@@ -1311,13 +1311,6 @@ static void kill_me_maybe(struct callback_head *cb)
return;
}
- /*
- * -EHWPOISON from memory_failure() means that it already sent SIGBUS
- * to the current process with the proper error info,
- * -EOPNOTSUPP means hwpoison_filter() filtered the error event,
- *
- * In both cases, no further processing is required.
- */
if (ret == -EHWPOISON || ret == -EOPNOTSUPP)
return;
@@ -452,28 +452,41 @@ 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);
+ kfree(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("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;
@@ -486,6 +499,18 @@ static bool ghes_do_memory_failure(u64 physical_addr, int flags)
return false;
}
+ if (flags == MF_ACTION_REQUIRED && current->mm) {
+ twcb = kmalloc(sizeof(*twcb), GFP_ATOMIC);
+ 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;
}
@@ -654,7 +679,7 @@ static void ghes_defer_non_standard_event(struct acpi_hest_generic_data *gdata,
schedule_work(&entry->work);
}
-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;
@@ -698,7 +723,12 @@ static bool ghes_do_proc(struct ghes *ghes,
}
}
- return queued;
+ /*
+ * If no memory failure work is queued for abnormal synchronous
+ * errors, do a force kill.
+ */
+ if (sync && !queued)
+ force_sig(SIGBUS);
}
static void __ghes_print_estatus(const char *pfx,
@@ -1000,9 +1030,7 @@ 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);
/*
@@ -1017,25 +1045,16 @@ 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;
}
@@ -1096,7 +1115,6 @@ 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)) {
@@ -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 {
@@ -2073,7 +2073,9 @@ static DEFINE_MUTEX(mf_mutex);
*
* Return: 0 for successfully handled the memory error,
* -EOPNOTSUPP for hwpoison_filter() filtered the error event,
- * < 0(except -EOPNOTSUPP) on failure.
+ * -EHWPOISON for already sent SIGBUS to the current process with
+ * the proper error info,
+ * other negative error code on failure.
*/
int memory_failure(unsigned long pfn, int flags)
{
@@ -2355,19 +2357,6 @@ 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 synchronous interrupt, e.g. when an error is detected by a background scrubber, or signaled by synchronous exception, e.g. when an uncorrected error is consumed. Both synchronous and asynchronous error are queued and handled by a dedicated kthread in workqueue. commit 7f17b4a121d0 ("ACPI: APEI: Kick the memory_failure() queue for synchronous errors") keep track of whether memory_failure() work was queued, and make task_work pending to flush out the workqueue so that the work for synchronous error is processed before returning to user-space. The trick ensures that the corrupted page is unmapped and poisoned. And after returning to user-space, the task starts at current instruction which triggering a page fault in which kernel will send SIGBUS to current process due to VM_FAULT_HWPOISON. However, the memory failure recovery for hwpoison-aware mechanisms does not work as expected. For example, hwpoison-aware user-space processes like QEMU register their customized SIGBUS handler and enable early kill mode by seting PF_MCE_EARLY at initialization. Then the kernel will directy notify the process by sending a SIGBUS signal in memory failure with wrong si_code: the actual user-space process accessing the corrupt memory location, but its memory failure work is handled in a kthread context, so it will send SIGBUS with BUS_MCEERR_AO si_code to the actual user-space process instead of BUS_MCEERR_AR in kill_proc(). To this end, separate synchronous and asynchronous error handling into different paths like X86 platform does: - valid synchronous errors: queue a task_work to synchronously send SIGBUS before ret_to_user. - valid asynchronous errors: queue a work into workqueue to asynchronously handle memory failure. - abnormal branches such as invalid PA, unexpected severity, no memory failure config support, invalid GUID section, OOM, etc. Then for valid synchronous errors, the current context in memory failure is exactly belongs to the task consuming poison data and it will send SIBBUS with proper si_code. Fixes: 7f17b4a121d0 ("ACPI: APEI: Kick the memory_failure() queue for synchronous errors") Signed-off-by: Shuai Xue <xueshuai@linux.alibaba.com> Tested-by: Ma Wupeng <mawupeng1@huawei.com> Reviewed-by: Kefeng Wang <wangkefeng.wang@huawei.com> --- arch/x86/kernel/cpu/mce/core.c | 7 --- drivers/acpi/apei/ghes.c | 82 +++++++++++++++++++++------------- include/acpi/ghes.h | 3 -- mm/memory-failure.c | 17 ++----- 4 files changed, 53 insertions(+), 56 deletions(-)