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hugetlb: make free_huge_page irq safe

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Commit c77c0a8ac4 ("mm/hugetlb: defer freeing of huge pages if in
non-task context") was added to address the issue of free_huge_page being
called from irq context.  That commit hands off free_huge_page processing
to a workqueue if !in_task.  However, this doesn't cover all the cases as
pointed out by 0day bot lockdep report [1].

:  Possible interrupt unsafe locking scenario:
:
:        CPU0                    CPU1
:        ----                    ----
:   lock(hugetlb_lock);
:                                local_irq_disable();
:                                lock(slock-AF_INET);
:                                lock(hugetlb_lock);
:   <Interrupt>
:     lock(slock-AF_INET);

Shakeel has later explained that this is very likely TCP TX zerocopy from
hugetlb pages scenario when the networking code drops a last reference to
hugetlb page while having IRQ disabled.  Hugetlb freeing path doesn't
disable IRQ while holding hugetlb_lock so a lock dependency chain can lead
to a deadlock.

This commit addresses the issue by doing the following:
 - Make hugetlb_lock irq safe. This is mostly a simple process of
   changing spin_*lock calls to spin_*lock_irq* calls.
 - Make subpool lock irq safe in a similar manner.
 - Revert the !in_task check and workqueue handoff.

[1] https://lore.kernel.org/linux-mm/000000000000f1c03b05bc43aadc@google.com/

Link: https://lkml.kernel.org/r/20210409205254.242291-8-mike.kravetz@oracle.com
Signed-off-by: Mike Kravetz <mike.kravetz@oracle.com>
Acked-by: Michal Hocko <mhocko@suse.com>
Reviewed-by: Muchun Song <songmuchun@bytedance.com>
Reviewed-by: Oscar Salvador <osalvador@suse.de>
Cc: "Aneesh Kumar K . V" <aneesh.kumar@linux.ibm.com>
Cc: Barry Song <song.bao.hua@hisilicon.com>
Cc: David Hildenbrand <david@redhat.com>
Cc: David Rientjes <rientjes@google.com>
Cc: Hillf Danton <hdanton@sina.com>
Cc: HORIGUCHI NAOYA <naoya.horiguchi@nec.com>
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Miaohe Lin <linmiaohe@huawei.com>
Cc: Mina Almasry <almasrymina@google.com>
Cc: Peter Xu <peterx@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Roman Gushchin <guro@fb.com>
Cc: Shakeel Butt <shakeelb@google.com>
Cc: Waiman Long <longman@redhat.com>
Cc: Will Deacon <will@kernel.org>
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 2021-05-04 18:35:07 -07:00 committed by Linus Torvalds
parent 10c6ec4980
commit db71ef79b5
2 changed files with 67 additions and 110 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

