Commit 59838b25 authored by Frank van der Linden's avatar Frank van der Linden Committed by Andrew Morton
Browse files

mm, hugetlb: remove HUGETLB_CGROUP_MIN_ORDER 

Originally, hugetlb_cgroup was the only hugetlb user of tail page
structure fields.  So, the code defined and checked against
HUGETLB_CGROUP_MIN_ORDER to make sure pages weren't too small to use.

However, by now, tail page #2 is used to store hugetlb hwpoison and
subpool information as well.  In other words, without that tail page
hugetlb doesn't work.

Acknowledge this fact by getting rid of HUGETLB_CGROUP_MIN_ORDER and
checks against it.  Instead, just check for the minimum viable page order
at hstate creation time.

Link: https://lkml.kernel.org/r/20231004153248.3842997-1-fvdl@google.com


Signed-off-by: default avatarFrank van der Linden <fvdl@google.com>
Reviewed-by: default avatarMike Kravetz <mike.kravetz@oracle.com>
Cc: Muchun Song <muchun.song@linux.dev>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
parent 2580d554

include/linux/hugetlb_cgroup.h

+0 −11
Original line number Diff line number Diff line
@@ -22,13 +22,6 @@ struct resv_map; 
struct file_region;



#ifdef CONFIG_CGROUP_HUGETLB

/*

 * Minimum page order trackable by hugetlb cgroup.

 * At least 3 pages are necessary for all the tracking information.

 * The second tail page contains all of the hugetlb-specific fields.

 */

#define HUGETLB_CGROUP_MIN_ORDER order_base_2(__NR_USED_SUBPAGE)



enum hugetlb_memory_event {

	HUGETLB_MAX,

	HUGETLB_NR_MEMORY_EVENTS,
@@ -68,8 +61,6 @@ static inline struct hugetlb_cgroup * 
__hugetlb_cgroup_from_folio(struct folio *folio, bool rsvd)

{

	VM_BUG_ON_FOLIO(!folio_test_hugetlb(folio), folio);

	if (folio_order(folio) < HUGETLB_CGROUP_MIN_ORDER)

		return NULL;

	if (rsvd)

		return folio->_hugetlb_cgroup_rsvd;

	else
@@ -91,8 +82,6 @@ static inline void __set_hugetlb_cgroup(struct folio *folio, 
				       struct hugetlb_cgroup *h_cg, bool rsvd)

{

	VM_BUG_ON_FOLIO(!folio_test_hugetlb(folio), folio);

	if (folio_order(folio) < HUGETLB_CGROUP_MIN_ORDER)

		return;

	if (rsvd)

		folio->_hugetlb_cgroup_rsvd = h_cg;

	else

mm/hugetlb.c

+1 −1
Original line number Diff line number Diff line
@@ -4361,7 +4361,7 @@ void __init hugetlb_add_hstate(unsigned int order) 
		return;

	}

	BUG_ON(hugetlb_max_hstate >= HUGE_MAX_HSTATE);

	BUG_ON(order == 0);

	BUG_ON(order < order_base_2(__NR_USED_SUBPAGE));

	h = &hstates[hugetlb_max_hstate++];

	mutex_init(&h->resize_lock);

	h->order = order;

mm/hugetlb_cgroup.c

+2 −18
Original line number Diff line number Diff line
@@ -262,12 +262,6 @@ static int __hugetlb_cgroup_charge_cgroup(int idx, unsigned long nr_pages, 


	if (hugetlb_cgroup_disabled())

		goto done;

	/*

	 * We don't charge any cgroup if the compound page have less

	 * than 3 pages.

	 */

	if (huge_page_order(&hstates[idx]) < HUGETLB_CGROUP_MIN_ORDER)

		goto done;

again:

	rcu_read_lock();

	h_cg = hugetlb_cgroup_from_task(current);
@@ -397,9 +391,6 @@ static void __hugetlb_cgroup_uncharge_cgroup(int idx, unsigned long nr_pages, 
	if (hugetlb_cgroup_disabled() || !h_cg)

		return;



	if (huge_page_order(&hstates[idx]) < HUGETLB_CGROUP_MIN_ORDER)

		return;



	page_counter_uncharge(__hugetlb_cgroup_counter_from_cgroup(h_cg, idx,

								   rsvd),

			      nr_pages);
@@ -869,16 +860,9 @@ void __init hugetlb_cgroup_file_init(void) 
{

	struct hstate *h;



	for_each_hstate(h) {

		/*

		 * Add cgroup control files only if the huge page consists

		 * of more than two normal pages. This is because we use

		 * page[2].private for storing cgroup details.

		 */

		if (huge_page_order(h) >= HUGETLB_CGROUP_MIN_ORDER)

	for_each_hstate(h)

		__hugetlb_cgroup_file_init(hstate_index(h));

}

}



/*

 * hugetlb_lock will make sure a parallel cgroup rmdir won't happen