| Message ID | 20240204080144.7977-4-xueshuai@linux.alibaba.com |
|---|---|
| State | New |
| Headers | show |
| Series | None | expand |
On 2024/2/4 16:01, Shuai Xue wrote: > Hardware errors could be signaled by asynchronous interrupt, e.g. when an > error is detected by a background scrubber, or signaled by synchronous > exception, e.g. when a CPU tries to access a poisoned cache line. 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 should > terminate the current process which accessing the 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, the memory failure recovery is incorrectly sending a SIGBUS > with wrong error code BUS_MCEERR_AO for synchronous errors in early kill > mode, even MF_ACTION_REQUIRED is set. The main problem is that > synchronous errors are queued as a memory_failure() work, and are > executed within a kernel thread context, not the user-space process that > encountered the corrupted memory on ARM64 platform. As a result, when > kill_proc() is called to terminate the process, it sends the incorrect > SIGBUS error code because the context in which it operates is not the > one where the error was triggered. > > To this end, queue memory_failure() as a task_work so that it runs in > the context of the process that is actually consuming the poisoned data, > and it will send SIBBUS with si_code BUS_MCEERR_AR. > > Signed-off-by: Shuai Xue <xueshuai@linux.alibaba.com> > Tested-by: Ma Wupeng <mawupeng1@huawei.com> > Reviewed-by: Kefeng Wang <wangkefeng.wang@huawei.com> > Reviewed-by: Xiaofei Tan <tanxiaofei@huawei.com> > Reviewed-by: Baolin Wang <baolin.wang@linux.alibaba.com> > --- > drivers/acpi/apei/ghes.c | 77 +++++++++++++++++++++++----------------- > include/acpi/ghes.h | 3 -- > mm/memory-failure.c | 13 ------- > 3 files changed, 44 insertions(+), 49 deletions(-) > > diff --git a/drivers/acpi/apei/ghes.c b/drivers/acpi/apei/ghes.c > index 0892550732d4..e5086d795bee 100644 > --- a/drivers/acpi/apei/ghes.c > +++ b/drivers/acpi/apei/ghes.c > @@ -465,28 +465,41 @@ 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 sync_task_work - for synchronous RAS event > + * > + * @twork: callback_head for task work > + * @pfn: page frame number of corrupted page > + * @flags: fine tune action taken > + * > + * Structure to pass task work to be handled before > + * ret_to_user via task_work_add(). > */ > -static void ghes_kick_task_work(struct callback_head *head) > +struct sync_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; > + int ret; > + struct sync_task_work *twcb = > + container_of(twork, struct sync_task_work, twork); > > - 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("Sending SIGBUS to current task due to memory error not recovered"); > + force_sig(SIGBUS); > } > > static bool ghes_do_memory_failure(u64 physical_addr, int flags) > { > unsigned long pfn; > + struct sync_task_work *twcb; > > if (!IS_ENABLED(CONFIG_ACPI_APEI_MEMORY_FAILURE)) > return false; > @@ -499,6 +512,18 @@ static bool ghes_do_memory_failure(u64 physical_addr, int flags) > return false; > } > > + if (flags == MF_ACTION_REQUIRED && current->mm) { > + twcb = (void *)gen_pool_alloc(ghes_estatus_pool, sizeof(*twcb)); > + if (!twcb) > + return false; > + > + twcb->pfn = pfn; > + twcb->flags = 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; > } > @@ -746,7 +771,7 @@ int cxl_cper_unregister_callback(cxl_cper_callback callback) > } > EXPORT_SYMBOL_NS_GPL(cxl_cper_unregister_callback, CXL); > > -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; > @@ -814,8 +839,6 @@ static bool ghes_do_proc(struct ghes *ghes, > pr_err("Sending SIGBUS to current task due to memory error not recovered"); > force_sig(SIGBUS); > } > - > - return