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Wed, 02 Jul 2025 08:34:45 -0700 (PDT) Received: from localhost.localdomain ([121.185.186.233]) by smtp.gmail.com with ESMTPSA id 98e67ed59e1d1-31a9cc72255sm110682a91.21.2025.07.02.08.34.43 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 02 Jul 2025 08:34:44 -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 6.12.y] mm/vmalloc: fix data race in show_numa_info() Date: Thu, 3 Jul 2025 00:34:28 +0900 Message-ID: <20250702153428.352047-1-aha310510@gmail.com> X-Mailer: git-send-email 2.47.2 MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Stat-Signature: 5mfso9pmbds598smcfruurz4bk3wysn6 X-Rspamd-Queue-Id: DDA884000D X-Rspamd-Server: rspam11 X-Rspam-User: X-HE-Tag: 1751470486-340670 X-HE-Meta: U2FsdGVkX1+bq1g4qioVLj6lwSWgidrFNh1zRpPBitzzzb97cxRKj6RfG+TARBZl1BxFCsjnIPFvk5VwvfxhyHuvaTDO01r0cS9knWV+Farv6Sq4uvZNX/ltBd22J+86S4wh4dyxMAquL+Cpf2KxgrQVnsmk/k6LKkaU0rcpcZ/Y1m7okyCfZPtC6qZ+6Yar3dJdgpDfiZK1pg1LjA7PNOwvBXdW2tAoNntnEtoKR1XZbPgp20Li5/R44VIe+00WAaKUkhUShsARYzz2Xv+F6Og5JdHsT96QLDr8E0kVadx2jNyIoXQaIp7dxnTzSYVS35QhW8+kpq2E6Nzd+WuLeRGXo8li+9MSCZyhfgIwdU6yqNX8mUN3OwN2dNBYFcRmq5gSLQWSxtljHxKbjBnf+6SF7EtfHsVkBFuKZFrVhk1Wju1Dx06BD3QAmWvZVYvFBdPevaa893x/f4iZvMKhoc8l5mTaAAvXm+CXTUB7tlUCX/wiQ7WAqjXXyWwo/o9lVeu0R5OHB9UiQqgot1cuQFZzvVDDQ5ADvExGXGeFdIXH0x3blGlKRjqQmHFjorSk1y/Mk82+BKi1igRyilKq1+y73fvKvgffLYdwq/ZqKEQPXbqRaLWwyr2Lw1FpRWzddw74Cr0mAKew8ihEyCNmm2zw/4uUZUn1v42WkiK65lGtsG6Vv9PYu2fk9fASGF4EJI9yhTz6ytHsdBXAdA6Zb2tNWzAMHCWzS9CJgW0Gz6r+ViqpfOxhYCdlOtBIJAgrk7KskAehTShaz6eCk8gD/oVDH17sf3Ljfyn0WieS0dyXbxCoSmhd04S4WpAtkZiCTYgBuI2amJjkYpdMJK8BBZwa1ClP9nsp80m7ayK3x1dCteRtktl/bzSdy7PZJYT6ZPC5rBjqjc6GsTlYW/ocRz4Zwpu6vaCw768dgOt4rHvcWiIp0uDbe2xcla+FF2maO4ZSHw93T70u7ziHoQR wiFsbT7H 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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 cc04e501b1c5..7888600b6a79 100644 --- a/mm/vmalloc.c +++ b/mm/vmalloc.c @@ -3095,7 +3095,7 @@ 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; @@ -4938,28 +4938,29 @@ 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) @@ -4987,6 +4988,10 @@ 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]; @@ -5003,6 +5008,11 @@ 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); @@ -5037,7 +5047,9 @@ 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); @@ -5047,19 +5059,14 @@ 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); --