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Message-ID: <34d5d58b-7fc2-4f93-9d3b-3051ec5e6a23@linux.alibaba.com> Date: Fri, 6 Sep 2024 09:53:30 +0800 From: Shuai Xue <xueshuai@...ux.alibaba.com> To: Jarkko Sakkinen <jarkko@...nel.org>, bp@...en8.de, rafael@...nel.org, wangkefeng.wang@...wei.com, tanxiaofei@...wei.com, mawupeng1@...wei.com, tony.luck@...el.com, linmiaohe@...wei.com, naoya.horiguchi@....com, james.morse@....com, tongtiangen@...wei.com, gregkh@...uxfoundation.org, will@...nel.org Cc: linux-acpi@...r.kernel.org, linux-mm@...ck.org, linux-kernel@...r.kernel.org, akpm@...ux-foundation.org, linux-edac@...r.kernel.org, x86@...nel.org, justin.he@....com, ardb@...nel.org, ying.huang@...el.com, ashish.kalra@....com, baolin.wang@...ux.alibaba.com, tglx@...utronix.de, mingo@...hat.com, dave.hansen@...ux.intel.com, lenb@...nel.org, hpa@...or.com, robert.moore@...el.com, lvying6@...wei.com, xiexiuqi@...wei.com, zhuo.song@...ux.alibaba.com Subject: Re: [PATCH v12 1/3] ACPI: APEI: send SIGBUS to current task if synchronous memory error not recovered 在 2024/9/5 22:17, Jarkko Sakkinen 写道: > On Thu Sep 5, 2024 at 5:14 PM EEST, Jarkko Sakkinen wrote: >> On Thu Sep 5, 2024 at 6:04 AM EEST, Shuai Xue wrote: >>> >>> >>> 在 2024/9/4 00:09, Jarkko Sakkinen 写道: >>>> On Mon Sep 2, 2024 at 6:00 AM EEST, Shuai Xue wrote: >>>>> Synchronous error was detected as a result of user-space process accessing >>>>> a 2-bit uncorrected error. The CPU will take a synchronous error exception >>>>> such as Synchronous External Abort (SEA) on Arm64. The kernel will queue a >>>>> memory_failure() work which poisons the related page, unmaps the page, and >>>>> then sends a SIGBUS to the process, so that a system wide panic can be >>>>> avoided. >>>>> >>>>> However, no memory_failure() work will be queued unless all bellow >>>>> preconditions check passed: >>>>> >>>>> - `if (!(mem_err->validation_bits & CPER_MEM_VALID_PA))` in ghes_handle_memory_failure() >>>>> - `if (flags == -1)` in ghes_handle_memory_failure() >>>>> - `if (!IS_ENABLED(CONFIG_ACPI_APEI_MEMORY_FAILURE))` in ghes_do_memory_failure() >>>>> - `if (!pfn_valid(pfn) && !arch_is_platform_page(physical_addr)) ` in ghes_do_memory_failure() >>>>> >>>>> In such case, the user-space process will trigger SEA again. This loop >>>>> can potentially exceed the platform firmware threshold or even trigger a >>>>> kernel hard lockup, leading to a system reboot. >>>>> >>>>> Fix it by performing a force kill if no memory_failure() work is queued >>>>> for synchronous errors. >>>>> >>>>> Suggested-by: Xiaofei Tan <tanxiaofei@...wei.com> >>>>> Signed-off-by: Shuai Xue <xueshuai@...ux.alibaba.com> >>>>> >>>>> --- >>>>> drivers/acpi/apei/ghes.c | 10 ++++++++++ >>>>> 1 file changed, 10 insertions(+) >>>>> >>>>> diff --git a/drivers/acpi/apei/ghes.c b/drivers/acpi/apei/ghes.c >>>>> index 623cc0cb4a65..b0b20ee533d9 100644 >>>>> --- a/drivers/acpi/apei/ghes.c >>>>> +++ b/drivers/acpi/apei/ghes.c >>>>> @@ -801,6 +801,16 @@ static bool ghes_do_proc(struct ghes *ghes, >>>>> } >>>>> } >>>>> >>>>> + /* >>>>> + * If no memory failure work is queued for abnormal synchronous >>>>> + * errors, do a force kill. >>>>> + */ >>>>> + if (sync && !queued) { >>>>> + pr_err("Sending SIGBUS to %s:%d due to hardware memory corruption\n", >>>>> + current->comm, task_pid_nr(current)); >>>> >>>> Hmm... doest this need "hardware" or would "memory corruption" be >>>> enough? >>>> >>>> Also, does this need to say that it is sending SIGBUS when the signal >>>> itself tells that already? >>>> >>>> I.e. could "%s:%d has memory corruption" be enough information? >>> >>> Hi, Jarkko, >>> >>> Thank you for your suggestion. Maybe it could. >>> >>> There are some similar error info which use "hardware memory error", e.g. >> >> By tweaking my original suggestion just a bit: >> >> "%s:%d: hardware memory corruption" >> >> Can't get clearer than that, right? > > And obvious reason that shorter and more consistent klog message is easy > to spot and grep. It is simply less convoluted. > > If you want also SIGBUS, I'd just put it as "%s:%d: hardware memory > corruption (SIGBUS)" > > BR, Jarkko Hi, Jarkko, I will change it to "%s:%d: hardware memory corruption (SIGBUS)". Thank you for valuable suggestion. Best Regards, Shuai
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