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Message-Id: <D3ZA3WBGABKG.1SE9YOAX30B2Y@kernel.org> Date: Fri, 06 Sep 2024 17:42:20 +0300 From: "Jarkko Sakkinen" <jarkko@...nel.org> To: "Shuai Xue" <xueshuai@...ux.alibaba.com>, <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 On Fri Sep 6, 2024 at 4:53 AM EEST, Shuai Xue wrote: > > > 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. Yeah, no intention nitpick, it has a practical value when debugging issues :-) > > Best Regards, > Shuai BR, Jarkko
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