From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (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 2889C189533; Tue, 3 Sep 2024 16:11:20 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1725379881; cv=none; b=MBttoIUu99Oon8hQ8VcsweN0LbKBrU/wQFkIAR6VoK2LoEwv2SA0c1uMbfpBR4dkybzwrSczBAULx44AxKUTtzfFEQMG1zB1UE8fq/CmfbH1t1xP9I0IhcWE/r307jRauppRGWiJTjYFAyd2FLmYOJ4uf84XCboI8jjij7LEHTs= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1725379881; c=relaxed/simple; bh=THL7/x1mxCQjeHgf9Z1afIiTqKiqdomoJs/oxr9ZHSk=; h=Mime-Version:Content-Type:Date:Message-Id:Cc:Subject:From:To: References:In-Reply-To; b=HnDWauDze0HIkSAIcMuYfPLe+U9klr8v1WI29C/vvpEqP6lqc5PSJd4V+AfcF4tLRCfffRnfUQGevKzAcfAZf0fDAhYIMEoMpOuIN+Q5RSsTKYFSC2o4/RWwGLfy8gc2rMaVNLRWyX7L9ejPAxL9G2U8D7s9sE/4Pa2xPItDnR8= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=sRQkYDgV; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="sRQkYDgV" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 166DDC4CEC4; Tue, 3 Sep 2024 16:11:20 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1725379880; bh=THL7/x1mxCQjeHgf9Z1afIiTqKiqdomoJs/oxr9ZHSk=; h=Date:Cc:Subject:From:To:References:In-Reply-To:From; b=sRQkYDgVPjZRMwh03glgbKlEIEb0fCPvVmEx1ARP8MG91ewgcqJBPr17D9i9gMSlu 5w7iuezwKG0WMef/9Vka5VFd/MzpypFFVLC3oFsE3WDOa6bv4zn1sD4d2pwNVUMeXo gIKNn2uPcPeGzK8V3yo01hZBKEJdoD70pyN6v4Jx4+IVTpV/KGBO6cr72TfIZ7NsI4 h4XU942uP5Sly+9QvCnYuEq6y4qprGpBS/mKtqP4DToU9JchT3Wez+eGPQc1qlnVVM iajs0d6nHdsvjxPp67n5OAVSHz21GHg0jZCoZCGU1Sy7rXVlZtPkKTiM4EZqnILUMW plBnJjBXcx0Ow== Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: Mime-Version: 1.0 Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset=UTF-8 Date: Tue, 03 Sep 2024 19:11:17 +0300 Message-Id: Cc: , , , , , , , , , , , , , , , , , , , Subject: Re: [PATCH v12 3/3] ACPI: APEI: handle synchronous exceptions in task work From: "Jarkko Sakkinen" To: "Shuai Xue" , , , , , , , , , , , , X-Mailer: aerc 0.18.2 References: <20221027042445.60108-1-xueshuai@linux.alibaba.com> <20240902030034.67152-4-xueshuai@linux.alibaba.com> In-Reply-To: <20240902030034.67152-4-xueshuai@linux.alibaba.com> On Mon Sep 2, 2024 at 6:00 AM EEST, 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 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=3D1 > vm.memory_failure_early_kill =3D 1 > > # STEP2: inject an UCE error and consume it to trigger a synchronous er= ror > #einj_mem_uc single > 0: single vaddr =3D 0xffffb0d75400 paddr =3D 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: s/patch set/patch/ > > # STEP1: enable early kill mode > #sysctl -w vm.memory_failure_early_kill=3D1 > vm.memory_failure_early_kill =3D 1 > > # STEP2: inject an UCE error and consume it to trigger a synchronous er= ror > #einj_mem_uc single > 0: single vaddr =3D 0xffffb0d75400 paddr =3D 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 re= lated page > #einj_mem_uc single > 0: single vaddr =3D 0xffffb0d75400 paddr =3D 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 pr= ocess. > > 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, > } > =20 > /* > - * 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 =3D container_of(twork, struct task_work, twork)= ; > + unsigned long pfn =3D twcb->pfn; > + int ret; > =20 > - estatus_node =3D 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 =3D memory_failure(twcb->pfn, twcb->flags); > + gen_pool_free(ghes_estatus_pool, (unsigned long)twcb, sizeof(*twcb)); > =20 > - estatus =3D GHES_ESTATUS_FROM_NODE(estatus_node); > - node_len =3D GHES_ESTATUS_NODE_LEN(cper_estatus_len(estatus)); > - gen_pool_free(ghes_estatus_pool, (unsigned long)estatus_node, node_len)= ; > + if (!ret || ret =3D=3D -EHWPOISON || ret =3D=3D -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); > } > =20 > static bool ghes_do_memory_failure(u64 physical_addr, int flags) > { > unsigned long pfn; > + struct task_work *twcb; > =20 > 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; > } > =20 > + if (flags =3D=3D MF_ACTION_REQUIRED && current->mm) { > + twcb =3D (void *)gen_pool_alloc(ghes_estatus_pool, sizeof(*twcb)); > + if (!twcb) > + return false; > + > + twcb->pfn =3D pfn; > + twcb->flags =3D 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); > =20 > -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; > } > =20 > static void __ghes_print_estatus(const char *pfx, > @@ -1113,9 +1137,7 @@ static void ghes_proc_in_irq(struct irq_work *irq_w= ork) > 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; > =20 > llnode =3D llist_del_all(&ghes_estatus_llist); > /* > @@ -1130,25 +1152,16 @@ static void ghes_proc_in_irq(struct irq_work *irq= _work) > estatus =3D GHES_ESTATUS_FROM_NODE(estatus_node); > len =3D cper_estatus_len(estatus); > node_len =3D GHES_ESTATUS_NODE_LEN(len); > - task_work_pending =3D ghes_do_proc(estatus_node->ghes, estatus); > + > + ghes_do_proc(estatus_node->ghes, estatus); > + > if (!ghes_estatus_cached(estatus)) { > generic =3D 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 =3D ghes_kick_task_work; > - estatus_node->task_work_cpu =3D smp_processor_id(); > - ret =3D task_work_add(current, &estatus_node->task_work, > - TWA_RESUME); > - if (ret) > - estatus_node->task_work.func =3D 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); > =20 > llnode =3D next; > } > @@ -1209,7 +1222,6 @@ static int ghes_in_nmi_queue_one_entry(struct ghes = *ghes, > =20 > estatus_node->ghes =3D ghes; > estatus_node->generic =3D ghes->generic; > - estatus_node->task_work.func =3D NULL; > estatus =3D GHES_ESTATUS_FROM_NODE(estatus_node); > =20 > 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; > }; > =20 > 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_s= truct *work) > } > } > =20 > -/* > - * Process memory_failure work queued on the specified CPU. > - * Used to avoid return-to-userspace racing with the memory_failure work= queue. > - */ > -void memory_failure_queue_kick(int cpu) > -{ > - struct memory_failure_cpu *mf_cpu; > - > - mf_cpu =3D &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; BR, Jarkko