[dpdk-dev] [PATCH v4] eal: detach memsegs on cleanup

[Anatoly Burakov <anatoly.burakov@intel.com>]

Currently, we don't detach the shared memory on EAL cleanup, which
leaves the page table descriptors still holding on to the file
descriptors as well as memory space occupied by them. Fix it by adding
another detach stage that closes the internal memory allocator resource
references, detaches shared fbarrays and unmaps the shared mem config.

Bugzilla ID: 380
Bugzilla ID: 381

Signed-off-by: Anatoly Burakov <anatoly.burakov@intel.com>
---

Notes:
    v4:
    - Fix Windows build
    
    v3:
    - Added missing Bugzilla ID for similar bug
    - Fixed deadlock on exit
    
    v2:
    - Fixed checkpatch warnings
    
    Not backporting to stable because this fix isn't critical but is rather
    "nice to have".

 lib/librte_eal/common/eal_common_memory.c | 54 ++++++++++++++
 lib/librte_eal/common/eal_memalloc.h      |  3 +
 lib/librte_eal/common/eal_private.h       |  7 ++
 lib/librte_eal/freebsd/eal.c              |  2 +
 lib/librte_eal/freebsd/eal_memalloc.c     |  5 ++
 lib/librte_eal/linux/eal.c                |  2 +
 lib/librte_eal/linux/eal_memalloc.c       | 85 +++++++++++++++++++++++
 lib/librte_eal/windows/eal.c              |  3 +-
 lib/librte_eal/windows/eal_memalloc.c     |  7 ++
 9 files changed, 167 insertions(+), 1 deletion(-)

diff --git a/lib/librte_eal/common/eal_common_memory.c b/lib/librte_eal/common/eal_common_memory.c
index 33917fa835..0e99986d3d 100644
--- a/lib/librte_eal/common/eal_common_memory.c
+++ b/lib/librte_eal/common/eal_common_memory.c
@@ -1002,6 +1002,60 @@ rte_extmem_detach(void *va_addr, size_t len)
 	return sync_memory(va_addr, len, false);
 }
 
+/* detach all EAL memory */
+int
+rte_eal_memory_detach(void)
+{
+	struct rte_mem_config *mcfg = rte_eal_get_configuration()->mem_config;
+	size_t page_sz = rte_mem_page_size();
+	unsigned int i;
+
+	rte_rwlock_write_lock(&mcfg->memory_hotplug_lock);
+
+	/* detach internal memory subsystem data first */
+	if (eal_memalloc_cleanup())
+		RTE_LOG(ERR, EAL, "Could not release memory subsystem data\n");
+
+	for (i = 0; i < RTE_DIM(mcfg->memsegs); i++) {
+		struct rte_memseg_list *msl = &mcfg->memsegs[i];
+
+		/* skip uninitialized segments */
+		if (msl->base_va == NULL)
+			continue;
+		/*
+		 * external segments are supposed to be detached at this point,
+		 * but if they aren't, we can't really do anything about it,
+		 * because if we skip them here, they'll become invalid after
+		 * we unmap the memconfig anyway. however, if this is externally
+		 * referenced memory, we have no business unmapping it.
+		 */
+		if (!msl->external)
+			if (rte_mem_unmap(msl->base_va, msl->len) != 0)
+				RTE_LOG(ERR, EAL, "Could not unmap memory: %s\n",
+						strerror(errno));
+
+		/*
+		 * we are detaching the fbarray rather than destroying because
+		 * other processes might still reference this fbarray, and we
+		 * have no way of knowing if they still do.
+		 */
+		if (rte_fbarray_detach(&msl->memseg_arr))
+			RTE_LOG(ERR, EAL, "Could not detach fbarray: %s\n",
+					rte_strerror(rte_errno));
+	}
+	rte_rwlock_write_unlock(&mcfg->memory_hotplug_lock);
+
+	/*
+	 * we've detached the memseg lists, so we can unmap the shared mem
+	 * config - we can't zero it out because it might still be referenced
+	 * by other processes.
+	 */
+	rte_mem_unmap(mcfg, RTE_ALIGN(sizeof(*mcfg), page_sz));
+	rte_eal_get_configuration()->mem_config = NULL;
+
+	return 0;
+}
+
 /* init memory subsystem */
 int
 rte_eal_memory_init(void)
diff --git a/lib/librte_eal/common/eal_memalloc.h b/lib/librte_eal/common/eal_memalloc.h
index e953cd84e6..ebc3a6f6c1 100644
--- a/lib/librte_eal/common/eal_memalloc.h
+++ b/lib/librte_eal/common/eal_memalloc.h
@@ -93,4 +93,7 @@ eal_memalloc_get_seg_fd_offset(int list_idx, int seg_idx, size_t *offset);
 int
 eal_memalloc_init(void);
 
