ANDROID: vendor_hooks: add hook before batch free into pcp

Some path will release folios into pcp batched, like binder
put(shmem release), HeapTaskDaemon reclaim and batch release.

By this hook, we can hold folios before it into pcp.

Bug: 389826135

Change-Id: I0b5023e2362fed54a56513f695da1b45ffee4339
Signed-off-by: Huan Yang <link@vivo.corp-partner.google.com>

drivers/android/vendor_hooks.c

@@ -222,3 +222,4 @@ EXPORT_TRACEPOINT_SYMBOL_GPL(android_vh_flush_work_wait_start);
 EXPORT_TRACEPOINT_SYMBOL_GPL(android_vh_flush_work_wait_finish);
 EXPORT_TRACEPOINT_SYMBOL_GPL(android_vh_enable_thermal_genl_check);
 EXPORT_TRACEPOINT_SYMBOL_GPL(android_vh_alloc_pages_entry);
+EXPORT_TRACEPOINT_SYMBOL_GPL(android_vh_free_unref_folios_to_pcp_bypass);

include/trace/hooks/mm.h

@@ -11,6 +11,7 @@
 
 struct shmem_inode_info;
 struct folio;
+struct folio_batch;
 
 DECLARE_RESTRICTED_HOOK(android_rvh_shmem_get_folio,
 			TP_PROTO(struct shmem_inode_info *info, struct folio **folio),
@@ -87,6 +88,10 @@ DECLARE_HOOK(android_vh_alloc_pages_entry,
 	TP_PROTO(gfp_t *gfp, unsigned int order, int preferred_nid,
 		nodemask_t *nodemask),
 	TP_ARGS(gfp, order, preferred_nid, nodemask));
+
+DECLARE_HOOK(android_vh_free_unref_folios_to_pcp_bypass,
+	TP_PROTO(struct folio_batch *folios, bool *bypass),
+	TP_ARGS(folios, bypass));
 #endif /* _TRACE_HOOK_MM_H */
 
 /* This part must be outside protection */

mm/page_alloc.c

@@ -2703,6 +2703,7 @@ void free_unref_folios(struct folio_batch *folios)
 	struct per_cpu_pages *pcp = NULL;
 	struct zone *locked_zone = NULL;
 	int i, j;
+	bool skip_free = false;
 
 	/* Prepare folios for freeing */
 	for (i = 0, j = 0; i < folios->nr; i++) {
@@ -2728,6 +2729,10 @@ void free_unref_folios(struct folio_batch *folios)
 	}
 	folios->nr = j;
 
+	trace_android_vh_free_unref_folios_to_pcp_bypass(folios, &skip_free);
+	if (skip_free)
+		goto out;
+
 	for (i = 0; i < folios->nr; i++) {
 		struct folio *folio = folios->folios[i];
 		struct zone *zone = folio_zone(folio);
@@ -2789,6 +2794,7 @@ void free_unref_folios(struct folio_batch *folios)
 		pcp_spin_unlock(pcp);
 		pcp_trylock_finish(UP_flags);
 	}
+out:
 	folio_batch_reinit(folios);
 }