From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mga05.intel.com (mga05.intel.com [192.55.52.43]) by dpdk.org (Postfix) with ESMTP id ADB4B1B295; Tue, 4 Dec 2018 13:22:27 +0100 (CET) X-Amp-Result: SKIPPED(no attachment in message) X-Amp-File-Uploaded: False Received: from orsmga003.jf.intel.com ([10.7.209.27]) by fmsmga105.fm.intel.com with ESMTP/TLS/DHE-RSA-AES256-GCM-SHA384; 04 Dec 2018 04:22:26 -0800 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.56,314,1539673200"; d="scan'208";a="107164456" Received: from irvmail001.ir.intel.com ([163.33.26.43]) by orsmga003.jf.intel.com with ESMTP; 04 Dec 2018 04:22:25 -0800 Received: from sivswdev01.ir.intel.com (sivswdev01.ir.intel.com [10.237.217.45]) by irvmail001.ir.intel.com (8.14.3/8.13.6/MailSET/Hub) with ESMTP id wB4CMORO029836; Tue, 4 Dec 2018 12:22:24 GMT Received: from sivswdev01.ir.intel.com (localhost [127.0.0.1]) by sivswdev01.ir.intel.com with ESMTP id wB4CMOnK023590; Tue, 4 Dec 2018 12:22:24 GMT Received: (from aburakov@localhost) by sivswdev01.ir.intel.com with LOCAL id wB4CMKht023493; Tue, 4 Dec 2018 12:22:20 GMT From: Anatoly Burakov To: dev@dpdk.org Cc: thomas@monjalon.net, stable@dpdk.org Date: Tue, 4 Dec 2018 12:22:20 +0000 Message-Id: <884a355bde19652d57c253c6b36036571c4f46ee.1543926108.git.anatoly.burakov@intel.com> X-Mailer: git-send-email 1.7.0.7 Subject: [dpdk-dev] [PATCH 18.11] malloc: fix deadlock when using malloc stats X-BeenThere: dev@dpdk.org X-Mailman-Version: 2.1.15 Precedence: list List-Id: DPDK patches and discussions List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Tue, 04 Dec 2018 12:22:28 -0000 Currently, malloc statistics and external heap creation code use memory hotplug lock as a way to synchronize accesses to heaps (as in, locking the hotplug lock to prevent list of heaps from changing under our feet). At the same time, malloc statistics code will also lock the heap because it needs to access heap data and does not want any other thread to allocate anything from that heap. In such scheme, it is possible to enter a deadlock with the following sequence of events: thread 1 thread 2 rte_malloc() rte_malloc_dump_stats() take heap lock take hotplug lock failed to allocate, attempt to take hotplug lock attempt to take heap lock Neither thread will be able to continue, as both of them are waiting for the other one to drop the lock. Adding an additional lock will require an ABI change, so instead of that, make malloc statistics calls thread-unsafe with respect to creating/destroying heaps. Fixes: 72cf92b31855 ("malloc: index heaps using heap ID rather than NUMA node") Cc: stable@dpdk.org Signed-off-by: Anatoly Burakov --- Notes: IMO this is the best we can do for 18.11 without breaking ABI. For 19.02, we can introduce a new global heap lock (something i should've done in the first place...), so this patch is not applicable to 19.02. For 19.02, we can fix this properly by introducing another lock and breaking the EAL ABI. Not sure where to put docs update, feedback welcome. lib/librte_eal/common/include/rte_malloc.h | 9 +++++++++ lib/librte_eal/common/rte_malloc.c | 19 +++---------------- 2 files changed, 12 insertions(+), 16 deletions(-) diff --git a/lib/librte_eal/common/include/rte_malloc.h b/lib/librte_eal/common/include/rte_malloc.h index 7249e6aae..cde6232f9 100644 --- a/lib/librte_eal/common/include/rte_malloc.h +++ b/lib/librte_eal/common/include/rte_malloc.h @@ -251,6 +251,9 @@ rte_malloc_validate(const void *ptr, size_t *size); /** * Get heap statistics for the specified heap. * + * @note This function is not thread-safe with respect to + * ``rte_malloc_heap_create()``/``rte_malloc_heap_destroy()`` functions. + * * @param socket * An unsigned integer specifying the socket to get heap statistics for * @param socket_stats @@ -461,6 +464,9 @@ rte_malloc_heap_socket_is_external(int socket_id); * Dump for the specified type to a file. If the type argument is * NULL, all memory types will be dumped. * + * @note This function is not thread-safe with respect to + * ``rte_malloc_heap_create()``/``rte_malloc_heap_destroy()`` functions. + * * @param f * A pointer to a file for output * @param type @@ -473,6 +479,9 @@ rte_malloc_dump_stats(FILE *f, const char *type); /** * Dump contents of all malloc heaps to a file. * + * @note This function is not thread-safe with respect to + * ``rte_malloc_heap_create()``/``rte_malloc_heap_destroy()`` functions. + * * @param f * A pointer to a file for output */ diff --git a/lib/librte_eal/common/rte_malloc.c b/lib/librte_eal/common/rte_malloc.c index 0da5ad5e8..bc2b74d19 100644 --- a/lib/librte_eal/common/rte_malloc.c +++ b/lib/librte_eal/common/rte_malloc.c @@ -156,20 +156,14 @@ rte_malloc_get_socket_stats(int socket, struct rte_malloc_socket_stats *socket_stats) { struct rte_mem_config *mcfg = rte_eal_get_configuration()->mem_config; - int heap_idx, ret = -1; - - rte_rwlock_read_lock(&mcfg->memory_hotplug_lock); + int heap_idx; heap_idx = malloc_socket_to_heap_id(socket); if (heap_idx < 0) - goto unlock; + return -1; - ret = malloc_heap_get_stats(&mcfg->malloc_heaps[heap_idx], + return malloc_heap_get_stats(&mcfg->malloc_heaps[heap_idx], socket_stats); -unlock: - rte_rwlock_read_unlock(&mcfg->memory_hotplug_lock); - - return ret; } /* @@ -181,14 +175,10 @@ rte_malloc_dump_heaps(FILE *f) struct rte_mem_config *mcfg = rte_eal_get_configuration()->mem_config; unsigned int idx; - rte_rwlock_read_lock(&mcfg->memory_hotplug_lock); - for (idx = 0; idx < RTE_MAX_HEAPS; idx++) { fprintf(f, "Heap id: %u\n", idx); malloc_heap_dump(&mcfg->malloc_heaps[idx], f); } - - rte_rwlock_read_unlock(&mcfg->memory_hotplug_lock); } int @@ -262,8 +252,6 @@ rte_malloc_dump_stats(FILE *f, __rte_unused const char *type) unsigned int heap_id; struct rte_malloc_socket_stats sock_stats; - rte_rwlock_read_lock(&mcfg->memory_hotplug_lock); - /* Iterate through all initialised heaps */ for (heap_id = 0; heap_id < RTE_MAX_HEAPS; heap_id++) { struct malloc_heap *heap = &mcfg->malloc_heaps[heap_id]; @@ -280,7 +268,6 @@ rte_malloc_dump_stats(FILE *f, __rte_unused const char *type) fprintf(f, "\tAlloc_count:%u,\n",sock_stats.alloc_count); fprintf(f, "\tFree_count:%u,\n", sock_stats.free_count); } - rte_rwlock_read_unlock(&mcfg->memory_hotplug_lock); return; } -- 2.17.1