The patch titled
Subject: mm: don't account memmap per-node
has been added to the -mm mm-hotfixes-unstable branch. Its filename is
mm-dont-account-memmap-per-node.patch
This patch will shortly appear at
https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches/mm-dont-account-memmap-per-node.patch
This patch will later appear in the mm-hotfixes-unstable branch at
git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm
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------------------------------------------------------
From: Pasha Tatashin <pasha.tatashin@xxxxxxxxxx>
Subject: mm: don't account memmap per-node
Date: Thu, 8 Aug 2024 21:34:36 +0000
Fix invalid access to pgdat during hot-remove operation:
ndctl users reported a GPF when trying to destroy a namespace:
$ ndctl destroy-namespace all -r all -f
Segmentation fault
dmesg:
Oops: general protection fault, probably for
non-canonical address 0xdffffc0000005650: 0000 [#1] PREEMPT SMP KASAN
PTI
KASAN: probably user-memory-access in range
[0x000000000002b280-0x000000000002b287]
CPU: 26 UID: 0 PID: 1868 Comm: ndctl Not tainted 6.11.0-rc1 #1
Hardware name: Dell Inc. PowerEdge R640/08HT8T, BIOS
2.20.1 09/13/2023
RIP: 0010:mod_node_page_state+0x2a/0x110
cxl-test users report a GPF when trying to unload the test module:
$ modrpobe -r cxl-test
dmesg
BUG: unable to handle page fault for address: 0000000000004200
#PF: supervisor read access in kernel mode
#PF: error_code(0x0000) - not-present page
PGD 0 P4D 0
Oops: Oops: 0000 [#1] PREEMPT SMP PTI
CPU: 0 UID: 0 PID: 1076 Comm: modprobe Tainted: G O N 6.11.0-rc1 #197
Tainted: [O]=OOT_MODULE, [N]=TEST
Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 0.0.0 02/06/15
RIP: 0010:mod_node_page_state+0x6/0x90
Currently, when memory is hot-plugged or hot-removed the accounting is
done based on the assumption that memmap is allocated from the same node
as the hot-plugged/hot-removed memory, which is not always the case.
In addition, there are challenges with keeping the node id of the memory
that is being remove to the time when memmap accounting is actually
performed: since this is done after remove_pfn_range_from_zone(), and
also after remove_memory_block_devices(). Meaning that we cannot use
pgdat nor walking though memblocks to get the nid.
Given all of that, account the memmap overhead system wide instead.
For this we are going to be using global atomic counters, but given that
memmap size is rarely modified, and normally is only modified either
during early boot when there is only one CPU, or under a hotplug global
mutex lock, therefore there is no need for per-cpu optimizations.
Also, while we are here rename nr_memmap to nr_memmap_pages, and
nr_memmap_boot to nr_memmap_boot_pages to be self explanatory that the
units are in page count.
Link: https://lkml.kernel.org/r/20240808213437.682006-4-pasha.tatashin@xxxxxxxxxx
Fixes: 15995a352474 ("mm: report per-page metadata information")
Signed-off-by: Pasha Tatashin <pasha.tatashin@xxxxxxxxxx>
