+ kernel-resource-fix-kfree-of-bootmem-memory-again.patch added to -mm tree

[Andrew Morton <akpm@linux-foundation.org>]

The patch titled
     Subject: kernel/resource: fix kfree() of bootmem memory again
has been added to the -mm tree.  Its filename is
     kernel-resource-fix-kfree-of-bootmem-memory-again.patch

This patch should soon appear at
    https://ozlabs.org/~akpm/mmots/broken-out/kernel-resource-fix-kfree-of-bootmem-memory-again.patch
and later at
    https://ozlabs.org/~akpm/mmotm/broken-out/kernel-resource-fix-kfree-of-bootmem-memory-again.patch

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------------------------------------------------------
From: Miaohe Lin <linmiaohe@huawei.com>
Subject: kernel/resource: fix kfree() of bootmem memory again

Since commit ebff7d8f270d ("mem hotunplug: fix kfree() of bootmem
memory"), we could get a resource allocated during boot via
alloc_resource().  And it's required to release the resource using
free_resource().  Howerver, many people use kfree directly which will
result in kernel BUG.  In order to fix this without fixing every call
site, just leak a couple of bytes in such corner case.

Link: https://lkml.kernel.org/r/20220217083619.19305-1-linmiaohe@huawei.com
Fixes: ebff7d8f270d ("mem hotunplug: fix kfree() of bootmem memory")
Signed-off-by: Miaohe Lin <linmiaohe@huawei.com>
Suggested-by: David Hildenbrand <david@redhat.com>
Cc: Dan Williams <dan.j.williams@intel.com>
Cc: Alistair Popple <apopple@nvidia.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---

 kernel/resource.c |   41 ++++++++---------------------------------
 1 file changed, 8 insertions(+), 33 deletions(-)

--- a/kernel/resource.c~kernel-resource-fix-kfree-of-bootmem-memory-again
+++ a/kernel/resource.c
@@ -56,14 +56,6 @@ struct resource_constraint {
 
 static DEFINE_RWLOCK(resource_lock);
 
-/*
- * For memory hotplug, there is no way to free resource entries allocated
- * by boot mem after the system is up. So for reusing the resource entry
- * we need to remember the resource.
- */
-static struct resource *bootmem_resource_free;
-static DEFINE_SPINLOCK(bootmem_resource_lock);
-
 static struct resource *next_resource(struct resource *p)
 {
 	if (p->child)
@@ -160,36 +152,19 @@ __initcall(ioresources_init);
 
 static void free_resource(struct resource *res)
 {
-	if (!res)
-		return;
-
-	if (!PageSlab(virt_to_head_page(res))) {
-		spin_lock(&bootmem_resource_lock);
-		res->sibling = bootmem_resource_free;
-		bootmem_resource_free = res;
-		spin_unlock(&bootmem_resource_lock);
-	} else {
+	/**
+	 * If the resource was allocated using memblock early during boot
+	 * we'll leak it here: we can only return full pages back to the
+	 * buddy and trying to be smart and reusing them eventually in
+	 * alloc_resource() overcomplicates resource handling.
+	 */
+	if (res && PageSlab(virt_to_head_page(res)))
 		kfree(res);
-	}
 }
 
 static struct resource *alloc_resource(gfp_t flags)
 {
-	struct resource *res = NULL;
-
-	spin_lock(&bootmem_resource_lock);
-	if (bootmem_resource_free) {
-		res = bootmem_resource_free;
-		bootmem_resource_free = res->sibling;
-	}
-	spin_unlock(&bootmem_resource_lock);
-
-	if (res)
-		memset(res, 0, sizeof(struct resource));
-	else
-		res = kzalloc(sizeof(struct resource), flags);
-
-	return res;
+	return kzalloc(sizeof(struct resource), flags);
 }
 
 /* Return the conflict entry if you can't request it */
_

Patches currently in -mm which might be from linmiaohe@huawei.com are

mm-memremap-avoid-calling-kasan_remove_zero_shadow-for-device-private-memory.patch
filemap-remove-find_get_pages.patch
mm-use-helper-function-range_in_vma.patch
mm-sparse-make-mminit_validate_memmodel_limits-static.patch
mm-vmalloc-remove-unneeded-function-forward-declaration.patch
mm-mmzoneh-remove-unused-macros.patch
mm-memory-failurec-minor-clean-up-for-memory_failure_dev_pagemap.patch
mm-memory-failurec-catch-unexpected-efault-from-vma_address.patch
mm-memory-failurec-rework-the-signaling-logic-in-kill_proc.patch
mm-memory-failurec-fix-race-with-changing-page-more-robustly.patch
mm-memory-failurec-remove-pageslab-check-in-hwpoison_filter_dev.patch
mm-memory-failurec-rework-the-try_to_unmap-logic-in-hwpoison_user_mappings.patch
mm-memory-failurec-remove-obsolete-comment-in-__soft_offline_page.patch
mm-memory-failurec-remove-unnecessary-pagetranstail-check.patch
mm-hwpoison-inject-support-injecting-hwpoison-to-free-page.patch
mm-ksm-use-helper-macro-__attr_rw.patch
mm-balloon_compaction-make-balloon-page-compaction-callbacks-static.patch
mm-memory_hotplug-remove-obsolete-comment-of-__add_pages.patch
mm-memory_hotplug-avoid-calling-zone_intersects-for-zone_normal.patch
mm-memory_hotplug-clean-up-try_offline_node.patch
mm-memory_hotplug-fix-misplaced-comment-in-offline_pages.patch
mm-highmem-remove-unnecessary-done-label.patch
mm-hmmc-remove-unneeded-local-variable-ret.patch
kernel-resource-fix-kfree-of-bootmem-memory-again.patch