169
mm/hugetlb.c
View File

@ -94,9 +94,10 @@ static inline bool subpool_is_free(struct hugepage_subpool *spool)
return true;
}
static inline void unlock_or_release_subpool(struct hugepage_subpool *spool)
static inline void unlock_or_release_subpool(struct hugepage_subpool *spool,
unsigned long irq_flags)
{
spin_unlock(&spool->lock);
spin_unlock_irqrestore(&spool->lock, irq_flags);
/* If no pages are used, and no other handles to the subpool
* remain, give up any reservations based on minimum size and
@ -135,10 +136,12 @@ struct hugepage_subpool *hugepage_new_subpool(struct hstate *h, long max_hpages,
void hugepage_put_subpool(struct hugepage_subpool *spool)
{
spin_lock(&spool->lock);
unsigned long flags;
spin_lock_irqsave(&spool->lock, flags);
BUG_ON(!spool->count);
spool->count--;
unlock_or_release_subpool(spool);
unlock_or_release_subpool(spool, flags);
}
/*
@ -157,7 +160,7 @@ static long hugepage_subpool_get_pages(struct hugepage_subpool *spool,
if (!spool)
return ret;
spin_lock(&spool->lock);
spin_lock_irq(&spool->lock);
if (spool->max_hpages != -1) { /* maximum size accounting */
if ((spool->used_hpages + delta) <= spool->max_hpages)
@ -184,7 +187,7 @@ static long hugepage_subpool_get_pages(struct hugepage_subpool *spool,
}
unlock_ret:
spin_unlock(&spool->lock);
spin_unlock_irq(&spool->lock);
return ret;
}
@ -198,11 +201,12 @@ static long hugepage_subpool_put_pages(struct hugepage_subpool *spool,
long delta)
{
long ret = delta;
unsigned long flags;
if (!spool)
return delta;
spin_lock(&spool->lock);
spin_lock_irqsave(&spool->lock, flags);
if (spool->max_hpages != -1) /* maximum size accounting */
spool->used_hpages -= delta;
@ -223,7 +227,7 @@ static long hugepage_subpool_put_pages(struct hugepage_subpool *spool,
* If hugetlbfs_put_super couldn't free spool due to an outstanding
* quota reference, free it now.
*/
unlock_or_release_subpool(spool);
unlock_or_release_subpool(spool, flags);
return ret;
}
@ -1412,7 +1416,7 @@ struct hstate *size_to_hstate(unsigned long size)
return NULL;
}
static void __free_huge_page(struct page *page)
void free_huge_page(struct page *page)
{
/*
* Can't pass hstate in here because it is called from the
@ -1422,6 +1426,7 @@ static void __free_huge_page(struct page *page)
int nid = page_to_nid(page);
struct hugepage_subpool *spool = hugetlb_page_subpool(page);
bool restore_reserve;
unsigned long flags;
VM_BUG_ON_PAGE(page_count(page), page);
VM_BUG_ON_PAGE(page_mapcount(page), page);
@ -1450,7 +1455,7 @@ static void __free_huge_page(struct page *page)
restore_reserve = true;
}
spin_lock(&hugetlb_lock);
spin_lock_irqsave(&hugetlb_lock, flags);
ClearHPageMigratable(page);
hugetlb_cgroup_uncharge_page(hstate_index(h),
pages_per_huge_page(h), page);
@ -1461,68 +1466,20 @@ static void __free_huge_page(struct page *page)
if (HPageTemporary(page)) {
remove_hugetlb_page(h, page, false);
spin_unlock(&hugetlb_lock);
spin_unlock_irqrestore(&hugetlb_lock, flags);
update_and_free_page(h, page);
} else if (h->surplus_huge_pages_node[nid]) {
/* remove the page from active list */
remove_hugetlb_page(h, page, true);
spin_unlock(&hugetlb_lock);
spin_unlock_irqrestore(&hugetlb_lock, flags);
update_and_free_page(h, page);
} else {
arch_clear_hugepage_flags(page);
enqueue_huge_page(h, page);
spin_unlock(&hugetlb_lock);
spin_unlock_irqrestore(&hugetlb_lock, flags);
}
}
/*
* As free_huge_page() can be called from a non-task context, we have
* to defer the actual freeing in a workqueue to prevent potential
* hugetlb_lock deadlock.
*
* free_hpage_workfn() locklessly retrieves the linked list of pages to
* be freed and frees them one-by-one. As the page->mapping pointer is
* going to be cleared in __free_huge_page() anyway, it is reused as the
* llist_node structure of a lockless linked list of huge pages to be freed.
*/
static LLIST_HEAD(hpage_freelist);
static void free_hpage_workfn(struct work_struct *work)
{
struct llist_node *node;
struct page *page;
node = llist_del_all(&hpage_freelist);
while (node) {
page = container_of((struct address_space **)node,
struct page, mapping);
node = node->next;
__free_huge_page(page);
}
}
static DECLARE_WORK(free_hpage_work, free_hpage_workfn);
void free_huge_page(struct page *page)
{
/*
* Defer freeing if in non-task context to avoid hugetlb_lock deadlock.
*/
if (!in_task()) {
/*
* Only call schedule_work() if hpage_freelist is previously
* empty. Otherwise, schedule_work() had been called but the
* workfn hasn't retrieved the list yet.
*/
if (llist_add((struct llist_node *)&page->mapping,
&hpage_freelist))
schedule_work(&free_hpage_work);
return;
}
__free_huge_page(page);
}
static void prep_new_huge_page(struct hstate *h, struct page *page, int nid)
