From: Muchun Song <songmuchun@bytedance.com>
To: corbet@lwn.net, mike.kravetz@oracle.com, tglx@linutronix.de,
mingo@redhat.com, bp@alien8.de, x86@kernel.org, hpa@zytor.com,
dave.hansen@linux.intel.com, luto@kernel.org,
peterz@infradead.org, viro@zeniv.linux.org.uk,
akpm@linux-foundation.org, paulmck@kernel.org,
mchehab+huawei@kernel.org, pawan.kumar.gupta@linux.intel.com,
rdunlap@infradead.org, oneukum@suse.com,
anshuman.khandual@arm.com, jroedel@suse.de,
almasrymina@google.com, rientjes@google.com
Cc: linux-doc@vger.kernel.org, linux-kernel@vger.kernel.org,
linux-mm@kvack.org, linux-fsdevel@vger.kernel.org,
Muchun Song <songmuchun@bytedance.com>
Subject: [RFC PATCH 12/24] mm/hugetlb: Defer freeing of hugetlb pages
Date: Tue, 15 Sep 2020 20:59:35 +0800 [thread overview]
Message-ID: <20200915125947.26204-13-songmuchun@bytedance.com> (raw)
In-Reply-To: <20200915125947.26204-1-songmuchun@bytedance.com>
In the subsequent patch, we will allocate the vmemmap pages when free
huge pages. But update_and_free_page() is be called from a non-task
context(and hold hugetlb_lock), we can defer the actual freeing in
a workqueue to prevent use GFP_ATOMIC to allocate the vmemmap pages.
Signed-off-by: Muchun Song <songmuchun@bytedance.com>
---
mm/hugetlb.c | 94 +++++++++++++++++++++++++++++++++++++++++++++++-----
1 file changed, 85 insertions(+), 9 deletions(-)
diff --git a/mm/hugetlb.c b/mm/hugetlb.c
index a628588a075a..6b57a1183785 100644
--- a/mm/hugetlb.c
+++ b/mm/hugetlb.c
@@ -1292,6 +1292,8 @@ static inline void destroy_compound_gigantic_page(struct page *page,
unsigned int order) { }
#endif
+static void __free_hugepage(struct hstate *h, struct page *page);
+
#ifdef CONFIG_HUGETLB_PAGE_FREE_VMEMMAP
#include <linux/bootmem_info.h>
@@ -1642,6 +1644,64 @@ static void free_huge_page_vmemmap(struct hstate *h, struct page *head)
free_vmemmap_page_list(&free_pages);
}
+
+/*
+ * As update_and_free_page() is be called from a non-task context(and hold
+ * hugetlb_lock), we can defer the actual freeing in a workqueue to prevent
+ * use GFP_ATOMIC to allocate a lot of vmemmap pages.
+ *
+ * update_hpage_vmemmap_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 update_hpage_vmemmap_workfn() anyway, it is
+ * reused as the llist_node structure of a lockless linked list of huge
+ * pages to be freed.
+ */
+static LLIST_HEAD(hpage_update_freelist);
+
+static void update_hpage_vmemmap_workfn(struct work_struct *work)
+{
+ struct llist_node *node;
+ struct page *page;
+
+ node = llist_del_all(&hpage_update_freelist);
+
+ while (node) {
+ page = container_of((struct address_space **)node,
+ struct page, mapping);
+ node = node->next;
+ page->mapping = NULL;
+ __free_hugepage(page_hstate(page), page);
+
+ cond_resched();
+ }
+}
+static DECLARE_WORK(hpage_update_work, update_hpage_vmemmap_workfn);
+
+static inline void __update_and_free_page(struct hstate *h, struct page *page)
+{
+ /* No need to allocate vmemmap pages */
+ if (!nr_free_vmemmap(h)) {
+ __free_hugepage(h, page);
+ return;
+ }
+
+ /*
+ * Defer freeing to avoid using GFP_ATOMIC to allocate vmemmap
+ * pages.