queued; > } > > static void __ghes_print_estatus(const char *pfx, > @@ -1117,9 +1140,7 @@ static void ghes_proc_in_irq(struct irq_work *irq_work) > 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; > > llnode = llist_del_all(&ghes_estatus_llist); > /* > @@ -1134,25 +1155,16 @@ static void ghes_proc_in_irq(struct irq_work *irq_work) > estatus = GHES_ESTATUS_FROM_NODE(estatus_node); > len = cper_estatus_len(estatus); > node_len = GHES_ESTATUS_NODE_LEN(len); > - task_work_pending = ghes_do_proc(estatus_node->ghes, estatus); > + > + ghes_do_proc(estatus_node->ghes, estatus); > + > if (!ghes_estatus_cached(estatus)) { > generic = 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 = ghes_kick_task_work; > - estatus_node->task_work_cpu = smp_processor_id(); > - ret = task_work_add(current, &estatus_node->task_work, > - TWA_RESUME); > - if (ret) > - estatus_node->task_work.func = 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); > > llnode = next; > } > @@ -1213,7 +1225,6 @@ static int ghes_in_nmi_queue_one_entry(struct ghes *ghes, > > estatus_node->ghes = ghes; > estatus_node->generic = ghes->generic; > - estatus_node->task_work.func = NULL; > estatus = GHES_ESTATUS_FROM_NODE(estatus_node); > > 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; > }; > > struct ghes_estatus_cache { > diff --git a/mm/memory-failure.c b/mm/memory-failure.c > index d33729c48eff..4ad663bdc1d5 100644 > --- a/mm/memory-failure.c > +++ b/mm/memory-failure.c > @@ -2462,19 +2462,6 @@ static void memory_failure_work_func(struct work_struct *work) > } > } > > -/* > - * Process memory_failure work queued on the specified CPU. > - * Used to avoid return-to-userspace racing with the memory_failure workqueue. > - */ > -void memory_failure_queue_kick(int cpu) > -{ > - struct memory_failure_cpu *mf_cpu; > - > - mf_cpu = &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; Hi, Tony, Borislav, and James: Any comments to this patch? Looking forward to hear from you. Best Regards, Shuai
On Sun, Feb 04, 2024 at 04:01:44PM +0800, Shuai Xue wrote: > Hardware errors could be signaled by asynchronous interrupt, e.g. when an > error is detected by a background scrubber, or signaled by synchronous > exception, e.g. when a CPU tries to access a poisoned cache line. 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 should > terminate the current process which accessing the poisoned page. This is "which has accessed poison data" > done by sending a SIGBUS signal with an error code BUS_MCEERR_AR, > indicating an action-required machine check error on read. > > However, the memory failure recovery is incorrectly sending a SIGBUS > with wrong error code BUS_MCEERR_AO for synchronous errors in early kill > mode, even MF_ACTION_REQUIRED is set. The main problem is that "even if" > synchronous errors are queued as a memory_failure() work, and are > executed within a kernel thread context, not the user-space process that > encountered the corrupted memory on ARM64 platform. As a result, when > kill_proc() is called to terminate the process, it sends the incorrect > SIGBUS error code because the context in which it operates is not the > one where the error was triggered. > > To this end, queue memory_failure() as a task_work so that it runs in > the context of the process that is actually consuming the poisoned data, > and it will send SIBBUS with si_code BUS_MCEERR_AR. SIGBUS > > Signed-off-by: Shuai Xue <xueshuai@linux.alibaba.com> > Tested-by: Ma Wupeng <mawupeng1@huawei.com> > Reviewed-by: Kefeng Wang <wangkefeng.wang@huawei.com> > Reviewed-by: Xiaofei Tan <tanxiaofei@huawei.com> > Reviewed-by: Baolin Wang <baolin.wang@linux.alibaba.com> > --- > drivers/acpi/apei/ghes.c | 77 +++++++++++++++++++++++----------------- > include/acpi/ghes.h | 3 -- > mm/memory-failure.c | 13 ------- > 3 files changed, 44 insertions(+), 49 deletions(-) > > diff --git a/drivers/acpi/apei/ghes.c b/drivers/acpi/apei/ghes.c > index 0892550732d4..e5086d795bee 100644 > --- a/drivers/acpi/apei/ghes.c > +++ b/drivers/acpi/apei/ghes.c > @@ -465,28 +465,41 @@ 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 sync_task_work - for synchronous RAS event What's so special about it being a "sync_"? task_work is just fine and something else could use it too. > + * > + * @twork: callback_head for task work > + * @pfn: page frame number of corrupted page > + * @flags: fine tune action taken s/fine tune action taken/work control flags/ > + * > + * Structure to pass task work to be handled before > + * ret_to_user via task_work_add(). What is "ret_to_user"? If this is an ARM thing, then make sure you explain stuff properly and detailed. This driver is used by multiple architectures. > */ > -static void ghes_kick_task_work(struct callback_head *head) > +struct sync_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; > + int ret; > + struct sync_task_work *twcb = > + container_of(twork, struct sync_task_work, twork); Ugly linebreak - no need for it. > - 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("Sending SIGBUS to current task due to memory error not recovered"); > + force_sig(SIGBUS); > } > > static bool ghes_do_memory_failure(u64 physical_addr, int flags) > { > unsigned long pfn; > + struct sync_task_work *twcb; > > if (!IS_ENABLED(CONFIG_ACPI_APEI_MEMORY_FAILURE)) > return false; > @@ -499,6 +512,18 @@ static bool ghes_do_memory_failure(u64 physical_addr, int flags) > return false; > } > > + if (flags == MF_ACTION_REQUIRED && current->mm) { > + twcb = (void *)gen_pool_alloc(ghes_estatus_pool, sizeof(*twcb)); > + if (!twcb) > + return false; > + > + twcb->pfn = pfn; > + twcb->flags = 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; > } > @@ -746,7 +771,7 @@ int cxl_cper_unregister_callback(cxl_cper_callback callback) > } > EXPORT_SYMBOL_NS_GPL(cxl_cper_unregister_callback, CXL); > > -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; > @@ -814,8 +839,6 @@ static bool ghes_do_proc(struct ghes *ghes, > pr_err("Sending SIGBUS to current task due to memory error not recovered"); > force_sig(SIGBUS); > } > - > - return queued; > } > > static void __ghes_print_estatus(const char *pfx, > @@ -1117,9 +1140,7 @@ static void ghes_proc_in_irq(struct irq_work *irq_work) > 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; > > llnode = llist_del_all(&ghes_estatus_llist); > /* > @@ -1134,25 +1155,16 @@ static void ghes_proc_in_irq(struct irq_work *irq_work) > estatus = GHES_ESTATUS_FROM_NODE(estatus_node); > len = cper_estatus_len(estatus); > node_len = GHES_ESTATUS_NODE_LEN(len); > - task_work_pending = ghes_do_proc(estatus_node->ghes, estatus); > + > + ghes_do_proc(estatus_node->ghes, estatus); > + > if (!ghes_estatus_cached(estatus)) { > generic = 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 = ghes_kick_task_work; > - estatus_node->task_work_cpu = smp_processor_id(); > - ret = task_work_add(current, &estatus_node->task_work, > - TWA_RESUME); > - if (ret) > - estatus_node->task_work.func = NULL; > - } > - > - if (!estatus_node->task_work.func) > - gen_pool_free(ghes_estatus_pool, > - (unsigned long)estatus_node, node_len); I have no clue why this is being removed. Why doesn't a synchronous exception on ARM call into ghes_proc_in_irq()? That SDEI thing certainly does. Well looka here: 7f17b4a121d0 ("ACPI: APEI: Kick the memory_failure() queue for synchronous errors") that thing does exactly what you're trying to "fix". So why doesn't that work for you?
