_subsys hugetlb_subsys = {
.name = "hugetlb",
- .can_attach = hugetlbcgroup_can_attach,
.create = hugetlbcgroup_create,
.pre_destroy = hugetlbcgroup_pre_destroy,
.destroy = hugetlbcgroup_destroy,
@@ -406,53 +382,3 @@ long hugetlb_truncate_cgroup_range(struct hstate *h,
}
return chg;
}
-
-int hugetlb_priv_page_charge(struct resv_map *map, struct hstate *h, long chg)
-{
- long csize;
- int idx, ret;
- struct hugetlb_cgroup *h_cg;
- struct res_counter *fail_res;
-
- /*
- * Get the task cgroup within rcu_readlock and also
- * get cgroup reference to make sure cgroup destroy won't
- * race with page_charge. We don't allow a cgroup destroy
- * when the cgroup have some charge against it
- */
- rcu_read_lock();
- h_cg = task_hugetlbcgroup(current);
- css_get(&h_cg->css);
- rcu_read_unlock();
-
- if (hugetlb_cgroup_is_root(h_cg)) {
- ret = chg;
- goto err_out;
- }
-
- csize = chg * huge_page_size(h);
- idx = h - hstates;
- ret = res_counter_charge(&h_cg->memhuge[idx], csize, &fail_res);
- if (!ret) {
- map->nr_pages[idx] += chg << huge_page_order(h);
- ret = chg;
- }
-err_out:
- css_put(&h_cg->css);
- return ret;
-}
-
-void hugetlb_priv_page_uncharge(struct resv_map *map, int idx, long nr_pages)
-{
- struct hugetlb_cgroup *h_cg;
- unsigned long csize = nr_pages * PAGE_SIZE;
-
- rcu_read_lock();
- h_cg = task_hugetlbcgroup(current);
- if (!hugetlb_cgroup_is_root(h_cg)) {
- res_counter_uncharge(&h_cg->memhuge[idx], csize);
- map->nr_pages[idx] -= nr_pages;
- }
- rcu_read_unlock();
- return;
-}
diff --git a/fs/hugetlbfs/region.c b/fs/hugetlbfs/region.c
index 8ac63b0..483473f 100644
--- a/fs/hugetlbfs/region.c
+++ b/fs/hugetlbfs/region.c
@@ -177,30 +177,6 @@ long region_truncate(struct list_head *head, long end)
return chg;
}

-long region_count(struct list_head *head, long f, long t)
-{
- struct file_region *rg;
- long chg = 0;
-
- /* Locate each segment we overlap with, and count that overlap. */
- list_for_each_entry(rg, head, link) {
- int seg_from;
- int seg_to;
-
- if (rg->to <= f)
- continue;
- if (rg->from >= t)
- break;
-
- seg_from = max(rg->from, f);
- seg_to = min(rg->to, t);
-
- chg += seg_to - seg_from;
- }
-
- return chg;
-}
-
long region_truncate_range(struct list_head *head, long from, long to)
{
long chg = 0;
diff --git a/include/linux/hugetlb.h b/include/linux/hugetlb.h
index 8576fa0..226f488 100644
--- a/include/linux/hugetlb.h
+++ b/include/linux/hugetlb.h
@@ -255,7 +255,6 @@ struct hstate *size_to_hstate(unsigned long size);

struct resv_map {
struct kref refs;
- long nr_pages[HUGE_MAX_HSTATE];
struct list_head regions;
};

