* Peng Zhang zhangpeng.00@bytedance.com [231011 22:52]:

在 2023/10/10 22:17, Liam R. Howlett 写道:

...

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 testing in the maple tree fork testing needed to be altered to use the correct locking type so that allocations would not trigger sleeping and thus failures in the testing. 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.

You still haven't updated check_forking() and bench_forking(). It will still produce the same error as [1].

This did not show up on my testing, I will pull the bots config as I must be missing something in there.

Thanks.

[1] https://lore.kernel.org/oe-lkp/202309242123.7ebe65b5-oliver.sang@intel.com/

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Link: https://lkml.kernel.org/r/20230915093243epcms1p46fa00bbac1ab7b7dca94acb66c44... Fixes: 54a611b60590 ("Maple Tree: add new data structure") Cc: stable@vger.kernel.org Cc: jason.sim@samsung.com Signed-off-by: Liam R. Howlett Liam.Howlett@oracle.com

---

lib/maple_tree.c | 2 +- lib/test_maple_tree.c | 13 ++++++++---- tools/include/linux/rwsem.h | 40 +++++++++++++++++++++++++++++++++++++ 3 files changed, 50 insertions(+), 5 deletions(-) create mode 100644 tools/include/linux/rwsem.h

diff --git a/lib/maple_tree.c b/lib/maple_tree.c index 0e00a84e8e8f..bb24d84a4922 100644 --- a/lib/maple_tree.c +++ b/lib/maple_tree.c @@ -5627,7 +5627,7 @@ 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 06959165e2f9..204743bc161c 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 #define CONFIG_MAPLE_SEARCH @@ -2616,6 +2617,10 @@ 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;

@@ -2625,9 +2630,9 @@ 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);

@@ -2640,9 +2645,9 @@ 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 index 000000000000..83971b3cbfce --- /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 */