+int
+eal_memalloc_cleanup(void);
+
 #endif /* EAL_MEMALLOC_H */
diff --git a/lib/librte_eal/common/eal_private.h b/lib/librte_eal/common/eal_private.h
index a6a6381567..84c4621768 100644
--- a/lib/librte_eal/common/eal_private.h
+++ b/lib/librte_eal/common/eal_private.h
@@ -433,6 +433,13 @@ int rte_eal_hugepage_init(void);
  */
 int rte_eal_hugepage_attach(void);
 
+/**
+ * Detaches all memory mappings from a process.
+ *
+ * This function is private to the EAL.
+ */
+int rte_eal_memory_detach(void);
+
 /**
  * Find a bus capable of identifying a device.
  *
diff --git a/lib/librte_eal/freebsd/eal.c b/lib/librte_eal/freebsd/eal.c
index 798add0b59..361593a005 100644
--- a/lib/librte_eal/freebsd/eal.c
+++ b/lib/librte_eal/freebsd/eal.c
@@ -963,6 +963,8 @@ rte_eal_cleanup(void)
 		eal_get_internal_configuration();
 	rte_service_finalize();
 	rte_mp_channel_cleanup();
+	/* after this point, any DPDK pointers will become dangling */
+	rte_eal_memory_detach();
 	rte_trace_save();
 	eal_trace_fini();
 	eal_cleanup_config(internal_conf);
diff --git a/lib/librte_eal/freebsd/eal_memalloc.c b/lib/librte_eal/freebsd/eal_memalloc.c
index 6893448db7..00ab02cb63 100644
--- a/lib/librte_eal/freebsd/eal_memalloc.c
+++ b/lib/librte_eal/freebsd/eal_memalloc.c
@@ -74,6 +74,11 @@ eal_memalloc_get_seg_fd_offset(int list_idx __rte_unused,
 	return -ENOTSUP;
 }
 
+int eal_memalloc_cleanup(void)
+{
+	return 0;
+}
+
 int
 eal_memalloc_init(void)
 {
diff --git a/lib/librte_eal/linux/eal.c b/lib/librte_eal/linux/eal.c
index 0960f01d05..eb69f4aedf 100644
--- a/lib/librte_eal/linux/eal.c
+++ b/lib/librte_eal/linux/eal.c
@@ -1359,6 +1359,8 @@ rte_eal_cleanup(void)
 		rte_memseg_walk(mark_freeable, NULL);
 	rte_service_finalize();
 	rte_mp_channel_cleanup();
+	/* after this point, any DPDK pointers will become dangling */
+	rte_eal_memory_detach();
 	rte_trace_save();
 	eal_trace_fini();
 	eal_cleanup_config(internal_conf);
diff --git a/lib/librte_eal/linux/eal_memalloc.c b/lib/librte_eal/linux/eal_memalloc.c
index db60e79975..e782734c98 100644
--- a/lib/librte_eal/linux/eal_memalloc.c
+++ b/lib/librte_eal/linux/eal_memalloc.c
@@ -1418,6 +1418,31 @@ secondary_msl_create_walk(const struct rte_memseg_list *msl,
 	return 0;
 }
 
+static int
+secondary_msl_destroy_walk(const struct rte_memseg_list *msl,
+		void *arg __rte_unused)
+{
+	struct rte_mem_config *mcfg = rte_eal_get_configuration()->mem_config;
+	struct rte_memseg_list *local_msl;
+	int msl_idx, ret;
+
+	if (msl->external)
+		return 0;
+
+	msl_idx = msl - mcfg->memsegs;
+	local_msl = &local_memsegs[msl_idx];
+
+	ret = rte_fbarray_destroy(&local_msl->memseg_arr);
+	if (ret < 0) {
+		RTE_LOG(ERR, EAL, "Cannot destroy local memory map\n");
+		return -1;
+	}
+	local_msl->base_va = NULL;
+	local_msl->len = 0;
+
+	return 0;
+}
+
 static int
 alloc_list(int list_idx, int len)
 {
@@ -1450,6 +1475,34 @@ alloc_list(int list_idx, int len)
 	return 0;
 }
 