diff --git a/include/linux/hugetlb_cgroup.h b/include/linux/hugetlb_cgroup.h
index 68c1d61..9d51235 100644
--- a/include/linux/hugetlb_cgroup.h
+++ b/include/linux/hugetlb_cgroup.h
@@ -26,7 +26,6 @@ extern long region_chg(struct list_head *head, long f, long t,
extern void region_add(struct list_head *head, long f, long t,
unsigned long data);
extern long region_truncate(struct list_head *head, long end);
-extern long region_count(struct list_head *head, long f, long t);
extern long region_truncate_range(struct list_head *head, long from, long end);
#ifdef CONFIG_CGROUP_HUGETLB_RES_CTLR
extern u64 hugetlb_cgroup_read(struct cgroup *cgroup, struct cftype *cft);
@@ -43,10 +42,6 @@ extern long hugetlb_truncate_cgroup(struct hstate *h,
extern long hugetlb_truncate_cgroup_range(struct hstate *h,
struct list_head *head,
long from, long end);
-extern int hugetlb_priv_page_charge(struct resv_map *map,
- struct hstate *h, long chg);
-extern void hugetlb_priv_page_uncharge(struct resv_map *map,
- int idx, long nr_pages);
#else
static inline long hugetlb_page_charge(struct list_head *head,
struct hstate *h, long f, long t)
@@ -78,17 +73,5 @@ static inline long hugetlb_truncate_cgroup_range(struct hstate *h,
{
return region_truncate_range(head, from, end);
}
-
-static inline int hugetlb_priv_page_charge(struct resv_map *map,
- struct hstate *h, long chg)
-{
- return chg;
-}
-
-static inline void hugetlb_priv_page_uncharge(struct resv_map *map,
- int idx, long nr_pages)
-{
- return;
-}
#endif /* CONFIG_CGROUP_HUGETLB_RES_CTLR */
#endif
diff --git a/mm/hugetlb.c b/mm/hugetlb.c
index 08555c6..aaed6d3 100644
--- a/mm/hugetlb.c
+++ b/mm/hugetlb.c
@@ -156,18 +156,15 @@ static struct resv_map *resv_map_alloc(void)
return resv_map;
}

-static void resv_map_release(struct kref *ref)
+static void resv_map_release(struct hstate *h, struct resv_map *resv_map)
{
- int idx;
- struct resv_map *resv_map = container_of(ref, struct resv_map, refs);
-
- /* Clear out any active regions before we release the map. */
- region_truncate(&resv_map->regions, 0);
- /* drop the hugetlb cgroup charge */
- for (idx = 0; idx < HUGE_MAX_HSTATE; idx++) {
- hugetlb_priv_page_uncharge(resv_map, idx,
- resv_map->nr_pages[idx]);
- }
+ /*
+ * We should not have any regions left here, if we were able to
+ * do memory allocation when in trunage_cgroup_range.
+ *
+ * Clear out any active regions before we release the map
+ */
+ hugetlb_truncate_cgroup(h, &resv_map->regions, 0);
kfree(resv_map);
}

@@ -380,9 +377,7 @@ static void free_huge_page(struct page *page)
*/
struct hstate *h = page_hstate(page);
int nid = page_to_nid(page);
- struct address_space *mapping;

- mapping = (struct address_space *) page_private(page);
set_page_private(page, 0);
page->mapping = NULL;
BUG_ON(page_count(page));
@@ -398,8 +393,6 @@ static void free_huge_page(struct page *page)
enqueue_huge_page(h, page);
}
spin_unlock(&hugetlb_lock);
- if (mapping)
- hugetlb_put_quota(mapping, 1);
}

static void prep_new_huge_page(struct hstate *h, struct page *page, int nid)
@@ -822,12 +815,12 @@ static void return_unused_surplus_pages(struct hstate *h,
static long vma_needs_reservation(struct hstate *h,
struct vm_area_struct *vma, unsigned long addr)
{
+ pgoff_t idx = vma_hugecache_offset(h, vma, addr);
struct address_space *mapping = vma->vm_file->f_mapping;
struct inode *inode = mapping->host;