On 2024/3/8 18:18, Borislav Petkov wrote: > On Sun, Feb 04, 2024 at 04:01:44PM +0800, Shuai Xue wrote: >> Hardware errors could be signaled by asynchronous interrupt, e.g. when an >> error is detected by a background scrubber, or signaled by synchronous >> exception, e.g. when a CPU tries to access a poisoned cache line. 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 should >> terminate the current process which accessing the poisoned page. This is > > "which has accessed poison data" Thank you. Will fix the grammer. > >> done by sending a SIGBUS signal with an error code BUS_MCEERR_AR, >> indicating an action-required machine check error on read. >> >> However, the memory failure recovery is incorrectly sending a SIGBUS >> with wrong error code BUS_MCEERR_AO for synchronous errors in early kill >> mode, even MF_ACTION_REQUIRED is set. The main problem is that > > "even if" Thank you. Will fix the grammer. > >> synchronous errors are queued as a memory_failure() work, and are >> executed within a kernel thread context, not the user-space process that >> encountered the corrupted memory on ARM64 platform. As a result, when >> kill_proc() is called to terminate the process, it sends the incorrect >> SIGBUS error code because the context in which it operates is not the >> one where the error was triggered. >> >> To this end, queue memory_failure() as a task_work so that it runs in >> the context of the process that is actually consuming the poisoned data, >> and it will send SIBBUS with si_code BUS_MCEERR_AR. > > SIGBUS Sorry, will fix the typo. > >> >> Signed-off-by: Shuai Xue <xueshuai@linux.alibaba.com> >> Tested-by: Ma Wupeng <mawupeng1@huawei.com> >> Reviewed-by: Kefeng Wang <wangkefeng.wang@huawei.com> >> Reviewed-by: Xiaofei Tan <tanxiaofei@huawei.com> >> Reviewed-by: Baolin Wang <baolin.wang@linux.alibaba.com> >> --- >> drivers/acpi/apei/ghes.c | 77 +++++++++++++++++++++++----------------- >> include/acpi/ghes.h | 3 -- >> mm/memory-failure.c | 13 ------- >> 3 files changed, 44 insertions(+), 49 deletions(-) >> >> diff --git a/drivers/acpi/apei/ghes.c b/drivers/acpi/apei/ghes.c >> index 0892550732d4..e5086d795bee 100644 >> --- a/drivers/acpi/apei/ghes.c >> +++ b/drivers/acpi/apei/ghes.c >> @@ -465,28 +465,41 @@ 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 sync_task_work - for synchronous RAS event > > What's so special about it being a "sync_"? > > task_work is just fine and something else could use it too. You are right, the `sync_task_work` is only use for synchronous RAS event right, but it could be also use for other purpose in the future. The purpose can be specified through flags. I will remove the `sync_` prefix. > >> + * >> + * @twork: callback_head for task work >> + * @pfn: page frame number of corrupted page >> + * @flags: fine tune action taken > > s/fine tune action taken/work control flags/ > Will fix it. >> + * >> + * Structure to pass task work to be handled before >> + * ret_to_user via task_work_add(). > > What is "ret_to_user"? > > If this is an ARM thing, then make sure you explain stuff properly and > detailed. This driver is used by multiple architectures. It is not ARM specific thing. I mean it is used by task_work before returning to user-space. + * 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 sync_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; >> + int ret; >> + struct sync_task_work *twcb = >> + container_of(twork, struct sync_task_work, twork); > > Ugly linebreak - no need for it. Will fix it. > >> - 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("Sending SIGBUS to current task due to memory error not recovered"); >> + force_sig(SIGBUS); >> } >> >> static bool ghes_do_memory_failure(u64 physical_addr, int flags) >> { >> unsigned long pfn; >> + struct sync_task_work *twcb; >> >> if (!IS_ENABLED(CONFIG_ACPI_APEI_MEMORY_FAILURE)) >> return false; >> @@ -499,6 +512,18 @@ static bool ghes_do_memory_failure(u64 physical_addr, int flags) >> return false; >> } >> >> + if (flags == MF_ACTION_REQUIRED && current->mm) { >> + twcb = (void *)gen_pool_alloc(ghes_estatus_pool, sizeof(*twcb)); >> + if (!twcb) >> + return false; >> + >> + twcb->pfn = pfn; >> + twcb->flags = 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; >> } >> @@ -746,7 +771,7 @@ int cxl_cper_unregister_callback(cxl_cper_callback callback) >> } >> EXPORT_SYMBOL_NS_GPL(cxl_cper_unregister_callback, CXL); >> >> -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; >> @@ -814,8 +839,6 @@ static bool ghes_do_proc(struct ghes *ghes, >> pr_err("Sending SIGBUS to current task due to memory error not recovered"); >> force_sig(SIGBUS); >> } >> - >> - return queued; >> } >> >> static void __ghes_print_estatus(const char *pfx, >> @@ -1117,9 +1140,7 @@ static void ghes_proc_in_irq(struct irq_work *irq_work) >> 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; >> >> llnode = llist_del_all(&ghes_estatus_llist); >> /* >> @@ -1134,25 +1155,16 @@ static void ghes_proc_in_irq(struct irq_work *irq_work) >> estatus = GHES_ESTATUS_FROM_NODE(estatus_node); >> len = cper_estatus_len(estatus); >> node_len = GHES_ESTATUS_NODE_LEN(len); >> - task_work_pending = ghes_do_proc(estatus_node->ghes, estatus); >> + >> + ghes_do_proc(estatus_node->ghes, estatus); >> + >> if (!ghes_estatus_cached(estatus)) { >> generic = 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 = ghes_kick_task_work; >> - estatus_node->task_work_cpu = smp_processor_id(); >> - ret = task_work_add(current, &estatus_node->task_work, >> - TWA_RESUME); >> - if (ret) >> - estatus_node->task_work.func = NULL; >> - } >> - >> - if (!estatus_node->task_work.func) >> - gen_pool_free(ghes_estatus_pool, >> - (unsigned long)estatus_node, node_len); > > I have no clue why this is being removed. Before this patch, a memory_failure() work is queued into workqueue for both the asynchronous interrupt and synchronous exception. So memory_failure() will be executed asynchronously. For NMIlike notifications, commit 7f17b4a121d0 ("ACPI: APEI: Kick the memory_failure() queue for synchronous errors") keeps track of whether memory_failure() work was queued, and makes task_work pending to flush out the queue. It ensures any queued work has been done before we return to the context that triggered the notification. In this patch: - a memory_failure() work is queued into workqueue for asynchronous interrupt - a memory_failure() task_work is queued by task_work_add for synchronous exception The memory_failure() task_work will be handled before returning to user space, so we does not need to queue a flushing task_work any anymore. > > Why doesn't a synchronous exception on ARM call into ghes_proc_in_irq()? /* * SEA can interrupt SError, mask it and describe this as an NMI so * that APEI defers the handling. */ local_daif_restore(DAIF_ERRCTX); nmi_enter(); => ghes_notify_sea => ghes_in_nmi_spool_from_list => ghes_in_nmi_queue_one_entry // also called in __ghes_sdei_callback => irq_work_queue(&ghes_proc_irq_work); nmi_exit(); > > That SDEI thing certainly does. > > Well looka here: > > 7f17b4a121d0 ("ACPI: APEI: Kick the memory_failure() queue for synchronous errors") > > that thing does exactly what you're trying to "fix". So why doesn't that > work for you? > Commit a70297d22132 (ACPI: APEI: set memory failure flags as MF_ACTION_REQUIRED on synchronous events) set MF_ACTION_REQUIRED for synchronous events. /* * Send all the processes who have the page mapped a signal. * ``action optional'' if they are not immediately affected by the error * ``action required'' if error happened in current execution context */ static int kill_proc(struct to_kill *tk, unsigned long pfn, int flags) { ... if ((flags & MF_ACTION_REQUIRED) && (t == current)) ret = force_sig_mceerr(BUS_MCEERR_AR, (void __user *)tk->addr, addr_lsb); else ret = send_sig_mceerr(BUS_MCEERR_AO, (void __user *)tk->addr, addr_lsb, t); ... } Because the memory_failure() running in a kthread context, the false branch in kill_proc() will send SIGBUS with BUS_MCEERR_AO. But we except it as a BUS_MCEERR_AR. Thank you for valuable comments :) Best Regards, Shuai
diff --git a/drivers/acpi/apei/ghes.c b/drivers/acpi/apei/ghes.c index 0892550732d4..e5086d795bee 100644 --- a/drivers/acpi/apei/ghes.c +++ b/drivers/acpi/apei/ghes.c @@ -465,28 +465,41 @@ 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 sync_task_work - for synchronous RAS event + * + * @twork: callback_head for task work + * @pfn: page frame number of corrupted page + * @flags: fine tune action taken + * + * Structure to pass task work to be handled before + * ret_to_user via task_work_add(). */ -static void ghes_kick_task_work(struct callback_head *head) +struct sync_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; + int ret; + struct sync_task_work *twcb = + container_of(twork, struct sync_task_work, twork); - 