+static int
+destroy_list(int list_idx)
+{
+	const struct internal_config *internal_conf =
+			eal_get_internal_configuration();
+
+	/* single-file segments mode does not need fd list */
+	if (!internal_conf->single_file_segments) {
+		int *fds = fd_list[list_idx].fds;
+		int i;
+		/* go through each fd and ensure it's closed */
+		for (i = 0; i < fd_list[list_idx].len; i++) {
+			if (fds[i] >= 0) {
+				close(fds[i]);
+				fds[i] = -1;
+			}
+		}
+		free(fds);
+		fd_list[list_idx].fds = NULL;
+		fd_list[list_idx].len = 0;
+	} else if (fd_list[list_idx].memseg_list_fd >= 0) {
+		close(fd_list[list_idx].memseg_list_fd);
+		fd_list[list_idx].count = 0;
+		fd_list[list_idx].memseg_list_fd = -1;
+	}
+	return 0;
+}
+
 static int
 fd_list_create_walk(const struct rte_memseg_list *msl,
 		void *arg __rte_unused)
@@ -1467,6 +1520,20 @@ fd_list_create_walk(const struct rte_memseg_list *msl,
 	return alloc_list(msl_idx, len);
 }
 
+static int
+fd_list_destroy_walk(const struct rte_memseg_list *msl, void *arg __rte_unused)
+{
+	struct rte_mem_config *mcfg = rte_eal_get_configuration()->mem_config;
+	int msl_idx;
+
+	if (msl->external)
+		return 0;
+
+	msl_idx = msl - mcfg->memsegs;
+
+	return destroy_list(msl_idx);
+}
+
 int
 eal_memalloc_set_seg_fd(int list_idx, int seg_idx, int fd)
 {
@@ -1603,6 +1670,24 @@ eal_memalloc_get_seg_fd_offset(int list_idx, int seg_idx, size_t *offset)
 	return 0;
 }
 
+int
+eal_memalloc_cleanup(void)
+{
+	/* close all remaining fd's - these are per-process, so it's safe */
+	if (rte_memseg_list_walk_thread_unsafe(fd_list_destroy_walk, NULL))
+		return -1;
+
+	/* destroy the shadow page table if we're a secondary process */
+	if (rte_eal_process_type() == RTE_PROC_PRIMARY)
+		return 0;
+
+	if (rte_memseg_list_walk_thread_unsafe(secondary_msl_destroy_walk,
+			NULL))
+		return -1;
+
+	return 0;
+}
+
 int
 eal_memalloc_init(void)
 {
diff --git a/lib/librte_eal/windows/eal.c b/lib/librte_eal/windows/eal.c
index e50601dd36..d5db007717 100644
--- a/lib/librte_eal/windows/eal.c
+++ b/lib/librte_eal/windows/eal.c
@@ -250,7 +250,8 @@ rte_eal_cleanup(void)
 {
 	struct internal_config *internal_conf =
 		eal_get_internal_configuration();
-
+	/* after this point, any DPDK pointers will become dangling */
+	rte_eal_memory_detach();
 	eal_cleanup_config(internal_conf);
 	return 0;
 }
diff --git a/lib/librte_eal/windows/eal_memalloc.c b/lib/librte_eal/windows/eal_memalloc.c
index d8cae3ebc1..85a9712cea 100644
--- a/lib/librte_eal/windows/eal_memalloc.c
+++ b/lib/librte_eal/windows/eal_memalloc.c
@@ -437,6 +437,13 @@ eal_memalloc_sync_with_primary(void)
 	return -1;
 }
 
+int
+eal_memalloc_cleanup(void)
+{
+	/* not implemented */
+	return 0;
+}
+
 int
 eal_memalloc_init(void)
 {
-- 
2.17.1