From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from out30-101.freemail.mail.aliyun.com (out30-101.freemail.mail.aliyun.com [115.124.30.101]) (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 45DA7323D; Tue, 22 Oct 2024 01:11:45 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=115.124.30.101 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1729559510; cv=none; b=YLWl7NsmvU3kaxdEcMoKHGkugwyXMG57DeTVmHapbPLrP4+nUpkMaIMwE0jvuoO6CSHElvOnTVU0YSGoQ8/0esQYSJFmNw2T0/E9LE1DyVPK1oPmvUa7TKCFNU8UqTx7LjQ0Pl1AmBfBkKHWv4EMkKI95Yvr9uGDi7MC3xR+AXA= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1729559510; c=relaxed/simple; bh=dyaqIfWu5jk9N2YZ1V36RrpXXNxAHtG8g2KDweEv5es=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=d1uUWDFZBsn394QeLStBJFWfVRJNhzts9VZ0MsoNOlkZrP/ZZlbkiiDqrwotVgmqRKm+iGR5zTxTT1h7BpgjRy/Voiq/LZ4fckmL9GCEk06m//o6ff+C26QqxVqP8GnXDM+Iz1eAepCb0d/rvKLYSu4s8utBGqedYRNr7YsXqfg= 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=bC3gFGbM; arc=none smtp.client-ip=115.124.30.101 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="bC3gFGbM" DKIM-Signature:v=1; a=rsa-sha256; c=relaxed/relaxed; d=linux.alibaba.com; s=default; t=1729559503; h=Message-ID:Date:MIME-Version:Subject:To:From:Content-Type; bh=Su0JCUUNtQowa7ZUF9W/JcsQXW+zdoUv4LGM6ZfbIrs=; b=bC3gFGbMrgwot0glVG484iR6MOclDdfrgbMLWEbjCCWYCe5XNus7ounxXcWYetdISXL4ROkPn5M9SuSvS6Ucsdry1OHSOKs/OAjfnLtf7V4zFanOmaPnwV1posy9CX1D9/EIUxmk0OZaD3mvEE8muqWwW4CcGheHsa9hRkmvbKo= Received: from 30.246.160.103(mailfrom:xueshuai@linux.alibaba.com fp:SMTPD_---0WHfusch_1729559498 cluster:ay36) by smtp.aliyun-inc.com; Tue, 22 Oct 2024 09:11:40 +0800 Message-ID: <05a8d26b-b023-426f-879c-7d33be4a6406@linux.alibaba.com> Date: Tue, 22 Oct 2024 09:11:37 +0800 Precedence: bulk X-Mailing-List: linux-acpi@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v14 3/3] ACPI: APEI: handle synchronous exceptions in task work To: 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, 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, 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: <20221027042445.60108-1-xueshuai@linux.alibaba.com> <20241014084240.18614-4-xueshuai@linux.alibaba.com> From: Shuai Xue In-Reply-To: <20241014084240.18614-4-xueshuai@linux.alibaba.com> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit Hi, Jarkko, 在 2024/10/14 16:42, Shuai Xue 写道: > 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: > > #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. > > 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 BUS_MCEERR_AR > error as we expected. > > Issue 2: a synchronous error infinite loop > > 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 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 > --- > 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 f2ee28c44d7a..95e9520eb803 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 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(). > */ Do you have any futer comments about this patch? Any comments are welcomed. If not, are you happy to explictly give the reveiwed-by tag? Best Regard, Shuai