* [to-be-updated] mm-hugetlb-add-a-kernel-parameter-hugetlb_free_vmemmap.patch removed from -mm tree
@ 2021-03-18 0:52 akpm
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From: akpm @ 2021-03-18 0:52 UTC (permalink / raw)
To: almasrymina, anshuman.khandual, bodeddub, bp, bsingharora,
chenhuang5, corbet, dave.hansen, david, hpa, joao.m.martins,
jroedel, linmiaohe, luto, mchehab+huawei, mhocko, mike.kravetz,
mingo, mm-commits, naoya.horiguchi, oneukum, osalvador, paulmck,
pawan.kumar.gupta, peterz, rdunlap, rientjes, song.bao.hua,
songmuchun, tglx, viro, willy
The patch titled
Subject: mm: hugetlb: add a kernel parameter hugetlb_free_vmemmap
has been removed from the -mm tree. Its filename was
mm-hugetlb-add-a-kernel-parameter-hugetlb_free_vmemmap.patch
This patch was dropped because an updated version will be merged
------------------------------------------------------
From: Muchun Song <songmuchun@bytedance.com>
Subject: mm: hugetlb: add a kernel parameter hugetlb_free_vmemmap
Add a kernel parameter hugetlb_free_vmemmap to enable the feature of
freeing unused vmemmap pages associated with each hugetlb page on boot.
We disable PMD mapping of vmemmap pages for x86-64 arch when this feature
is enabled. Because vmemmap_remap_free() depends on vmemmap being base
page mapped.
Link: https://lkml.kernel.org/r/20210315092015.35396-8-songmuchun@bytedance.com
Signed-off-by: Muchun Song <songmuchun@bytedance.com>
Reviewed-by: Oscar Salvador <osalvador@suse.de>
Reviewed-by: Barry Song <song.bao.hua@hisilicon.com>
Reviewed-by: Miaohe Lin <linmiaohe@huawei.com>
Tested-by: Chen Huang <chenhuang5@huawei.com>
Tested-by: Bodeddula Balasubramaniam <bodeddub@amazon.com>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Anshuman Khandual <anshuman.khandual@arm.com>
Cc: Balbir Singh <bsingharora@gmail.com>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: David Hildenbrand <david@redhat.com>
Cc: David Rientjes <rientjes@google.com>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Joao Martins <joao.m.martins@oracle.com>
Cc: Joerg Roedel <jroedel@suse.de>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Matthew Wilcox (Oracle) <willy@infradead.org>
Cc: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Mike Kravetz <mike.kravetz@oracle.com>
Cc: Mina Almasry <almasrymina@google.com>
Cc: Naoya Horiguchi <naoya.horiguchi@nec.com>
Cc: Oliver Neukum <oneukum@suse.com>
Cc: "Paul E. McKenney" <paulmck@kernel.org>
Cc: Pawan Gupta <pawan.kumar.gupta@linux.intel.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Randy Dunlap <rdunlap@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---
Documentation/admin-guide/kernel-parameters.txt | 17 +++++++++
Documentation/admin-guide/mm/hugetlbpage.rst | 3 +
arch/x86/mm/init_64.c | 8 +++-
include/linux/hugetlb.h | 19 +++++++++++
mm/hugetlb_vmemmap.c | 24 ++++++++++++++
5 files changed, 69 insertions(+), 2 deletions(-)
--- a/arch/x86/mm/init_64.c~mm-hugetlb-add-a-kernel-parameter-hugetlb_free_vmemmap
+++ a/arch/x86/mm/init_64.c
@@ -34,6 +34,7 @@
#include <linux/gfp.h>
#include <linux/kcore.h>
#include <linux/bootmem_info.h>
+#include <linux/hugetlb.h>
#include <asm/processor.h>
#include <asm/bios_ebda.h>
@@ -1610,7 +1611,8 @@ int __meminit vmemmap_populate(unsigned
VM_BUG_ON(!IS_ALIGNED(start, PAGE_SIZE));
VM_BUG_ON(!IS_ALIGNED(end, PAGE_SIZE));
- if (end - start < PAGES_PER_SECTION * sizeof(struct page))
+ if ((is_hugetlb_free_vmemmap_enabled() && !altmap) ||
+ end - start < PAGES_PER_SECTION * sizeof(struct page))
err = vmemmap_populate_basepages(start, end, node, NULL);
else if (boot_cpu_has(X86_FEATURE_PSE))
err = vmemmap_populate_hugepages(start, end, node, altmap);
@@ -1638,6 +1640,8 @@ void register_page_bootmem_memmap(unsign
pmd_t *pmd;
unsigned int nr_pmd_pages;
struct page *page;
+ bool base_mapping = !boot_cpu_has(X86_FEATURE_PSE) ||
+ is_hugetlb_free_vmemmap_enabled();
for (; addr < end; addr = next) {
pte_t *pte = NULL;
@@ -1663,7 +1667,7 @@ void register_page_bootmem_memmap(unsign
}
get_page_bootmem(section_nr, pud_page(*pud), MIX_SECTION_INFO);
- if (!boot_cpu_has(X86_FEATURE_PSE)) {
+ if (base_mapping) {
next = (addr + PAGE_SIZE) & PAGE_MASK;
pmd = pmd_offset(pud, addr);
if (pmd_none(*pmd))
--- a/Documentation/admin-guide/kernel-parameters.txt~mm-hugetlb-add-a-kernel-parameter-hugetlb_free_vmemmap
+++ a/Documentation/admin-guide/kernel-parameters.txt
@@ -1557,6 +1557,23 @@
Documentation/admin-guide/mm/hugetlbpage.rst.
