x86/amd_node: Fix PCI device reference counting in amd_smn_init()grafted

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 <sashiko-bot@kernel.org>
Assisted-by: LLM
Signed-off-by: Yazen Ghannam <yazen.ghannam@amd.com>
Signed-off-by: Borislav Petkov (AMD) <bp@alien8.de>
Reviewed-by: Mario Limonciello (AMD) <superm1@kernel.org>
Cc: <stable@kernel.org>
Link: https://patch.msgid.link/20260903154325.74343-1-yazen.ghannam@amd.com

1 files changed, 91 insertions, 0 deletions

diff --git a/include/trace/events/pagemap.h b/include/trace/events/pagemap.h
new file mode 100644
index 000000000..36c3a90f0
--- /dev/null
+++ b/include/trace/events/pagemap.h
@@ -0,0 +1,91 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+#undef TRACE_SYSTEM
+#define TRACE_SYSTEM pagemap
+
+#if !defined(_TRACE_PAGEMAP_H) || defined(TRACE_HEADER_MULTI_READ)
+#define _TRACE_PAGEMAP_H
+
+#include <linux/tracepoint.h>
+#include <linux/mm.h>
+
+#define	PAGEMAP_MAPPED		0x0001u
+#define PAGEMAP_ANONYMOUS	0x0002u
+#define PAGEMAP_FILE		0x0004u
+#define PAGEMAP_SWAPCACHE	0x0008u
+#define PAGEMAP_SWAPBACKED	0x0010u
+#define PAGEMAP_MAPPEDDISK	0x0020u
+#define PAGEMAP_BUFFERS		0x0040u
+
+#define trace_pagemap_flags(folio) ( \
+	(folio_test_anon(folio)		? PAGEMAP_ANONYMOUS  : PAGEMAP_FILE) | \
+	(folio_mapped(folio)		? PAGEMAP_MAPPED     : 0) | \
+	(folio_test_swapcache(folio)	? PAGEMAP_SWAPCACHE  : 0) | \
+	(folio_test_swapbacked(folio)	? PAGEMAP_SWAPBACKED : 0) | \
+	(folio_test_mappedtodisk(folio)	? PAGEMAP_MAPPEDDISK : 0) | \
+	(folio_test_private(folio)	? PAGEMAP_BUFFERS    : 0) \
+	)
+
+TRACE_EVENT(mm_lru_insertion,
+
+	TP_PROTO(struct folio *folio),
+
+	TP_ARGS(folio),
+
+	TP_STRUCT__entry(
+		__field(struct folio *,	folio	)
+		__field(unsigned long,	pfn	)
+		__field(enum lru_list,	lru	)
+		__field(unsigned long,	flags	)
+	),
+
+	TP_fast_assign(
+		__entry->folio	= folio;
+		__entry->pfn	= folio_pfn(folio);
+		__entry->lru	= folio_lru_list(folio);
+		__entry->flags	= trace_pagemap_flags(folio);
+	),
+
+	/* Flag format is based on page-types.c formatting for pagemap */
+	TP_printk("folio=%p pfn=0x%lx lru=%d flags=%s%s%s%s%s%s",
+			__entry->folio,
+			__entry->pfn,
+			__entry->lru,
+			__entry->flags & PAGEMAP_MAPPED		? "M" : " ",
+			__entry->flags & PAGEMAP_ANONYMOUS	? "a" : "f",
+			__entry->flags & PAGEMAP_SWAPCACHE	? "s" : " ",
+			__entry->flags & PAGEMAP_SWAPBACKED	? "b" : " ",
+			__entry->flags & PAGEMAP_MAPPEDDISK	? "d" : " ",
+			__entry->flags & PAGEMAP_BUFFERS	? "B" : " ")
+);
+
+TRACE_EVENT(mm_lru_activate,
+
+	TP_PROTO(struct folio *folio),
+
+	TP_ARGS(folio),
+
+	TP_STRUCT__entry(
+		__field(struct folio *,	folio	)
+		__field(unsigned long,	pfn	)
+	),
+
+	TP_fast_assign(
+		__entry->folio	= folio;
+		__entry->pfn	= folio_pfn(folio);
+	),
+
+	TP_printk("folio=%p pfn=0x%lx", __entry->folio, __entry->pfn)
+);
+
+DECLARE_TRACE(mm_lru_add_drain,
+	      TP_PROTO(int cpu, unsigned int nr_folios),
+	      TP_ARGS(cpu, nr_folios));
+
+DECLARE_TRACE(mm_lru_add_drain_all,
+	      TP_PROTO(bool force_all_cpus),
+	      TP_ARGS(force_all_cpus));
+
+#endif /* _TRACE_PAGEMAP_H */
+
+/* This part must be outside protection */
+#include <trace/define_trace.h>