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, 148 insertions, 0 deletions

diff --git a/include/trace/events/migrate.h b/include/trace/events/migrate.h
new file mode 100644
index 000000000..15ee2ef20
--- /dev/null
+++ b/include/trace/events/migrate.h
@@ -0,0 +1,148 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+#undef TRACE_SYSTEM
+#define TRACE_SYSTEM migrate
+
+#if !defined(_TRACE_MIGRATE_H) || defined(TRACE_HEADER_MULTI_READ)
+#define _TRACE_MIGRATE_H
+
+#include <linux/tracepoint.h>
+
+#define MIGRATE_MODE						\
+	EM( MIGRATE_ASYNC,	"MIGRATE_ASYNC")		\
+	EM( MIGRATE_SYNC_LIGHT,	"MIGRATE_SYNC_LIGHT")		\
+	EMe(MIGRATE_SYNC,	"MIGRATE_SYNC")
+
+
+#define MIGRATE_REASON						\
+	EM( MR_COMPACTION,	"compaction")			\
+	EM( MR_MEMORY_FAILURE,	"memory_failure")		\
+	EM( MR_MEMORY_HOTPLUG,	"memory_hotplug")		\
+	EM( MR_SYSCALL,		"syscall_or_cpuset")		\
+	EM( MR_MEMPOLICY_MBIND,	"mempolicy_mbind")		\
+	EM( MR_NUMA_MISPLACED,	"numa_misplaced")		\
+	EM( MR_CONTIG_RANGE,	"contig_range")			\
+	EM( MR_LONGTERM_PIN,	"longterm_pin")			\
+	EM( MR_DEMOTION,	"demotion")			\
+	EM( MR_DAMON,		"damon")			\
+	EMe(MR_NEVER,		"never_migrated")
+
+/*
+ * First define the enums in the above macros to be exported to userspace
+ * via TRACE_DEFINE_ENUM().
+ */
+#undef EM
+#undef EMe
+#define EM(a, b)	TRACE_DEFINE_ENUM(a);
+#define EMe(a, b)	TRACE_DEFINE_ENUM(a);
+
+MIGRATE_MODE
+MIGRATE_REASON
+
+/*
+ * Now redefine the EM() and EMe() macros to map the enums to the strings
+ * that will be printed in the output.
+ */
+#undef EM
+#undef EMe
+#define EM(a, b)	{a, b},
+#define EMe(a, b)	{a, b}
+
+TRACE_EVENT(mm_migrate_pages,
+
+	TP_PROTO(unsigned long succeeded, unsigned long failed,
+		 unsigned long thp_succeeded, unsigned long thp_failed,
+		 unsigned long thp_split, unsigned long large_folio_split,
+		 enum migrate_mode mode, enum migrate_reason reason),
+
+	TP_ARGS(succeeded, failed, thp_succeeded, thp_failed,
+		thp_split, large_folio_split, mode, reason),
+
+	TP_STRUCT__entry(
+		__field(	unsigned long,		succeeded)
+		__field(	unsigned long,		failed)
+		__field(	unsigned long,		thp_succeeded)
+		__field(	unsigned long,		thp_failed)
+		__field(	unsigned long,		thp_split)
+		__field(	unsigned long,		large_folio_split)
+		__field(	enum migrate_mode,	mode)
+		__field(	enum migrate_reason,	reason)
+	),
+
+	TP_fast_assign(
+		__entry->succeeded			= succeeded;
+		__entry->failed				= failed;
+		__entry->thp_succeeded		= thp_succeeded;
+		__entry->thp_failed			= thp_failed;
+		__entry->thp_split			= thp_split;
+		__entry->large_folio_split	= large_folio_split;
+		__entry->mode				= mode;
+		__entry->reason				= reason;
+	),
+
+	TP_printk("nr_succeeded=%lu nr_failed=%lu nr_thp_succeeded=%lu nr_thp_failed=%lu nr_thp_split=%lu nr_split=%lu mode=%s reason=%s",
+		__entry->succeeded,
+		__entry->failed,
+		__entry->thp_succeeded,
+		__entry->thp_failed,
+		__entry->thp_split,
+		__entry->large_folio_split,
+		__print_symbolic(__entry->mode, MIGRATE_MODE),
+		__print_symbolic(__entry->reason, MIGRATE_REASON))
+);
+
+TRACE_EVENT(mm_migrate_pages_start,
+
+	TP_PROTO(enum migrate_mode mode, enum migrate_reason reason),
+
+	TP_ARGS(mode, reason),
+
+	TP_STRUCT__entry(
+		__field(enum migrate_mode, mode)
+		__field(enum migrate_reason, reason)
+	),
+
+	TP_fast_assign(
+		__entry->mode	= mode;
+		__entry->reason	= reason;
+	),
+
+	TP_printk("mode=%s reason=%s",
+		  __print_symbolic(__entry->mode, MIGRATE_MODE),
+		  __print_symbolic(__entry->reason, MIGRATE_REASON))
+);
+
+DECLARE_EVENT_CLASS(migration_pte,
+
+		TP_PROTO(unsigned long addr, unsigned long pte, int order),
+
+		TP_ARGS(addr, pte, order),
+
+		TP_STRUCT__entry(
+			__field(unsigned long, addr)
+			__field(unsigned long, pte)
+			__field(int, order)
+		),
+
+		TP_fast_assign(
+			__entry->addr = addr;
+			__entry->pte = pte;
+			__entry->order = order;
+		),
+
+		TP_printk("addr=%lx, pte=%lx order=%d", __entry->addr, __entry->pte, __entry->order)
+);
+
+DEFINE_EVENT(migration_pte, set_migration_pte,
+	TP_PROTO(unsigned long addr, unsigned long pte, int order),
+	TP_ARGS(addr, pte, order)
+);
+
+DEFINE_EVENT(migration_pte, remove_migration_pte,
+	TP_PROTO(unsigned long addr, unsigned long pte, int order),
+	TP_ARGS(addr, pte, order)
+);
+
+#endif /* _TRACE_MIGRATE_H */
+
+/* This part must be outside protection */
+#include <trace/define_trace.h>