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Wed, 02 Jul 2025 08:33:20 -0700 (PDT) Received: from localhost.localdomain ([121.185.186.233]) by smtp.gmail.com with ESMTPSA id d9443c01a7336-23acb39bf5fsm140889545ad.115.2025.07.02.08.33.17 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 02 Jul 2025 08:33:20 -0700 (PDT) From: Jeongjun Park To: stable@vger.kernel.org Cc: urezki@gmail.com, akpm@linux-foundation.org, edumazet@google.com, linux-mm@kvack.org, linux-kernel@vger.kernel.org, Jeongjun Park Subject: [PATCH 6.15.y] mm/vmalloc: fix data race in show_numa_info() Date: Thu, 3 Jul 2025 00:33:12 +0900 Message-ID: <20250702153312.351080-1-aha310510@gmail.com> X-Mailer: git-send-email 2.47.2 MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Stat-Signature: jf4gpa55dgjartm74kho9jcqz3fsqe6b X-Rspamd-Queue-Id: 68B7440003 X-Rspamd-Server: rspam11 X-Rspam-User: X-HE-Tag: 1751470402-311953 X-HE-Meta: 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 LDLDh86b 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 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: List-Subscribe: List-Unsubscribe: commit 5c5f0468d172ddec2e333d738d2a1f85402cf0bc upstream. The following data-race was found in show_numa_info(): ================================================================== BUG: KCSAN: data-race in vmalloc_info_show / vmalloc_info_show read to 0xffff88800971fe30 of 4 bytes by task 8289 on cpu 0: show_numa_info mm/vmalloc.c:4936 [inline] vmalloc_info_show+0x5a8/0x7e0 mm/vmalloc.c:5016 seq_read_iter+0x373/0xb40 fs/seq_file.c:230 proc_reg_read_iter+0x11e/0x170 fs/proc/inode.c:299 .... write to 0xffff88800971fe30 of 4 bytes by task 8287 on cpu 1: show_numa_info mm/vmalloc.c:4934 [inline] vmalloc_info_show+0x38f/0x7e0 mm/vmalloc.c:5016 seq_read_iter+0x373/0xb40 fs/seq_file.c:230 proc_reg_read_iter+0x11e/0x170 fs/proc/inode.c:299 .... value changed: 0x0000008f -> 0x00000000 ================================================================== According to this report,there is a read/write data-race because m->private is accessible to multiple CPUs. To fix this, instead of allocating the heap in proc_vmalloc_init() and passing the heap address to m->private, vmalloc_info_show() should allocate the heap. Link: https://lkml.kernel.org/r/20250508165620.15321-1-aha310510@gmail.com Fixes: 8e1d743 ("mm: vmalloc: support multiple nodes in vmallocinfo") Signed-off-by: Jeongjun Park Suggested-by: Eric Dumazet Suggested-by: Andrew Morton Reviewed-by: "Uladzislau Rezki (Sony)" Signed-off-by: Andrew Morton --- mm/vmalloc.c | 63 +++++++++++++++++++++++++++++----------------------- 1 file changed, 35 insertions(+), 28 deletions(-) diff --git a/mm/vmalloc.c b/mm/vmalloc.c index 00cf1b575c89..3fb534dcf14d 100644 --- a/mm/vmalloc.c +++ b/mm/vmalloc.c @@ -3100,7 +3100,7 @@ static void clear_vm_uninitialized_flag(struct vm_struct *vm) /* * Before removing VM_UNINITIALIZED, * we should make sure that vm has proper values. - * Pair with smp_rmb() in show_numa_info(). + * Pair with smp_rmb() in vread_iter() and vmalloc_info_show(). */ smp_wmb(); vm->flags &= ~VM_UNINITIALIZED; @@ -4934,28 +4934,29 @@ bool vmalloc_dump_obj(void *object) #endif #ifdef CONFIG_PROC_FS -static void show_numa_info(struct seq_file *m, struct vm_struct *v) -{ - if (IS_ENABLED(CONFIG_NUMA)) { - unsigned int nr, *counters = m->private; - unsigned int step = 1U << vm_area_page_order(v); - if (!counters) - return; +/* + * Print number of pages allocated on each memory node. + * + * This function can only be called if CONFIG_NUMA is enabled + * and VM_UNINITIALIZED bit in v->flags is disabled. + */ +static void show_numa_info(struct seq_file *m, struct vm_struct *v, + unsigned int *counters) +{ + unsigned int nr; + unsigned int step = 1U << vm_area_page_order(v); - if (v->flags & VM_UNINITIALIZED) - return; - /* Pair with smp_wmb() in clear_vm_uninitialized_flag() */ - smp_rmb(); + if (!counters) + return; - memset(counters, 0, nr_node_ids * sizeof(unsigned int)); + memset(counters, 0, nr_node_ids * sizeof(unsigned int)); - for (nr = 0; nr < v->nr_pages; nr += step) - counters[page_to_nid(v->pages[nr])] += step; - for_each_node_state(nr, N_HIGH_MEMORY) - if (counters[nr]) - seq_printf(m, " N%u=%u", nr, counters[nr]); - } + for (nr = 0; nr < v->nr_pages; nr += step) + counters[page_to_nid(v->pages[nr])] += step; + for_each_node_state(nr, N_HIGH_MEMORY) + if (counters[nr]) + seq_printf(m, " N%u=%u", nr, counters[nr]); } static void show_purge_info(struct seq_file *m) @@ -4983,6 +4984,10 @@ static int vmalloc_info_show(struct seq_file *m, void *p) struct vmap_area *va; struct vm_struct *v; int i; + unsigned int *counters; + + if (IS_ENABLED(CONFIG_NUMA)) + counters = kmalloc(nr_node_ids * sizeof(unsigned int), GFP_KERNEL); for (i = 0; i < nr_vmap_nodes; i++) { vn = &vmap_nodes[i]; @@ -4999,6 +5004,11 @@ static int vmalloc_info_show(struct seq_file *m, void *p) } v = va->vm; + if (v->flags & VM_UNINITIALIZED) + continue; + + /* Pair with smp_wmb() in clear_vm_uninitialized_flag() */ + smp_rmb(); seq_printf(m, "0x%pK-0x%pK %7ld", v->addr, v->addr + v->size, v->size); @@ -5033,7 +5043,9 @@ static int vmalloc_info_show(struct seq_file *m, void *p) if (is_vmalloc_addr(v->pages)) seq_puts(m, " vpages"); - show_numa_info(m, v); + if (IS_ENABLED(CONFIG_NUMA)) + show_numa_info(m, v, counters); + seq_putc(m, '\n'); } spin_unlock(&vn->busy.lock); @@ -5043,19 +5055,14 @@ static int vmalloc_info_show(struct seq_file *m, void *p) * As a final step, dump "unpurged" areas. */ show_purge_info(m); + if (IS_ENABLED(CONFIG_NUMA)) + kfree(counters); return 0; } static int __init proc_vmalloc_init(void) { - void *priv_data = NULL; - - if (IS_ENABLED(CONFIG_NUMA)) - priv_data = kmalloc(nr_node_ids * sizeof(unsigned int), GFP_KERNEL); - - proc_create_single_data("vmallocinfo", - 0400, NULL, vmalloc_info_show, priv_data); - + proc_create_single("vmallocinfo", 0400, NULL, vmalloc_info_show); return 0; } module_init(proc_vmalloc_init); --