Reported-by: Yi Zhang <yi.zhang@xxxxxxxxxx>
Closes: https://lore.kernel.org/linux-cxl/CAHj4cs9Ax1=CoJkgBGP_+sNu6-6=6v=_L-ZBZY0bVLD3wUWZQg@xxxxxxxxxxxxxx
Reported-by: Alison Schofield <alison.schofield@xxxxxxxxx>
Closes: https://lore.kernel.org/linux-mm/Zq0tPd2h6alFz8XF@aschofie-mobl2/#t
Tested-by: Dan Williams <dan.j.williams@xxxxxxxxx>
Cc: David Hildenbrand <david@xxxxxxxxxx>
Cc: David Rientjes <rientjes@xxxxxxxxxx>
Cc: Domenico Cerasuolo <cerasuolodomenico@xxxxxxxxx>
Cc: Fan Ni <fan.ni@xxxxxxxxxxx>
Cc: Joel Granados <j.granados@xxxxxxxxxxx>
Cc: Johannes Weiner <hannes@xxxxxxxxxxx>
Cc: Li Zhijian <lizhijian@xxxxxxxxxxx>
Cc: Matthew Wilcox (Oracle) <willy@xxxxxxxxxxxxx>
Cc: Mike Rapoport <rppt@xxxxxxxxxx>
Cc: Muchun Song <muchun.song@xxxxxxxxx>
Cc: Nhat Pham <nphamcs@xxxxxxxxx>
Cc: Sourav Panda <souravpanda@xxxxxxxxxx>
Cc: Vlastimil Babka <vbabka@xxxxxxx>
Cc: Yosry Ahmed <yosryahmed@xxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
include/linux/mmzone.h | 2 -
include/linux/vmstat.h | 7 +++---
mm/hugetlb_vmemmap.c | 8 +++---
mm/mm_init.c | 3 --
mm/page_alloc.c | 1
mm/page_ext.c | 18 +++------------
mm/sparse-vmemmap.c | 11 +++------
mm/sparse.c | 5 +---
mm/vmstat.c | 45 ++++++++++++++++++---------------------
9 files changed, 40 insertions(+), 60 deletions(-)
--- a/include/linux/mmzone.h~mm-dont-account-memmap-per-node
+++ a/include/linux/mmzone.h
@@ -220,8 +220,6 @@ enum node_stat_item {
PGDEMOTE_KSWAPD,
PGDEMOTE_DIRECT,
PGDEMOTE_KHUGEPAGED,
- NR_MEMMAP, /* page metadata allocated through buddy allocator */
- NR_MEMMAP_BOOT, /* page metadata allocated through boot allocator */
NR_VM_NODE_STAT_ITEMS
};
--- a/include/linux/vmstat.h~mm-dont-account-memmap-per-node
+++ a/include/linux/vmstat.h
@@ -38,6 +38,8 @@ struct reclaim_stat {
enum vm_stat_item {
NR_DIRTY_THRESHOLD,
NR_DIRTY_BG_THRESHOLD,
+ NR_MEMMAP, /* page metadata allocated through buddy allocator */
+ NR_MEMMAP_BOOT, /* page metadata allocated through boot allocator */
NR_VM_STAT_ITEMS,
};
@@ -618,7 +620,6 @@ static inline void lruvec_stat_sub_folio
lruvec_stat_mod_folio(folio, idx, -folio_nr_pages(folio));
}
-void __meminit mod_node_early_perpage_metadata(int nid, long delta);
-void __meminit store_early_perpage_metadata(void);
-
+void mod_memmap_boot(long delta);
+void mod_memmap(long delta);
#endif /* _LINUX_VMSTAT_H */
--- a/mm/hugetlb_vmemmap.c~mm-dont-account-memmap-per-node
+++ a/mm/hugetlb_vmemmap.c
@@ -185,11 +185,11 @@ static int vmemmap_remap_range(unsigned
static inline void free_vmemmap_page(struct page *page)
{
if (PageReserved(page)) {
+ mod_memmap_boot(-1);
free_bootmem_page(page);
- mod_node_page_state(page_pgdat(page), NR_MEMMAP_BOOT, -1);
} else {
+ mod_memmap(-1);
__free_page(page);
- mod_node_page_state(page_pgdat(page), NR_MEMMAP, -1);
}
}
@@ -341,7 +341,7 @@ static int vmemmap_remap_free(unsigned l
copy_page(page_to_virt(walk.reuse_page),
(void *)walk.reuse_addr);
list_add(&walk.reuse_page->lru, vmemmap_pages);
- mod_node_page_state(NODE_DATA(nid), NR_MEMMAP, 1);
+ mod_memmap(1);
}
/*
