maple_tree: add GFP_KERNEL to allocations in mas_expected_entries()

commit 099d7439ce03d0e7bc8f0c3d7878b562f3a48d3d upstream.

Users complained about OOM errors during fork without triggering
compaction.  This can be fixed by modifying the flags used in
mas_expected_entries() so that the compaction will be triggered in low
memory situations.  Since mas_expected_entries() is only used during fork,
the extra argument does not need to be passed through.

Additionally, the two test_maple_tree test cases and one benchmark test
were altered to use the correct locking type so that allocations would not
trigger sleeping and thus fail.  Testing was completed with lockdep atomic
sleep detection.

The additional locking change requires rwsem support additions to the
tools/ directory through the use of pthreads pthread_rwlock_t.  With this
change test_maple_tree works in userspace, as a module, and in-kernel.

Users may notice that the system gave up early on attempting to start new
processes instead of attempting to reclaim memory.

Link: https://lkml.kernel.org/r/20230915093243epcms1p46fa00bbac1ab7b7dca94acb66c44c456@epcms1p4
Link: https://lkml.kernel.org/r/20231012155233.2272446-1-Liam.Howlett@oracle.com
Fixes: 54a611b60590 ("Maple Tree: add new data structure")
Signed-off-by: Liam R. Howlett <Liam.Howlett@oracle.com>
Reviewed-by: Peng Zhang <zhangpeng.00@bytedance.com>
Cc: <jason.sim@samsung.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

2 files changed, 25 insertions, 12 deletions

diff --git a/lib/maple_tree.c b/lib/maple_tree.c
index 250b4c67fac8..4976522e3e48 100644
--- a/lib/maple_tree.c
+++ b/lib/maple_tree.c
@@ -5913,7 +5913,7 @@ int mas_expected_entries(struct ma_state *mas, unsigned long nr_entries)
 	/* Internal nodes */
 	nr_nodes += DIV_ROUND_UP(nr_nodes, nonleaf_cap);
 	/* Add working room for split (2 nodes) + new parents */
-	mas_node_count(mas, nr_nodes + 3);
+	mas_node_count_gfp(mas, nr_nodes + 3, GFP_KERNEL);
 
 	/* Detect if allocations run out */
 	mas->mas_flags |= MA_STATE_PREALLOC;
diff --git a/lib/test_maple_tree.c b/lib/test_maple_tree.c
index fad668042f3e..ab9d4461abc9 100644
--- a/lib/test_maple_tree.c
+++ b/lib/test_maple_tree.c
@@ -9,6 +9,7 @@
 
 #include <linux/maple_tree.h>
 #include <linux/module.h>
+#include <linux/rwsem.h>
 
 #define MTREE_ALLOC_MAX 0x2000000000000Ul
 #ifndef CONFIG_DEBUG_MAPLE_TREE
@@ -1678,17 +1679,21 @@ static noinline void __init check_forking(struct maple_tree *mt)
 	void *val;
 	MA_STATE(mas, mt, 0, 0);
 	MA_STATE(newmas, mt, 0, 0);
+	struct rw_semaphore newmt_lock;
+
+	init_rwsem(&newmt_lock);
 
 	for (i = 0; i <= nr_entries; i++)
 		mtree_store_range(mt, i*10, i*10 + 5,
 				  xa_mk_value(i), GFP_KERNEL);
 
 	mt_set_non_kernel(99999);
-	mt_init_flags(&newmt, MT_FLAGS_ALLOC_RANGE);
+	mt_init_flags(&newmt, MT_FLAGS_ALLOC_RANGE | MT_FLAGS_LOCK_EXTERN);
+	mt_set_external_lock(&newmt, &newmt_lock);
 	newmas.tree = &newmt;
 	mas_reset(&newmas);
 	mas_reset(&mas);
-	mas_lock(&newmas);
+	down_write(&newmt_lock);
 	mas.index = 0;
 	mas.last = 0;
 	if (mas_expected_entries(&newmas, nr_entries)) {
@@ -1703,10 +1708,10 @@ static noinline void __init check_forking(struct maple_tree *mt)
 	}
 	rcu_read_unlock();
 	mas_destroy(&newmas);
-	mas_unlock(&newmas);
 	mt_validate(&newmt);
 	mt_set_non_kernel(0);
-	mtree_destroy(&newmt);
+	__mt_destroy(&newmt);
+	up_write(&newmt_lock);
 }
 
 static noinline void __init check_iteration(struct maple_tree *mt)
@@ -1818,6 +1823,10 @@ static noinline void __init bench_forking(struct maple_tree *mt)
 	void *val;
 	MA_STATE(mas, mt, 0, 0);
 	MA_STATE(newmas, mt, 0, 0);
+	struct rw_semaphore newmt_lock;
+
+	init_rwsem(&newmt_lock);
+	mt_set_external_lock(&newmt, &newmt_lock);
 
 	for (i = 0; i <= nr_entries; i++)
 		mtree_store_range(mt, i*10, i*10 + 5,
@@ -1832,7 +1841,7 @@ static noinline void __init bench_forking(struct maple_tree *mt)
 		mas.index = 0;
 		mas.last = 0;
 		rcu_read_lock();
-		mas_lock(&newmas);
+		down_write(&newmt_lock);
 		if (mas_expected_entries(&newmas, nr_entries)) {
 			printk("OOM!");
 			BUG_ON(1);
@@ -1843,11 +1852,11 @@ static noinline void __init bench_forking(struct maple_tree *mt)
 			mas_store(&newmas, val);
 		}
 		mas_destroy(&newmas);
-		mas_unlock(&newmas);
 		rcu_read_unlock();
 		mt_validate(&newmt);
 		mt_set_non_kernel(0);
-		mtree_destroy(&newmt);
+		__mt_destroy(&newmt);
+		up_write(&newmt_lock);
 	}
 }
 #endif
@@ -2453,6 +2462,10 @@ static noinline void __init check_dup_gaps(struct maple_tree *mt,
 	void *tmp;
 	MA_STATE(mas, mt, 0, 0);
 	MA_STATE(newmas, &newmt, 0, 0);
+	struct rw_semaphore newmt_lock;
+
+	init_rwsem(&newmt_lock);
+	mt_set_external_lock(&newmt, &newmt_lock);
 
 	if (!zero_start)
 		i = 1;
@@ -2462,9 +2475,9 @@ static noinline void __init check_dup_gaps(struct maple_tree *mt,
 		mtree_store_range(mt, i*10, (i+1)*10 - gap,
 				  xa_mk_value(i), GFP_KERNEL);
 
-	mt_init_flags(&newmt, MT_FLAGS_ALLOC_RANGE);
+	mt_init_flags(&newmt, MT_FLAGS_ALLOC_RANGE | MT_FLAGS_LOCK_EXTERN);
 	mt_set_non_kernel(99999);
-	mas_lock(&newmas);
+	down_write(&newmt_lock);
 	ret = mas_expected_entries(&newmas, nr_entries);
 	mt_set_non_kernel(0);
 	MT_BUG_ON(mt, ret != 0);
@@ -2477,9 +2490,9 @@ static noinline void __init check_dup_gaps(struct maple_tree *mt,
 	}
 	rcu_read_unlock();
 	mas_destroy(&newmas);
-	mas_unlock(&newmas);
 
-	mtree_destroy(&newmt);
+	__mt_destroy(&newmt);
+	up_write(&newmt_lock);
 }
 
 /* Duplicate many sizes of trees.  Mainly to test expected entry values */