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mm/memory_hotplug: add missing mem_hotplug_lock 

[ Upstream commit 001002e73712cdf6b8d9a103648cda3040ad7647 ]

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: a08a2ae346 ("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>
Signed-off-by: Sasha Levin <sashal@kernel.org>
This commit is contained in:
Sumanth Korikkar 2023-11-20 15:53:52 +01:00 committed by Greg Kroah-Hartman
parent a576780a2a
commit 4666f003af
2 changed files with 21 additions and 10 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

18
drivers/base/memory.c
View File

@ -175,6 +175,9 @@ int memory_notify(unsigned long val, void *v)
return blocking_notifier_call_chain(&memory_chain, val, v);
}
/*
* 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);
@ -193,10 +196,11 @@ static int memory_block_online(struct memory_block *mem)
* stage helps to keep accounting easier to follow - e.g vmemmaps
* belong to the same zone as the memory they backed.
*/
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,
@ -204,7 +208,7 @@ 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;
}
/*
@ -216,9 +220,14 @@ 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);
@ -233,6 +242,7 @@ static int memory_block_offline(struct memory_block *mem)
* Unaccount before offlining, such that unpopulated zone and kthreads
* can properly be torn down in offline_pages().
*/
mem_hotplug_begin();
if (nr_vmemmap_pages)
adjust_present_page_count(pfn_to_page(start_pfn), mem->group,
-nr_vmemmap_pages);
@ -244,13 +254,15 @@ 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;
}

13
mm/memory_hotplug.c
View File

@ -1069,6 +1069,9 @@ void mhp_deinit_memmap_on_memory(unsigned long pfn, unsigned long nr_pages)
kasan_remove_zero_shadow(__va(PFN_PHYS(pfn)), PFN_PHYS(nr_pages));
}
/*
* Must be called with mem_hotplug_lock in write mode.
*/
int __ref online_pages(unsigned long pfn, unsigned long nr_pages,
struct zone *zone, struct memory_group *group)
{
@ -1089,7 +1092,6 @@ int __ref online_pages(unsigned long pfn, unsigned long nr_pages,
!IS_ALIGNED(pfn + nr_pages, PAGES_PER_SECTION)))
return -EINVAL;
mem_hotplug_begin();
/* associate pfn range with the zone */
move_pfn_range_to_zone(zone, pfn, nr_pages, NULL, MIGRATE_ISOLATE);
@ -1148,7 +1150,6 @@ int __ref online_pages(unsigned long pfn, unsigned long nr_pages,
writeback_set_ratelimit();
memory_notify(MEM_ONLINE, &arg);
mem_hotplug_done();
return 0;
failed_addition:
@ -1157,7 +1158,6 @@ int __ref online_pages(unsigned long pfn, unsigned long nr_pages,
(((unsigned long long) pfn + nr_pages) << PAGE_SHIFT) - 1);
memory_notify(MEM_CANCEL_ONLINE, &arg);
remove_pfn_range_from_zone(zone, pfn, nr_pages);
mem_hotplug_done();
return ret;
}
@ -1787,6 +1787,9 @@ static int count_system_ram_pages_cb(unsigned long start_pfn,
return 0;
}
/*
* Must be called with mem_hotplug_lock in write mode.
*/
int __ref offline_pages(unsigned long start_pfn, unsigned long nr_pages,
struct zone *zone, struct memory_group *group)
{
@ -1809,8 +1812,6 @@ int __ref offline_pages(unsigned long start_pfn, unsigned long nr_pages,
!IS_ALIGNED(start_pfn + nr_pages, PAGES_PER_SECTION)))
return -EINVAL;
mem_hotplug_begin();
/*
* Don't allow to offline memory blocks that contain holes.
* Consequently, memory blocks with holes can never get onlined
@ -1946,7 +1947,6 @@ int __ref offline_pages(unsigned long start_pfn, unsigned long nr_pages,
memory_notify(MEM_OFFLINE, &arg);
remove_pfn_range_from_zone(zone, start_pfn, nr_pages);
mem_hotplug_done();
return 0;
failed_removal_isolated:
@ -1961,7 +1961,6 @@ int __ref offline_pages(unsigned long start_pfn, unsigned long nr_pages,
(unsigned long long) start_pfn << PAGE_SHIFT,
((unsigned long long) end_pfn << PAGE_SHIFT) - 1,
reason);
mem_hotplug_done();
return ret;
}