| Message ID | 20241014084240.18614-4-xueshuai@linux.alibaba.com (mailing list archive) |
|---|---|
| State | Superseded, archived |
| Headers | show |
| Series | None | expand |
On Mon, 14 Oct 2024 16:42:40 +0800 Shuai Xue <xueshuai@linux.alibaba.com> 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 exception > 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. memory_failure() to execute in kworker context. (spell check in general) > > 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: context, memory_failure(): //No subject of the following two bullets otherwise. > > - 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 devmem accesses a poisoned page for which the HWPoison flag is 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 context > EFAULT. So, devmem will access the posioned page and trigger an > excepction again, resulting in a synchronous error infinite loop. Such exception > 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 <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> One other trivial comment inline. Whilst this also looks fine to me, there are others who (hopefully) understand these paths better than me. With that said. Reviewed-by: Jonathan Cameron <Jonathan.Cameron@huawei.com> > --- > 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(). > */ > -static void ghes_kick_task_work(struct callback_head *head) > +struct ghes_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 ghes_task_work *twcb = container_of(twork, struct ghes_task_work, twork); > + unsigned long pfn = twcb->pfn; This local variable is not used consistently. I'd just drop it in favor of always accessing via twcb->pfn > + int ret; > > - 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("%#lx: Sending SIGBUS to %s:%d due to hardware memory corruption\n", > + pfn, current->comm, task_pid_nr(current)); > + force_sig(SIGBUS); > }
在 2024/10/17 17:56, Jonathan Cameron 写道: > On Mon, 14 Oct 2024 16:42:40 +0800 > Shuai Xue <xueshuai@linux.alibaba.com> 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 > > exception > >> 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. > memory_failure() to execute in kworker context. > > (spell check in general) Sorry for typos. Will fix it in next version. Thanks. >> >> 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: > context, memory_failure(): > //No subject of the following two bullets otherwise. I see, will fix it. >> >> - 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 > > devmem accesses a poisoned page for which the HWPoison flag is 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 > > context > >> EFAULT. So, devmem will access the posioned page and trigger an >> excepction again, resulting in a synchronous error infinite loop. Such > > exception I see, will fix it. > >> 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 <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> > One other trivial comment inline. > > Whilst this also looks fine to me, there are others who (hopefully) > understand these paths better than me. With that said. > > Reviewed-by: Jonathan Cameron <Jonathan.Cameron@huawei.com> Thank you for valuable comments. > >> --- >> 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(). >> */ >> -static void ghes_kick_task_work(struct callback_head *head) >> +struct ghes_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 ghes_task_work *twcb = container_of(twork, struct ghes_task_work, twork); >> + unsigned long pfn = twcb->pfn; > > This local variable is not used consistently. I'd just > drop it in favor of always accessing via twcb->pfn Agreed, will remove local pfn. Best Regards, Shuai
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 <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 | 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
On Tue Oct 22, 2024 at 4:11 AM EEST, Shuai Xue wrote: > 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 <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 | 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? Sorry I've been busy switching to a new job. I read this now through and both commit messages and the code changes look sane to me so I guess I don't have any problem with that: Reviewed-by: Jarkko Sakkinen <jarkko@kernel.org> > > Best Regard, > Shuai BR, Jarkko
在 2024/10/25 22:40, Jarkko Sakkinen 写道: > On Tue Oct 22, 2024 at 4:11 AM EEST, Shuai Xue wrote: >> 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 <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 | 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? > > Sorry I've been busy switching to a new job. > > I read this now through and both commit messages and the code changes > look sane to me so I guess I don't have any problem with that: > > Reviewed-by: Jarkko Sakkinen <jarkko@kernel.org> > >> >> Best Regard, >> Shuai > > BR, Jarkko Thank you. BR. Shuai
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(). */ -static void ghes_kick_task_work(struct callback_head *head) +struct ghes_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 ghes_task_work *twcb = container_of(twork, struct ghes_task_work, twork); + unsigned long pfn = twcb->pfn; + int ret; - 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("%#lx: Sending SIGBUS to %s:%d due to hardware memory corruption\n", + pfn, current->comm, task_pid_nr(current)); + force_sig(SIGBUS); } static bool ghes_do_memory_failure(u64 physical_addr, int flags) { unsigned long pfn; + struct ghes_task_work *twcb; 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; } + 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; } @@ -745,7 +771,7 @@ int cxl_cper_kfifo_get(struct cxl_cper_work_data *wd) } EXPORT_SYMBOL_NS_GPL(cxl_cper_kfifo_get, 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; @@ -810,8 +836,6 @@ static bool ghes_do_proc(struct ghes *ghes, current->comm, task_pid_nr(current)); force_sig(SIGBUS); } - - return queued; } static void __ghes_print_estatus(const char *pfx, @@ -1113,9 +1137,7 @@ 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); /* @@ -1130,25 +1152,16 @@ 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; } @@ -1209,7 +1222,6 @@ 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/include/linux/mm.h b/include/linux/mm.h index ecf63d2b0582..a1286053dd29 100644 --- a/include/linux/mm.h +++ b/include/linux/mm.h @@ -3923,7 +3923,6 @@ 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 1c5098f32d48..c86e10e5c839 100644 --- a/mm/memory-failure.c +++ b/mm/memory-failure.c @@ -2496,19 +2496,6 @@ 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;
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 <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 | 78 +++++++++++++++++++++++----------------- include/acpi/ghes.h | 3 -- include/linux/mm.h | 1 - mm/memory-failure.c | 13 ------- 4 files changed, 45 insertions(+), 50 deletions(-)