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[34.123.190.156]) by smtp.gmail.com with ESMTPSA id k8-20020a926f08000000b00348880831fdsm3701371ilc.58.2023.08.30.04.04.06 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 30 Aug 2023 04:04:07 -0700 (PDT) From: "Joel Fernandes (Google)" To: linux-kernel@vger.kernel.org, Andrew Morton , Uladzislau Rezki , Christoph Hellwig , Lorenzo Stoakes Cc: "Joel Fernandes (Google)" , Zhen Lei , "Paul E . McKenney" , rcu@vger.kernel.org, Zqiang , linux-mm@kvack.org Subject: [PATCH 1/2] mm/vmalloc: Add a safer version of find_vm_area() for debug Date: Wed, 30 Aug 2023 11:03:59 +0000 Message-ID: <20230830110402.386898-1-joel@joelfernandes.org> X-Mailer: git-send-email 2.42.0.rc2.253.gd59a3bf2b4-goog MIME-Version: 1.0 X-Rspamd-Queue-Id: 92D7F40006 X-Rspam-User: X-Rspamd-Server: rspam04 X-Stat-Signature: pkhjpcsgzmgrjfqhe36cgec9ys7htfcj X-HE-Tag: 1693393448-555832 X-HE-Meta: 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 I3UZzEiS 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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: It is unsafe to dump vmalloc area information when trying to do so from some contexts. Add a safer trylock version of the same function to do a best-effort VMA finding and use it from vmalloc_dump_obj(). Reported-by: Zhen Lei Cc: Paul E. McKenney Cc: rcu@vger.kernel.org Cc: Zqiang Signed-off-by: Joel Fernandes (Google) Reviewed-by: Matthew Wilcox (Oracle) --- mm/vmalloc.c | 35 ++++++++++++++++++++++++++++++++++- 1 file changed, 34 insertions(+), 1 deletion(-) diff --git a/mm/vmalloc.c b/mm/vmalloc.c index 93cf99aba335..dae347e446e6 100644 --- a/mm/vmalloc.c +++ b/mm/vmalloc.c @@ -1865,6 +1865,18 @@ struct vmap_area *find_vmap_area(unsigned long addr) return va; } +static struct vmap_area *find_vmap_area_trylock(unsigned long addr) +{ + struct vmap_area *va; + + if (!spin_trylock(&vmap_area_lock)) + return NULL; + va = __find_vmap_area(addr, &vmap_area_root); + spin_unlock(&vmap_area_lock); + + return va; +} + static struct vmap_area *find_unlink_vmap_area(unsigned long addr) { struct vmap_area *va; @@ -2671,6 +2683,27 @@ struct vm_struct *find_vm_area(const void *addr) return va->vm; } +/** + * try_to_find_vm_area - find a continuous kernel virtual area + * @addr: base address + * + * This function is the same as find_vm_area() except that it is + * safe to call if vmap_area_lock is already held and returns NULL + * if it is. See comments in find_vmap_area() for other details. + * + * Return: the area descriptor on success or %NULL on failure. + */ +static struct vm_struct *try_to_find_vm_area(const void *addr) +{ + struct vmap_area *va; + + va = find_vmap_area_trylock((unsigned long)addr); + if (!va) + return NULL; + + return va->vm; +} + /** * remove_vm_area - find and remove a continuous kernel virtual area * @addr: base address @@ -4277,7 +4310,7 @@ bool vmalloc_dump_obj(void *object) struct vm_struct *vm; void *objp = (void *)PAGE_ALIGN((unsigned long)object); - vm = find_vm_area(objp); + vm = try_to_find_vm_area(objp); if (!vm) return false; pr_cont(" %u-page vmalloc region starting at %#lx allocated at %pS\n", From patchwork Wed Aug 30 11:04:00 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Joel Fernandes X-Patchwork-Id: 13370178 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by smtp.lore.kernel.org (Postfix) with ESMTP id 67C62C83F01 for ; 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[34.123.190.156]) by smtp.gmail.com with ESMTPSA id k8-20020a926f08000000b00348880831fdsm3701371ilc.58.2023.08.30.04.04.08 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 30 Aug 2023 04:04:08 -0700 (PDT) From: "Joel Fernandes (Google)" To: linux-kernel@vger.kernel.org, Andrew Morton Cc: Zqiang , Zhen Lei , "Paul E . McKenney" , rcu@vger.kernel.org, Joel