From 27600805e62f800bacf990354632eae4e487d34c Mon Sep 17 00:00:00 2001 From: Yazen Ghannam Date: Thu, 3 Sep 2026 10:43:25 -0500 Subject: x86/amd_node: Fix PCI device reference counting in amd_smn_init() The local "root" pointer is a temporary variable used during the device search. Therefore, refcount related to the search iterators should be cleaned up after the search is complete. Use the __free() cleanup macro to ensure the refcount is decremented when the temporary pointer goes out of scope. Additionally, increment the refcount when caching a root pointer. This ensures the in-use refcount is separate from the temporary search refcounting. Finally, drop the redundant "root = NULL" before the second search loop. The pci_get_class() iterator always decrements the refcount of its "from" argument, so the first loop can only fall through with "root" already NULL. Fixes: 0a4b61d9c2e4 ("x86/amd_node: Fix AMD root device caching") Closes: https://sashiko.dev/#/patchset/20260806160159.230453-1-jason.andryuk%40amd.com Reported-by: Sashiko Assisted-by: LLM Signed-off-by: Yazen Ghannam Signed-off-by: Borislav Petkov (AMD) Reviewed-by: Mario Limonciello (AMD) Cc: Link: https://patch.msgid.link/20260903154325.74343-1-yazen.ghannam@amd.com --- lib/test_free_pages.c | 48 ++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 48 insertions(+) create mode 100644 lib/test_free_pages.c (limited to 'lib/test_free_pages.c') diff --git a/lib/test_free_pages.c b/lib/test_free_pages.c new file mode 100644 index 000000000..48952364c --- /dev/null +++ b/lib/test_free_pages.c @@ -0,0 +1,48 @@ +// SPDX-License-Identifier: GPL-2.0+ +/* + * test_free_pages.c: Check that free_pages() doesn't leak memory + * Copyright (c) 2020 Oracle + * Author: Matthew Wilcox + */ + +#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt + +#include +#include +#include + +static void test_free_pages(gfp_t gfp) +{ + unsigned int i; + + for (i = 0; i < 1000 * 1000; i++) { + unsigned long addr = __get_free_pages(gfp, 3); + struct page *page = virt_to_page((void *)addr); + + /* Simulate page cache getting a speculative reference */ + get_page(page); + free_pages(addr, 3); + put_page(page); + } +} + +static int m_in(void) +{ + pr_info("Testing with GFP_KERNEL\n"); + test_free_pages(GFP_KERNEL); + pr_info("Testing with GFP_KERNEL | __GFP_COMP\n"); + test_free_pages(GFP_KERNEL | __GFP_COMP); + pr_info("Test completed\n"); + + return 0; +} + +static void m_ex(void) +{ +} + +module_init(m_in); +module_exit(m_ex); +MODULE_AUTHOR("Matthew Wilcox "); +MODULE_DESCRIPTION("Check that free_pages() doesn't leak memory"); +MODULE_LICENSE("GPL"); -- cgit v1.3.1