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Fri, 16 Oct 2020 02:46:13 +0000 (UTC) Received: from localhost.localdomain (c-73-231-172-41.hsd1.ca.comcast.net [73.231.172.41]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id AE90A2145D; Fri, 16 Oct 2020 02:46:11 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1602816372; bh=C5jIIUAAEdWsLo34nPRoDaB1pKuxd4AGb5OYRqWxTwY=; h=Date:From:To:Subject:In-Reply-To:From; b=alqEIS9SnfcErQaEo5BUvBM8WafrU7e8DqEwXEk0M1s2rUEwjb9ihwFq68vuCCi/i 0/MXeUUqy8gCe6PhZoYpN36qOCPI2QuIg/qky38/l2fM3Mr5+n84Wv6sdcwy3kU42i vKMwS16OqaadaTJvUnkN/nShDNqBKJw95aaCASck= Date: Thu, 15 Oct 2020 19:46:11 -0700 From: Andrew Morton To: akpm@linux-foundation.org, cheloha@linux.ibm.com, david@redhat.com, fenghua.yu@intel.com, gregkh@linuxfoundation.org, ldufour@linux.ibm.com, linux-mm@kvack.org, mhocko@suse.com, mm-commits@vger.kernel.org, nathanl@linux.ibm.com, osalvador@suse.de, rafael@kernel.org, tony.luck@intel.com, torvalds@linux-foundation.org Subject: [patch 078/156] mm: don't panic when links can't be created in sysfs Message-ID: <20201016024611.TiQ7xtt7k%akpm@linux-foundation.org> In-Reply-To: <20201015192732.f448da14e9854c7cb7299956@linux-foundation.org> User-Agent: s-nail v14.8.16 X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: From: Laurent Dufour Subject: mm: don't panic when links can't be created in sysfs At boot time, or when doing memory hot-add operations, if the links in sysfs can't be created, the system is still able to run, so just report the error in the kernel log rather than BUG_ON and potentially make system unusable because the callpath can be called with locks held. Since the number of memory blocks managed could be high, the messages are rate limited. As a consequence, link_mem_sections() has no status to report anymore. Link: https://lkml.kernel.org/r/20200915094143.79181-4-ldufour@linux.ibm.com Signed-off-by: Laurent Dufour Acked-by: Michal Hocko Acked-by: David Hildenbrand Reviewed-by: Oscar Salvador Cc: Greg Kroah-Hartman Cc: Fenghua Yu Cc: Nathan Lynch Cc: "Rafael J . Wysocki" Cc: Scott Cheloha Cc: Tony Luck Signed-off-by: Andrew Morton --- drivers/base/node.c | 33 +++++++++++++++++++++------------ include/linux/node.h | 16 +++++++--------- mm/memory_hotplug.c | 5 ++--- 3 files changed, 30 insertions(+), 24 deletions(-) --- a/drivers/base/node.c~mm-dont-panic-when-links-cant-be-created-in-sysfs +++ a/drivers/base/node.c @@ -772,8 +772,8 @@ static int __ref get_nid_for_pfn(unsigne return pfn_to_nid(pfn); } -static int do_register_memory_block_under_node(int nid, - struct memory_block *mem_blk) +static void do_register_memory_block_under_node(int nid, + struct memory_block *mem_blk) { int ret; @@ -786,12 +786,19 @@ static int do_register_memory_block_unde ret = sysfs_create_link_nowarn(&node_devices[nid]->dev.kobj, &mem_blk->dev.kobj, kobject_name(&mem_blk->dev.kobj)); - if (ret) - return ret; + if (ret && ret != -EEXIST) + dev_err_ratelimited(&node_devices[nid]->dev, + "can't create link to %s in sysfs (%d)\n", + kobject_name(&mem_blk->dev.kobj), ret); - return sysfs_create_link_nowarn(&mem_blk->dev.kobj, + ret = sysfs_create_link_nowarn(&mem_blk->dev.kobj, &node_devices[nid]->dev.kobj, kobject_name(&node_devices[nid]->dev.kobj)); + if (ret && ret != -EEXIST) + dev_err_ratelimited(&mem_blk->dev, + "can't create link to %s in sysfs (%d)\n", + kobject_name(&node_devices[nid]->dev.kobj), + ret); } /* register memory section under specified node if it spans that node */ @@ -827,7 +834,8 @@ static int register_mem_block_under_node if (page_nid != nid) continue; - return do_register_memory_block_under_node(nid, mem_blk); + do_register_memory_block_under_node(nid, mem_blk); + return 0; } /* mem section does not span the specified node */ return 0; @@ -842,7 +850,8 @@ static int register_mem_block_under_node { int nid = *(int *)arg; - return do_register_memory_block_under_node(nid, mem_blk); + do_register_memory_block_under_node(nid, mem_blk); + return 0; } /* @@ -860,8 +869,8 @@ void unregister_memory_block_under_nodes kobject_name(&node_devices[mem_blk->nid]->dev.kobj)); } -int link_mem_sections(int nid, unsigned long start_pfn, unsigned long end_pfn, - enum meminit_context context) +void link_mem_sections(int nid, unsigned long start_pfn, unsigned long end_pfn, + enum meminit_context context) { walk_memory_blocks_func_t func; @@ -870,9 +879,9 @@ int link_mem_sections(int nid, unsigned else func = register_mem_block_under_node_early; - return walk_memory_blocks(PFN_PHYS(start_pfn), - PFN_PHYS(end_pfn - start_pfn), (void *)&nid, - func); + walk_memory_blocks(PFN_PHYS(start_pfn), PFN_PHYS(end_pfn - start_pfn), + (void *)&nid, func); + return; } #ifdef CONFIG_HUGETLBFS --- a/include/linux/node.h~mm-dont-panic-when-links-cant-be-created-in-sysfs +++ a/include/linux/node.h @@ -99,15 +99,14 @@ extern struct node *node_devices[]; typedef void (*node_registration_func_t)(struct node *); #if defined(CONFIG_MEMORY_HOTPLUG_SPARSE) && defined(CONFIG_NUMA) -int link_mem_sections(int nid, unsigned long start_pfn, - unsigned long end_pfn, - enum meminit_context context); +void link_mem_sections(int nid, unsigned long start_pfn, + unsigned long end_pfn, + enum meminit_context context); #else -static inline int link_mem_sections(int nid, unsigned long start_pfn, - unsigned long end_pfn, - enum meminit_context context) +static inline void link_mem_sections(int nid, unsigned long start_pfn, + unsigned long end_pfn, + enum meminit_context context) { - return 0; } #endif @@ -130,8 +129,7 @@ static inline int register_one_node(int if (error) return error; /* link memory sections under this node */ - error = link_mem_sections(nid, start_pfn, end_pfn, - MEMINIT_EARLY); + link_mem_sections(nid, start_pfn, end_pfn, MEMINIT_EARLY); } return error; --- a/mm/memory_hotplug.c~mm-dont-panic-when-links-cant-be-created-in-sysfs +++ a/mm/memory_hotplug.c @@ -1092,9 +1092,8 @@ int __ref add_memory_resource(int nid, s } /* link memory sections under this node.*/ - ret = link_mem_sections(nid, PFN_DOWN(start), PFN_UP(start + size - 1), - MEMINIT_HOTPLUG); - BUG_ON(ret); + link_mem_sections(nid, PFN_DOWN(start), PFN_UP(start + size - 1), + MEMINIT_HOTPLUG); /* create new memmap entry */ if (!strcmp(res->name, "System RAM"))