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bh=BifK0Clid7OESoXNef0gZrr4lzWKcwPmPBCzPd9yXiE=; b=jFR/gZtHg4MVwOAd+ebQdI4Pxuebg0QaZl4hxMIl+FiLxVZlUrohJWXTJpgSjzB9rvdVGw9Nh0vH8obu59eO4NZr+jWuzXtW7wARRj3VlfHK/Awqk3wWry9T7l62anG6AkAeTwIangkufVVLhe2j+laj7qLSgoSM+PIjQWxBIdk= Received: from localhost.localdomain(mailfrom:xueshuai@linux.alibaba.com fp:SMTPD_---0WE1odpl_1725246049) by smtp.aliyun-inc.com; Mon, 02 Sep 2024 11:00:50 +0800 From: Shuai Xue To: bp@alien8.de, rafael@kernel.org, wangkefeng.wang@huawei.com, tanxiaofei@huawei.com, mawupeng1@huawei.com, tony.luck@intel.com, linmiaohe@huawei.com, naoya.horiguchi@nec.com, james.morse@arm.com, tongtiangen@huawei.com, gregkh@linuxfoundation.org, will@kernel.org, jarkko@kernel.org Cc: linux-acpi@vger.kernel.org, linux-mm@kvack.org, linux-kernel@vger.kernel.org, akpm@linux-foundation.org, linux-edac@vger.kernel.org, x86@kernel.org, xueshuai@linux.alibaba.com, justin.he@arm.com, ardb@kernel.org, ying.huang@intel.com, ashish.kalra@amd.com, baolin.wang@linux.alibaba.com, tglx@linutronix.de, mingo@redhat.com, dave.hansen@linux.intel.com, lenb@kernel.org, hpa@zytor.com, robert.moore@intel.com, lvying6@huawei.com, xiexiuqi@huawei.com, zhuo.song@linux.alibaba.com Subject: [PATCH v12 3/3] ACPI: APEI: handle synchronous exceptions in task work Date: Mon, 2 Sep 2024 11:00:34 +0800 Message-ID: <20240902030034.67152-4-xueshuai@linux.alibaba.com> X-Mailer: git-send-email 2.44.0 In-Reply-To: <20221027042445.60108-1-xueshuai@linux.alibaba.com> References: <20221027042445.60108-1-xueshuai@linux.alibaba.com> MIME-Version: 1.0 X-Rspamd-Queue-Id: 9232912000C X-Rspam-User: X-Rspamd-Server: rspam05 X-Stat-Signature: 9iuz86u8npmpaxx7r4pisri96wyn9tnn X-HE-Tag: 1725246055-491156 X-HE-Meta: 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 qeRWvNhb w0oGkzHBdMIVsPv8EQG86SslHhQ+RgyoYnxW95cdgiI8dwgB6puXVCR5KvM541Y9ZxegYfA1flf5hi5aax//It7Icsg21dscrXrArD2gKHg2kNOcoTwVu2T6P+hAkz1ktrhccxEyA0v3eASZhB8ZyA9d5vVPQV92oOB8o32AbXayzoP/fwjQb72AMZbtaLgbjkJwFDeNUQYGcAUR+NBkqmQ+q21R9pLmEG+MA8r58kHZH0l0y9sHkTvft0QS6Jjt0x87B 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: The memory uncorrected error could be signaled by asynchronous interrupt (specifically, SPI in arm64 platform), e.g. when an error is detected by a background scrubber, or signaled by synchronous exception (specifically, data abort excepction in arm64 platform), e.g. when a CPU tries to access a poisoned cache line. Currently, both synchronous and asynchronous error use memory_failure_queue() to schedule memory_failure() exectute in kworker context. As a result, when a user-space process is accessing a poisoned data, a data abort is taken and the memory_failure() is executed in the kworker context: - will send wrong si_code by SIGBUS signal in early_kill mode, and - can not kill the user-space in some cases resulting a synchronous error infinite loop Issue 1: send wrong si_code in early_kill mode Since commit a70297d22132 ("ACPI: APEI: set memory failure flags as MF_ACTION_REQUIRED on synchronous events")', the flag MF_ACTION_REQUIRED could be used to determine whether a synchronous exception occurs on ARM64 platform. When a synchronous exception is detected, the kernel is expected to terminate the current process which has accessed poisoned page. This is done by sending a SIGBUS signal with an error code BUS_MCEERR_AR, indicating an action-required machine check error on read. However, when kill_proc() is called to terminate the processes who have the poisoned page mapped, it sends the incorrect SIGBUS error code BUS_MCEERR_AO because the context in which it operates is not the one where the error was triggered. To reproduce this problem: # STEP1: enable early kill mode #sysctl -w vm.memory_failure_early_kill=1 vm.memory_failure_early_kill = 1 # STEP2: inject an UCE error and consume it to trigger a synchronous error #einj_mem_uc single 0: single vaddr = 0xffffb0d75400 paddr = 4092d55b400 injecting ... triggering ... signal 7 code 5 addr 0xffffb0d75000 page not present Test passed The si_code (code 5) from einj_mem_uc