{
INIT_LIST_HEAD(&page->lru);
@ -1530,11 +1487,11 @@ static void prep_new_huge_page(struct hstate *h, struct page *page, int nid)
hugetlb_set_page_subpool(page, NULL);
set_hugetlb_cgroup(page, NULL);
set_hugetlb_cgroup_rsvd(page, NULL);
spin_lock(&hugetlb_lock);
spin_lock_irq(&hugetlb_lock);
h->nr_huge_pages++;
h->nr_huge_pages_node[nid]++;
ClearHPageFreed(page);
spin_unlock(&hugetlb_lock);
spin_unlock_irq(&hugetlb_lock);
}
static void prep_compound_gigantic_page(struct page *page, unsigned int order)
@ -1780,7 +1737,7 @@ retry:
if (!PageHuge(page))
return 0;
spin_lock(&hugetlb_lock);
spin_lock_irq(&hugetlb_lock);
if (!PageHuge(page)) {
rc = 0;
goto out;
@ -1797,7 +1754,7 @@ retry:
* when it is dissolved.
*/
if (unlikely(!HPageFreed(head))) {
spin_unlock(&hugetlb_lock);
spin_unlock_irq(&hugetlb_lock);
cond_resched();
/*
@ -1821,12 +1778,12 @@ retry:
}
remove_hugetlb_page(h, page, false);
h->max_huge_pages--;
spin_unlock(&hugetlb_lock);
spin_unlock_irq(&hugetlb_lock);
update_and_free_page(h, head);
return 0;
}
out:
spin_unlock(&hugetlb_lock);
spin_unlock_irq(&hugetlb_lock);
return rc;
}
@ -1868,16 +1825,16 @@ static struct page *alloc_surplus_huge_page(struct hstate *h, gfp_t gfp_mask,
if (hstate_is_gigantic(h))
return NULL;
spin_lock(&hugetlb_lock);
spin_lock_irq(&hugetlb_lock);
if (h->surplus_huge_pages >= h->nr_overcommit_huge_pages)
goto out_unlock;
spin_unlock(&hugetlb_lock);
spin_unlock_irq(&hugetlb_lock);
page = alloc_fresh_huge_page(h, gfp_mask, nid, nmask, NULL);
if (!page)
return NULL;
spin_lock(&hugetlb_lock);
spin_lock_irq(&hugetlb_lock);
/*
* We could have raced with the pool size change.
* Double check that and simply deallocate the new page
@ -1887,7 +1844,7 @@ static struct page *alloc_surplus_huge_page(struct hstate *h, gfp_t gfp_mask,
*/
if (h->surplus_huge_pages >= h->nr_overcommit_huge_pages) {
SetHPageTemporary(page);
spin_unlock(&hugetlb_lock);
spin_unlock_irq(&hugetlb_lock);
put_page(page);
return NULL;
} else {
@ -1896,7 +1853,7 @@ static struct page *alloc_surplus_huge_page(struct hstate *h, gfp_t gfp_mask,
}
out_unlock:
spin_unlock(&hugetlb_lock);
spin_unlock_irq(&hugetlb_lock);
return page;
}
@ -1946,17 +1903,17 @@ struct page *alloc_buddy_huge_page_with_mpol(struct hstate *h,
struct page *alloc_huge_page_nodemask(struct hstate *h, int preferred_nid,
nodemask_t *nmask, gfp_t gfp_mask)
{
spin_lock(&hugetlb_lock);
spin_lock_irq(&hugetlb_lock);
if (h->free_huge_pages - h->resv_huge_pages > 0) {
struct page *page;
page = dequeue_huge_page_nodemask(h, gfp_mask, preferred_nid, nmask);
if (page) {
spin_unlock(&hugetlb_lock);
spin_unlock_irq(&hugetlb_lock);
return page;
}
}
spin_unlock(&hugetlb_lock);
spin_unlock_irq(&hugetlb_lock);
return alloc_migrate_huge_page(h, gfp_mask, preferred_nid, nmask);
}
@ -2004,7 +1961,7 @@ static int gather_surplus_pages(struct hstate *h, long delta)
ret = -ENOMEM;
retry:
spin_unlock(&hugetlb_lock);
spin_unlock_irq(&hugetlb_lock);
for (i = 0; i < needed; i++) {
page = alloc_surplus_huge_page(h, htlb_alloc_mask(h),
NUMA_NO_NODE, NULL);
@ -2021,7 +1978,7 @@ retry:
* After retaking hugetlb_lock, we need to recalculate 'needed'
* because either resv_huge_pages or free_huge_pages may have changed.
*/
spin_lock(&hugetlb_lock);
spin_lock_irq(&hugetlb_lock);
needed = (h->resv_huge_pages + delta) -
(h->free_huge_pages + allocated);
if (needed > 0) {
@ -2061,12 +2018,12 @@ retry:
enqueue_huge_page(h, page);
}
free:
spin_unlock(&hugetlb_lock);
spin_unlock_irq(&hugetlb_lock);
/* Free unnecessary surplus pages to the buddy allocator */
list_for_each_entry_safe(page, tmp, &surplus_list, lru)
put_page(page);
spin_lock(&hugetlb_lock);
spin_lock_irq(&hugetlb_lock);
return ret;
}
@ -2116,9 +2073,9 @@ static void return_unused_surplus_pages(struct hstate *h,
}
out:
spin_unlock(&hugetlb_lock);
spin_unlock_irq(&hugetlb_lock);
update_and_free_pages_bulk(h, &page_list);
spin_lock(&hugetlb_lock);
spin_lock_irq(&hugetlb_lock);
}
@ -2352,7 +2309,7 @@ struct page *alloc_huge_page(struct vm_area_struct *vma,
if (ret)
goto out_uncharge_cgroup_reservation;
spin_lock(&hugetlb_lock);
spin_lock_irq(&hugetlb_lock);
/*
* glb_chg is passed to indicate whether or not a page must be taken
* from the global free pool (global change). gbl_chg == 0 indicates
@ -2360,7 +2317,7 @@ struct page *alloc_huge_page(struct vm_area_struct *vma,
*/
page = dequeue_huge_page_vma(h, vma, addr, avoid_reserve, gbl_chg);
if (!page) {
spin_unlock(&hugetlb_lock);
spin_unlock_irq(&hugetlb_lock);
page = alloc_buddy_huge_page_with_mpol(h, vma, addr);
if (!page)
goto out_uncharge_cgroup;
@ -2368,7 +2325,7 @@ struct page *alloc_huge_page(struct vm_area_struct *vma,
SetHPageRestoreReserve(page);
