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authorSumanth Korikkar <sumanthk@linux.ibm.com>2023-11-20 15:53:52 +0100
committerAndrew Morton <akpm@linux-foundation.org>2023-12-06 16:12:46 -0800
commit001002e73712cdf6b8d9a103648cda3040ad7647 (patch)
tree9a223035a97fa85431c392b9ecedc0973baf27de /drivers
parentc540b03828dff96e1b36e9e75714f0a8e807a92e (diff)
mm/memory_hotplug: add missing mem_hotplug_lock
From Documentation/core-api/memory-hotplug.rst: When adding/removing/onlining/offlining memory or adding/removing heterogeneous/device memory, we should always hold the mem_hotplug_lock in write mode to serialise memory hotplug (e.g. access to global/zone variables). mhp_(de)init_memmap_on_memory() functions can change zone stats and struct page content, but they are currently called w/o the mem_hotplug_lock. When memory block is being offlined and when kmemleak goes through each populated zone, the following theoretical race conditions could occur: CPU 0: | CPU 1: memory_offline() | -> offline_pages() | -> mem_hotplug_begin() | ... | -> mem_hotplug_done() | | kmemleak_scan() | -> get_online_mems() | ... -> mhp_deinit_memmap_on_memory() | [not protected by mem_hotplug_begin/done()]| Marks memory section as offline, | Retrieves zone_start_pfn poisons vmemmap struct pages and updates | and struct page members. the zone related data | | ... | -> put_online_mems() Fix this by ensuring mem_hotplug_lock is taken before performing mhp_init_memmap_on_memory(). Also ensure that mhp_deinit_memmap_on_memory() holds the lock. online/offline_pages() are currently only called from memory_block_online/offline(), so it is safe to move the locking there. Link: https://lkml.kernel.org/r/20231120145354.308999-2-sumanthk@linux.ibm.com Fixes: a08a2ae34613 ("mm,memory_hotplug: allocate memmap from the added memory range") Signed-off-by: Sumanth Korikkar <sumanthk@linux.ibm.com> Reviewed-by: Gerald Schaefer <gerald.schaefer@linux.ibm.com> Acked-by: David Hildenbrand <david@redhat.com> Cc: Alexander Gordeev <agordeev@linux.ibm.com> Cc: Aneesh Kumar K.V <aneesh.kumar@linux.ibm.com> Cc: Anshuman Khandual <anshuman.khandual@arm.com> Cc: Heiko Carstens <hca@linux.ibm.com> Cc: Michal Hocko <mhocko@suse.com> Cc: Oscar Salvador <osalvador@suse.de> Cc: Vasily Gorbik <gor@linux.ibm.com> Cc: kernel test robot <lkp@intel.com> Cc: <stable@vger.kernel.org> [5.15+] Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Diffstat (limited to 'drivers')
-rw-r--r--drivers/base/memory.c18
1 files changed, 15 insertions, 3 deletions
diff --git a/drivers/base/memory.c b/drivers/base/memory.c
index f3b9a4d0fa3b..8a13babd826c 100644
--- a/drivers/base/memory.c
+++ b/drivers/base/memory.c
@@ -180,6 +180,9 @@ static inline unsigned long memblk_nr_poison(struct memory_block *mem)
}
#endif
+/*
+ * Must acquire mem_hotplug_lock in write mode.
+ */
static int memory_block_online(struct memory_block *mem)
{
unsigned long start_pfn = section_nr_to_pfn(mem->start_section_nr);
@@ -204,10 +207,11 @@ static int memory_block_online(struct memory_block *mem)
if (mem->altmap)
nr_vmemmap_pages = mem->altmap->free;
+ mem_hotplug_begin();
if (nr_vmemmap_pages) {
ret = mhp_init_memmap_on_memory(start_pfn, nr_vmemmap_pages, zone);
if (ret)
- return ret;
+ goto out;
}
ret = online_pages(start_pfn + nr_vmemmap_pages,
@@ -215,7 +219,7 @@ static int memory_block_online(struct memory_block *mem)
if (ret) {
if (nr_vmemmap_pages)
mhp_deinit_memmap_on_memory(start_pfn, nr_vmemmap_pages);
- return ret;
+ goto out;
}
/*
@@ -227,9 +231,14 @@ static int memory_block_online(struct memory_block *mem)
nr_vmemmap_pages);
mem->zone = zone;
+out:
+ mem_hotplug_done();
return ret;
}
+/*
+ * Must acquire mem_hotplug_lock in write mode.
+ */
static int memory_block_offline(struct memory_block *mem)
{
unsigned long start_pfn = section_nr_to_pfn(mem->start_section_nr);
@@ -247,6 +256,7 @@ static int memory_block_offline(struct memory_block *mem)
if (mem->altmap)
nr_vmemmap_pages = mem->altmap->free;
+ mem_hotplug_begin();
if (nr_vmemmap_pages)
adjust_present_page_count(pfn_to_page(start_pfn), mem->group,
-nr_vmemmap_pages);
@@ -258,13 +268,15 @@ static int memory_block_offline(struct memory_block *mem)
if (nr_vmemmap_pages)
adjust_present_page_count(pfn_to_page(start_pfn),
mem->group, nr_vmemmap_pages);
- return ret;
+ goto out;
}
if (nr_vmemmap_pages)
mhp_deinit_memmap_on_memory(start_pfn, nr_vmemmap_pages);
mem->zone = NULL;
+out:
+ mem_hotplug_done();
return ret;
}