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("Sending SIGBUS to current task due to memory error not recovered"); + force_sig(SIGBUS); } static bool ghes_do_memory_failure(u64 physical_addr, int flags) { unsigned long pfn; + struct sync_task_work *twcb; if (!IS_ENABLED(CONFIG_ACPI_APEI_MEMORY_FAILURE)) return false; @@ -499,6 +512,18 @@ static bool ghes_do_memory_failure(u64 physical_addr, int flags) return false; } + if (flags == MF_ACTION_REQUIRED && current->mm) { + twcb = (void *)gen_pool_alloc(ghes_estatus_pool, sizeof(*twcb)); + if (!twcb) + return false; + + twcb->pfn = pfn; + twcb->flags = 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; } @@ -746,7 +771,7 @@ int cxl_cper_unregister_callback(cxl_cper_callback callback) } EXPORT_SYMBOL_NS_GPL(cxl_cper_unregister_callback, CXL); -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; @@ -814,8 +839,6 @@ static bool ghes_do_proc(struct ghes *ghes, pr_err("Sending SIGBUS to current task due to memory error not recovered"); force_sig(SIGBUS); } - - return queued; } static void __ghes_print_estatus(const char *pfx, @@ -1117,9 +1140,7 @@ static void ghes_proc_in_irq(struct irq_work *irq_work) 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; llnode = llist_del_all(&ghes_estatus_llist); /* @@ -1134,25 +1155,16 @@ static void ghes_proc_in_irq(struct irq_work *irq_work) estatus = GHES_ESTATUS_FROM_NODE(estatus_node); len = cper_estatus_len(estatus); node_len = GHES_ESTATUS_NODE_LEN(len); - task_work_pending = ghes_do_proc(estatus_node->ghes, estatus); + + ghes_do_proc(estatus_node->ghes, estatus); + if (!ghes_estatus_cached(estatus)) { generic = 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 = ghes_kick_task_work; - estatus_node->task_work_cpu = smp_processor_id(); - ret = task_work_add(current, &estatus_node->task_work, - TWA_RESUME); - if (ret) - estatus_node->task_work.func = 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); llnode = next; } @@ -1213,7 +1225,6 @@ static int ghes_in_nmi_queue_one_entry(struct ghes *ghes, estatus_node->ghes = ghes; estatus_node->generic = ghes->generic; - estatus_node->task_work.func = NULL; estatus = GHES_ESTATUS_FROM_NODE(estatus_node); 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; }; struct ghes_estatus_cache { diff --git a/mm/memory-failure.c b/mm/memory-failure.c index d33729c48eff..4ad663bdc1d5 100644 --- a/mm/memory-failure.c +++ b/mm/memory-failure.c @@ -2462,19 +2462,6 @@ static void memory_failure_work_func(struct work_struct *work) } } -/* - * Process memory_failure work queued on the specified CPU. - * Used to avoid return-to-userspace racing with the memory_failure workqueue. - */ -void memory_failure_queue_kick(int cpu) -{ - struct memory_failure_cpu *mf_cpu; - - mf_cpu = &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;
Hardware errors could be signaled by asynchronous interrupt, e.g. when an error is detected by a background scrubber, or signaled by synchronous exception, e.g. when a CPU tries to access a poisoned cache line. 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 should terminate the current process which accessing the 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, the memory failure recovery is incorrectly sending a SIGBUS with wrong error code BUS_MCEERR_AO for synchronous errors in early kill mode, even MF_ACTION_REQUIRED is set. The main problem is that synchronous errors are queued as a memory_failure() work, and are executed within a kernel thread context, not the user-space process that encountered the corrupted memory on ARM64 platform. As a result, when kill_proc() is called to terminate the process, it sends the incorrect SIGBUS error code because the context in which it operates is not the one where the error was triggered. To this end, queue memory_failure() as a task_work so that it runs in the context of the process that is actually consuming the poisoned data, and it will send SIBBUS with si_code BUS_MCEERR_AR. Signed-off-by: Shuai Xue <xueshuai@linux.alibaba.com> Tested-by: Ma Wupeng <mawupeng1@huawei.com> Reviewed-by: Kefeng Wang <wangkefeng.wang@huawei.com> Reviewed-by: Xiaofei Tan <tanxiaofei@huawei.com> Reviewed-by: Baolin Wang <baolin.wang@linux.alibaba.com> --- drivers/acpi/apei/ghes.c | 77 +++++++++++++++++++++++----------------- include/acpi/ghes.h | 3 -- mm/memory-failure.c | 13 ------- 3 files changed, 44 insertions(+), 49 deletions(-)