ANDROID: mm: shmem: add vendor hooks in shmem folio allocation path

Add vendor hooks in shmem folio allocation paths to tune the higher
order folios.
With vendor hook possibly overriding shmem_allowable_huge_orders()
result, `order` inside shmem_get_folio_gfp() becomes variable when
when CONFIG_TRANSPARENT_HUGEPAGE=n and the block that calls
vma_thp_gfp_mask() is not compiled out anymore, leading to the
following linker error:

ld.lld: error: undefined symbol: vma_thp_gfp_mask
>>> referenced by shmem.c

Fix this by making the block dependent on CONFIG_TRANSPARENT_HUGEPAGE.

Bug: 397599006
Change-Id: Ia0e126c674a9f08cb10fe5ee06f5efac7b5cbe7f
Signed-off-by: Charan Teja Kalla <quic_charante@quicinc.com>
Signed-off-by: Suren Baghdasaryan <surenb@google.com>

drivers/android/vendor_hooks.c

@@ -286,6 +286,8 @@ EXPORT_TRACEPOINT_SYMBOL_GPL(android_vh_tune_swappiness);
 EXPORT_TRACEPOINT_SYMBOL_GPL(android_vh_logbuf_pr_cont);
 EXPORT_TRACEPOINT_SYMBOL_GPL(android_vh_calc_alloc_flags);
 EXPORT_TRACEPOINT_SYMBOL_GPL(android_vh_regmap_update);
+EXPORT_TRACEPOINT_SYMBOL_GPL(android_rvh_shmem_suitable_orders);
+EXPORT_TRACEPOINT_SYMBOL_GPL(android_rvh_shmem_allowable_huge_orders);
 EXPORT_TRACEPOINT_SYMBOL_GPL(android_rvh_shmem_get_folio);
 EXPORT_TRACEPOINT_SYMBOL_GPL(android_vh_slab_folio_alloced);
 EXPORT_TRACEPOINT_SYMBOL_GPL(android_vh_kmalloc_large_alloced);

include/trace/hooks/mm.h

@@ -20,7 +20,14 @@ DECLARE_RESTRICTED_HOOK(android_rvh_try_alloc_pages_gfp,
 			TP_PROTO(struct page **page, unsigned int order,
 				gfp_t gfp, enum zone_type highest_zoneidx),
 			TP_ARGS(page, order, gfp, highest_zoneidx), 1);
-
+DECLARE_RESTRICTED_HOOK(android_rvh_shmem_suitable_orders,
+			TP_PROTO(struct inode *inode, pgoff_t index,
+				unsigned long orders, unsigned long *suitable_orders),
+			TP_ARGS(inode, index, orders, suitable_orders), 4);
+DECLARE_RESTRICTED_HOOK(android_rvh_shmem_allowable_huge_orders,
+			TP_PROTO(struct inode *inode, pgoff_t index,
+				struct vm_area_struct *vma, unsigned long *orders),
+			TP_ARGS(inode, index, vma, orders), 4);
 /*
 
 DECLARE_RESTRICTED_HOOK(android_rvh_set_skip_swapcache_flags,

mm/shmem.c

@@ -1804,6 +1804,8 @@ static struct folio *shmem_alloc_and_add_folio(struct vm_fault *vmf,
 		suitable_orders = shmem_suitable_orders(inode, vmf,
 							mapping, index, orders);
 
+		trace_android_rvh_shmem_suitable_orders(inode, index,
+							orders, &suitable_orders);
 		order = highest_order(suitable_orders);
 		while (suitable_orders) {
 			pages = 1UL << order;
@@ -2322,6 +2324,13 @@ repeat:
 
 	/* Find hugepage orders that are allowed for anonymous shmem and tmpfs. */
 	orders = shmem_allowable_huge_orders(inode, vma, index, write_end, false);
+	trace_android_rvh_shmem_allowable_huge_orders(inode, index, vma, &orders);
+	/*
+	 * With the above hook `order` is not always 0 anymore and the following
+	 * if block does not get compiled out. With CONFIG_TRANSPARENT_HUGEPAGE=n
+	 * vma_thp_gfp_mask() becomes undefined and linker fails.
+	 */
+#ifdef CONFIG_TRANSPARENT_HUGEPAGE
 	if (orders > 0) {
 		gfp_t huge_gfp;
 
@@ -2338,6 +2347,7 @@ repeat:
 		if (PTR_ERR(folio) == -EEXIST)
 			goto repeat;
 	}
+#endif
 
 	folio = shmem_alloc_and_add_folio(vmf, gfp, inode, index, fault_mm, 0);
 	if (IS_ERR(folio)) {