From: Gabor Juhos Date: Fri, 27 Jun 2025 07:58:54 +0000 (+0200) Subject: interconnect: avoid memory allocation when 'icc_bw_lock' is held X-Git-Tag: v6.16-rc7~10^2~15^2 X-Git-Url: http://git.ipfire.org/?a=commitdiff_plain;h=c5b60592886f97b01503c1bb553f88d6a7df42ea;p=thirdparty%2Flinux.git interconnect: avoid memory allocation when 'icc_bw_lock' is held The 'icc_bw_lock' mutex is introduced in commit af42269c3523 ("interconnect: Fix locking for runpm vs reclaim") in order to decouple serialization of bw aggregation from codepaths that require memory allocation. However commit d30f83d278a9 ("interconnect: core: Add dynamic id allocation support") added a devm_kasprintf() call into a path protected by the 'icc_bw_lock' which causes the following lockdep warning on machines like the Lenovo ThinkPad X13s: ====================================================== WARNING: possible circular locking dependency detected 6.16.0-rc3 #15 Not tainted ------------------------------------------------------ (udev-worker)/342 is trying to acquire lock: ffffb973f7ec4638 (fs_reclaim){+.+.}-{0:0}, at: __kmalloc_node_track_caller_noprof+0xa0/0x3e0 but task is already holding lock: ffffb973f7f7f0e8 (icc_bw_lock){+.+.}-{4:4}, at: icc_node_add+0x44/0x154 which lock already depends on the new lock. the existing dependency chain (in reverse order) is: -> #1 (icc_bw_lock){+.+.}-{4:4}: icc_init+0x48/0x108 do_one_initcall+0x64/0x30c kernel_init_freeable+0x27c/0x500 kernel_init+0x20/0x1d8 ret_from_fork+0x10/0x20 -> #0 (fs_reclaim){+.+.}-{0:0}: __lock_acquire+0x136c/0x2114 lock_acquire+0x1c8/0x354 fs_reclaim_acquire+0x74/0xa8 __kmalloc_node_track_caller_noprof+0xa0/0x3e0 devm_kmalloc+0x54/0x124 devm_kvasprintf+0x74/0xd4 devm_kasprintf+0x58/0x80 icc_node_add+0xb4/0x154 qcom_osm_l3_probe+0x20c/0x314 [icc_osm_l3] platform_probe+0x68/0xd8 really_probe+0xc0/0x38c __driver_probe_device+0x7c/0x160 driver_probe_device+0x40/0x110 __driver_attach+0xfc/0x208 bus_for_each_dev+0x74/0xd0 driver_attach+0x24/0x30 bus_add_driver+0x110/0x234 driver_register+0x60/0x128 __platform_driver_register+0x24/0x30 osm_l3_driver_init+0x20/0x1000 [icc_osm_l3] do_one_initcall+0x64/0x30c do_init_module+0x58/0x23c load_module+0x1df8/0x1f70 init_module_from_file+0x88/0xc4 idempotent_init_module+0x188/0x280 __arm64_sys_finit_module+0x6c/0xd8 invoke_syscall+0x48/0x110 el0_svc_common.constprop.0+0xc0/0xe0 do_el0_svc+0x1c/0x28 el0_svc+0x4c/0x158 el0t_64_sync_handler+0xc8/0xcc el0t_64_sync+0x198/0x19c other info that might help us debug this: Possible unsafe locking scenario: CPU0 CPU1 ---- ---- lock(icc_bw_lock); lock(fs_reclaim); lock(icc_bw_lock); lock(fs_reclaim); *** DEADLOCK *** The icc_node_add() functions is not designed to fail, and as such it should not do any memory allocation. In order to avoid this, add a new helper function for the name generation to be called by drivers which are using the new dynamic id feature. Fixes: d30f83d278a9 ("interconnect: core: Add dynamic id allocation support") Signed-off-by: Gabor Juhos Link: https://lore.kernel.org/r/20250625-icc-bw-lockdep-v3-1-2b8f8b8987c4@gmail.com Co-developed-by: Johan Hovold Signed-off-by: Johan Hovold Link: https://lore.kernel.org/r/20250627075854.26943-1-johan+linaro@kernel.org Signed-off-by: Georgi Djakov --- diff --git a/drivers/interconnect/core.c b/drivers/interconnect/core.c index 3a41b2717edd..3ebf37ddfc18 100644 --- a/drivers/interconnect/core.c +++ b/drivers/interconnect/core.c @@ -909,10 +909,35 @@ void icc_node_destroy(int id) return; kfree(node->links); + if (node->id >= ICC_DYN_ID_START) + kfree(node->name); kfree(node); } EXPORT_SYMBOL_GPL(icc_node_destroy); +/** + * icc_node_set_name() - set node name + * @node: node + * @provider: node provider + * @name: node name + * + * Return: 0 on success, or -ENOMEM on allocation failure + */ +int icc_node_set_name(struct icc_node *node, const struct icc_provider *provider, const char *name) +{ + if (node->id >= ICC_DYN_ID_START) { + node->name = kasprintf(GFP_KERNEL, "%s@%s", name, + dev_name(provider->dev)); + if (!node->name) + return -ENOMEM; + } else { + node->name = name; + } + + return 0; +} +EXPORT_SYMBOL_GPL(icc_node_set_name); + /** * icc_link_nodes() - create link between two nodes * @src_node: source node @@ -1041,10 +1066,6 @@ void icc_node_add(struct icc_node *node, struct icc_provider *provider) node->avg_bw = node->init_avg; node->peak_bw = node->init_peak; - if (node->id >= ICC_DYN_ID_START) - node->name = devm_kasprintf(provider->dev, GFP_KERNEL, "%s@%s", - node->name, dev_name(provider->dev)); - if (node->avg_bw || node->peak_bw) { if (provider->pre_aggregate) provider->pre_aggregate(node); diff --git a/drivers/interconnect/qcom/icc-rpmh.c b/drivers/interconnect/qcom/icc-rpmh.c index 41bfc6e7ee1d..001404e91041 100644 --- a/drivers/interconnect/qcom/icc-rpmh.c +++ b/drivers/interconnect/qcom/icc-rpmh.c @@ -293,7 +293,12 @@ int qcom_icc_rpmh_probe(struct platform_device *pdev) goto err_remove_nodes; } - node->name = qn->name; + ret = icc_node_set_name(node, provider, qn->name); + if (ret) { + icc_node_destroy(node->id); + goto err_remove_nodes; + } + node->data = qn; icc_node_add(node, provider); diff --git a/drivers/interconnect/qcom/osm-l3.c b/drivers/interconnect/qcom/osm-l3.c index baecbf2533f7..b33f00da1880 100644 --- a/drivers/interconnect/qcom/osm-l3.c +++ b/drivers/interconnect/qcom/osm-l3.c @@ -236,7 +236,12 @@ static int qcom_osm_l3_probe(struct platform_device *pdev) goto err; } - node->name = qnodes[i]->name; + ret = icc_node_set_name(node, provider, qnodes[i]->name); + if (ret) { + icc_node_destroy(node->id); + goto err; + } + /* Cast away const and add it back in qcom_osm_l3_set() */ node->data = (void *)qnodes[i]; icc_node_add(node, provider); diff --git a/include/linux/interconnect-provider.h b/include/linux/interconnect-provider.h index 55cfebc658e6..8a2f652a05ff 100644 --- a/include/linux/interconnect-provider.h +++ b/include/linux/interconnect-provider.h @@ -119,6 +119,7 @@ int icc_std_aggregate(struct icc_node *node, u32 tag, u32 avg_bw, struct icc_node *icc_node_create_dyn(void); struct icc_node *icc_node_create(int id); void icc_node_destroy(int id); +int icc_node_set_name(struct icc_node *node, const struct icc_provider *provider, const char *name); int icc_link_nodes(struct icc_node *src_node, struct icc_node **dst_node); int icc_link_create(struct icc_node *node, const int dst_id); void icc_node_add(struct icc_node *node, struct icc_provider *provider); @@ -152,6 +153,12 @@ static inline void icc_node_destroy(int id) { } +static inline int icc_node_set_name(struct icc_node *node, const struct icc_provider *provider, + const char *name) +{ + return -EOPNOTSUPP; +} + static inline int icc_link_nodes(struct icc_node *src_node, struct icc_node **dst_node) { return -EOPNOTSUPP;