h->resv_huge_pages--;
}
spin_lock(&hugetlb_lock);
spin_lock_irq(&hugetlb_lock);
list_add(&page->lru, &h->hugepage_activelist);
/* Fall through */
}
@ -2381,7 +2338,7 @@ struct page *alloc_huge_page(struct vm_area_struct *vma,
h_cg, page);
}
spin_unlock(&hugetlb_lock);
spin_unlock_irq(&hugetlb_lock);
hugetlb_set_page_subpool(page, spool);
@ -2593,9 +2550,9 @@ static void try_to_free_low(struct hstate *h, unsigned long count,
}
out:
spin_unlock(&hugetlb_lock);
spin_unlock_irq(&hugetlb_lock);
update_and_free_pages_bulk(h, &page_list);
spin_lock(&hugetlb_lock);
spin_lock_irq(&hugetlb_lock);
}
#else
static inline void try_to_free_low(struct hstate *h, unsigned long count,
@ -2660,7 +2617,7 @@ static int set_max_huge_pages(struct hstate *h, unsigned long count, int nid,
* pages in hstate via the proc/sysfs interfaces.
*/
mutex_lock(&h->resize_lock);
spin_lock(&hugetlb_lock);
spin_lock_irq(&hugetlb_lock);
/*
* Check for a node specific request.
@ -2691,7 +2648,7 @@ static int set_max_huge_pages(struct hstate *h, unsigned long count, int nid,
*/
if (hstate_is_gigantic(h) && !IS_ENABLED(CONFIG_CONTIG_ALLOC)) {
if (count > persistent_huge_pages(h)) {
spin_unlock(&hugetlb_lock);
spin_unlock_irq(&hugetlb_lock);
mutex_unlock(&h->resize_lock);
NODEMASK_FREE(node_alloc_noretry);
return -EINVAL;
@ -2721,14 +2678,14 @@ static int set_max_huge_pages(struct hstate *h, unsigned long count, int nid,
* page, free_huge_page will handle it by freeing the page
* and reducing the surplus.
*/
spin_unlock(&hugetlb_lock);
spin_unlock_irq(&hugetlb_lock);
/* yield cpu to avoid soft lockup */
cond_resched();
ret = alloc_pool_huge_page(h, nodes_allowed,
node_alloc_noretry);
spin_lock(&hugetlb_lock);
spin_lock_irq(&hugetlb_lock);
if (!ret)
goto out;
@ -2767,9 +2724,9 @@ static int set_max_huge_pages(struct hstate *h, unsigned long count, int nid,
list_add(&page->lru, &page_list);
}
/* free the pages after dropping lock */
spin_unlock(&hugetlb_lock);
spin_unlock_irq(&hugetlb_lock);
update_and_free_pages_bulk(h, &page_list);
spin_lock(&hugetlb_lock);
spin_lock_irq(&hugetlb_lock);
while (count < persistent_huge_pages(h)) {
if (!adjust_pool_surplus(h, nodes_allowed, 1))
@ -2777,7 +2734,7 @@ static int set_max_huge_pages(struct hstate *h, unsigned long count, int nid,
}
out:
h->max_huge_pages = persistent_huge_pages(h);
spin_unlock(&hugetlb_lock);
spin_unlock_irq(&hugetlb_lock);
mutex_unlock(&h->resize_lock);
NODEMASK_FREE(node_alloc_noretry);
@ -2933,9 +2890,9 @@ static ssize_t nr_overcommit_hugepages_store(struct kobject *kobj,
if (err)
return err;
spin_lock(&hugetlb_lock);
spin_lock_irq(&hugetlb_lock);
h->nr_overcommit_huge_pages = input;
spin_unlock(&hugetlb_lock);
spin_unlock_irq(&hugetlb_lock);
return count;
}
@ -3522,9 +3479,9 @@ int hugetlb_overcommit_handler(struct ctl_table *table, int write,
goto out;
if (write) {
spin_lock(&hugetlb_lock);
spin_lock_irq(&hugetlb_lock);
h->nr_overcommit_huge_pages = tmp;
spin_unlock(&hugetlb_lock);
spin_unlock_irq(&hugetlb_lock);
}
out:
return ret;
@ -3620,7 +3577,7 @@ static int hugetlb_acct_memory(struct hstate *h, long delta)
if (!delta)
return 0;
spin_lock(&hugetlb_lock);
spin_lock_irq(&hugetlb_lock);
/*
* When cpuset is configured, it breaks the strict hugetlb page
* reservation as the accounting is done on a global variable. Such
@ -3659,7 +3616,7 @@ static int hugetlb_acct_memory(struct hstate *h, long delta)
return_unused_surplus_pages(h, (unsigned long) -delta);
out:
spin_unlock(&hugetlb_lock);
spin_unlock_irq(&hugetlb_lock);
return ret;
}
@ -5687,7 +5644,7 @@ bool isolate_huge_page(struct page *page, struct list_head *list)
{
bool ret = true;
spin_lock(&hugetlb_lock);
spin_lock_irq(&hugetlb_lock);
if (!PageHeadHuge(page) ||
!HPageMigratable(page) ||
!get_page_unless_zero(page)) {
@ -5697,16 +5654,16 @@ bool isolate_huge_page(struct page *page, struct list_head *list)
ClearHPageMigratable(page);
list_move_tail(&page->lru, list);
unlock:
spin_unlock(&hugetlb_lock);
spin_unlock_irq(&hugetlb_lock);
return ret;
}
void putback_active_hugepage(struct page *page)
{
spin_lock(&hugetlb_lock);
spin_lock_irq(&hugetlb_lock);
SetHPageMigratable(page);
list_move_tail(&page->lru, &(page_hstate(page))->hugepage_activelist);
spin_unlock(&hugetlb_lock);
spin_unlock_irq(&hugetlb_lock);
put_page(page);
}
@ -5740,12 +5697,12 @@ void move_hugetlb_state(struct page *oldpage, struct page *newpage, int reason)
*/
if (new_nid == old_nid)
return;
spin_lock(&hugetlb_lock);
spin_lock_irq(&hugetlb_lock);
if (h->surplus_huge_pages_node[old_nid]) {
h->surplus_huge_pages_node[old_nid]--;
h->surplus_huge_pages_node[new_nid]++;
}
spin_unlock(&hugetlb_lock);
spin_unlock_irq(&hugetlb_lock);
}
}

