linux-kernel - [PATCH v3 2/3] mm/memory_hotplug: fix error handling in add_memory

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Date:   Mon, 20 Nov 2023 15:53:53 +0100
From:   Sumanth Korikkar <sumanthk@...ux.ibm.com>
To:     linux-mm <linux-mm@...ck.org>,
        Andrew Morton <akpm@...ux-foundation.org>,
        David Hildenbrand <david@...hat.com>
Cc:     Oscar Salvador <osalvador@...e.de>, Michal Hocko <mhocko@...e.com>,
        "Aneesh Kumar K.V" <aneesh.kumar@...ux.ibm.com>,
        Anshuman Khandual <anshuman.khandual@....com>,
        Gerald Schaefer <gerald.schaefer@...ux.ibm.com>,
        Alexander Gordeev <agordeev@...ux.ibm.com>,
        Heiko Carstens <hca@...ux.ibm.com>,
        Vasily Gorbik <gor@...ux.ibm.com>,
        linux-s390 <linux-s390@...r.kernel.org>,
        LKML <linux-kernel@...r.kernel.org>
Subject: [PATCH v3 2/3] mm/memory_hotplug: fix error handling in add_memory_resource()

In add_memory_resource(), creation of memory block devices occurs after
successful call to arch_add_memory(). However, creation of memory block
devices could fail.  In that case, arch_remove_memory() is called to
perform necessary cleanup.

Currently with or without altmap support, arch_remove_memory() is always
passed with altmap set to NULL during error handling. This leads to
freeing of struct pages using free_pages(), eventhough the allocation
might have been performed with altmap support via
altmap_alloc_block_buf().

Fix the error handling by passing altmap in arch_remove_memory(). This
ensures the following:
* When altmap is disabled, deallocation of the struct pages array occurs
  via free_pages().
* When altmap is enabled, deallocation occurs via vmem_altmap_free().

Fixes: a08a2ae34613 ("mm,memory_hotplug: allocate memmap from the added memory range")
Cc: stable@...r.kernel.org # 5.15+
Reviewed-by: Gerald Schaefer <gerald.schaefer@...ux.ibm.com>
Acked-by: David Hildenbrand <david@...hat.com>
Signed-off-by: Sumanth Korikkar <sumanthk@...ux.ibm.com>
---
 mm/memory_hotplug.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/mm/memory_hotplug.c b/mm/memory_hotplug.c
index c8238fc5edcb..4f476a970e84 100644
--- a/mm/memory_hotplug.c
+++ b/mm/memory_hotplug.c
@@ -1458,7 +1458,7 @@ int __ref add_memory_resource(int nid, struct resource *res, mhp_t mhp_flags)
 	/* create memory block devices after memory was added */
 	ret = create_memory_block_devices(start, size, params.altmap, group);
 	if (ret) {
-		arch_remove_memory(start, size, NULL);
+		arch_remove_memory(start, size, params.altmap);
 		goto error_free;
 	}

-- 
2.41.0