indicates that it is BUS_MCEERR_AO error and it is not fact. To fix it, queue memory_failure() as a task_work so that it runs in the context of the process that is actually consuming the poisoned data. After this patch set: # STEP1: enable early kill mode #sysctl -w vm.memory_failure_early_kill=1 vm.memory_failure_early_kill = 1 # STEP2: inject an UCE error and consume it to trigger a synchronous error #einj_mem_uc single 0: single vaddr = 0xffffb0d75400 paddr = 4092d55b400 injecting ... triggering ... signal 7 code 4 addr 0xffffb0d75000 page not present Test passed The si_code (code 4) from einj_mem_uc indicates that it is BUS_MCEERR_AR error as we expected. Issue 2: a synchronous error infinite loop due to memory_failure() failed If a user-space process, e.g. devmem, a poisoned page which has been set HWPosion flag, kill_accessing_process() is called to send SIGBUS to the current processs with error info. Because the memory_failure() is executed in the kworker contex, it will just do nothing but return EFAULT. So, devmem will access the posioned page and trigger an excepction again, resulting in a synchronous error infinite loop. Such loop may cause platform firmware to exceed some threshold and reboot when Linux could have recovered from this error. To reproduce this problem: # STEP 1: inject an UCE error, and kernel will set HWPosion flag for related page #einj_mem_uc single 0: single vaddr = 0xffffb0d75400 paddr = 4092d55b400 injecting ... triggering ... signal 7 code 4 addr 0xffffb0d75000 page not present Test passed # STEP 2: access the same page and it will trigger a synchronous error infinite loop devmem 0x4092d55b400 To fix it, if memory_failure() failed, perform a force kill to current process. Signed-off-by: Shuai Xue Tested-by: Ma Wupeng Reviewed-by: Kefeng Wang Reviewed-by: Xiaofei Tan Reviewed-by: Baolin Wang --- drivers/acpi/apei/ghes.c | 78 +++++++++++++++++++++++----------------- include/acpi/ghes.h | 3 -- include/linux/mm.h | 1 - mm/memory-failure.c | 13 ------- 4 files changed, 45 insertions(+), 50 deletions(-) diff --git a/drivers/acpi/apei/ghes.c b/drivers/acpi/apei/ghes.c index b0b20ee533d9..b956e9ed020f 100644 --- a/drivers/acpi/apei/ghes.c +++ b/drivers/acpi/apei/ghes.c @@ -467,28 +467,42 @@ static void ghes_clear_estatus(struct ghes *ghes, } /* - * Called as task_work before returning to user-space. - * Ensure any queued work has been done before we return to the context that - * triggered the notification. + * struct task_work - for synchronous RAS event + * + * @twork: callback_head for task work + * @pfn: page frame number of corrupted page + * @flags: work control flags + * + * Structure to pass task work to be handled before + * returning to user-space via task_work_add(). */ -static void ghes_kick_task_work(struct callback_head *head) +struct task_work { + struct callback_head twork; + u64 pfn; + int flags; +}; + +static void memory_failure_cb(struct callback_head *twork) { - struct acpi_hest_generic_status *estatus; - struct ghes_estatus_node *estatus_node; - u32 node_len; + struct task_work *twcb = container_of(twork, struct task_work, twork); + unsigned long pfn = twcb->pfn; + int ret; - estatus_node = container_of(head, struct ghes_estatus_node, task_work); - if (IS_ENABLED(CONFIG_ACPI_APEI_MEMORY_FAILURE)) - memory_failure_queue_kick(estatus_node->task_work_cpu); + ret = memory_failure(twcb->pfn, twcb->flags); + gen_pool_free(ghes_estatus_pool, (unsigned long)twcb, sizeof(*twcb)); - estatus = GHES_ESTATUS_FROM_NODE(estatus_node); - node_len = GHES_ESTATUS_NODE_LEN(cper_estatus_len(estatus)); - gen_pool_free(ghes_estatus_pool, (unsigned long)estatus_node, node_len); + if (!ret || ret == -EHWPOISON || ret == -EOPNOTSUPP) + return; + + pr_err("%#lx: Sending SIGBUS to %s:%d due to hardware memory corruption\n", + pfn, current->comm, task_pid_nr(current)); + force_sig(SIGBUS); } static bool ghes_do_memory_failure(u64 physical_addr, int flags) { unsigned long pfn; + struct task_work *twcb; if (!IS_ENABLED(CONFIG_ACPI_APEI_MEMORY_FAILURE)) return false; @@ -501,6 +515,18 @@ static bool ghes_do_memory_failure(u64 physical_addr, int flags) return false; } + if (flags == MF_ACTION_REQUIRED && current->mm) { + twcb = (void *)gen_pool_alloc(ghes_estatus_pool, sizeof(*twcb)); + if (!twcb) + return false; + + twcb->pfn = pfn; + twcb->flags = flags; + init_task_work(&twcb->twork, memory_failure_cb); + task_work_add(current, &twcb->twork, TWA_RESUME); + return true; + } + memory_failure_queue(pfn, flags); return true; } @@ -745,7 +771,7 @@ int cxl_cper_kfifo_get(struct cxl_cper_work_data *wd) } EXPORT_SYMBOL_NS_GPL(cxl_cper_kfifo_get, CXL); -static bool ghes_do_proc(struct ghes *ghes, +static void ghes_do_proc(struct ghes *ghes, const struct acpi_hest_generic_status *estatus) { int sev, sec_sev; @@ -810,8 +836,6 @@ static bool ghes_do_proc(struct ghes *ghes, current->comm, task_pid_nr(current)); force_sig(SIGBUS); } - - return queued; } static void __ghes_print_estatus(const char *pfx, @@ -1113,9 +1137,7 @@ static void ghes_proc_in_irq(struct irq_work *irq_work) struct ghes_estatus_node *estatus_node; struct acpi_hest_generic *generic; struct acpi_hest_generic_status *estatus; - bool task_work_pending; u32 len, node_len; - int ret; llnode = llist_del_all(&ghes_estatus_llist); /* @@ -1130,25 +1152,16 @@ static void ghes_proc_in_irq(struct irq_work *irq_work) estatus = GHES_ESTATUS_FROM_NODE(estatus_node); len = cper_estatus_len(estatus); node_len = GHES_ESTATUS_NODE_LEN(len); - task_work_pending = ghes_do_proc(estatus_node->ghes, estatus); + + ghes_do_proc(estatus_node->ghes, estatus); + if (!ghes_estatus_cached(estatus)) { generic = estatus_node->generic; if (ghes_print_estatus(NULL, generic, estatus)) ghes_estatus_cache_add(generic, estatus); } - - if (task_work_pending && current->mm) { - estatus_node->task_work.func = ghes_kick_task_work; - estatus_node->task_work_cpu = smp_processor_id(); - ret = task_work_add(current, &estatus_node->task_work, - TWA_RESUME); - if (ret) - estatus_node->task_work.func = NULL; - } - - if (!estatus_node->task_work.func) - gen_pool_free(ghes_estatus_pool, - (unsigned long)estatus_node, node_len); + gen_pool_free(ghes_estatus_pool, (unsigned long)estatus_node, + node_len); llnode = next; } @@ -1209,7 +1222,6 @@ static int ghes_in_nmi_queue_one_entry(struct ghes *ghes, estatus_node->ghes = ghes; estatus_node->generic = ghes->generic; - estatus_node->task_work.func = NULL; estatus = GHES_ESTATUS_FROM_NODE(estatus_node); if (__ghes_read_estatus(estatus, buf_paddr, fixmap_idx, len)) { diff --git a/include/acpi/ghes.h b/include/acpi/ghes.h index be1dd4c1a917..ebd21b05fe6e 100644 --- a/include/acpi/ghes.h +++ b/include/acpi/ghes.h @@ -35,9 +35,6 @@ struct ghes_estatus_node { struct llist_node llnode; struct acpi_hest_generic *generic; struct ghes *ghes; - - int task_work_cpu; - struct callback_head task_work; }; struct ghes_estatus_cache { diff --git a/include/linux/mm.h b/include/linux/mm.h index 6549d0979b28..f5f1d6a8a07d 100644 --- a/include/linux/mm.h +++ b/include/linux/mm.h @@ -3981,7 +3981,6 @@ enum mf_flags { int mf_dax_kill_procs(struct address_space *mapping, pgoff_t index, unsigned long count, int mf_flags); extern int memory_failure(unsigned long pfn, int flags); -extern void memory_failure_queue_kick(int cpu); extern int unpoison_memory(unsigned long pfn); extern atomic_long_t num_poisoned_pages __read_mostly; extern int soft_offline_page(unsigned long pfn, int flags); diff --git a/mm/memory-failure.c b/mm/memory-failure.c index df26e2ff5e06..e369aae2da1f 100644 --- a/mm/memory-failure.c +++ b/mm/memory-failure.c @@ -2486,19 +2486,6 @@ static void memory_failure_work_func(struct work_struct *work) } } -/* - * Process memory_failure work queued on the specified CPU. - * Used to avoid return-to-userspace racing with the memory_failure workqueue. - */ -void memory_failure_queue_kick(int cpu) -{ - struct memory_failure_cpu *mf_cpu; - - mf_cpu = &per_cpu(memory_failure_cpu, cpu); - cancel_work_sync(&mf_cpu->work); - memory_failure_work_func(&mf_cpu->work); -} - static int __init memory_failure_init(void) { struct memory_failure_cpu *mf_cpu;