@@ -396,7 +396,7 @@ static int alloc_vmemmap_page_list(unsig
goto out;
list_add(&page->lru, list);
}
- mod_node_page_state(NODE_DATA(nid), NR_MEMMAP, nr_pages);
+ mod_memmap(nr_pages);
return 0;
out:
--- a/mm/mm_init.c~mm-dont-account-memmap-per-node
+++ a/mm/mm_init.c
@@ -1623,8 +1623,7 @@ static void __init alloc_node_mem_map(st
panic("Failed to allocate %ld bytes for node %d memory map\n",
size, pgdat->node_id);
pgdat->node_mem_map = map + offset;
- mod_node_early_perpage_metadata(pgdat->node_id,
- DIV_ROUND_UP(size, PAGE_SIZE));
+ mod_memmap_boot(DIV_ROUND_UP(size, PAGE_SIZE));
pr_debug("%s: node %d, pgdat %08lx, node_mem_map %08lx\n",
__func__, pgdat->node_id, (unsigned long)pgdat,
(unsigned long)pgdat->node_mem_map);
--- a/mm/page_alloc.c~mm-dont-account-memmap-per-node
+++ a/mm/page_alloc.c
@@ -5755,7 +5755,6 @@ void __init setup_per_cpu_pageset(void)
for_each_online_pgdat(pgdat)
pgdat->per_cpu_nodestats =
alloc_percpu(struct per_cpu_nodestat);
- store_early_perpage_metadata();
}
__meminit void zone_pcp_init(struct zone *zone)
--- a/mm/page_ext.c~mm-dont-account-memmap-per-node
+++ a/mm/page_ext.c
@@ -214,8 +214,7 @@ static int __init alloc_node_page_ext(in
return -ENOMEM;
NODE_DATA(nid)->node_page_ext = base;
total_usage += table_size;
- mod_node_page_state(NODE_DATA(nid), NR_MEMMAP_BOOT,
- DIV_ROUND_UP(table_size, PAGE_SIZE));
+ mod_memmap_boot(DIV_ROUND_UP(table_size, PAGE_SIZE));
return 0;
}
@@ -275,10 +274,8 @@ static void *__meminit alloc_page_ext(si
else
addr = vzalloc_node(size, nid);
- if (addr) {
- mod_node_page_state(NODE_DATA(nid), NR_MEMMAP,
- DIV_ROUND_UP(size, PAGE_SIZE));
- }
+ if (addr)
+ mod_memmap(DIV_ROUND_UP(size, PAGE_SIZE));
return addr;
}
@@ -323,25 +320,18 @@ static void free_page_ext(void *addr)
{
size_t table_size;
struct page *page;
- struct pglist_data *pgdat;
table_size = page_ext_size * PAGES_PER_SECTION;
+ mod_memmap(-1L * (DIV_ROUND_UP(table_size, PAGE_SIZE)));
if (is_vmalloc_addr(addr)) {
- page = vmalloc_to_page(addr);
- pgdat = page_pgdat(page);
vfree(addr);
} else {
page = virt_to_page(addr);
- pgdat = page_pgdat(page);
BUG_ON(PageReserved(page));
kmemleak_free(addr);
free_pages_exact(addr, table_size);
}
-
- mod_node_page_state(pgdat, NR_MEMMAP,
- -1L * (DIV_ROUND_UP(table_size, PAGE_SIZE)));
-
}
static void __free_page_ext(unsigned long pfn)
--- a/mm/sparse.c~mm-dont-account-memmap-per-node
+++ a/mm/sparse.c
@@ -463,7 +463,7 @@ static void __init sparse_buffer_init(un
sparsemap_buf = memmap_alloc(size, section_map_size(), addr, nid, true);
sparsemap_buf_end = sparsemap_buf + size;
#ifndef CONFIG_SPARSEMEM_VMEMMAP
- mod_node_early_perpage_metadata(nid, DIV_ROUND_UP(size, PAGE_SIZE));
+ mod_memmap_boot(DIV_ROUND_UP(size, PAGE_SIZE));
#endif
}
@@ -643,8 +643,7 @@ static void depopulate_section_memmap(un
unsigned long start = (unsigned long) pfn_to_page(pfn);
unsigned long end = start + nr_pages * sizeof(struct page);
- mod_node_page_state(page_pgdat(pfn_to_page(pfn)), NR_MEMMAP,
- -1L * (DIV_ROUND_UP(end - start, PAGE_SIZE)));