if (vma->vm_flags & VM_MAYSHARE) {
- pgoff_t idx = vma_hugecache_offset(h, vma, addr);
return hugetlb_page_charge(&inode->i_mapping->private_list,
h, idx, idx + 1);
} else if (!is_vma_resv_set(vma, HPAGE_RESV_OWNER)) {
@@ -842,18 +835,13 @@ static long vma_needs_reservation(struct hstate *h,
return -ENOMEM;
set_vma_resv_map(vma, resv_map);
}
- return hugetlb_priv_page_charge(resv_map, h, 1);
- } else {
- /* We did the priv page charging in mmap call */
- long err;
- pgoff_t idx = vma_hugecache_offset(h, vma, addr);
- struct resv_map *reservations = vma_resv_map(vma);
-
- err = region_chg(&reservations->regions, idx, idx + 1, 0);
- if (err < 0)
- return err;
- return 0;
+ return hugetlb_page_charge(&resv_map->regions,
+ h, idx, idx + 1);
}
+ /*
+ * We did the private page charging in mmap call
+ */
+ return 0;
}

static void vma_uncharge_reservation(struct hstate *h,
@@ -861,40 +849,37 @@ static void vma_uncharge_reservation(struct hstate *h,
unsigned long chg)
{
int idx = h - hstates;
+ struct list_head *region_list;
struct address_space *mapping = vma->vm_file->f_mapping;
struct inode *inode = mapping->host;


- if (vma->vm_flags & VM_MAYSHARE) {
- return hugetlb_page_uncharge(&inode->i_mapping->private_list,
- idx, chg << huge_page_order(h));
- } else {
+ if (vma->vm_flags & VM_MAYSHARE)
+ region_list = &inode->i_mapping->private_list;
+ else {
struct resv_map *resv_map = vma_resv_map(vma);
-
- return hugetlb_priv_page_uncharge(resv_map,
- idx,
- chg << huge_page_order(h));
+ region_list = &resv_map->regions;
}
+ return hugetlb_page_uncharge(region_list,
+ idx, chg << huge_page_order(h));
}

static void vma_commit_reservation(struct hstate *h,
struct vm_area_struct *vma, unsigned long addr)
{
-
+ struct list_head *region_list;
+ pgoff_t idx = vma_hugecache_offset(h, vma, addr);
struct address_space *mapping = vma->vm_file->f_mapping;
struct inode *inode = mapping->host;

if (vma->vm_flags & VM_MAYSHARE) {
- pgoff_t idx = vma_hugecache_offset(h, vma, addr);
- hugetlb_commit_page_charge(&inode->i_mapping->private_list,
- idx, idx + 1);
- } else if (is_vma_resv_set(vma, HPAGE_RESV_OWNER)) {
- pgoff_t idx = vma_hugecache_offset(h, vma, addr);
+ region_list = &inode->i_mapping->private_list;
+ } else {
struct resv_map *reservations = vma_resv_map(vma);
-
- /* Mark this page used in the map. */
- region_add(&reservations->regions, idx, idx + 1, 0);
+ region_list = &reservations->regions;
}
+ hugetlb_commit_page_charge(region_list, idx, idx + 1);
+ return;
}

static struct page *alloc_huge_page(struct vm_area_struct *vma,
@@ -937,10 +922,9 @@ static struct page *alloc_huge_page(struct vm_area_struct *vma,
return ERR_PTR(-VM_FAULT_SIGBUS);
}
}
-
set_page_private(page, (unsigned long) mapping);
-
- vma_commit_reservation(h, vma, addr);
+ if (chg)
+ vma_commit_reservation(h, vma, addr);
return page;
}

@@ -2045,20 +2029,19 @@ static void hugetlb_vm_op_open(struct vm_area_struct *vma)
static void hugetlb_vm_op_close(struct vm_area_struct *vma)
{
struct hstate *h = hstate_vma(vma);
- struct resv_map *reservations = vma_resv_map(vma);
- unsigned long reserve;
- unsigned long start;
- unsigned long end;
+ struct resv_map *resv_map = vma_resv_map(vma);
+ unsigned long reserve, start, end;

