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>

diff --git a/lib/maple_tree.c b/lib/maple_tree.c
index 250b4c67fac8f50ac9f0452e9306580a5fcbb943..4976522e3e481a575aa86bdb17cd6d6e9b88b886 100644 (file)
--- 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 fad668042f3e7284643b0aff6b5367f5ca206b16..ab9d4461abc9dc57e99cb4d7d6aac21797fe70fc 100644 (file)
--- 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 */

diff --git a/tools/include/linux/rwsem.h b/tools/include/linux/rwsem.h
new file mode 100644 (file)
index 0000000..83971b3
--- /dev/null
+++ b/tools/include/linux/rwsem.h
@@ -0,0 +1,40 @@
+/* SPDX-License-Identifier: GPL-2.0+ */
+#ifndef _TOOLS__RWSEM_H
+#define _TOOLS__RWSEM_H
+
+#include <pthread.h>
+
+struct rw_semaphore {
+       pthread_rwlock_t lock;
+};
+
+static inline int init_rwsem(struct rw_semaphore *sem)
+{
+       return pthread_rwlock_init(&sem->lock, NULL);
+}
+
+static inline int exit_rwsem(struct rw_semaphore *sem)
+{
+       return pthread_rwlock_destroy(&sem->lock);
+}
+
+static inline int down_read(struct rw_semaphore *sem)
+{
+       return pthread_rwlock_rdlock(&sem->lock);
+}
+
+static inline int up_read(struct rw_semaphore *sem)
+{
+       return pthread_rwlock_unlock(&sem->lock);
+}
+
+static inline int down_write(struct rw_semaphore *sem)
+{
+       return pthread_rwlock_wrlock(&sem->lock);
+}
+
+static inline int up_write(struct rw_semaphore *sem)
+{
+       return pthread_rwlock_unlock(&sem->lock);
+}
+#endif /* _TOOLS_RWSEM_H */