+ mod_memmap(-1L * (DIV_ROUND_UP(end - start, PAGE_SIZE)));
vmemmap_free(start, end, altmap);
}
static void free_map_bootmem(struct page *memmap)
--- a/mm/sparse-vmemmap.c~mm-dont-account-memmap-per-node
+++ a/mm/sparse-vmemmap.c
@@ -469,13 +469,10 @@ struct page * __meminit __populate_secti
if (r < 0)
return NULL;
- if (system_state == SYSTEM_BOOTING) {
- mod_node_early_perpage_metadata(nid, DIV_ROUND_UP(end - start,
- PAGE_SIZE));
- } else {
- mod_node_page_state(NODE_DATA(nid), NR_MEMMAP,
- DIV_ROUND_UP(end - start, PAGE_SIZE));
- }
+ if (system_state == SYSTEM_BOOTING)
+ mod_memmap_boot(DIV_ROUND_UP(end - start, PAGE_SIZE));
+ else
+ mod_memmap(DIV_ROUND_UP(end - start, PAGE_SIZE));
return pfn_to_page(pfn);
}
--- a/mm/vmstat.c~mm-dont-account-memmap-per-node
+++ a/mm/vmstat.c
@@ -1033,6 +1033,23 @@ unsigned long node_page_state(struct pgl
}
#endif
+/*
+ * Count number of pages "struct page" and "struct page_ext" consume.
+ * nr_memmap_boot: # of pages allocated by boot allocator & not part of MemTotal
+ * nr_memmap: # of pages that were allocated by buddy allocator
+ */
+static atomic_long_t nr_memmap_boot, nr_memmap;
+
+void mod_memmap_boot(long delta)
+{
+ atomic_long_add(delta, &nr_memmap_boot);
+}
+
+void mod_memmap(long delta)
+{
+ atomic_long_add(delta, &nr_memmap);
+}
+
#ifdef CONFIG_COMPACTION
struct contig_page_info {
@@ -1255,11 +1272,11 @@ const char * const vmstat_text[] = {
"pgdemote_kswapd",
"pgdemote_direct",
"pgdemote_khugepaged",
- "nr_memmap",
- "nr_memmap_boot",
/* system-wide enum vm_stat_item counters */
"nr_dirty_threshold",
"nr_dirty_background_threshold",
+ "nr_memmap_pages",
+ "nr_memmap_boot_pages",
#if defined(CONFIG_VM_EVENT_COUNTERS) || defined(CONFIG_MEMCG)
/* enum vm_event_item counters */
@@ -1827,6 +1844,8 @@ static void *vmstat_start(struct seq_fil
global_dirty_limits(v + NR_DIRTY_BG_THRESHOLD,
v + NR_DIRTY_THRESHOLD);
+ v[NR_MEMMAP_BOOT] = atomic_long_read(&nr_memmap_boot);
+ v[NR_MEMMAP] = atomic_long_read(&nr_memmap);
v += NR_VM_STAT_ITEMS;
#ifdef CONFIG_VM_EVENT_COUNTERS
@@ -2285,25 +2304,3 @@ static int __init extfrag_debug_init(voi
module_init(extfrag_debug_init);
#endif
-
-/*
- * Page metadata size (struct page and page_ext) in pages
- */
-static unsigned long early_perpage_metadata[MAX_NUMNODES] __meminitdata;
-
-void __meminit mod_node_early_perpage_metadata(int nid, long delta)
-{
- early_perpage_metadata[nid] += delta;
-}
-
-void __meminit store_early_perpage_metadata(void)
-{
- int nid;
- struct pglist_data *pgdat;
-
- for_each_online_pgdat(pgdat) {
- nid = pgdat->node_id;
- mod_node_page_state(NODE_DATA(nid), NR_MEMMAP_BOOT,
- early_perpage_metadata[nid]);
- }
-}
_
Patches currently in -mm which might be from pasha.tatashin@xxxxxxxxxx are
mm-dont-account-memmap-on-failure.patch
mm-add-system-wide-stats-items-category.patch
mm-dont-account-memmap-per-node.patch
memcg-increase-the-valid-index-range-for-memcg-stats-v5.patch
vmstat-kernel-stack-usage-histogram.patch
task_stack-uninline-stack_not_used.patch
