ANDROID: GKI: add vendor hooks android_vh_page_should_be_protected() and android_vh_page_referenced_check_bypass().

add two vendor hooks:
    android_vh_page_should_be_protected():protect pages from memory
reclaim.
    android_vh_page_referenced_check_bypass():bypass rmap in active list
shrink.

The new vendor data field in scan_control are used to track how many
pages are protected in current reclaim and the "protected / scanned"
rate. These parameters are useful for understanding the impact of page
protection operations on LRU and reclaim, helping us make better
decsions.

Bug: 399782297
Change-Id: I49567a4b1f978821a94da0a8339b2b8fdfd52daf
Signed-off-by: Yuxuan Yan <yanyuxuan3@xiaomi.corp-partner.google.com>

drivers/android/vendor_hooks.c

@@ -354,6 +354,8 @@ EXPORT_TRACEPOINT_SYMBOL_GPL(android_vh_madvise_pageout_bypass);
 EXPORT_TRACEPOINT_SYMBOL_GPL(android_vh_free_pages_prepare_bypass);
 EXPORT_TRACEPOINT_SYMBOL_GPL(android_vh_free_pages_ok_bypass);
 EXPORT_TRACEPOINT_SYMBOL_GPL(android_vh_split_large_folio_bypass);
+EXPORT_TRACEPOINT_SYMBOL_GPL(android_vh_page_should_be_protected);
+EXPORT_TRACEPOINT_SYMBOL_GPL(android_vh_page_referenced_check_bypass);
 EXPORT_TRACEPOINT_SYMBOL_GPL(android_vh_do_read_fault);
 EXPORT_TRACEPOINT_SYMBOL_GPL(android_vh_filemap_read);
 EXPORT_TRACEPOINT_SYMBOL_GPL(android_vh_filemap_map_pages);

include/trace/hooks/mm.h

@@ -235,6 +235,10 @@ DECLARE_HOOK(android_vh_free_pages_ok_bypass,
 DECLARE_HOOK(android_vh_split_large_folio_bypass,
 	TP_PROTO(bool *bypass),
 	TP_ARGS(bypass));
+DECLARE_HOOK(android_vh_page_should_be_protected,
+	TP_PROTO(struct folio *folio, unsigned long nr_scanned,
+	s8 priority, u64 *ext, int *should_protect),
+	TP_ARGS(folio, nr_scanned, priority, ext, should_protect));
 DECLARE_HOOK(android_vh_do_read_fault,
 	TP_PROTO(struct vm_fault *vmf, unsigned long fault_around_bytes),
 	TP_ARGS(vmf, fault_around_bytes));

include/trace/hooks/vmscan.h

@@ -49,6 +49,9 @@ DECLARE_HOOK(android_vh_use_vm_swappiness,
 DECLARE_HOOK(android_vh_tune_scan_control,
 	TP_PROTO(bool *skip_swap),
 	TP_ARGS(skip_swap));
+DECLARE_HOOK(android_vh_page_referenced_check_bypass,
+	TP_PROTO(struct folio *folio, unsigned long nr_to_scan, int lru, bool *bypass),
+	TP_ARGS(folio, nr_to_scan, lru, bypass));
 #endif /* _TRACE_HOOK_VMSCAN_H */
 /* This part must be outside protection */
 #include <trace/define_trace.h>

mm/vmscan.c

@@ -876,6 +876,10 @@ static enum folio_references folio_check_references(struct folio *folio,
 	unsigned long vm_flags;
 	int ret = 0;
 
+#ifdef CONFIG_ANDROID_VENDOR_OEM_DATA
+	trace_android_vh_page_should_be_protected(folio, sc->nr_scanned,
+		sc->priority, &sc->android_vendor_data1, &ret);
+#endif
 	trace_android_vh_check_folio_look_around_ref(folio, &ret);
 	if (ret)
 		return ret;
@@ -2070,6 +2074,8 @@ static void shrink_active_list(unsigned long nr_to_scan,
 	unsigned nr_rotated = 0;
 	bool file = is_file_lru(lru);
 	struct pglist_data *pgdat = lruvec_pgdat(lruvec);
+	int should_protect = 0;
+	bool bypass = false;
 
 	lru_add_drain();
 
@@ -2106,6 +2112,20 @@ static void shrink_active_list(unsigned long nr_to_scan,
 			}
 		}
 
+#ifdef CONFIG_ANDROID_VENDOR_OEM_DATA
+		trace_android_vh_page_should_be_protected(folio, sc->nr_scanned,
+			sc->priority, &sc->android_vendor_data1, &should_protect);
+#endif
+		if (unlikely(should_protect)) {
+			nr_rotated += folio_nr_pages(folio);
+			list_add(&folio->lru, &l_active);
+			continue;
+		}
+
+		trace_android_vh_page_referenced_check_bypass(folio, nr_to_scan, lru, &bypass);
+		if (bypass)
+			goto skip_folio_referenced;
+
 		/* Referenced or rmap lock contention: rotate */
 		if (folio_referenced(folio, 0, sc->target_mem_cgroup,
 				     &vm_flags) != 0) {
@@ -2125,6 +2145,7 @@ static void shrink_active_list(unsigned long nr_to_scan,
 			}
 		}
 
+skip_folio_referenced:
 		folio_clear_active(folio);	/* we are de-activating */
 		folio_set_workingset(folio);
 		list_add(&folio->lru, &l_inactive);