8
mm/hugetlb_cgroup.c
View File

@ -204,11 +204,11 @@ static void hugetlb_cgroup_css_offline(struct cgroup_subsys_state *css)
do {
idx = 0;
for_each_hstate(h) {
spin_lock(&hugetlb_lock);
spin_lock_irq(&hugetlb_lock);
list_for_each_entry(page, &h->hugepage_activelist, lru)
hugetlb_cgroup_move_parent(idx, h_cg, page);
spin_unlock(&hugetlb_lock);
spin_unlock_irq(&hugetlb_lock);
idx++;
}
cond_resched();
@ -784,7 +784,7 @@ void hugetlb_cgroup_migrate(struct page *oldhpage, struct page *newhpage)
if (hugetlb_cgroup_disabled())
return;
spin_lock(&hugetlb_lock);
spin_lock_irq(&hugetlb_lock);
h_cg = hugetlb_cgroup_from_page(oldhpage);
h_cg_rsvd = hugetlb_cgroup_from_page_rsvd(oldhpage);
set_hugetlb_cgroup(oldhpage, NULL);
@ -794,7 +794,7 @@ void hugetlb_cgroup_migrate(struct page *oldhpage, struct page *newhpage)
set_hugetlb_cgroup(newhpage, h_cg);
set_hugetlb_cgroup_rsvd(newhpage, h_cg_rsvd);
list_move(&newhpage->lru, &h->hugepage_activelist);
spin_unlock(&hugetlb_lock);
spin_unlock_irq(&hugetlb_lock);
return;
}