From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from out30-99.freemail.mail.aliyun.com (out30-99.freemail.mail.aliyun.com [115.124.30.99]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 3350C4500E; Thu, 19 Dec 2024 01:44:06 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=115.124.30.99 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1734572651; cv=none; b=XV8vUDmO7HRa2FaEE1xIMKONah7K/zzmxFWVCVh6Qbn0UjmKbJAxxBmnjzWZDOtBOy8yiKZ8QUUV6/3JDMJYXjLyRHodtZ9/YlDbhDuzhSeLsePXtVLDv0ypCNuNroQKCPIZV6+zMBGbifS0uQJuMtdky7n1hjgDXoXRPfTu56Y= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1734572651; c=relaxed/simple; bh=1hpsXkLcVMhZv7MpBmGJZ03DjaR5kIqPOIFze6W+RMs=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=gzOpasUuYjxSE0drso9STkqNI7AvbFGPPCvaFf0Z0SjvLgCYZ49IszZVfioJlyqepC8JvFVCWir1t14FUMbiTs6t/42DdofdZPnSkyhe2Vn3+xwtTcKFdsrTyiIxOlr7Xc6v/NfQamJgpLTKw/l2/Pm/99Z3y7uJ0XUIt1wzarM= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.alibaba.com; spf=pass smtp.mailfrom=linux.alibaba.com; dkim=pass (1024-bit key) header.d=linux.alibaba.com header.i=@linux.alibaba.com header.b=aCRC4JkE; arc=none smtp.client-ip=115.124.30.99 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.alibaba.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=linux.alibaba.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linux.alibaba.com header.i=@linux.alibaba.com header.b="aCRC4JkE" DKIM-Signature:v=1; a=rsa-sha256; c=relaxed/relaxed; d=linux.alibaba.com; s=default; t=1734572645; h=Message-ID:Date:MIME-Version:Subject:To:From:Content-Type; bh=LsMRam799y1BeBH01GzJpZAfi+0+C0lyLFmFJu0j0GQ=; b=aCRC4JkEajWHQwHxXoWPVfw1/MSoLSTfQEGaYaiFNigymQx1tIA1B+pfw1cUM9t9UZPd+VvapQ55GcRFnYH9JF0LMi0G2U9j3lqn/IMyo+q8yzM4FiGpjhfmA5AsANyWdSGeAsVA8uUFg9yWIz/h8DgSqo5jovpLqER/qalq738= Received: from 30.246.161.240(mailfrom:xueshuai@linux.alibaba.com fp:SMTPD_---0WLoNiHx_1734572640 cluster:ay36) by smtp.aliyun-inc.com; Thu, 19 Dec 2024 09:44:02 +0800 Message-ID: Date: Thu, 19 Dec 2024 09:43:59 +0800 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v17 3/3] ACPI: APEI: handle synchronous exceptions in task work To: Yazen Ghannam Cc: mark.rutland@arm.com, catalin.marinas@arm.com, mingo@redhat.com, robin.murphy@arm.com, Jonathan.Cameron@huawei.com, bp@alien8.de, rafael@kernel.org, linux-arm-kernel@lists.infradead.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, 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, justin.he@arm.com, ardb@kernel.org, ying.huang@intel.com, ashish.kalra@amd.com, baolin.wang@linux.alibaba.com, tglx@linutronix.de, 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 References: <20241202030527.20586-1-xueshuai@linux.alibaba.com> <20241202030527.20586-4-xueshuai@linux.alibaba.com> <20241218165331.GF1155365@yaz-khff2.amd.com> From: Shuai Xue In-Reply-To: <20241218165331.GF1155365@yaz-khff2.amd.com> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit 在 2024/12/19 00:53, Yazen Ghannam 写道: > On Mon, Dec 02, 2024 at 11:05:27AM +0800, Shuai Xue wrote: >> 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 exception 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() to exectute in a 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, memory_failure(): >> >> - 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: >> >> #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 the fact. >> >> After this patch: >> >> # 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 a BUS_MCEERR_AR >> error as we expected. >> >> Issue 2: a synchronous error infinite loop >> >> If a user-space process, e.g. devmem, accesses a poisoned page for which >> the HWPoison flag is set, kill_accessing_process() is called to send >> SIGBUS to current processs with error info. Because the memory_failure() >> is executed in the kworker context, it will just do nothing but return >> EFAULT. So, devmem will access the posioned page and trigger an >> exception again, resulting in a synchronous error infinite loop. Such >> exception 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 above two issues, queue memory_failure() as a task_work so that >> it runs in the context of the process that is actually consuming the >> poisoned data. >> >> Signed-off-by: Shuai Xue >> Tested-by: Ma Wupeng >> Reviewed-by: Kefeng Wang >> Reviewed-by: Xiaofei Tan >> Reviewed-by: Baolin Wang >> Reviewed-by: Jarkko Sakkinen >> Reviewed-by: Jonathan Cameron >> --- >> drivers/acpi/apei/ghes.c | 77 +++++++++++++++++++++++----------------- >> include/acpi/ghes.h | 3 -- >> include/linux/mm.h | 1 - >> mm/memory-failure.c | 13 ------- >> 4 files changed, 44 insertions(+), 50 deletions(-) >> >> diff --git a/drivers/acpi/apei/ghes.c b/drivers/acpi/apei/ghes.c >> index 106486bdfefc..70f2ee3ad1a8 100644 >> --- a/drivers/acpi/apei/ghes.c >> +++ b/drivers/acpi/apei/ghes.c >> @@ -467,28 +467,41 @@ static void ghes_clear_estatus(struct ghes *ghes, >> } >> >> /* > > The "kernel-doc" format needs an opening "/**". > >> - * 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 ghes_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 ghes_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 ghes_task_work *twcb = container_of(twork, struct ghes_task_work, twork); >> + 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("%#llx: Sending SIGBUS to %s:%d due to hardware memory corruption\n", >> + twcb->pfn, current->comm, task_pid_nr(current)); > > This is basically the same as the message in kill_proc(). Was there any > consideration to have a shared function? Maybe this could be a future > patch. Yep, I'd like to refactor in a future. > >> + force_sig(SIGBUS); >> } >> >> static bool ghes_do_memory_failure(u64 physical_addr, int flags) >> { >> unsigned long pfn; >> + struct ghes_task_work *twcb; > > Minor nit: A common preference I've seen is to order variable > declarations from longest->shortest line length. Will fix it if this patch set still misses the next merge window. > > But overall, looks okay to me. > > Reviewed-by: Yazen Ghannam > > Thanks, > Yazen Thanks for valuable comments. Best Regards, Shuai