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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: Frank van der Linden <fvdl@google.com>
Reviewed-by: Mike Kravetz <mike.kravetz@oracle.com>
Cc: Muchun Song <muchun.song@linux.dev>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
This commit is contained in:
Frank van der Linden 2023-10-04 15:32:48 +00:00 committed by Andrew Morton
parent 2580d55458
commit 59838b2566
3 changed files with 3 additions and 30 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

11
include/linux/hugetlb_cgroup.h
View File

@ -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

2
mm/hugetlb.c
View File

@ -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;

20
mm/hugetlb_cgroup.c
View File

@ -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);
@ -869,15 +860,8 @@ 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)
__hugetlb_cgroup_file_init(hstate_index(h));
}
for_each_hstate(h)
__hugetlb_cgroup_file_init(hstate_index(h));
}
/*