Format: size[KMG]
+ hugetlb_free_vmemmap=
+ [KNL] Reguires CONFIG_HUGETLB_PAGE_FREE_VMEMMAP
+ enabled.
+ Allows heavy hugetlb users to free up some more
+ memory (6 * PAGE_SIZE for each 2MB hugetlb page).
+ This feauture is not free though. Large page
+ tables are not used to back vmemmap pages which
+ can lead to a performance degradation for some
+ workloads. Also there will be memory allocation
+ required when hugetlb pages are freed from the
+ pool which can lead to corner cases under heavy
+ memory pressure.
+ Format: { on | off (default) }
+
+ on: enable the feature
+ off: disable the feature
+
hung_task_panic=
[KNL] Should the hung task detector generate panics.
Format: 0 | 1
--- a/Documentation/admin-guide/mm/hugetlbpage.rst~mm-hugetlb-add-a-kernel-parameter-hugetlb_free_vmemmap
+++ a/Documentation/admin-guide/mm/hugetlbpage.rst
@@ -153,6 +153,9 @@ default_hugepagesz
will all result in 256 2M huge pages being allocated. Valid default
huge page size is architecture dependent.
+hugetlb_free_vmemmap
+ When CONFIG_HUGETLB_PAGE_FREE_VMEMMAP is set, this enables freeing
+ unused vmemmap pages associated with each HugeTLB page.
When multiple huge page sizes are supported, ``/proc/sys/vm/nr_hugepages``
indicates the current number of pre-allocated huge pages of the default size.
--- a/include/linux/hugetlb.h~mm-hugetlb-add-a-kernel-parameter-hugetlb_free_vmemmap
+++ a/include/linux/hugetlb.h
@@ -886,6 +886,20 @@ static inline void huge_ptep_modify_prot
}
#endif
+#ifdef CONFIG_HUGETLB_PAGE_FREE_VMEMMAP
+extern bool hugetlb_free_vmemmap_enabled;
+
+static inline bool is_hugetlb_free_vmemmap_enabled(void)
+{
+ return hugetlb_free_vmemmap_enabled;
+}
+#else
+static inline bool is_hugetlb_free_vmemmap_enabled(void)
+{
+ return false;
+}
+#endif
+
#else /* CONFIG_HUGETLB_PAGE */
struct hstate {};
@@ -1039,6 +1053,11 @@ static inline void set_huge_swap_pte_at(
pte_t *ptep, pte_t pte, unsigned long sz)
{
}
+
+static inline bool is_hugetlb_free_vmemmap_enabled(void)
+{
+ return false;
+}
#endif /* CONFIG_HUGETLB_PAGE */
static inline spinlock_t *huge_pte_lock(struct hstate *h,
--- a/mm/hugetlb_vmemmap.c~mm-hugetlb-add-a-kernel-parameter-hugetlb_free_vmemmap
+++ a/mm/hugetlb_vmemmap.c
@@ -168,6 +168,8 @@
* (last) level. So this type of HugeTLB page can be optimized only when its
* size of the struct page structs is greater than 2 pages.
*/
+#define pr_fmt(fmt) "HugeTLB: " fmt
+
#include "hugetlb_vmemmap.h"
/*
@@ -180,6 +182,28 @@
#define RESERVE_VMEMMAP_NR 2U
#define RESERVE_VMEMMAP_SIZE (RESERVE_VMEMMAP_NR << PAGE_SHIFT)
+bool hugetlb_free_vmemmap_enabled;
+
+static int __init early_hugetlb_free_vmemmap_param(char *buf)
+{
+ /* We cannot optimize if a "struct page" crosses page boundaries. */
+ if ((!is_power_of_2(sizeof(struct page)))) {
+ pr_warn("cannot free vmemmap pages because \"struct page\" crosses page boundaries\n");
+ return 0;
+ }
+
+ if (!buf)
+ return -EINVAL;
+
+ if (!strcmp(buf, "on"))
+ hugetlb_free_vmemmap_enabled = true;
+ else if (strcmp(buf, "off"))
+ return -EINVAL;
+
+ return 0;
+}
+early_param("hugetlb_free_vmemmap", early_hugetlb_free_vmemmap_param);
+
static inline unsigned long free_vmemmap_pages_size_per_hpage(struct hstate *h)
{
return (unsigned long)free_vmemmap_pages_per_hpage(h) << PAGE_SHIFT;
_
Patches currently in -mm which might be from songmuchun@bytedance.com are
mm-memcontrol-fix-kernel-stack-account.patch
mm-hugetlb-introduce-nr_free_vmemmap_pages-in-the-struct-hstate.patch
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2021-03-18 0:52 [to-be-updated] mm-hugetlb-add-a-kernel-parameter-hugetlb_free_vmemmap.patch removed from -mm tree akpm
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