+ *
+ * Only call schedule_work() if hpage_update_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_update_freelist))
+ schedule_work(&hpage_update_work);
+}
+
+static inline void free_gigantic_page_comm(struct hstate *h, struct page *page)
+{
+ free_gigantic_page(page, huge_page_order(h));
+}
#else
static inline void hugetlb_vmemmap_init(struct hstate *h)
{
@@ -1659,17 +1719,39 @@ static inline void vmemmap_pgtable_free(struct hstate *h, struct page *page)
static inline void free_huge_page_vmemmap(struct hstate *h, struct page *head)
{
}
+
+static inline void __update_and_free_page(struct hstate *h, struct page *page)
+{
+ __free_hugepage(h, page);
+}
+
+static inline void free_gigantic_page_comm(struct hstate *h, struct page *page)
+{
+ /*
+ * Temporarily drop the hugetlb_lock, because
+ * we might block in free_gigantic_page().
+ */
+ spin_unlock(&hugetlb_lock);
+ free_gigantic_page(page, huge_page_order(h));
+ spin_lock(&hugetlb_lock);
+}
#endif
static void update_and_free_page(struct hstate *h, struct page *page)
{
- int i;
-
if (hstate_is_gigantic(h) && !gigantic_page_runtime_supported())
return;
h->nr_huge_pages--;
h->nr_huge_pages_node[page_to_nid(page)]--;
+
+ __update_and_free_page(h, page);
+}
+
+static void __free_hugepage(struct hstate *h, struct page *page)
+{
+ int i;
+
for (i = 0; i < pages_per_huge_page(h); i++) {
page[i].flags &= ~(1 << PG_locked | 1 << PG_error |
1 << PG_referenced | 1 << PG_dirty |
@@ -1681,14 +1763,8 @@ static void update_and_free_page(struct hstate *h, struct page *page)
set_compound_page_dtor(page, NULL_COMPOUND_DTOR);
set_page_refcounted(page);
if (hstate_is_gigantic(h)) {
- /*
- * Temporarily drop the hugetlb_lock, because
- * we might block in free_gigantic_page().
- */
- spin_unlock(&hugetlb_lock);
destroy_compound_gigantic_page(page, huge_page_order(h));
- free_gigantic_page(page, huge_page_order(h));
- spin_lock(&hugetlb_lock);
+ free_gigantic_page_comm(h, page);
} else {
__free_pages(page, huge_page_order(h));
}
--
2.20.1
next prev parent reply other threads:[~2020-09-15 13:02 UTC|newest]
Thread overview: 48+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-09-15 12:59 [RFC PATCH 00/24] mm/hugetlb: Free some vmemmap pages of hugetlb page Muchun Song
2020-09-15 12:59 ` [RFC PATCH 01/24] mm/memory_hotplug: Move bootmem info registration API to bootmem_info.c Muchun Song
2020-09-29 22:46 ` Mike Kravetz
2020-09-15 12:59 ` [RFC PATCH 02/24] mm/memory_hotplug: Move {get,put}_page_bootmem() " Muchun Song
2020-09-29 23:30 ` Mike Kravetz
2020-09-15 12:59 ` [RFC PATCH 03/24] mm/hugetlb: Introduce a new config HUGETLB_PAGE_FREE_VMEMMAP Muchun Song
2020-09-16 2:13 ` Randy Dunlap
2020-09-29 23:41 ` Mike Kravetz
2020-09-30 2:56 ` [External] " Muchun Song
2020-09-15 12:59 ` [RFC PATCH 04/24] mm/hugetlb: Register bootmem info when CONFIG_HUGETLB_PAGE_FREE_VMEMMAP Muchun Song
