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FAILED: patch "[PATCH] mm/memory_hotplug: add missing mem_hotplug_lock" failed to apply to 6.1-stable tree

PATCH [email protected] 1 participant 1 message Dec 9, 2023

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Stable branch Memory management Driver core Memory hot(un)plug
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The patch below does not apply to the 6.1-stable tree.
If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to <[email protected]>.

To reproduce the conflict and resubmit, you may use the following commands:

git fetch https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/ linux-6.1.y
git checkout FETCH_HEAD
git cherry-pick -x 001002e73712cdf6b8d9a103648cda3040ad7647
# <resolve conflicts, build, test, etc.>
git commit -s
git send-email --to '<[email protected]>' --in-reply-to '2023120925-hazard-mustard-8df5@gregkh' --subject-prefix 'PATCH 6.1.y' HEAD^..

Possible dependencies:

001002e73712 ("mm/memory_hotplug: add missing mem_hotplug_lock")
1a8c64e11043 ("mm/memory_hotplug: embed vmem_altmap details in memory block") 2d1f649c7c08 ("mm/memory_hotplug: support memmap_on_memory when memmap is not aligned to pageblocks") 85a2b4b08f20 ("mm/memory_hotplug: allow architecture to override memmap on memory support check") e3c2bfdd33a3 ("mm/memory_hotplug: allow memmap on memory hotplug request to fallback") 5033091de814 ("mm/hwpoison: introduce per-memory_block hwpoison counter") a46c9304b4bb ("mm/hwpoison: pass pfn to num_poisoned_pages_*()")
d027122d8363 ("mm/hwpoison: move definitions of num_poisoned_pages_* to memory-failure.c") e591ef7d96d6 ("mm,hwpoison,hugetlb,memory_hotplug: hotremove memory section with hwpoisoned hugepage")

thanks,

greg k-h

------------------ original commit in Linus's tree ------------------

From 001002e73712cdf6b8d9a103648cda3040ad7647 Mon Sep 17 00:00:00 2001
From: Sumanth Korikkar <[email protected]>
Date: Mon, 20 Nov 2023 15:53:52 +0100
Subject: [PATCH] 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/[email protected] open here
Fixes a08a2ae34613 ("mm,memory_hotplug: allocate memmap from the added memory range")
Signed-off-by Sumanth Korikkar <[email protected]>
Reviewed-by Gerald Schaefer <[email protected]>
Acked-by David Hildenbrand <[email protected]>
Cc Alexander Gordeev <[email protected]>
Cc Aneesh Kumar K.V <[email protected]>
Cc Anshuman Khandual <[email protected]>
Cc Heiko Carstens <[email protected]>
Cc Michal Hocko <[email protected]>
Cc Oscar Salvador <[email protected]>
Cc Vasily Gorbik <[email protected]>
Cc kernel test robot <[email protected]>
Cc <[email protected]> [5.15+]
Signed-off-by Andrew Morton <[email protected]>
drivers/base/memory.c +15 -3
index f3b9a4d0fa3b..8a13babd826c 100644
@@ -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;
 }
mm/memory_hotplug.c +6 -7
index ab41a511e20a..bb908289679e 100644
@@ -1129,6 +1129,9 @@ 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)
 {

@@ -1149,7 +1152,6 @@ 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);

@@ -1208,7 +1210,6 @@ 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:

@@ -1217,7 +1218,6 @@ 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;
 }
 

@@ -1863,6 +1863,9 @@ 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)
 {

@@ -1885,8 +1888,6 @@ 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

@@ -2031,7 +2032,6 @@ 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:

@@ -2046,7 +2046,6 @@ 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;
 }