- if (reservations) {
+ if (resv_map) {
start = vma_hugecache_offset(h, vma, vma->vm_start);
end = vma_hugecache_offset(h, vma, vma->vm_end);

- reserve = (end - start) -
- region_count(&reservations->regions, start, end);
-
- kref_put(&reservations->refs, resv_map_release);
-
+ reserve = hugetlb_truncate_cgroup_range(h, &resv_map->regions,
+ start, end);
+ /* open coded kref_put */
+ if (atomic_sub_and_test(1, &resv_map->refs.refcount)) {
+ resv_map_release(h, resv_map);
+ }
if (reserve) {
hugetlb_acct_memory(h, -reserve);
hugetlb_put_quota(vma->vm_file->f_mapping, reserve);
@@ -2842,6 +2825,7 @@ int hugetlb_reserve_pages(struct inode *inode,
vm_flags_t vm_flags)
{
long ret, chg;
+ struct list_head *region_list;
struct hstate *h = hstate_inode(inode);
struct resv_map *resv_map = NULL;
/*
@@ -2859,20 +2843,17 @@ int hugetlb_reserve_pages(struct inode *inode,
* called to make the mapping read-write. Assume !vma is a shm mapping
*/
if (!vma || vma->vm_flags & VM_MAYSHARE) {
- chg = hugetlb_page_charge(&inode->i_mapping->private_list,
- h, from, to);
+ region_list = &inode->i_mapping->private_list;
} else {
resv_map = resv_map_alloc();
if (!resv_map)
return -ENOMEM;

- chg = to - from;
-
set_vma_resv_map(vma, resv_map);
set_vma_resv_flags(vma, HPAGE_RESV_OWNER);
- chg = hugetlb_priv_page_charge(resv_map, h, chg);
+ region_list = &resv_map->regions;
}
-
+ chg = hugetlb_page_charge(region_list, h, from, to);
if (chg < 0)
return chg;

@@ -2888,32 +2869,15 @@ int hugetlb_reserve_pages(struct inode *inode,
ret = hugetlb_acct_memory(h, chg);
if (ret < 0)
goto err_acct_mem;
- /*
- * Account for the reservations made. Shared mappings record regions
- * that have reservations as they are shared by multiple VMAs.
- * When the last VMA disappears, the region map says how much
- * the reservation was and the page cache tells how much of
- * the reservation was consumed. Private mappings are per-VMA and
- * only the consumed reservations are tracked. When the VMA
- * disappears, the original reservation is the VMA size and the
- * consumed reservations are stored in the map. Hence, nothing
- * else has to be done for private mappings here
- */
- if (!vma || vma->vm_flags & VM_MAYSHARE)
- hugetlb_commit_page_charge(&inode->i_mapping->private_list,
- from, to);
+
+ hugetlb_commit_page_charge(region_list, from, to);
return 0;
err_acct_mem:
hugetlb_put_quota(inode->i_mapping, chg);
err_quota:
- if (!vma || vma->vm_flags & VM_MAYSHARE)
- hugetlb_page_uncharge(&inode->i_mapping->private_list,
- h - hstates, chg << huge_page_order(h));
- else
- hugetlb_priv_page_uncharge(resv_map, h - hstates,
- chg << huge_page_order(h));
+ hugetlb_page_uncharge(region_list, h - hstates,
+ chg << huge_page_order(h));
return ret;
-
}

void hugetlb_unreserve_pages(struct inode *inode, long offset, long freed)
@@ -2927,7 +2891,7 @@ void hugetlb_unreserve_pages(struct inode *inode, long offset, long freed)
inode->i_blocks -= (blocks_per_huge_page(h) * freed);
spin_unlock(&inode->i_lock);

- hugetlb_put_quota(inode->i_mapping, (chg - freed));
+ hugetlb_put_quota(inode->i_mapping, chg);
hugetlb_acct_memory(h, -(chg - freed));
}

--
1.7.9


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