Fernandes , linux-mm@kvack.org Subject: [PATCH 2/2] rcu: Dump vmalloc memory info safely Date: Wed, 30 Aug 2023 11:04:00 +0000 Message-ID: <20230830110402.386898-2-joel@joelfernandes.org> X-Mailer: git-send-email 2.42.0.rc2.253.gd59a3bf2b4-goog In-Reply-To: <20230830110402.386898-1-joel@joelfernandes.org> References: <20230830110402.386898-1-joel@joelfernandes.org> MIME-Version: 1.0 X-Rspamd-Server: rspam09 X-Rspamd-Queue-Id: BE41618002F X-Stat-Signature: h4j541kqbcnnfoam9a9xhy8dtuqg4q68 X-Rspam-User: X-HE-Tag: 1693393449-898914 X-HE-Meta: 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 rBYEkRmE 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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: From: Zqiang Currently, for double invoke call_rcu(), will dump rcu_head objects memory info, if the objects is not allocated from the slab allocator, the vmalloc_dump_obj() will be invoke and the vmap_area_lock spinlock need to be held, since the call_rcu() can be invoked in interrupt context, therefore, there is a possibility of spinlock deadlock scenarios. And in Preempt-RT kernel, the rcutorture test also trigger the following lockdep warning: BUG: sleeping function called from invalid context at kernel/locking/spinlock_rt.c:48 in_atomic(): 1, irqs_disabled(): 1, non_block: 0, pid: 1, name: swapper/0 preempt_count: 1, expected: 0 RCU nest depth: 1, expected: 1 3 locks held by swapper/0/1: #0: ffffffffb534ee80 (fullstop_mutex){+.+.}-{4:4}, at: torture_init_begin+0x24/0xa0 #1: ffffffffb5307940 (rcu_read_lock){....}-{1:3}, at: rcu_torture_init+0x1ec7/0x2370 #2: ffffffffb536af40 (vmap_area_lock){+.+.}-{3:3}, at: find_vmap_area+0x1f/0x70 irq event stamp: 565512 hardirqs last enabled at (565511): [] __call_rcu_common+0x218/0x940 hardirqs last disabled at (565512): [] rcu_torture_init+0x20b2/0x2370 softirqs last enabled at (399112): [] __local_bh_enable_ip+0x126/0x170 softirqs last disabled at (399106): [] inet_register_protosw+0x9/0x1d0 Preemption disabled at: [] rcu_torture_init+0x1f13/0x2370 CPU: 0 PID: 1 Comm: swapper/0 Tainted: G W 6.5.0-rc4-rt2-yocto-preempt-rt+ #15 Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS rel-1.16.2-0-gea1b7a073390-prebuilt.qemu.org 04/01/2014 Call Trace: dump_stack_lvl+0x68/0xb0 dump_stack+0x14/0x20 __might_resched+0x1aa/0x280 ? __pfx_rcu_torture_err_cb+0x10/0x10 rt_spin_lock+0x53/0x130 ? find_vmap_area+0x1f/0x70 find_vmap_area+0x1f/0x70 vmalloc_dump_obj+0x20/0x60 mem_dump_obj+0x22/0x90 __call_rcu_common+0x5bf/0x940 ? debug_smp_processor_id+0x1b/0x30 call_rcu_hurry+0x14/0x20 rcu_torture_init+0x1f82/0x2370 ? __pfx_rcu_torture_leak_cb+0x10/0x10 ? __pfx_rcu_torture_leak_cb+0x10/0x10 ? __pfx_rcu_torture_init+0x10/0x10 do_one_initcall+0x6c/0x300 ? debug_smp_processor_id+0x1b/0x30 kernel_init_freeable+0x2b9/0x540 ? __pfx_kernel_init+0x10/0x10 kernel_init+0x1f/0x150 ret_from_fork+0x40/0x50 ? __pfx_kernel_init+0x10/0x10 ret_from_fork_asm+0x1b/0x30 The previous patch fixes this by using the deadlock-safe best-effort version of find_vm_area. However, in case of failure print the fact that the pointer was a vmalloc pointer so that we print at least something. Reported-by: Zhen Lei Cc: Paul E. McKenney Cc: rcu@vger.kernel.org Signed-off-by: Zqiang Signed-off-by: Joel Fernandes (Google) Reviewed-by: Matthew Wilcox (Oracle) --- mm/util.c | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-) diff --git a/mm/util.c b/mm/util.c index dd12b9531ac4..406634f26918 100644 --- a/mm/util.c +++ b/mm/util.c @@ -1071,7 +1071,9 @@ void mem_dump_obj(void *object) if (vmalloc_dump_obj(object)) return; - if (virt_addr_valid(object)) + if (is_vmalloc_addr(object)) + type = "vmalloc memory"; + else if (virt_addr_valid(object)) type = "non-slab/vmalloc memory"; else if (object == NULL) type = "NULL pointer";