ANDROID: vendor_hooks: Allow shared pages reclaim via MADV_PAGEOUT

Add a hook in madvise_cold_or_pageout_pte_range() to allow
vendor modules to influence the shared pages reclaim.

Bug: 242678506
Change-Id: I269a385b59f7291c2e96478674bb3d05f94584cb
Signed-off-by: Pavankumar Kondeti <quic_pkondeti@quicinc.com>

drivers/android/vendor_hooks.c

@@ -402,6 +402,7 @@ EXPORT_TRACEPOINT_SYMBOL_GPL(android_vh_check_hibernation_swap);
 EXPORT_TRACEPOINT_SYMBOL_GPL(android_vh_save_cpu_resume);
 EXPORT_TRACEPOINT_SYMBOL_GPL(android_vh_save_hib_resume_bdev);
 EXPORT_TRACEPOINT_SYMBOL_GPL(android_rvh_dma_buf_stats_teardown);
+EXPORT_TRACEPOINT_SYMBOL_GPL(android_vh_madvise_cold_or_pageout);
 
 /*
  * For type visibility

include/trace/hooks/mm.h

@@ -150,6 +150,9 @@ DECLARE_HOOK(android_vh_rmqueue,
 DECLARE_HOOK(android_vh_kmalloc_slab,
 	TP_PROTO(unsigned int index, gfp_t flags, struct kmem_cache **s),
 	TP_ARGS(index, flags, s));
+DECLARE_HOOK(android_vh_madvise_cold_or_pageout,
+	TP_PROTO(struct vm_area_struct *vma, bool *allow_shared),
+	TP_ARGS(vma, allow_shared));
 #endif /* _TRACE_HOOK_MM_H */
 
 /* This part must be outside protection */

mm/madvise.c

@@ -31,6 +31,7 @@
 #include <linux/swapops.h>
 #include <linux/shmem_fs.h>
 #include <linux/mmu_notifier.h>
+#include <trace/hooks/mm.h>
 
 #include <asm/tlb.h>
 
@@ -324,10 +325,12 @@ static int madvise_cold_or_pageout_pte_range(pmd_t *pmd,
 	spinlock_t *ptl;
 	struct page *page = NULL;
 	LIST_HEAD(page_list);
+	bool allow_shared = false;
 
 	if (fatal_signal_pending(current))
 		return -EINTR;
 
+	trace_android_vh_madvise_cold_or_pageout(vma, &allow_shared);
 #ifdef CONFIG_TRANSPARENT_HUGEPAGE
 	if (pmd_trans_huge(*pmd)) {
 		pmd_t orig_pmd;
@@ -443,7 +446,7 @@ regular_page:
 		}
 
 		/* Do not interfere with other mappings of this page */
-		if (page_mapcount(page) != 1)
+		if (!allow_shared && page_mapcount(page) != 1)
 			continue;
 
 		VM_BUG_ON_PAGE(PageTransCompound(page), page);