hugetlb: make free_huge_page irq safe

Commit c77c0a8ac4c5 ("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>

1 files changed, 4 insertions, 4 deletions

diff --git a/mm/hugetlb_cgroup.c b/mm/hugetlb_cgroup.c
index 726b85f4f303..5383023d0cca 100644
--- a/mm/hugetlb_cgroup.c
+++ b/mm/hugetlb_cgroup.c
@@ -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;
 }