2020-09-15 12:59 ` [RFC PATCH 05/24] mm/hugetlb: Introduce nr_free_vmemmap_pages in the struct hstate Muchun Song
2020-09-30 22:41 ` Mike Kravetz
2020-10-01 2:57 ` [External] " Muchun Song
2020-09-15 12:59 ` [RFC PATCH 06/24] mm/hugetlb: Introduce pgtable allocation/freeing helpers Muchun Song
2020-09-15 12:59 ` [RFC PATCH 07/24] mm/hugetlb: Add freeing unused vmemmap pages support for x86 Muchun Song
2020-09-15 12:59 ` [RFC PATCH 08/24] mm/bootmem_info: Introduce {free,prepare}_vmemmap_page() Muchun Song
2020-09-15 12:59 ` [RFC PATCH 09/24] x86/mm: Introduce VMEMMAP_SIZE/VMEMMAP_END macro Muchun Song
2020-09-15 12:59 ` [RFC PATCH 10/24] mm/hugetlb: Free the vmemmap pages associated with each hugetlb page Muchun Song
2020-09-15 12:59 ` [RFC PATCH 11/24] mm/hugetlb: Add vmemmap_pmd_huge macro for x86 Muchun Song
2020-09-15 12:59 ` Muchun Song [this message]
2020-09-15 12:59 ` [RFC PATCH 13/24] mm/hugetlb: Allocate the vmemmap pages associated with each hugetlb page Muchun Song
2020-09-15 12:59 ` [RFC PATCH 14/24] mm/hugetlb: Introduce remap_huge_page_pmd_vmemmap helper Muchun Song
2020-09-15 12:59 ` [RFC PATCH 15/24] mm/hugetlb: Use PG_slab to indicate split pmd Muchun Song
2020-09-15 12:59 ` [RFC PATCH 16/24] mm/hugetlb: Support freeing vmemmap pages of gigantic page Muchun Song
2020-09-15 12:59 ` [RFC PATCH 17/24] mm/hugetlb: Add a BUILD_BUG_ON to check if struct page size is a power of two Muchun Song
2020-09-15 12:59 ` [RFC PATCH 18/24] mm/hugetlb: Clear PageHWPoison on the non-error memory page Muchun Song
2020-09-15 12:59 ` [RFC PATCH 19/24] mm/hugetlb: Flush work when dissolving hugetlb page Muchun Song
2020-09-15 12:59 ` [RFC PATCH 20/24] mm/hugetlb: Add a kernel parameter hugetlb_free_vmemmap Muchun Song
2020-09-16 2:10 ` Randy Dunlap
2020-09-16 2:50 ` [External] " Muchun Song
2020-09-15 12:59 ` [RFC PATCH 21/24] mm/hugetlb: Merge pte to huge pmd only for gigantic page Muchun Song
2020-09-20 9:59 ` Muchun Song
2020-09-15 12:59 ` [RFC PATCH 22/24] mm/hugetlb: Implement vmemmap_pmd_mkhuge macro Muchun Song
2020-09-15 12:59 ` [RFC PATCH 23/24] mm/hugetlb: Gather discrete indexes of tail page Muchun Song
2020-09-15 12:59 ` [RFC PATCH 24/24] mm/hugetlb: Add BUILD_BUG_ON to catch invalid usage of tail struct page Muchun Song
2020-09-15 14:32 ` [RFC PATCH 00/24] mm/hugetlb: Free some vmemmap pages of hugetlb page Matthew Wilcox
2020-09-15 14:53 ` Dave Hansen
2020-09-15 15:28 ` [External] " Muchun Song
2020-09-15 15:42 ` Matthew Wilcox
2020-09-15 17:32 ` Muchun Song
2020-09-15 17:39 ` Matthew Wilcox
2020-09-15 18:03 ` Muchun Song
2020-09-15 18:15 ` Matthew Wilcox
2020-09-16 2:45 ` Muchun Song
2020-09-29 21:58 ` Mike Kravetz
2020-09-30 3:13 ` Matthew Wilcox
2020-10-07 21:12 ` Mike Kravetz
2020-10-09 4:13 ` [External] " Muchun Song
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